ASSOCIAÇÃO BRASILEIRA DE PESQUISAE PÓS-GRADUAÇÃO EM FISIOTERAPIA

ISSN 1413-3555

2015 Sept/Oct; 19(5)

Brazilian Journal of P

hysical Therapy2015 Sept/O

ct; 19(5)

ISSN 1413-3555

2015 Sept/Oct; 19(5)

Editorial329 Editorial

Deborah A. Nawoczenski

Review Article331 Prevention of shoulder injuries in overhead athletes: a science-based approach

Ann M. Cools, Fredrik R. Johansson, Dorien Borms, Annelies Maenhout

340 Aconceptualframeworkforasportskneeinjuryperformanceprofile(SKIPP)andreturntoactivitycriteria(RTAC)David Logerstedt, Amelia Arundale, Andrew Lynch, Lynn Snyder-Mackler

360 CriticalreviewoftheimpactofcorestabilityonupperextremityathleticinjuryandperformanceSheri P. Silfies, David Ebaugh, Marisa Pontillo, Courtney M. Butowicz

369 Measuring sports injuries on the pitch: a guide to use in practiceLuiz C. Hespanhol Junior, Saulo D. Barboza, Willem van Mechelen, Evert Verhagen

381 Improvingperformanceingolf:currentresearchandimplicationsfromaclinicalperspectiveKerrie Evans, Neil Tuttle

Original Articles390 SportsinjuriesprofileofafirstdivisionBraziliansoccerteam:adescriptivecohortstudy

Guilherme F. Reis, Thiago R. T. Santos, Rodrigo C. P. Lasmar, Otaviano Oliveira Júnior, Rômulo F. F. Lopes, Sérgio T. Fonseca

398 Multicenter trial of motion analysis for injury risk prediction: lessons learned from prospective longitudinal large cohort combined biomechanical -epidemiological studiesTimothy E. Hewett, Benjamin Roewer, Kevin Ford, Greg Myer

410 Physical therapists’ role in prevention and management of patellar tendinopathy injuries in youth, collegiate, and middle-aged indoor volleyball athletesKornelia Kulig, Lisa M. Noceti-DeWit, Stephen F. Reischl, Rob F. Landel

421 MaleandfemalerunnersdemonstratedifferentsagittalplanemechanicsasafunctionofstatichamstringflexibilityD. S. Blaise Williams III*, Lee M. Welch

ClinicalCommentary429 Clinicalcommentaryoftheevolutionofthetreatmentforchronicpainfulmid-portionAchillestendinopathy

Håkan Alfredson

Editorial Rules

EDITORSDébora Bevilaqua Grossi – Universidade de São Paulo - Ribeirão Preto, SP, BrazilPaula Rezende Camargo – Universidade Federal de São Carlos - São Carlos, SP, BrazilSérgio Teixeira Fonseca – Universidade Federal de Minas Gerais - Belo Horizonte, MG, BrazilADMINISTRATIVE EDITORAparecida Maria Catai – Universidade Federal de São Carlos - São Carlos, SP, BrazilINTERNATIONAL EDITORDavid J. Magee – University of Alberta - CanadaLIBRARIAN AND GENERAL COORDINATORDormélia Pereira Cazella – FAI/ Universidade Federal de São Carlos - São Carlos, SP, BrazilSPECIALIST EDITORSAna Beatriz de Oliveira - Universidade Federal de São Carlos - São Carlos, SP, BrazilAna Cláudia Mattiello-Sverzut – Universidade de São Paulo - Ribeirão Preto, SP, BrazilAnamaria Siriani de Oliveira – Universidade de São Paulo - Ribeirão Preto, SP, BrazilAnielle Cristhine de Medeiros Takahashi – Universidade Federal de São Carlos - São Carlos, SP, BrazilAudrey Borghi e Silva – Universidade Federal de São Carlos - São Carlos, SP, BrazilChristina Danielli Coelho de Morais Faria - Universidade Federal de Minas Gerais - Belo Horizonte, MG, BrazilElaine Caldeira de Oliveira Guirro – Universidade de São Paulo - Ribeirão Preto, SP, BrazilFrancisco Alburquerque Sendín - Universidad de Salamanca – SpainHelenice Jane Cote Gil Coury – Universidade Federal de São Carlos - São Carlos, SP, BrazilHugo Celso Dutra de Souza - Universidade de São Paulo - Ribeirão Preto, SP, BrazilIsabel Camargo Neves Sacco – Universidade de São Paulo - São Paulo, SP, BrazilJoão Luiz Quagliotti Durigan - Universidade de Brasília – Brasília, DF, BrazilLeani Souza Máximo Pereira – Universidade Federal de Minas Gerais - Belo Horizonte, MG, BrazilLeonardo Oliveira Pena Costa – Universidade Cidade de São Paulo - São Paulo, SP, BrazilLuci Fuscaldi Teixeira-Salmela – Universidade Federal de Minas Gerais - Belo Horizonte, MG, BrazilMarisa Cotta Mancini – Universidade Federal de Minas Gerais - Belo Horizonte, MG, BrazilNivaldo Antonio Parizotto – Universidade Federal de São Carlos - São Carlos, SP, BrazilPatrícia Driusso – Universidade Federal de São Carlos - São Carlos, SP, BrazilPaula Lanna Pereira da Silva – Universidade Federal de Minas Gerais - Belo Horizonte, MG, BrazilPedro Dal Lago – Universidade Federal de Ciências da Saúde de Porto Alegre - Porto Alegre, RS, BrazilRosana Ferreira Sampaio – Universidade Federal de Minas Gerais - Belo Horizonte, MG, BrazilStela Márcia Mattiello – Universidade Federal de São Carlos - São Carlos, SP, Brazil Tatiana de Oliveira Sato – Universidade Federal de São Carlos - São Carlos, SP, BrazilThiago Luiz de Russo – Universidade Federal de São Carlos - São Carlos, SP, BrazilVerônica Franco Parreira – Universidade Federal de Minas Gerais - Belo Horizonte, MG, BrazilBRAZILIAN EDITORIAL BOARDAda Clarice Gastaldi - Universidade de São Paulo - Ribeirão Preto, SPAmélia Pasqual Marques – Universidade de São Paulo - São Paulo, SP Ana Cláudia Muniz Rennó – Universidade Federal de São Paulo - Santos, SP André Luiz Felix Rodacki – Universidade Federal do Paraná- Curitiba, PR Anna Raquel Silveira Gomes – Universidade Federal do Paraná - Matinhos, PR Armèle Dornelas de Andrade – Universidade Federal do Pernambuco - Recife, PE Carlos Marcelo Pastre – Universidade Estadual Paulista - Presidente Prudente, SP Celso Ricardo Fernandes de Carvalho – Universidade de São Paulo - São Paulo, SPCláudia Santos Oliveira – Universidade Nove de Julho - São Paulo, SPCristiane Shinohara Moriguchi – Universidade Federal de São Carlos - São Carlos, SPCristina Maria Nunes Cabral – Universidade Cidade de São Paulo - São Paulo, SPDaniela Cristina Carvalho de Abreu – Universidade de São Paulo - Ribeirão Preto, SP Daniele Sirineu Pereira – Universidade Federal de Alfenas - Alfenas, MGDirceu Costa – Universidade Nove de Julho - São Paulo, SP Ester da Silva – Universidade Federal de São Carlos - São Carlos, SP Fábio de Oliveira Pitta – Universidade Estadual de Londrina - Londrina, PRFábio Viadanna Serrão – Universidade Federal de São Carlos - São Carlos, SPFátima Valéria Rodrigues de Paula – Universidade Federal de Minas Gerais - Belo Horizonte, MG Guilherme Augusto de Freitas Fregonezi – Universidade Federal do Rio Grande do Norte - Natal, RNJefferson Rosa Cardoso – Universidade Estadual de Londrina - Londrina, PR João Carlos Ferrari Corrêa – Universidade Nove de Julho - São Paulo, SP José Angelo Barela – Universidade Cruzeiro do Sul - São Paulo, SP Josimari Melo de Santana – Universidade Federal de Sergipe - Aracajú, SEJuliana de Melo Ocarino – Universidade Federal de Minas Gerais - Belo Horizonte, MGLucíola da Cunha Menezes Costa – Universidade Cidade de São Paulo - São Paulo, SPLuis Vicente Franco de Oliveira – Universidade Nove de Julho - São Paulo, SPLuiz Carlos Marques Vanderlei – Universidade Estadual Paulista - Presidente Prudente, SPLuzia Iara Pfeifer – Universidade de São Paulo - Ribeirão Preto, SPMarco Aurélio Vaz – Universidade Federal do Rio Grande do Sul - Porto Alegre, RSNaomi Kondo Nakagawa – Universidade de São Paulo - São Paulo, SPNelci Adriana Cicuto Ferreira Rocha – Universidade Federal de São Carlos - São Carlos, SPPaulo de Tarso Camillo de Carvalho – Universidade Nove de Julho - São Paulo, SPRaquel Rodrigues Britto – Universidade Federal de Minas Gerais - Belo Horizonte, MG Renata Noce Kirkwood – Universidade Federal de Minas Gerais - Belo Horizonte, MGRicardo Oliveira Guerra – Universidade Federal do Rio Grande do Norte - Natal, RN Richard Eloin Liebano – Universidade Cidade de São Paulo - São Paulo, SPRinaldo Roberto de Jesus Guirro – Universidade de São Paulo - Ribeirão Preto, SP Rosana Mattioli – Universidade Federal de São Carlos - São Carlos, SP Rosimeire Simprini Padula – Universidade Cidade de São Paulo - São Paulo, SPSara Lúcia Silveira de Menezes – Centro Universitário Augusto Motta - Rio de Janeiro, RJ Simone Dal Corso – Universidade Federal do Rio Grande do Sul - Porto Alegre, RSStella Maris Michaelsen – Universidade do Estado de Santa Catarina - Florianópolis, SCTania de Fátima Salvini – Universidade Federal de São Carlos - São Carlos, SPThaís Cristina Chaves – Universidade de São Paulo - Ribeirão Preto, SPINTERNATIONAL EDITORIAL BOARDAlan M. Jette – Boston University School of Public Health - USAChukuka S. Enwemeka – University of Wisconsin - USAEdgar Ramos Vieira – Florida International University - USA Gert-Ake Hansson – Lund University - SWEDENJanet Carr – University of Sydney - AUSTRALIA Kenneth G. Holt – Boston University - USALaDora V. Thompson – University of Minnesota - USALiisa Laakso – Griffith University - AUSTRALIALinda Fetters – University of Southern California - USAPaula M. Ludewig – University of Minnesota - USA Rik Gosselink – Katholieke Universiteit Leuven - BELGIUMRob Herbert – The George Institute for International Health - AUSTRALIASandra Olney – Queen’s University - CANADA

FINANCIAL SUPPORT

Braz J Phys Ther. 2015 Sept-Oct; 19(5):329-432

Printed in acid free paper.No part of this publication can be reproduced or transmitted by any media, be it electronic, mechanical or photocopy, without the express authorization of the editors.

Brazilian Journal of Physical Therapy / Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia. v. 1, n. 1 (1996). – São Carlos: Editora Cubo, 1996-

v. 19, n. 5 (September/October 2015).Bimonthly Continued Revista Brasileira de FisioterapiaISSN 1413-3555

1. Physical Therapy. 2. Studies. I. Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia.

Cataloguing Card

Librarian: Dormélia Pereira Cazella (CRB 8/4334)

Contact AddressBrazilian Journal of Physical TherapyRod. Washington Luís, Km 235, Caixa Postal 676, CEP 13565-905São Carlos, SP - Brasil+55(16) 3351-8755contato@rbf-bjpt.org.brwww.rbf-bjpt.org.br

Technical and Administrative SupportAna Paula de Luca Leonor A. Saidel Aizza

Desktop Publishing and Editorial Consulting

The Brazilian Journal of Physical Therapy is published by the Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia – ABRAPG-Ft (Brazilian Association for Research and Graduate Studies in Physical Therapy). Published since 1996, the Brazilian Journal of Physical Therapy adopts a peer review process. Each article is only published after it is accepted by the reviewers, who are maintained anonymous during the process.The editors accept no responsibility for damage to people or property, which may have been caused by the use of ideas, techniques or procedures described in the material published by this journal.The submission of articles presupposes that these articles, with the exception of extended summaries, have not been previously published elsewhere, nor submitted to any other publication.The abbreviated title of the journal is Braz J. Phys. Ther. and this must be used in references, footnotes and bibliographic legends.The Brazilian Journal of Physical Therapy is freely accessible at the homepage on the web: http://www.scielo.br/rbfis.

MissionTo publish original research articles on topics related to the areas of physical therapy and rehabilitation sciences, including clinical, basic or applied studies on the assessment, prevention, and treatment of movement disorders.

Indexed in

®

s u m m a r y

Editorial329 Editorial

Deborah A. Nawoczenski

Review Article331 Prevention of shoulder injuries in overhead athletes: a science-based approach

Ann M. Cools, Fredrik R. Johansson, Dorien Borms, Annelies Maenhout

340 A conceptual framework for a sports knee injury performance profile (SKIPP) and return to activity criteria (RTAC)David Logerstedt, Amelia Arundale, Andrew Lynch, Lynn Snyder-Mackler

360 Critical review of the impact of core stability on upper extremity athletic injury and performanceSheri P. Silfies, David Ebaugh, Marisa Pontillo, Courtney M. Butowicz

369 Measuring sports injuries on the pitch: a guide to use in practiceLuiz C. Hespanhol Junior, Saulo D. Barboza, Willem van Mechelen, Evert Verhagen

381 Improving performance in golf: current research and implications from a clinical perspectiveKerrie Evans, Neil Tuttle

Original Articles390 Sports injuries profile of a first division Brazilian soccer team: a descriptive cohort study

Guilherme F. Reis, Thiago R. T. Santos, Rodrigo C. P. Lasmar, Otaviano Oliveira Júnior, Rômulo F. F. Lopes, Sérgio T. Fonseca

398 Multicenter trial of motion analysis for injury risk prediction: lessons learned from prospective longitudinal large cohort combined biomechanical - epidemiological studiesTimothy E. Hewett, Benjamin Roewer, Kevin Ford, Greg Myer

410 Physical therapists’ role in prevention and management of patellar tendinopathy injuries in youth, collegiate, and middle-aged indoor volleyball athletesKornelia Kulig, Lisa M. Noceti-DeWit, Stephen F. Reischl, Rob F. Landel

421 Male and female runners demonstrate different sagittal plane mechanics as a function of static hamstring flexibilityD. S. Blaise Williams III, Lee M. Welch

Clinical Commentary429 Clinical commentary of the evolution of the treatment for chronic painful mid-portion

Achilles tendinopathyHåkan Alfredson

Editorial Rules

http://dx.doi.org/10.1590/bjpt-rbf.2014.0129

Editorial

329 Braz J Phys Ther. 2015 Sept-Oct; 19(5):329-330

In August 2016, more than 10,000 athletes representing over 200 countries will converge in Rio de Janeiro for the ‘biggest sporting event on the planet’1 and the first Olympic Games ever held in South America. In September 2016, another 4000 athletes will be participating in the Paralympics. The world’s elite athletes will be competing in 42 events for the Olympics and 22 events for the Paralympics. What an exciting time for Brazil!

This special issue on SPORTS in the Brazilian Journal of Physical Therapy comes at an opportune time for practitioners who work with athletes of all levels of ability and throughout various phases of their rehabilitation recovery. With contributions by an international group of ‘elite’ practitioners in their field, readers will be sure to find their topic of interest in this special SPORTS issue. These topics range from expert clinical commentaries and critical reviews to presentations of original research related to common sports injuries.

While the World Cup generates an international enthusiasm for soccer, it also informs the viewer about the injuries to soccer players. The article “SPORTS INJURIES PROFILE OF A FIRST DIVISION BRAZILIAN SOCCER TEAM: A DESCRIPTIVE COHORT STUDY” by Reis and colleagues provides information from a descriptive cohort study regarding injury profiles in first division Brazilian soccer players, including the influence of player’s age and position on injuries. An appropriate and relevant follow up to this manuscript is presented by Hespanhol Junior and colleagues: “MEASURING SPORTS INJURIES ON THE PITCH: A GUIDE TO USE IN PRACTICE.” This paper reviews the basic concepts of injury monitoring systems in sports participation and encourages the implementation of these concepts in practice.

Runners are featured in the manuscript “MALE AND FEMALE RUNNERS DEMONSTRATE DIFFERENT SAGITTAL PLANE MECHANICS AS A FUNCTION OF STATIC HAMSTRING FLEXIBILITY”. In this article, Blase Williams and colleagues assess the effect of hamstring length on running mechanics in both male and female runners and discuss the implications for injury. For athletes who have sustained a knee injury, the timing for when it is safe to return to sports can be challenging. In the manuscript “A CONCEPTUAL FRAMEWORK FOR A SPORTS KNEE INJURY PERFORMANCE PROFILE (SKIPP) AND RETURN TO ACTIVITY CRITERIA (RTAC),” Logerstedt and colleagues discuss a comprehensive system that focuses on specific indicators of rehabilitation progression, and present criteria for safe return to sports following knee injury.

Patellar tendinopathy is a common problem in athletes whose sports require jumping. In the article “PHYSICAL THERAPISTS’ ROLE IN PREVENTION AND MANAGEMENT OF PATELLAR TENDINOPATHY INJURIES IN YOUTH, COLLEGIATE, AND MIDDLE-AGED INDOOR VOLLEYBALL ATHLETES” Kulig and colleagues discuss intervention strategies that include education, rehabilitation, training and return to sport that are athlete-specific. Patellar tendinopathy is not the only condition linked to sports involving jumping. Achilles tendinopathy is also common and highly problematic in jumping activities. In the manuscript “CLINICAL COMMENTARY OF THE EVOLUTION OF THE TREATMENT FOR CHRONIC PAINFUL MID-PORTION ACHILLES TENDINOPATHY” Alfredson discusses the results of research that evolved and changed practice, including the newest treatment for Achilles tendinopathy.

Given that Golf will be returning to the 2016 Summer Games for the first time in 112 years, Evans and Tuttle’s “IMPROVING PERFORMANCE IN GOLF: CURRENT RESEARCH AND IMPLICATIONS FROM A CLINICAL PERSPECTIVE” is a well-timed contribution. Using best evidence from biomechanical and motor control research, the manuscript offers a pragmatic approach to enhancing golf performance.

Core stability is frequently a focus of an athlete’s rehabilitation program, yet there is little evidence to support the link between core stability and injury. The article by Silfies and colleagues, “CRITICAL REVIEW OF THE IMPACT OF CORE STABILITY ON UPPER EXTREMITY ATHLETIC INJURY AND PERFORMANCE” provides an in-depth review of the existing science regarding core stability and its association between upper limb injuries and athletic performance. The upper limb is also featured in the article by Cools and colleagues, “PREVENTION OF SHOULDER INJURIES IN OVERHEAD ATHLETES: A SCIENCE BASED APPROACH.” The authors discuss the key risk factors that may be used to guide injury prevention and return to sports after shoulder injury.

Editorial

Nawoczenski DA

330 Braz J Phys Ther. 2015 Sept-Oct; 19(5):329-330

Finally, an in-depth commentary regarding the importance of study design for injury risk prediction is presented in the manuscript by Hewett and colleagues “MULTI-CENTER TRIAL OF MOTION ANALYSIS FOR INJURY RISK PREDICTION: LESSONS LEARNED FROM PROSPECTIVE LONGITUDINAL LARGE COHORT COMBINED BIOMECHANICAL -EPIDEMIOLOGICAL STUDIES.” In their paper, the authors illustrate the research process and emphasize the need for continued, collaborative work in prospective study designs.

Passion and Transformation: this is the essence of the emblem2 chosen for the Olympic and Paralympic Games in Brazil that ‘synthesizes its values and guides its action’. The Passion through sports, reflected in the drive and desire for achievement. Transformation in the pride of creating a new reality for progress. This special issue of SPORTS captures the passion of the practitioner in the clinic/research laboratory who desires to optimize health and performance of all athletes, and likewise challenges physical therapists to continue to strive for the transformation of practice.

Parabéns Brasil!Deborah A. Nawoczenski PT, PhD

Guest Co-editor, SPORTS Special IssueBrazilian Journal of Physical Therapy

References1. Rio2016. Olympic games [Internet]. Rio de Janeiro; 2015 [cited 2015 Jul 7]. Available from: http://www.rio2016.com/en/the-games/

olympic.2. Rio2016. Olympic emblem: passion and transformation [Internet]. Rio de Janeiro; 2015 [cited 2015 Jul 6]. Available from: http://

www.rio2016.com/en/more-information/games-design/olympic-emblem.

http://dx.doi.org/10.1590/bjpt-rbf.2014.0109

review article

331 Braz J Phys Ther. 2015 Sept-Oct; 19(5):331-339

Prevention of shoulder injuries in overhead athletes: a science-based approach

Ann M. Cools1, Fredrik R. Johansson1, Dorien Borms1, Annelies Maenhout1

ABSTRACT | The shoulder is at high risk for injury during overhead sports, in particular in throwing or hitting activities, such as baseball, tennis, handball, and volleyball. In order to create a scientific basis for the prevention of recurrent injuries in overhead athletes, four steps need to be undertaken: (1) risk factors for injury and re-injury need to be defined; (2) established risk factors may be used as return-to-play criteria, with cut-off values based on normative databases; (3) these variables need to be measured using reliable, valid assessment tools and procedures; and (4) preventative training programs need to be designed and implemented into the training program of the athlete in order to prevent re-injury. In general, three risk factors have been defined that may form the basis for recommendations for the prevention of recurrent injury and return to play after injury: glenohumeral internal-rotation deficit (GIRD); rotator cuff strength, in particular the strength of the external rotators; and scapular dyskinesis, in particular scapular position and strength.Keywords: shoulder; injury prevention; return to play.

HOW TO CITE THIS ARTICLE

Cools AM, Johansson FR, Borms D, Maenhout A. Prevention of shoulder injuries in overhead athletes: a science-based approach. Braz J Phys Ther. 2015 Sept-Oct; 19(5):331-339. http://dx.doi.org/10.1590/bjpt-rbf.2014.0109

1 Department of Rehabilitation Sciences and Physiotherapy, Faculty of Medicine and Health Sciences, University Hospital Ghent, Ghent, BelgiumReceived: Jan. 02, 2015 Revised: May 15, 2015 Accepted: May 25, 2015

IntroductionThe shoulder is at high risk of injury in overhead

sports like tennis or volleyball because it faces high loads and forces during serving and smashing. Injury risk seems to increase with age1,2 and, despite some lack of evidence, has been suggested to be related to level and volume of play2-4.

Most of the reported shoulder injuries are strains, implicating a process over time, with chronic overload leading to injury1. Chronic shoulder pain in the overhead athlete is often attributed to sport-specific adaptations, alterations in strength, flexibility, and posture not only in the glenohumeral joint, but also in other links of the kinetic chain5-9. These alterations change biomechanics and movement strategies during serving and striking, possibly leading to overload injuries at the shoulder. In particular, glenohumeral internal-rotation deficit (GIRD), rotator cuff strength imbalance, scapular dyskinesis, thoracic spine stiffness and hyperkyphosis, lumbar core instability, and hip range of motion and strength deficits possibly create the “cascade to injury”, as defined by Kibler10 and Lintner et al.7 in overhead athletes. This kinetic chain “breakage” has been suggested to be a result of repetitive, vigorous activities in both young and older athletes7,10,11. In spite of the relevance of kinetic

chain alterations in the spine and lower extremities, the discussion of these variables is beyond the scope of this paper, which focusses on more local shoulder girdle factors.

In order to create a scientific basis for the prevention of recurrent injuries in overhead athletes, four steps need to be undertaken: (1) risk factors for injury and re-injury need to be defined12; (2) established risk factors may be used as return-to-play criteria, with cut-off values based on normative databases; (3) these variables need to be measured using reliable, valid assessment tools and procedures; and (4) preventive training programs need to be designed and implemented into the training program of the athlete in order to prevent re-injury. The purpose of the present paper is to review the literature regarding these steps and to suggest some clinical applications of the current knowledge to the clinician.

Risk factors for shoulder injury in overhead athletes

In spite of promising results from prospective studies, no consensus exists regarding intrinsic risk factors for shoulder pain in the overhead athlete.

Cools AM, Johansson FR, Borms D, Maenhout A

332 Braz J Phys Ther. 2015 Sept-Oct; 19(5):331-339

Different requirements on the shoulder and specific throwing activities across the spectrum of overhead athletes might account for these discrepancies. Recently GIRD and rotator cuff strength deficit, as well as scapular dyskinesis have been defined as possible risk factors in a population of baseball, rugby, and handball players13-18. In particular, pre-season reduced internal rotation range of motion14, reduced total range of motion13,15, a strength deficit in the external rotators13,16,17, and inadequate scapular position during clinical testing13,18 were shown to increase the risk for overuse chronic shoulder pain in these athletes.

Posterior shoulder stiffness is a common, if not the most common, adaptation seen on the dominant side of overhead athletes of multiple sports disciplines8. This manifests clinically as decreased glenohumeral cross-body adduction and internal rotation mobility and is believed to be the result of both capsular tightness and muscular contracture. It is hypothesized that the cumulative loads onto the posterior shoulder during the deceleration phase of the throwing motion cause microtrauma and scarring of these soft tissues8. Posterior shoulder stiffness, therefore, has been suggested to be a causative or perpetuating factor in shoulder impingement and labral pathology9,19,20. Abnormal humeral head translations, caused by selective tightening of the posterior-inferior capsule, may decrease the width of the subacromial space, thus causing subacromial impingement21. Other studies22 suggest a posterior and superior translation of the humeral head during cocking with a tight posterior capsule, possibly leading to an encroachment of the rotator cuff tendons against the postero-superior rim of the glenoid. In addition, posterior shoulder tightness seems to affect kinematics of the scapula and the humeral head. and is associated with a decreased acromiohumeral distance23. As a result, posterior capsule shortness possibly increases the risk for internal as well as subacromial impingement in the overhead athlete21,22. Recently, Clarsen et al.13 showed an odds ratio for sports-related shoulder pain of 0.77 per 5° change in total range of motion (adding up internal and external range of motion) in a population of handball players.

During overhead throwing and serving, the shoulder is highly loaded with an enormous challenge for the eccentric capacity of the external rotators during the deceleration phase. In specific sports such as tennis, it has been shown that elite players without shoulder injury have shoulder rotation muscle strength imbalances that alter the ratio between rotator cuff muscles24. Although these differences do not seem to

affect the athletic performance immediately, detection and prevention with exercise programs at an early age are recommended, since recently decreased external rotation strength has been identified as a risk factor for shoulder pain13.

There is a body of evidence showing an association between scapular dysfunction and shoulder pain, specifically in the overhead athlete25-30, however there is no consensus regarding the cause-consequence relationship between both clinical entities. Some studies revealed no causative relationship between scapular dysfunction and shoulder pain31,32, whereas others clearly identified scapular dyskinesis as a possible risk factor for chronic shoulder pain in a population of overhead athletes13,18,31. In particular, obvious scapular dyskinesis, as defined by McClure et al.33, and type III scapular dyskinesis, as defined by Kibler et al.34, were found to increase the risk for shoulder pain13,18. Other studies discussed scapular position in healthy tennis players, but also with conflicting results. While Silva et al.35 showed abnormal scapular position correlated with decreased acromiohumeral distance, Cools et al.36 described positive alterations in elite tennis players with increased scapular upward rotation on the dominant side.

In summary, glenohumeral range of motion, rotator cuff strength or imbalance, and scapular position and movement are important factors in the assessment of healthy and previously injured overhead athletes in order to define risk factors and guide the athlete into the return-to-play stage after injury.

In addition to the more local risk factors mentioned above, more functional deficits might be risk factors for injury like faulty biomechanics, throwing fatigue etc. In order to measure these variables, there is a need for functional testing in a throwing-specific position, for instance endurance tests of the shoulder into a throwing position, throwing distance, speed and accuracy. However, with the exception of some tests mimicking shoulder function, like the “seated medicine ball throw”37 or the “Y-balance test for the upper limb”38, to date no science-based functional test has been fully validated to determine risk factors for shoulder injury or return to play after injury.

Return-to-play criteria based on cut-off values from the risk factors

According to the decision-based return-to-play model described by Matheson et al.39, 3 steps need to be taken prior to full return to sports. First, the health status of the athlete is evaluated, including

Risk factors and return to play criteria

333 Braz J Phys Ther. 2015 Sept-Oct; 19(5):331-339

assessment of symptoms and a battery of analytical and functional tests (e.g. strength and flexibility, throwing performance, etc.). Then, the clinician evaluates the participation risk based on the type of sport, level of competition, and ability to protect the shoulder. Finally, some factors might modify the decision, such as the timing in the season, pressure from the athlete, or his environment. However, in spite of this science-based model to be implemented into clinical practice, little evidence exists regarding the physical return-to-play criteria of the shoulder after injury. From a clinical perspective, there is a need for cut-off values for each of the described risk factors to be used as criteria for return to training and return to play. In addition, the clinician needs objective and valid assessment tools applicable to the athlete’s field or training area. Finally, once deficits are assessed, there is a need for science-based training programs to restore normal values. The purpose of the following paragraphs is to discuss cut-off values, assessment tools, and intervention programs for GIRD, rotator cuff strength deficit, and scapular dyskinesis.

Glenohumeral range of motionWith respect to range of motion, loss of internal

range of motion is a known risk factor for chronic shoulder pain14,15,40. There is no consensus in literature with respect to the cut-off values for internal ROM, ranging from 18°15 up to 25°14 depending on the study design and population. Therefore, in view of maximal protection of the athlete, it is advised that side differences in internal rotation ROM should be less than 18°, and the difference in total range of motion should be no more than 5°15. The studies referring to selectively measuring GIRD, base their instruction on the proposition that it is the result of selective tightening of the posterior shoulder structures, such as the posterior capsule of the glenohumeral joint and the posterior cuff muscles. The relevance of the concept of total range of motion, in which internal and external ROM are added up, has been introduced in the literature since the first studies showing bony adaptations in the humeral torsion based on overhead sports activity41. Increased humeral torsion alters the arc of total range of motion into decreased internal rotation ROM and increased external rotation ROM. In this hypothesis, the athlete is not at risk as long as the loss of IR is compensated by a gain of ER. Therefore, it is advised, in particular in elite athletes, to take into account the total ROM rather than the internal rotation ROM as a risk factor. A recent study on professional baseball players found that pitchers

with GIRD displayed greater side-to-side differences and dominant humeral retrotorsion compared to those without GIRD. The authors concluded that the greater humeral retrotorsion may place greater stress on the posterior shoulder resulting in ROM deficits. Pitchers with greater humeral retrotorsion appear to be more susceptible to developing ROM deficits associated with injury and may need increased monitoring and customized treatment programs to mitigate their increased injury risk42.

The assessment of the ROM into rotation of the shoulder can be measured with a goniometer or an inclinometer, and in many positions of the body and the shoulder. A comprehensive reliability study43 showed high to excellent inter- and intra-tester reliability for a variety of test positions and equipment. Based on the results of this study, no specific procedure can be acknowledged to be superior to another one. However, the clinician has to take into account that there is great variability in the literature regarding shoulder position (e.g. scapular or frontal plane)15,24 and the specific method of scapular stabilization (none, hand on shoulder top, or specific fixation of coracoid). Based on the above-mentioned reliability study and in view of optimal standardization of body and shoulder position, the authors advise the following procedure: the patient is supine with the shoulder in the frontal plane and the elbow flexed 90°. The upper arm should be horizontal or if needed the arm can be supported by a towel to reach the horizontal position (for instance in case the patient has protracted shoulders or a thoracic kyphosis). For internal rotation, the examiner palpates the spine of the scapula and the coracoid. The inclinometer is aligned with the forearm (olecranon and styloid process of the ulna), and the shoulder is moved into internal rotation (Figure 1). The movement reaches

Figure 1. Measurement of internal rotation of the shoulder using a digital inclinometer24.

Cools AM, Johansson FR, Borms D, Maenhout A

334 Braz J Phys Ther. 2015 Sept-Oct; 19(5):331-339

its endpoint when the coracoid tends to move against the palpating thumb. For external rotation, the fixating hand is placed gently over the shoulder top, and the shoulder is moved into external rotation, aligning the inclinometer with the forearm.

In addition, horizontal adduction can be measured in the assessment of posterior capsule stiffness23. It is advised that measurement be performed with the shoulder at 90° of flexion and horizontally adducted until the scapula starts moving laterally. While one investigator manually fixes the lateral border of the scapula and palpates the lateral movement of the scapula, the second moves the upper arm toward horizontal adduction and measures the angle between the upper arm and the vertical23. In spite of the clinical relevance of this measurement, its predictive value in shoulder pain is unclear.

Given the evidenced impact of posterior shoulder tightness on shoulder kinematics, increasing posterior shoulder flexibility is advised when mobility deficits exceed the limits associated with increased injury risk. Both the cross-body stretch (Figure 2) and the sleeper stretch (Figure 3) can be recommended to decrease posterior shoulder tightness44. It was shown that a 6-week daily sleeper stretch program (3 reps of 30 seconds)

is able to significantly increase the acromiohumeral distance in the dominant shoulder of healthy overhead athletes with GIRD23. Additional joint mobilization performed by a physical therapist has a small but non-significant advantage over a home stretching program alone45. No difference in mobility gain was seen after angular (sleeper stretch and horizontal adduction stretch) and non-angular (dorsal and caudal humeral head glides) joint mobilization by a physical therapist46 in a 3-week stretching program in overhead athletes with impingement-related shoulder pain. Both programs however resulted in increased ROM and decreased pain during physical examination and improved shoulder functional outcome scores. Muscle energy techniques (hold-relax) during the sleeper stretch and the horizontal adduction stretch have proven useful to immediately increase internal rotation range of motion47. Two studies46,48 showed symptom relief after a stretching program in a population of overhead athletes with impingement-related shoulder pain. However, there is no evidence to support that a stretching program reduces the incidence of recurrent shoulder injury.

Rotator cuff strengthRegarding rotator cuff strength, it is generally

recognized that overhead athletes often exhibit sport-specific adaptations leading to a relative decrease in the strength of the external rotators, and thus muscular imbalance in the rotator cuff. Isokinetic49 as well as isometric24 and eccentric50 strength studies have been performed in healthy and injured athletes showing deficiencies in external rotator muscle performance. In these studies, absolute side differences as well as muscle balance ratio between external and internal rotators were examined. In general, with respect to cut-off values distinguishing a healthy shoulder from a shoulder at risk, an isokinetic ER/IR ratio of 66% or an isometric ER/IR ratio of 75% is advised, with a general rotator cuff strength increase of 10% of the dominant throwing side16,24,49 compared to the non-dominant side. Recently, focus has shifted from isometric or concentric to eccentric muscle strength of the rotator cuff. In particular, the eccentric strength of the external rotators are of interest51. These muscles function as a decelerator mechanism during powerful throwing, serving, or smashing.

In view of the importance of eccentric rotator cuff strength in relation to injury-free overhead throwing or serving, it is imperative that strength be assessed on a regular base in healthy as well as injured players. Figure 3. Sleeper’s stretch41.

Figure 2. Cross body stretch9.

Risk factors and return to play criteria

335 Braz J Phys Ther. 2015 Sept-Oct; 19(5):331-339

Numerous testing protocols have been described to examine isokinetic52-54 and isometric55 rotator cuff strength. The golden standard in strength measurement is the use of isokinetic devices, however these procedures are rather expensive, and not applicable on the field or training area. With respect to the isometric strength measurements, hand-held dynamometry (HHD) has attracted more and more interest during the last years due to the more practical, less expensive and user-friendly advantages over the more advanced and expensive isokinetic devices. HHD has demonstrated higher sensitivity and intra- and inter-examiner reliability than manual muscle testing in identifying strength deficits of the rotator cuff56.

Recently, a new testing protocol was published, showing that HHD measurements of eccentric external rotator strength show excellent intra-tester (ICC=0.88) and good inter-tester (ICC=0.71) reliability, as well as concurrent validity (compared to an isokinetic device, Pearson’s correlation = 0.78)51. During the procedure, the patient is seated gently supported by the arm of the tester, who brings the shoulder from 90° abduction-90° external rotation (throwing position) to 90° abduction-0° external rotation, loading the external rotators eccentrically (Figure 4). A large normative database on 200 overhead athletes (volleyball, tennis, and handball) was recently set up (unpublished data) and shows an average normalized eccentric external rotator strength (N/kg) of approximately 2, with significant side differences in favor of the dominant sides, and significant higher values for handball and tennis compared to volleyball.

Numerous exercises have been described to strengthen the rotator cuff muscles, including concentric, isometric, eccentric, and plyometric exercises41. In view of the eccentric component of the function of the external rotators, the sport-specific exercises for overhead athletes should focus on three areas:

1) Exercises that accentuate the eccentric phase and “avoid” the concentric phase in order to load the muscles based on their eccentric capacity. Figures 5 A-C show an example of an eccentric exercise for the external rotators in general in an abducted position.

2) Slow exercises for absolute strength, fast exercises for endurance and plyometric capacity. Endurance and plyometric capacity may be exercised using weight balls exercises in which the patient is instructed to “catch” the ball (Figure 6), as described by Ellenbecker and Cools41.

Figure 5. Eccentric exercise for the external rotators in an abducted position.

Figure 4. Eccentric testing protocol using an HHD51.

Cools AM, Johansson FR, Borms D, Maenhout A

336 Braz J Phys Ther. 2015 Sept-Oct; 19(5):331-339

3) Exercise highlighting the “stretch-shortening-cycle” of throwing. Specific devices can be used to train the stretch-shortening cycle, such as XCO trainer (Figure 7).

Scapular dyskinesisEvidence supporting cut-off values for prevention

of injury or return to play after injury with respect to scapular function is scarce. A number of studies used visual observation as a criterion13,18 whereas others provide objective data on healthy athletes as a reference base for return to play36,57. In general, visual observation is performed either by using the yes/no method (scapular dyskinesis or not), a method proven to be reliable and valid if the examiner/therapist is educated in a standardized manner33,58, or by categorizing the scapular dysfunction into different types, based on the specific position of the scapula34. However, the latter method was shown to have acceptable intra-rater, but low inter-rater reliability34. Clarsen et al.13 rated scapular dyskinesis in handball players as having normal scapular control, slight scapular dyskinesis, or obvious

dyskinesis13, and established obvious dyskinesis as a risk factor for shoulder pain. A statement saying that scapular behavior should be symmetrical in overhead athletes is not supported by research data. On the contrary, in volleyball as well as in handball players, asymmetry was found in resting scapular posture57,59. Uhl et al.58 also reported that the prevalence of scapular dyskinesis was almost identical in subjects with and without shoulder pain, questioning the clinical value of scapular asymmetry. Therefore, clinicians should be aware that some degree of scapular asymmetry may be normal in some athletes. It should not be considered automatically as a pathological sign, but rather an adaptation to sports practice and extensive use of upper limb.

Several studies measured scapular upward inclination in healthy overhead athletes46,60. These data may be used as a reference base and cut-off values for correct scapular positioning in several elevation angles. In general, a large variety is found in scapular upward inclination in the midrange of motion (probably due to a large variation between individuals), however in full elevation, most studies suggest that upward inclination should be at least 45-55°36,60.

For the scapular muscles proper inter- and intramuscular balance should be assessed. Isokinetic ratio protraction/retraction is shown to be 100% in a healthy population, with slight changes in overhead athletes, in case of throwing athletes in favor of the protractors25,36,61. In bilateral sports (swimming, rowing, gymnastics), there should be no side differences in scapular muscle strength. In one-handed overhead sports, an increase of 10% in scapular muscle strength is advised on the dominant side. In particular, the lower trapezius and serratus anterior should receive special attention, since these muscles are shown to be susceptible to weakness in injured athletes10,62.

In the assessment of scapular behavior, besides the clinical observation, several measurements can be performed for scapular position as well as muscle strength. The use of a digital inclinometer for the measurement of scapular upward rotation has been shown to exhibit high inter- and intra-rater reliability60. Key conditions for good measurements are adequate palpation of the reference points in the different humeral elevation angles and control of additional tilting of the inclinometer in planes other than the scapular plane. For the measurement of scapular muscle strength, several protocols have been described36,63. Differences between procedures are based on the equipment used, positioning of the

Figure 6. “Catching” exercise using a plyoball41.

Figure 7. Stretch-shortening cycle exercise, using the XCO trainer.

Risk factors and return to play criteria

337 Braz J Phys Ther. 2015 Sept-Oct; 19(5):331-339

dynamometer, patient positioning, and performing a “make” and “break” test. Different testing procedures result in different outcome, the clinician should take that into account using reference data from research in the clinical practice. In the authors’ experience, using the Kendall & Kendall position and performing a “make” test with a hand held dynamometer is an acceptable and clinically relevant method of strength measurement of the scapular muscles36.

Once deficits and imbalances in scapular behavior are assessed, an intervention program to restore flexibility and muscle performance needs to be installed. Recently, a science-based clinical reasoning algorithm was published guiding the clinician into the different steps and progression62. The main goals are: a) to restore flexibility of the surrounding soft tissue of the scapula, in particular pectoralis minor, levator scapulae, rhomboid, and posterior shoulder structures; and b) to increase scapular muscle performance around the scapula, focusing on either muscle control and inter- and intramuscular coordination or muscle strength and balance. Exercises to restore scapular muscle balance64 have been shown to increase isokinetic protraction and retraction65, increase external rotator strength of the shoulder66, and alter EMG activity of the scapular muscles in favor of efficient muscle recruitment during a loaded elevation task67.

ConclusionIn summary, with respect to injury prevention

as well as return to play after injury, the clinician should evaluate possible risk factors for injury in the shoulder, in particular GIRD, rotator cuff strength, and scapular performance, using reliable assessment tools. In case abnormal findings are established, the intervention should focus on stretching of the posterior shoulder capsule, strengthening of the posterior cuff, and restoration of flexibility and muscle balance of the scapular muscles.

References1. Kibler WB, Safran MR. Musculoskeletal injuries in the young

tennis player. Clin Sports Med. 2000;19(4):781-92. http://dx.doi.org/10.1016/S0278-5919(05)70237-4. PMid:11019740.

2. Pluim BM, Staal JB, Windler GE, Jayanthi N. Tennis injuries: occurrence, aetiology, and prevention. Br J Sports Med. 2006;40(5):415-23. http://dx.doi.org/10.1136/bjsm.2005.023184. PMid:16632572.

3. Baxter-Jones A, Maffulli N, Helms P. Low injury rates in elite athletes. Arch Dis Child. 1993;68(1):130-2. http://dx.doi.org/10.1136/adc.68.1.130. PMid:8434997.

4. Jayanthi NA, O’Boyle J, Durazo-Arvizu RA. Risk factors for medical withdrawals in United States tennis association junior national tennis tournaments: a descriptive epidemiologic study. Sports Health. 2009;1(3):231-5. http://dx.doi.org/10.1177/1941738109334274. PMid:23015877.

5. Sciascia A, Kibler WB. The pediatric overhead athlete: what is the real problem? Clin J Sport Med. 2006;16(6):471-7. http://dx.doi.org/10.1097/01.jsm.0000251182.44206.3b. PMid:17119360.

6. Kibler WB, Press J, Sciascia A. The role of core stability in athletic function. Sports Med. 2006;36(3):189-98. http://dx.doi.org/10.2165/00007256-200636030-00001. PMid:16526831.

7. Lintner D, Noonan TJ, Kibler WB. Injury patterns and biomechanics of the athlete’s shoulder. Clin Sports Med. 2008;27(4):527-51. http://dx.doi.org/10.1016/j.csm.2008.07.007. PMid:19064144.

8. Borsa PA, Laudner KG, Sauers EL. Mobility and stability adaptations in the shoulder of the overhead athlete: a theoretical and evidence-based perspective. Sports Med. 2008;38(1):17-36. http://dx.doi.org/10.2165/00007256-200838010-00003. PMid:18081365.

9. Cools AM, Declercq G, Cagnie B, Cambier D, Witvrouw E. Internal impingement in the tennis player: rehabilitation guidelines. Br J Sports Med. 2008;42(3):165-71. http://dx.doi.org/10.1136/bjsm.2007.036830. PMid:18070811.

10. Kibler WB. The role of the scapula in athletic shoulder function. Am J Sports Med. 1998;26(2):325-37. PMid:9548131.

11. Kibler WB, McMullen J. Scapular dyskinesis and its relation to shoulder pain. J Am Acad Orthop Surg. 2003;11(2):142-51. PMid:12670140.

12. Bahr R, Krosshaug T. Understanding injury mechanisms: a key component of preventing injuries in sport. Br J Sports Med. 2005;39(6):324-9. http://dx.doi.org/10.1136/bjsm.2005.018341. PMid:15911600.

13. Clarsen B, Bahr R, Andersson SH, Munk R, Myklebust G. Reduced glenohumeral rotation, external rotation weakness and scapular dyskinesis are risk factors for shoulder injuries among elite male handball players: a prospective cohort study. Br J Sports Med. 2014;48(17):1327-33. http://dx.doi.org/10.1136/bjsports-2014-093702. PMid:24948083.

14. Shanley E, Rauh MJ, Michener LA, Ellenbecker TS, Garrison JC, Thigpen CA. Shoulder range of motion measures as risk factors for shoulder and elbow injuries in high school softball and baseball players. Am J Sports Med. 2011;39(9):1997-2006. http://dx.doi.org/10.1177/0363546511408876. PMid:21685316.

15. Wilk KE, Macrina LC, Fleisig GS, Porterfield R, Simpson CD 2nd, Harker P, et al. Correlation of glenohumeral internal rotation deficit and total rotational motion to shoulder injuries in professional baseball pitchers. Am J Sports Med. 2011;39(2):329-35. http://dx.doi.org/10.1177/0363546510384223. PMid:21131681.

16. Byram IR, Bushnell BD, Dugger K, Charron K, Harrell FE Jr, Noonan TJ. Preseason shoulder strength measurements in professional baseball pitchers: identifying players at risk for injury. Am J Sports Med. 2010;38(7):1375-82. http://dx.doi.org/10.1177/0363546509360404. PMid:20489215.

17. Edouard P, Degache F, Oullion R, Plessis JY, Gleizes-Cervera S, Calmels P. Shoulder strength imbalances as injury risk in handball. Int J Sports Med. 2013;34(7):654-60. http://dx.doi.org/10.1055/s-0032-1312587. PMid:23444085.

18. Kawasaki T, Yamakawa J, Kaketa T, Kobayashi H, Kaneko K. Does scapular dyskinesis affect top rugby players during a game season? J Shoulder Elbow Surg. 2012;21(6):709-14. http://dx.doi.org/10.1016/j.jse.2011.11.032. PMid:22445626.

Cools AM, Johansson FR, Borms D, Maenhout A

338 Braz J Phys Ther. 2015 Sept-Oct; 19(5):331-339

19. Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology Part I: pathoanatomy and biomechanics. Arthroscopy. 2003;19(4):404-20. http://dx.doi.org/10.1053/jars.2003.50128. PMid:12671624.

20. Wilk KE, Obma P, Simpson CD 2nd, Cain EL, Dugas JR, Andrews JR. Shoulder injuries in the overhead athlete. J Orthop Sports Phys Ther. 2009;39(2):38-54. http://dx.doi.org/10.2519/jospt.2009.2929. PMid:19194026.

21. Huffman GR, Tibone JE, McGarry MH, Phipps BM, Lee YS, Lee TQ. Path of glenohumeral articulation throughout the rotational range of motion in a thrower’s shoulder model. Am J Sports Med. 2006;34(10):1662-9. http://dx.doi.org/10.1177/0363546506287740. PMid:16685095.

22. Gagey OJ, Boisrenoult P. Shoulder capsule shrinkage and consequences on shoulder movements. Clin Orthop Relat Res. 2004;419:218-22. http://dx.doi.org/10.1097/00003086-200402000-00036. PMid:15021158.

23. Maenhout A, Van Eessel V, Van Dyck L, Vanraes A, Cools A. Quantifying acromiohumeral distance in overhead athletes with glenohumeral internal rotation loss and the influence of a stretching program. Am J Sports Med. 2012;40(9):2105-12. http://dx.doi.org/10.1177/0363546512454530. PMid:22869627.

24. Cools AM, Palmans T, Johansson FR. Age-related, sport-specific adaptions of the shoulder girdle in elite adolescent tennis players. J Athl Train. 2014;49(5):647-53. http://dx.doi.org/10.4085/1062-6050-49.3.02. PMid:25098662.

25. Cools AM, Declercq GA, Cambier DC, Mahieu NN, Witvrouw EE. Trapezius activity and intramuscular balance during isokinetic exercise in overhead athletes with impingement symptoms. Scand J Med Sci Sports. 2007;17(1):25-33. PMid:16774650.

26. Cools AM, Witvrouw EE, Declercq GA, Danneels LA, Cambier DC. Scapular muscle recruitment patterns: trapezius muscle latency with and without impingement symptoms. Am J Sports Med. 2003;31(4):542-9. PMid:12860542.

27. Ludewig PM, Reynolds JF. The association of scapular kinematics and glenohumeral joint pathologies. J Orthop Sports Phys Ther. 2009;39(2):90-104. http://dx.doi.org/10.2519/jospt.2009.2808. PMid:19194022.

28. Struyf F, Cagnie B, Cools A, Baert I, Brempt JV, Struyf P, et al. Scapulothoracic muscle activity and recruitment timing in patients with shoulder impingement symptoms and glenohumeral instability. J Electromyogr Kinesiol. 2014;24(2):277-84. http://dx.doi.org/10.1016/j.jelekin.2013.12.002. PMid:24389333.

29. Lopes AD, Timmons MK, Grover M, Ciconelli RM, Michener LA. Visual scapular dyskinesis: kinematics and muscle activity alterations in patients with subacromial impingement syndrome. Arch Phys Med Rehabil. 2015;96(2):298-306. http://dx.doi.org/10.1016/j.apmr.2014.09.029. PMid:25449194.

30. Huang TS, Ou HL, Huang CY, Lin JJ. Specific kinematics and associated muscle activation in individuals with scapular dyskinesis. J Shoulder Elbow Surg. 2015 [Epub ahead of print]. http://dx.doi.org/10.1016/j.jse.2014.12.022.

31. Struyf F, Nijs J, Meeus M, Roussel NA, Mottram S, Truijen S, et al. Does scapular positioning predict shoulder pain in recreational overhead athletes? Int J Sports Med. 2014;35(1):75-82. PMid:23825003.

32. Myers JB, Oyama S, Hibberd EE. Scapular dysfunction in high school baseball players sustaining throwing-related upper extremity injury: a prospective study. J Shoulder Elbow Surg. 2013;22(9):1154-9. http://dx.doi.org/10.1016/j.jse.2012.12.029. PMid:23419606.

33. McClure P, Tate AR, Kareha S, Irwin D, Zlupko E. A clinical method for identifying scapular dyskinesis, part

1: reliability. J Athl Train. 2009;44(2):160-4. http://dx.doi.org/10.4085/1062-6050-44.2.160. PMid:19295960.

34. Kibler WB, Uhl TL, Maddux JW, Brooks PV, Zeller B, McMullen J. Qualitative clinical evaluation of scapular dysfunction: a reliability study. J Shoulder Elbow Surg. 2002;11(6):550-6. http://dx.doi.org/10.1067/mse.2002.126766. PMid:12469078.

35. Silva RT, Hartmann LG, Laurino CF, Biló JP. Clinical and ultrasonographic correlation between scapular dyskinesia and subacromial space measurement among junior elite tennis players. Br J Sports Med. 2010;44(6):407-10. http://dx.doi.org/10.1136/bjsm.2008.046284. PMid:18397969.

36. Cools AM, Johansson FR, Cambier DC, Velde AV, Palmans T, Witvrouw EE. Descriptive profile of scapulothoracic position, strength and flexibility variables in adolescent elite tennis players. Br J Sports Med. 2010;44(9):678-84. http://dx.doi.org/10.1136/bjsm.2009.070128. PMid:20587640.

37. van den Tillaar R, Marques MC. Reliability of seated and standing throwing velocity using differently weighted medicine balls. J Strength Cond Res. 2013;27(5):1234-8. http://dx.doi.org/10.1519/JSC.0b013e3182654a09. PMid:22744301.

38. Westrick RB, Miller JM, Carow SD, Gerber JP. Exploration of the y-balance test for assessment of upper quarter closed kinetic chain performance. Int J Sports Phys Ther. 2012;7(2):139-47. PMid:22530188.

39. Matheson GO, Shultz R, Bido J, Mitten MJ, Meeuwisse WH, Shrier I. Return-to-play decisions: are they the team physician’s responsibility? Clin J Sport Med. 2011;21(1):25-30. http://dx.doi.org/10.1097/JSM.0b013e3182095f92. PMid:21200167.

40. Shanley E, Thigpen CA, Clark JC, Wyland DJ, Hawkins RJ, Noonan TJ, et al. Changes in passive range of motion and development of glenohumeral internal rotation deficit (GIRD) in the professional pitching shoulder between spring training in two consecutive years. J Shoulder Elbow Surg. 2012;21(11):1605-12. http://dx.doi.org/10.1016/j.jse.2011.11.035. PMid:22835630.

41. Ellenbecker TS, Cools A. Rehabilitation of shoulder impingement syndrome and rotator cuff injuries: an evidence-based review. Br J Sports Med. 2010;44(5):319-27. http://dx.doi.org/10.1136/bjsm.2009.058875. PMid:20371557.

42. Noonan TJ, Shanley E, Bailey LB, Wyland DJ, Kissenberth MJ, Hawkins RJ, et al. Professional Pitchers With Glenohumeral Internal Rotation Deficit (GIRD) Display Greater Humeral Retrotorsion Than Pitchers Without GIRD. Am J Sports Med. 2015;43(6):1448-54. http://dx.doi.org/10.1177/0363546515575020. PMid:25807953.

43. Cools AM, De Wilde L, Van Tongel A, Ceyssens C, Ryckewaert R, Cambier DC. Measuring shoulder external and internal rotation strength and range of motion: comprehensive intra-rater and inter-rater reliability study of several testing protocols. J Shoulder Elbow Surg. 2014;23(10):1454-61. http://dx.doi.org/10.1016/j.jse.2014.01.006. PMid:24726484.

44. McClure P, Balaicuis J, Heiland D, Broersma ME, Thorndike CK, Wood A. A randomized controlled comparison of stretching procedures for posterior shoulder tightness. J Orthop Sports Phys Ther. 2007;37(3):108-14. http://dx.doi.org/10.2519/jospt.2007.2337. PMid:17416125.

45. Manske RC, Meschke M, Porter A, Smith B, Reiman M. A randomized controlled single-blinded comparison of stretching versus stretching and joint mobilization for posterior shoulder tightness measured by internal rotation motion loss. Sports Health. 2010;2(2):94-100. http://dx.doi.org/10.1177/1941738109347775. PMid:23015927.

Risk factors and return to play criteria

339 Braz J Phys Ther. 2015 Sept-Oct; 19(5):331-339

46. Cools AM, Johansson FR, Cagnie B, Cambier DC, Witvrouw EE. Stretching the posterior shoulder structures in subjects with internal rotation deficit: comparison of two stretching techniques. Shoulder Elbow. 2012;4(1):56-63. http://dx.doi.org/10.1111/j.1758-5740.2011.00159.x.

47. Moore SD, Laudner KG, McLoda TA, Shaffer MA. The immediate effects of muscle energy technique on posterior shoulder tightness: a randomized controlled trial. J Orthop Sports Phys Ther. 2011;41(6):400-7. http://dx.doi.org/10.2519/jospt.2011.3292. PMid:21471651.

48. Tyler TF, Nicholas SJ, Lee SJ, Mullaney M, McHugh MP. Correction of posterior shoulder tightness is associated with symptom resolution in patients with internal impingement. Am J Sports Med. 2010;38(1):114-9. http://dx.doi.org/10.1177/0363546509346050. PMid:19966099.

49. Ellenbecker T, Roetert EP. Age specific isokinetic glenohumeral internal and external rotation strength in elite junior tennis players. J Sci Med Sport. 2003;6(1):63-70. http://dx.doi.org/10.1016/S1440-2440(03)80009-9. PMid:12801211.

50. Saccol MF, Gracitelli GC, da Silva RT, Laurino CF, Fleury AM, Andrade MS, et al. Shoulder functional ratio in elite junior tennis players. Phys Ther Sport. 2010;11(1):8-11. http://dx.doi.org/10.1016/j.ptsp.2009.11.002. PMid:20129117.

51. Johansson FR, Skillgate E, Lapauw ML, Clijmans D, Deneulin VP, Palmans T, et al. Measuring eccentric strength of the shoulder external rotators using a handheld dynamometer: reliability and validity. J Athl Train. 2015 [Epub ahead of print]. http://dx.doi.org/10.4085/1062-6050-49.3.72. PMid:25974381.

52. Ellenbecker T, Roetert EP. Age specific isokinetic glenohumeral internal and external rotation strength in elite junior tennis players. J Sci Med Sport. 2003;6(1):63-70. http://dx.doi.org/10.1016/S1440-2440(03)80009-9. PMid:12801211.

53. Andrade MS, Fleury AM, de Lira CA, Dubas JP, da Silva AC. Profile of isokinetic eccentric-to-concentric strength ratios of shoulder rotator muscles in elite female team handball players. J Sports Sci. 2010;28(7):743-9. http://dx.doi.org/10.1080/02640411003645687. PMid:20496224.

54. Ellenbecker TS, Davies GJ. The application of isokinetics in testing and rehabilitation of the shoulder complex. J Athl Train. 2000;35(3):338-50. PMid:16558647.

55. Hébert LJ, Maltais DB, Lepage C, Saulnier J, Crête M, Perron M. Isometric muscle strength in youth assessed by hand-held dynamometry: a feasibility, reliability, and validity study. Pediatr Phys Ther. 2011;23(3):289-99. http://dx.doi.org/10.1097/PEP.0b013e318227ccff. PMid:21829128.

56. Cadogan A, Laslett M, Hing W, McNair P, Williams M. Reliability of a new hand-held dynamometer in measuring shoulder range of motion and strength. Man Ther. 2011;16(1):97-101. http://dx.doi.org/10.1016/j.math.2010.05.005. PMid:20621547.

57. Ribeiro A, Pascoal AG. Resting scapular posture in healthy overhead throwing athletes. Man Ther. 2013;18(6):547-50. http://dx.doi.org/10.1016/j.math.2013.05.010. PMid:23791560.

58. Uhl TL, Kibler WB, Gecewich B, Tripp BL. Evaluation of clinical assessment methods for scapular dyskinesis.

Arthroscopy. 2009;25(11):1240-8. http://dx.doi.org/10.1016/j.arthro.2009.06.007. PMid:19896045.

59. Oyama S, Myers JB, Wassinger CA, Daniel Ricci R, Lephart SM. Asymmetric resting scapular posture in healthy overhead athletes. J Athl Train. 2008;43(6):565-70. http://dx.doi.org/10.4085/1062-6050-43.6.565. PMid:19030133.

60. Struyf F, Nijs J, Mottram S, Roussel NA, Cools AM, Meeusen R. Clinical assessment of the scapula: a review of the literature. Br J Sports Med. 2014;48(11):883-90. http://dx.doi.org/10.1136/bjsports-2012-091059. PMid:22821720.

61. Cools AM, Geerooms E, Van den Berghe DF, Cambier DC, Witvrouw EE. Isokinetic scapular muscle performance in young elite gymnasts. J Athl Train. 2007;42(4):458-63. PMid:18174933.

62. Cools AM, Struyf F, De Mey K, Maenhout A, Castelein B, Cagnie B. Rehabilitation of scapular dyskinesis: from the office worker to the elite overhead athlete. Br J Sports Med. 2014;48(8):692-7. http://dx.doi.org/10.1136/bjsports-2013-092148. PMid:23687006.

63. Michener LA, Boardman ND, Pidcoe PE, Frith AM. Scapular muscle tests in subjects with shoulder pain and functional loss: reliability and construct validity. Phys Ther. 2005;85(11):1128-38. PMid:16253043.

64. Cools AM, Dewitte V, Lanszweert F, Notebaert D, Roets A, Soetens B, et al. Rehabilitation of scapular muscle balance: which exercises to prescribe? Am J Sports Med. 2007;35(10):1744-51. http://dx.doi.org/10.1177/0363546507303560. PMid:17606671.

65. Van de Velde A, De Mey K, Maenhout A, Calders P, Cools AM. Scapular-muscle performance: two training programs in adolescent swimmers. J Athl Train. 2011;46(2):160-7. http://dx.doi.org/10.4085/1062-6050-46.2.160. PMid:21391801.

66. Merolla G, De Santis E, Sperling JW, Campi F, Paladini P, Porcellini G. Infraspinatus strength assessment before and after scapular muscles rehabilitation in professional volleyball players with scapular dyskinesis. J Shoulder Elbow Surg. 2010;19(8):1256-64. http://dx.doi.org/10.1016/j.jse.2010.01.022. PMid:20421171.

67. De Mey K, Danneels L, Cagnie B, Cools AM. Scapular muscle rehabilitation exercises in overhead athletes with impingement symptoms: effect of a 6-week training program on muscle recruitment and functional outcome. Am J Sports Med. 2012;40(8):1906-15. http://dx.doi.org/10.1177/0363546512453297. PMid:22785606.

Correspondence Ann Cools University Hospital Ghent Department of Rehabilitation Sciences and Physiotherapy De Pintelaan 185, 2B3, B9000 Gent, Belgium e-mail: ann.cools@ugent.be

http://dx.doi.org/10.1590/bjpt-rbf.2014.0116

review article

340 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

A conceptual framework for a sports knee injury performance profile (SKIPP) and return to activity

criteria (RTAC)David Logerstedt1, Amelia Arundale2, Andrew Lynch3,4, Lynn Snyder-Mackler2,5

ABSTRACT | Injuries to the knee, including intra-articular fractures, ligamentous ruptures, and meniscal and articular cartilage lesions, are commonplace within sports. Despite advancements in surgical techniques and enhanced rehabilitation, athletes returning to cutting, pivoting, and jumping sports after a knee injury are at greater risk of sustaining a second injury. The clinical utility of objective criteria presents a decision-making challenge to ensure athletes are fully rehabilitated and safe to return to sport. A system centered on specific indicators that can be used to develop a comprehensive profile to monitor rehabilitation progression and to establish return to activity criteria is recommended to clear athletes to begin a progressive and systematic approach to activities and sports. Integration of a sports knee injury performance profile with return to activity criteria can guide clinicians in facilitating an athlete’s safe return to sport, prevention of subsequent injury, and life-long knee joint health. Keywords: lower extremity; limb symmetry; sports readiness; athletes.

HOW TO CITE THIS ARTICLE

Logerstedt D, Arundale A, Lynch A, Snyder-Mackler L. A conceptual framework for a sports knee injury performance profile (SKIPP) and return to activity criteria (RTAC). Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359. http://dx.doi.org/10.1590/bjpt-rbf.2014.0116

1 Department of Physical Therapy, University of the Sciences, Philadelphia, PA, USA2 Interdisciplinary Program in Biomechanics and Movement Science, University of Delaware, Newark, DE, USA3 Department of Physical Therapy, University of Pittsburgh, Pittsburgh, PA, USA 4 Center for Sports Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA, USA5 Department of Physical Therapy, University of Delaware, Newark, DE, USAReceived: Mar. 09, 2015 Revised: June 11, 2015 Accepted: June 18, 2015

IntroductionThe burden of musculoskeletal (MSK) injuries on

the health of our population is substantial as more than 110 million adults reported musculoskeletal injuries in 20081. MSK injuries are the leading cause of disability in the Unites States with annual direct and indirect costs totaling $950 billion2. MSK injuries can be the result of trauma, overuse, or a combination of acute on chronic injury leading to impaired function and reduced quality of life.

The knee is one of the most frequently injured joints in physically active individuals3-5. Many of these injuries, such as intra-articular fractures, ligamentous ruptures, and meniscal and articular cartilage injuries6, are traumatic in nature and occur during sports involving jumping, cutting, and pivoting7. Surgery for such knee injuries is common, totaling 984,607 arthroscopic knee surgeries performed in the US alone in 20068.

Traumatic knee injuries increase risk for the development of post-traumatic osteoarthritis (PTOA).

Individuals with a previous knee injury have a 56.8% lifetime risk of development of knee osteoarthritis (OA)9, resulting in activity limitations and participation restrictions. Furthermore, 13-18% of patients with total joint replacement report an identifiable traumatic injury to the joint10. Brown et al.11 estimated that 5.6 million individuals in the United States have PTOA, resulting in annual costs of $3.06 billion. Despite the short-term and long-term risks, many athletes desire to return to cutting and pivoting sports, which increases the risk of additional injuries.

Safe return to sports after a traumatic injury is the responsibility of all healthcare professionals involved. Despite best efforts, athletes returning to high-risk activity and demanding sports after a knee injury are at greater risk of sustaining a second injury. Many post-surgical rehabilitation guidelines are based solely on time from surgery and permit individuals to return to sports-specific activities between 4-9 months;

Sports knee injury performance profile

341 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

however, very few guidelines provide any objective criteria for assessing an athlete’s readiness12. The lack of clear objective criteria measuring patient function in sport-specific activities, and for returning to sports may place the injured athlete at risk for re-injury or suboptimal performance. Objective criteria are critical to ensure that athletes are fully rehabilitated and their knees are ready to meet the demands of their sport. Recovery of full function, return to prior activities, and long-term joint health are all goals of the athlete, surgeon, and physical therapist; yet there is little consensus to guide clinicians in facilitating an athlete’s safe return to sport, prevention of subsequent injury, and life-long knee joint health.

Currently, there is no system centered on specific indicators that can be used to develop a comprehensive profile to monitor rehabilitation progression and to compile all individualized data to standardize education about the risks of re-injury to the knee and the likelihood of returning to sports. The utilization of these profiles may provide a more accurate and complete representation of an athlete’s current status. The purpose of this paper is to build on the conceptual framework for the restoration of limb-to-limb symmetry in its role of secondary and tertiary knee injury prevention by 1) reviewing the epidemiology related to traumatic knee injuries, 2) identifying the risk factors that are associated with re-injury and poor knee function, 3) providing recommendations for objective measures utilizing limb-to-limb symmetry as a performance-based criteria for readiness to return to activity.

Epidemiology of traumatic knee injuriesPrevalence

While it is difficult to quantify the number of anterior cruciate ligament (ACL) injuries, recent estimates in the US have reported 81 per 100,000 individuals between the ages of 10 and 64 or about 250,000 per year13-15 with over 127,000 arthroscopic ACL reconstructions (ACLR)8. ACL surgeries account for 12.9% of all arthroscopic knee surgeries8. ACL injuries often are not isolated; 43-70% of those undergoing ACLR have meniscal lesions, 20-25% have cartilage lesions (about 5% full-thickness) and over 80% have bone bruises16-18.

Meniscal injuries are the fourth most common knee injury in high school athletes19. In 2006, medial and lateral meniscal surgeries were the first and third

most common arthroscopic surgeries, respectively8. In a six-year study encompassing approximately 9% of the US population under the age of 65, there were 387,833 meniscectomies, 23,640 meniscal repairs, and 84,927 ACLR with associated meniscal surgery. Over the six-year time frame, the number of meniscectomies decreased in favor of meniscal repairs20, a trend recommended by literature due to the impact on OA. Similar to ACL injuries, meniscal injuries are not common in isolation18.

Almost one million individuals are affected annually by articular cartilage injuries21,22. The prevalence of cartilage lesions in the general population is estimated between 5-11%, however in recreational and professional athletes the prevalence is 35%23 and higher in athletes participating in cutting and pivoting sports21,22. Upwards of 50% of adolescent athletes participating in cutting and pivoting sports undergoing knee surgery have articular cartilage injuries24, and when considering all patients undergoing knee arthroscopy, the prevalence is between 60-70%25-28. Small asymptomatic lesions left untreated can increase in size, resulting in a painful knee joint29. Thirty-two to 58% of articular cartilage lesions are the result of a traumatic, noncontact mechanism of injury25,29,30, and as might be expected, nearly three-quarters are concomitant with ACL injuries17,18. Articular cartilage damage after traumatic knee injuries increases the risk of cartilage degradation in all three knee compartments24. Consequently, articular cartilage damage is a strong risk factor for the development of osteoarthritis after knee surgeries31,32.

Failure/Re-injuryOverall, the risk of ACL injury in an athlete with

a history of ACLR is 15 times greater than that of a healthy athlete33, with an incidence of injury to either the contralateral or ipsilateral knee between 3 and 49%33,34. Athletes with allografts are five times more likely to require a revision compared to those with autografts35. There is no significant difference in second injuries between athletes with hamstring autografts and bone-patella-tendon-bone (BPTB) autografts; however, at 15-year follow-up, there were more ipsilateral injuries in the hamstring group and more contralateral injuries in the BPTB group36. Returning to cutting/pivoting sports increases the odds of ipsilateral injury 3.9 fold and contralateral 5 fold37. Furthermore, positive family history doubles the odds for both ipsilateral and contralateral rupture37. Injury

Logerstedt D, Arundale A, Lynch A, Snyder-Mackler L

342 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

side (contralateral vs ipsilateral) is associated with age and graft angle, respectively38.

Women with a history of ACL injury are at greater risk of a second ACL injury with 16-fold greater risk of injury compared to healthy controls and four times greater risk than men with a history of ACLR33. While most studies have reported an overall greater number of contralateral injuries compared to ipsilateral graft injuries33,38-40, women are six times more likely to suffer a contralateral injury33,40, whereas, men are three times more likely to injure their reconstructed graft36.

Younger athletes have greater rates of re-injury within 2 years of ACLR , with 17% of those under the age of 18 having a second ACL injury compared to 7% of those between 18 and 25, and only 4% of those over 2540. At three-year follow-up, 29% of those under the age of 20 had a second injury, the highest incidence of any age group37. When compared to the older age groups, the youngest age group had a six-fold increase in risk for ipsilateral and three-fold increase for contralateral injury37. Leys et al.36 calculated an odds ratio of 4.1 for contralateral injury in those under 18. In collegiate athletes, more athletes who had a primary ACLR prior to college went on to have a second injury compared to those who had their primary ACLR during college41.

Failure for all meniscal surgeries ranges from 20.2-24.3%, depending on the type of meniscal surgery and status of the ACL42. Athletes with meniscal repair and concomitant ACLR have a lower risk of revision for their meniscus injury43-45, suggesting that restoring passive knee stability reduces the incidence of further meniscal damage. Isolated lateral meniscal injury, earlier surgery, older age, and surgeons performing a high volume of meniscal repairs per year also decreases risk of revision43,44. Subsequent operation rates are greater for meniscal repairs compared to partial meniscectomies, greater for partial lateral meniscectomies compared partial medial meniscectomies, and greater for medial meniscus repairs compared to lateral meniscus repairs46.

After microfracture, those with a single defect have a lesser failure rate than individuals with multiple defects47. Those who had a prior surgery that penetrated the subchondral bone and marrow have a greater failure rate in autologous chondrocyte implantation (ACI) than those who have no history of surgery48. In a comparison of individuals who required multiple chondral surgeries, those who received ACI as a first line treatment had lesser failure rates and better International Knee Documentation Committee

2000 Subjective Knee Form (IKDC2000) scores compared to those who had microfracture as their first surgery. Despite a greater failure rate, however, the microfracture group still participated in the same amount of physical activity and at the same frequency and intensity as the ACI group49.

Return to sportIn a recent systematic review of outcomes after

ACLR, 88% of athletes returned to sport, 65% returning to their pre-injury level, and 55% returning to competitive play50. Athletes who had not returned to sport 12 months after surgery were just as likely to be playing 39 months after surgery as those who had returned to play at 12 months51. Self-reported function was different between those playing some sport and those who stopped all activity52. Five years after surgery, those who had not returned to sport have worse functional and self-report scores than those who had returned53.

Return to sport rates have been reported as high as 98% after meniscal surgery54. Even with concomitant grade III or IV articular surface lesions, 48% of individuals in their forties return to sport and 75% resume recreational activities55. In athletes under 40, nearly a quarter of those after medial meniscectomies and over half of those after lateral meniscectomies had pain at the time of return to sport; however, pain and swelling were not related to the size of the meniscal resection. In a five-year follow-up study of individuals younger than 45 years old, less than 25% modified their level of athletic participation after partial meniscectomy55. However, at 14 years after meniscal surgery, 46% reduced their sporting activity and 6.5% changed occupation as a result of their knees56. Seventy-five percent of soccer players after isolated meniscectomy were still playing soccer five years after surgery compared to 52% of those who had combined meniscectomy and ACLR. By the 20-year follow-up, 49% of the isolated meniscectomy group was still playing sports compared to 22% of meniscectomy+ACLR group57.

In recreational and amateur athletes, 66% return to sports in eight months after microfracture, with 67% of those eventually returning to a competition level. After 2-5 years however, 49% of athletes have reduced their level of play and 42% have poorer function58. In professional sports, return-to-play after microfracture has been studied in the National Football League (NFL) and National Basketball Association (NBA). Seventy-six percent of NFL

Sports knee injury performance profile

343 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

players59 and NBA players60,61 returned to play after microfracture. For most NBA athletes who returned, minutes played per game, points per game, and steals per game decreased compared to pre-surgery. There is conflicting data concerning length of NBA career after microfracture, with some finding no difference61 and others finding a decreased likelihood (-LR of 8.15) of continued participation60. Average return-to-sport rates in an athletic population after matrix-induced autologous chondrocyte implantation (MACI) is 74%62, osteochondral autologous transfer is 91%, and osteochondral allograft transplantation is 88%62,63. ACI is reported to allow the best longevity in sport, with 87% of patients after ACI able to maintain their ability to play at five years after surgery62.

Long-term impactA history of knee injury, regardless of type, places

an individual at a greater risk of subsequent injury. In a study of National Collegiate Athletic Association (NCAA) athletes, those with a history of knee surgery missed more days of sport, had a greater number of knee injuries, and received more magnetic resonance imaging (MRI) tests and surgeries than those athletes with no prior knee injury64. Former top-level male athletes with a history of knee injury have a nearly five-fold risk to develop OA65. Sports participation and history of ACL injury are both significant risk factors for the development of OA, but meniscal injury in combination with ACL injury may be one of the most potent combinations causing a ten-fold increase in risk compared to age-matched controls66,67.

Total knee arthroplasty and other reconstructive surgeries have advanced significantly in the last decade, allowing former athletes to remain active. However, at a rate of nearly 600,000 per year, with an expected increase to 3.5 million per year by 203068, it is imperative that efforts are made to prevent the need for such surgical procedures.

Risk factors for re-injury or suboptimal performance upon return to activities

In order to develop a system using rehabilitation indicators for profiling recovery after knee injury or surgery, an understanding of the non-modifiable and modifiable factors that can influence recovery or risk of re-injury is needed. A centralized portal that can track the longitudinal record of rehabilitation indicators can then be used as a means to define an athlete’s

recovery performance profile. Additionally, profiles can be utilized in establishing criteria to identify thresholds for safe return to sport. Furthermore, the profile can be used as a reference for any rehabilitation specialist interested in developing a similar recovery monitoring system.

Patient demographicsWhile patient demographics (e.g. age and sex) are

non-modifiable factors, understanding their relationship to re-injury and function can guide clinicians in monitoring and counseling athletes appropriately. Younger athletes with knee injuries typically return more frequently and earlier to sports than older athletes69,70. However, younger athletes (under the age of 25) are also more likely to suffer a second ACL injury after primary ACLR71-73.

Primary knee injury and subsequent 2nd knee injury may be sex-specific. While the incidence of injury to the ACL is greater in men due to the greater exposure to sports, women have a relative risk of injury two to eight times greater than men74,75. However, a recent meta-analysis found no difference between men and women in the risk of patellar tendon graft rupture (Odds ratio (95% confidence interval) = 0.76 (0.29, 2.09)), hamstring graft rupture (Odds ratio = 0.86 (0.53, 1.39)), or contralateral ACL rupture risk (Odds ratio = 0.58 (0.29, 1.17))76. Similarly, differences in patient-reported knee function do not appear to be sex-specific76, although women may return to less demanding activity levels after ACLR77,78.

Physical impairmentsRange of motion (ROM) symmetry is unique to the

individual; however, a knee extension loss of as little as 3o is associated with poor post-surgical, patient-reported outcomes and task-specific activities79-81. Knee ROM asymmetries are also associated with degenerative joint changes79,81.

Muscle strength deficits are pervasive after knee injury and surgery82-85. Muscle strength limb-to-limb symmetry has been proposed as an important marker for readiness to return to unrestricted sport86-89. Early after knee injury, specifically ACL injury, quadriceps strength deficits range from 12-15%90,91. Pre-operative quadriceps strength deficits are predictive of poor functional outcomes after ACLR92-94. The largest extent of quadriceps weakness occurs in the first six months after knee surgery92,95,96 and can be as great as 39-40%84,97-102. While hamstring strength deficits may be present after knee injury or surgery, these deficits

Logerstedt D, Arundale A, Lynch A, Snyder-Mackler L

344 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

do not influence clinical or functional outcomes103-105. However, the hamstrings-to-quadriceps ratio for torque production has been reported as a factor in primary ACL injury risk model106,107.

Quadriceps strength deficits can persist for months or years after any knee joint surgery, in spite of rehabilitation84,108. Consistent deficits in quadriceps strength have been found after surgery for the ACL, meniscus, and articular cartilage within the first year109, 2 years110,111, and up to 7 years112-114. Side-to-side deficits of more than 10% to 15% are considered significant and should be assessed throughout rehabilitation, and even into the second and third post-operative seasons109-114.

Quadriceps strength asymmetry can also be reflected in other impairment measures. Quadriceps index (QI) is expressed as a percentage of the peak value of the quadriceps muscles on the involved side divided by the peak value of the quadriceps muscles on the uninvolved side. After ACLR, those with QI less than 85% have worse hop scores than those with a QI greater than 90% or controls. QI is a better predictor of hop test distance than graft type, presence of meniscal injury, knee pain, or knee symptoms115. After meniscectomy, particularly in middle-aged athletes, greater quadriceps strength is associated with better self-reported knee joint function on all five subscales of the Knee Injury and Osteoarthritis Outcome Score (KOOS)116. The KOOS is a knee-specific, patient-reported instrument for knee injuries that can lead to post-traumatic osteoarthritis. The form includes 42 items in five separately scored subscales: Pain (9 items); other symptoms (7 items); function in activities of daily living (ADLs; 17 items); function in sport and recreation (Sports; 5 items); and knee-related quality of life (QoL; 4 items)117. Individuals, two years after meniscectomy, continued to have a mean 6% asymmetry in strength and scored between 10 and 26 points worse on all five KOOS subscales compared to controls118.

Balance and postural deficits have been reported after knee injury, and in particular, after ACL injury and reconstruction. Various assessments have been used to evaluate risk of injury, current status, and the magnitude of improvement after an intervention119. While static postural tasks may provide useful clinical information, dynamic postural tasks may provide a more accurate representation of sporting activities. Some of these tasks may be simple, such as the Star Excursion Balance Test and Y-Balance tests119, while others require instrumented equipment120,121. Though some authors have tried quantifying limb symmetry for postural deficits, evidence is limited122.

Performance-based measuresPerformance-based measures can be used to assess

a combination of muscle strength, neuromuscular control, confidence in the injured limb, and ability to complete sport-specific activities123. Many drills and performance-based measures are double-legged tasks; however, the performance may mask persistent deficits in the injured lower extremity124. Therefore, single-legged tasks should be used after knee injuries to detect side-to-side differences, evaluate function, monitor progress of rehabilitation, and assess readiness for return to sports123,125-128. Single-legged hop tests measure distance, time, or height and typically involve multi-movement patterns (i.e. multi-planar directions, change of direction, acceleration-deceleration, etc.) that attempt to resemble athletic movements and may prepare patients for return to sporting activities129-132.

Side-to-side limb symmetry appears to have a critical role in the prevention of injury and return to sports after knee injuries. Varying performance standards (i.e. muscle strength or hop performance), ranging from 70% to 90% limb symmetry index (LSI), have been suggested as benchmarks for determining normal symmetry86,125,132-134. However, this range provides health care professionals no indication of an expected standard or a timeline on which they should be achieved.

Early after injury or surgery, individuals have poor single-legged hop LSI and substantial limb-to-limb differences83,123,129. Performance deficits on single-legged hop tests range from 5-35% with up to 47% of athletes not achieving normal limb symmetry (85-90% LSI) six months after surgery83,85,129,135. By 12 months, the average LSI is greater than 90%, and by 24 months, individuals are able to maintain normal hop symmetry83,85,136. LSI calculated from the cross-over hop for distance and 6-meter timed single-legged hop tests can also predict self-reported knee function at one year after ACLR. Poor LSI can predict poor knee function, while normal LSI can predict normal knee function137,138. Athletes six months after ACLR with an LSI less than 88% for the 6-meter timed hop were five times more likely to rate themselves below normal ranges on the IKDC2000 one year after ACLR, whereas athletes with an LSI greater than 95% on the cross-over hop six months after ACLR were four times more likely to rate themselves within normal ranges on the IKDC2000 one year after ACLR138. Despite improvements in single-legged hop performance and symmetry in the first year after ACLR83,129, athletes two years after surgery have greater asymmetries in single-legged

Sports knee injury performance profile

345 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

hop distances when compared to controls139. Poor LSI and large limb-to-limb differences prior to seven months after ACLR reconstruction can be a concern, as most post-surgical rehabilitation guidelines enable individuals to return to sports-specific activities between 4 to 6 months140,141. It is likely that sports-specific activities are more challenging than landing from a planned hop in a controlled environment, thus the deficits seen in single-legged hop performance may be magnified, potentially predisposing the ipsilateral or contralateral knee to injury. Because hop testing assesses current knee function, individuals with poor LSI may exhibit suboptimal performance on the playing field and may be placed at greater risk for injury88,142,143.

When comparing individuals after ACI and after microfracture, those after ACI have greater single hop asymmetry than those after microfracture six and twelve months after surgery. However, there is no difference between the groups in cross-over or 6-meter timed hop tests at six and twelve months. At 24 months, the microfracture groups had minimal asymmetry in hop performance (4-8% asymmetry), while the ACI group had larger asymmetries (10-17% asymmetry) on all three hop tests111 .

SymptomsPersistent symptoms, such as knee pain, joint

swelling, stiffness, instability, or weakness, are common reasons many athletes cite for not returning to preinjury activity levels69. While pain may be a potential indicator of incomplete healing144, it typically resolves after knee injury and/or surgery. One year after ACLR, athletes who had not returned to sports reported an average pain intensity of 1.0±1.1 out of 10 (0=no pain, 10=worst imaginable pain)145. Upon returning to sport after meniscectomy, pain and effusion can persist and should be monitored70. Pain can have a role in the decision-making process for allowing athletes to safely return to sports, but it should not be the sole determinant. Pain and effusion can be reliably monitored using a pain-monitoring scale146, soreness guidelines147, and the modified stroke test148.

Joint effusion is an over-accumulation of fluid within the joint capsule, indicating inflammation or irritation148. Joint effusion can be helpful in establishing a diagnosis, determining exercise progression, and monitoring progress. The presence of effusion can impair adjacent muscle function and alter knee motion149,150. The presence of no effusion is also a significant contributor for the likelihood of return to

sports one year after ACLR145. Monitoring of joint effusion can be practically, reliability, and clinically useful. The modified stroke test and effusion grading scale offers an objective means of measuring and assessing knee joint effusion148. This modified stroke test is performed by sweeping fluid proximally out of the medial sulcus of the knee, and then performing a distally directed sweep along the lateral knee and watching for a wave of fluid returning to the medial sulcus148. An increase in effusion following treatment that does not return to baseline likely indicates that treatment progression was too aggressive. Furthermore, individuals should be able to demonstrate the ability to tolerate lower loading demands without pain or swelling before progressing to higher loads.

Symptomatic knee joint instability (giving way) is a hallmark of knee joint injury. Giving way episodes are usually described as buckling at the knee similar to the initial injury. While the magnitude of passive ligament instability is poorly associated with functional ability in ACL-deficient athletes151-153, dynamic knee stability may be more relevant. Subsequently, the absence of episodes of knee instability was a significant contributor (Wilks’ λ=0.357) for the likelihood of return to sports one year after ACLR145. Recurrent episodes of instability may be an indicator of undiagnosed concomitant injuries (other ligamentous structures, meniscus) and can potentially increase the likelihood of further joint damage25.

Gait asymmetryWhile the measurement of movement using motion

capture is not considered a typical rehabilitation indicator, it does provide additional insight on the ubiquity of asymmetries seen after knee injury and surgery. Side-to-side asymmetrical movement patterns after knee injury are common and can persist for months or years after injury or surgery154. Additionally, these altered movement patterns are not limited to the index knee. Neuromuscular adaptations are present in the hip and ankle and contralateral limb after knee injury and surgery as well as during gait and higher-demand tasks, such as jumping154-157. Underlying neuromuscular imbalances on the operated and non-operated limbs at the time of return to sport clearance are highly predictive of 2nd ACL injury158.

Even two years after ACLR, Roewer et al.108 found that the involved limb had smaller knee excursion and internal knee extension moments compared to the uninvolved limb at weight acceptance. Gait asymmetries after ACLR are associated with poor

Logerstedt D, Arundale A, Lynch A, Snyder-Mackler L

346 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

quadriceps strength and functional performance. At peak knee flexion, those with a QI less than 90% have a smaller knee flexion angle and significantly decreased internal knee extension moment compared to controls159. QI alone accounts for more than a quarter of variance in angle at peak knee flexion, and QI and KOS-ADLS accounts for 60% of variance in internal knee extension moment159. Broadening the criteria to include QI, single-legged hop LSI, KOS-ADLS, and GRS, those who scored less than 90% on any one of these measures had greater knee kinematic and kinetic asymmetries than those who scored greater than 90% on all criteria and had clinically significant limb-to-limb asymmetry in hip flexion at peak knee flexion160.

In higher-risk tasks such as jumping, women two years after ACLR demonstrate limb-to-limb asymmetries. Higher vertical ground reaction force and loading rate is seen on the uninvolved limb during landing compared to both the involved limb and controls161. During takeoff, women also show lower force generation on the involved side compared to the uninvolved side161. Both men and women after ACLR have smaller internal knee extension moments on the involved limb during lateral step-down and vertical jump take-off and landing when compared to the uninvolved limb and to controls162. The results of these studies and similar research highlight the need to resolve impairments and restore functional limb symmetry after ACLR.

Gait asymmetries have been noted following meniscal surgery. Smaller peak knee flexion angles and lower peak external moments in the sagittal plane and larger knee adduction moments have been observed in the involved limb compared to the uninvolved limb after partial meniscectomy and compared to controls163. Asymmetry may be worse in individuals with weaker quadriceps after partial meniscectomy. Increased average and peak external knee adduction moments throughout stance phase have been observed in patients after meniscectomy with weaker quadriceps compared to those patients after meniscectomy with normal strength and controls164. Bulgheroni et al.165 found that those after medial meniscectomy had decreased external hip extension moment during all phases of gait and increased external knee flexion moment at loading response, push off, and throughout swing. They also had increased hip and knee flexion and increased ankle dorsiflexion in late swing phase165.

After ACI surgery, aberrant movement patterns are present, specifically reduced knee motion during

weight acceptance and decreased external sagittal plane moments. These aberrant patterns can persist for months157,166, and alter joint loading167-169. Gait deviations may promote further cartilage damage through reduced shock absorption and increased joint loading170,171, predisposing the knee to degenerative changes167,172.

Patient-reported outcomesPatient-reported outcome (PRO) measures are

self-report questionnaires that measure an individual’s perception of daily life and physical activity173,174. PROs show a greater relationship to on patient satisfaction than standard clinical measures175. PROs specific to the knee joint contain items to assess symptoms (i.e. pain, swelling, giving ways, etc.) and activity limitations (i.e. ambulation, stair climbing, running, etc.)176. PROs are clinically useful in comparing the results of interventions on patient perspective after injury175,177. Performance-based measures capture different domains of function than PROs125,178. Performance-based measures assess the actual functional ability of an athlete, whereas, PROs assess the perceived ability of aspects considered important by patients with knee problems, ranging from stair climbing to running and jumping. Therefore, a combination of outcome measures is likely necessary to provide a comprehensive evaluation of functional success178,179.

Knee performance and self-reported function generally improve over the first year after ACLR83. By six months after surgery, almost half of individuals score greater than 90% on Knee Outcome Survey-Activities of Daily Living Scale (KOS-ADLS) and Global Rating Scale of Perceived Function (GRS), and 78% have achieved these scores by 12 months180. Poor self-report on outcome measures after ACLR are associated with chondral injury, previous surgery, return to sport, and poor radiological grade in ipsilateral medial compartment181. ACLR revision and extension deficits at 3 months are also predictors of poor long-term, patient-reported outcomes17,182.

The various surgical techniques for articular cartilage defects vary in their self-reported outcomes. Pooled data indicates that 67% of individuals report normal IKDC2000 one year after microfracture, and 80% of individuals have significant increases from pre-surgery in Lysholm, Tegner, and KOOS sports subscale scores183. While these patients have made significant improvements in their self-reported function, a large proportion of them continue to report function below normal levels. Four years after microfracture, the

Sports knee injury performance profile

347 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

KOOS-ADL subscale, Marx Activity Rating Scale, and Tegner Score decreased in 47% of athletes, but despite this decrease in self-report, 44% were still able to regularly participate in pivoting sports, and 57% of those at their pre-operative level184. In a 15-year longitudinal study, IKDC2000, Lysholm, and Tegner scores decreased over the course of the study; however, they were still better at 15 years after surgery than at baseline before surgery185. After osteochondral allograft transplantation for large chondral or osteochondral defects, athletes who returned to sport had better IKDC2000, KOOS, and Marx Activity Rating Scale scores186. Kreuz et al.187 compared inactive/rarely active individuals to active individuals after autologous chondrocyte implantation (ACI). Pre-operatively, there were no differences between groups, but at 6, 12, and 36 months after surgery, the active group had significantly better International Cartilage Repair Society (ICRS) and Cincinnati Knee Rating System scores compared to the inactive/rarely active group187. All five KOOS subscales increase over the course of the first one to two years after MACI and improvements are maintained five years after surgery. Improvements in IKDC2000, modified Cincinnati Knee Rating System, Tegner, Lysholm, and Short Form-36 (SF36) scores as well as knee extension range of motion continue to gradually improve over the first five years following MACI188,189.

Decision-making considerations and the importance of symmetry

Determining when a patient is performing well enough to safely and effectively return to play or activity is a complex decision that must take into account the risk factors for re-injury or poor function. Meeuwisse et al.190 has proposed a model that integrates the risk of the athlete within a dynamic sporting environment, considering both intrinsic and extrinsic factors that lead to different injury events and their variability. The remainder of this commentary outlines a proactive decision-making model that measures changes in intrinsic and extrinsic factors and can be predictive, preventative, personalized, and participatory. This model can provide rehabilitation specialists crucial data pertinent to patients’ current knee function, their progress during rehabilitation, the necessity for additional rehabilitation, and their readiness to return to sporting activities.

Creighton et al.144 has proposed a decision-based return-to-play model that involves three steps. Step 1 is

an evaluation of health status that focuses on type and severity of the injury, clinical or physical signs and symptoms, functional performance, and psychological state. Step 2 evaluates the risk of sport participation from the type of sport, competition level, or position played to the use of protective equipment. Step 3 or decision-modification step frequently involves nonmedical factors, such as timing and season of the sport, external pressures to compete, and legal implications. For this review, we will focus on the components highlighted in Step 1 (Evaluation of Health Status) as these are likely the medical/clinical risk factors that can be modified by the clinician. The medical/clinical variables that are frequently associated with return to activities or sports include demographic factors, physical impairments, activity limitations, psychological factors, and patient-reported scores145,191,192.

Limb-to-limb symmetry or limb symmetry indexes are used after injury or surgery as important indicators of physical impairments, activity limitations, and function. They are also used to monitor the progress of rehabilitation and to assess readiness for return to activity or sports, therefore they should be benchmarked against performance standards. Unfortunately, no empirically based benchmarks or expert consensus benchmarks exist regarding performance standards at specific time points after knee injury. Development of standards can provide relevant information about patient performance and can help to determine if additional interventions are needed to achieve this level.

Profiling and monitoring recovery of athletes after knee injury or surgery

Injury to the meniscus, cartilage, or ligaments of the knee results in a fairly consistent clinical presentation and an increase in the risk for post-traumatic osteoarthritis. Creating a profile of these individuals is important to promote a comprehensive evaluation of the patient to eliminate basic impairments after surgery and to facilitate a safe and effective return to sport process that minimizes the risk for second injury. Additionally, using a consistent set of measures at consistent time frames allows for assessment of trends in patient outcomes.

One of the challenges in developing an injury risk profile for post-injury or post-operative management has been to select appropriate clinical or field tests that can detect side-to-side asymmetries, assess global knee function, and determine a patient’s readiness to

Logerstedt D, Arundale A, Lynch A, Snyder-Mackler L

348 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

return to sport. Batteries of tests have been developed to predict the risk for musculoskeletal injuries193, classify individuals early after ACL injury194, and identify important limb asymmetries after ACL injury and reconstruction195,196. One battery of performance-based tests was moderately correlated with the IKDC2000 and could discriminate between the operated and non-operated limbs of patients after ACLR197. However, very few studies incorporate performance-based and patient-reported outcomes into the clinical decision making to fully evaluate a patient’s knee function12,198. Clinical impairments, performance-based measures, and patient-reported outcomes capture different aspects of overall knee performance and are important indicators of function125,199-201. Therefore, a battery of tests utilizing performance-based and patient-reported outcomes can provide clinically relevant data applicable to current knee function, progress throughout rehabilitation and the necessity for additional targeted interventions, and their readiness to return to sporting activities.

Sports knee injury performance profileWhile many different tests and measures are available

for functional testing202,203, the Sports Knee Injury Performance Profile (SKIPP) is a battery of tests and measures consisting of thigh muscle strength testing, single-legged hop testing, and patient-reported outcome measures. The data included in the SKIPP have not been independently validated; however, that process is ongoing. Prior to performing the battery of tests, athletes should exhibit a minimum criteria of little to no joint effusion, full active range of motion, normal gait pattern upon visual observation, and ability to hop in place on a single leg without pain.

Quadriceps and hamstring strength can be tested using isokinetic peak torque or maximal voluntary isometric contraction (MVIC). Peak force or torque values achieved during strength testing bilaterally are recorded and used to calculate a quadriceps index (QI) or hamstrings index (HI). QI is expressed as a percentage of the peak value of the quadriceps muscles on the involved side divided by the peak value of the quadriceps muscles on the uninvolved side. Hamstrings index is expressed similarly.

Following quadriceps strength testing, participants perform single-legged hop tests. Four single-legged hop tests are used in our clinic: single hop for distance (single hop); cross-over hop for distance (cross-over hop); triple hop for distance (triple hop); and 6-meter timed hop132. A hop score for each test is calculated as the average of the two recorded trials. For the

single hop, cross-over hop, and triple hop LSI, these LSIs are expressed as the percentage performance on the involved side compared to the uninvolved side. For the 6-meter timed hop, the 6-meter timed hop LSI is expressed as the percentage performance of the uninvolved side compared to the involved side, given that faster times (low numbers) are better for this hop test.

Following hop testing, participants complete self-report questionnaires: KOS-ADLS, GRS, IKDC2000, and the ACL-Return to Sports after Injury (ACL-RSI). The KOS-ADLS is a 14-item patient-reported outcome of symptoms and functional limitations of the knee during ADLs204. Patients must be able to perform their ADLs at a normal level prior to attempting a return to sports, otherwise they are likely to report having difficulty with sporting activities and placing themselves at risk for subpar performance and re-injury. The GRS asks participants to rate their current knee function on a scale from 0 to 100, with 0 being the inability to perform any activity and 100 being the level of knee function prior to the injury, including sports204,205. The IKDC2000 is a frequently used assessment of function206 and can differentiate between individuals with low versus high knee function207. The published IKDC2000 normative dataset207 provides a reference standard for normal knee function (Table 1)137,138.

ACL-RSI is a 12-item patient-reported outcome of emotions, confidence in performance, and risk appraisal after ACLR. It can discriminate psychological differences between athletes who returned to sports and those who did not return to sports208,209. The data collected from this battery of tests can be used as a set of performance indicators that can detect side-to-side asymmetries, assess global knee function, and determine a patient’s readiness to return to sport. This permits the clinician to visualize and appreciate the dynamic profile of the injured athlete and aids the clinician in decision making about readiness to return to activity and in the formulation of targeted, personalized interventions to overcome performance barriers and optimize sports performance.

Recommendations for return to activity criteria

The rehabilitation indicators from the SKIPP can be used to determine readiness to return to activities or sports – an improvement over the current time-based rehabilitation protocols. No functional test battery for return to sports has been validated to identify cutoffs which reduce the risk of injury to this

Sports knee injury performance profile

349 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

point. Despite impairments, activity restrictions, poor self-report scores, and limb-to-limb asymmetries, many post-surgical rehabilitation guidelines permit individuals to return to sports-specific activities between three to nine months after surgery, depending on the lesion and surgical technique. However, the use of a time-based approach does not adequately account for these deficits210. A majority of clinicians continue to use a time-based approach and passive stability measures to allow return to play after ACLR211. A recent systematic review noted that only one or two criteria (muscle strength and single-leg hop test) have been used as objective measures for resuming play in the majority of studies12. In studies that did use objective measurable criteria, none provided cutoffs for their criteria that have been validated for normal knee function, successful return to activities, or re-injury rates12,211,212. Objective, measurable criteria are critical to ensure that athletes are fully rehabilitated and their knees are ready to meet the demands of their activities or sport.

Recently, two paradigms of return to activity criteria have been proposed by the European Board of Sports Rehabilitation and the University of Delaware as recommendations to clear athletes to begin a progressive and systematic approach to activities and sports89,194. The European Board of Sports Rehabilitation have developed a set of criteria using performance-based measures prior to athletes returning to activities or sport after ACLR89. Their recommendations are categorized based on type of activity: activities that are pivoting, contact, or competitive and activities that are non-pivoting, non-contact, or recreational. For the pivoting/contact/competitive group, they recommend that involved limb knee extensor and knee flexor muscle strength performance be equal to 100% of the uninvolved limb (100% LSI) and that involved limb hop performance on two maximum hop tests (e.g. single hop for distance, vertical hop, etc.) and one endurable hop test (e.g. triple hop, stair hop, side hop, etc.) be at least 90% of the uninvolved limb (90% LSI). For the non-pivoting/non-contact/recreational group, they recommend that involved limb knee extensor and knee flexor muscle strength performance be at least 90% of the uninvolved limb (90% LSI) and that involved limb hop performance on one maximum or one endurable hop tests be at least 90% of the uninvolved limb (90% LSI). These recommendations take into account both knee extensor and knee flexor strength and hop performance; however, one limitation of these recommendations is the omission of the use of

PROs as criteria for return to activity. As stated before, PROs do not correlate highly with performance-based measures, but capture different aspects of knee function. It has been suggested that both performance-based measures and PROs are needed to fully characterize an athlete’s knee function83.

The University of Delaware has instituted return to activity criteria and used them for over 15 years194. Functional testing to determine return to activity criteria includes performance-based and PRO measures from the SKIPP. These criteria are sensitive to knee functional changes over time and can provide clinicians with clinically relevant information about patients’ responses to different therapeutic interventions83. To pass return to activity, participants were required to achieve 90% or greater on each of the functional tests and measures from the battery of tests (QI, 4 hop LSIs, KOS-ADLS, and GRS) (Figure 1)86,194.

Work from our laboratory has demonstrated that the University of Delaware Return to Activity Criteria (RTAC) can accurately discern between two differently functioning cohorts of athletes after ACL injury or reconstruction. The RTAC demonstrated that participants who successfully returned to high-level activity after non-operative management of an ACL injury had less than a 10% deficit on their baseline scores on average194. Athletes who fail our RTAC six months after ACLR exhibit greater limb-to-limb movement asymmetries than those who pass our RTAC69. Six and 12 months after ACL surgery, poor IKDC2000 function scores were reasonably indicative of RTAC test battery failure, whereas normal IKDC2000 scores were not predictive of passing scores on the RTAC test battery138. Additionally, those athletes who demonstrated limb-to-limb movement symmetry and self-reported knee function 6 months after ACLR are more likely to return to their preinjury activity level 12 months after ACLR213. The results of these studies highlight the importance of using performance-based and patient-reported measures to identify participants with poor knee function and limb-to-limb movement asymmetry before clearing them to return to high-demand activities. The use of these RTAC can be used early after any knee injury or surgery to assess residual deficits that needed to be resolved prior to attempting a return to high-risk sporting activities.

The validation of the RTAC to determine safe and optimal return to activities or to predict future injuries is ongoing. Several clinical variables have been identified with returning to sports145,191,192,198;

Logerstedt D, Arundale A, Lynch A, Snyder-Mackler L

350 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

however, none have been studied to predict future injury154,214. Further research is needed to identify if the tests in the SKIPP and the criteria for the RTAC can accurately identify which athletes are more likely to return to activities and which ones are more likely to sustain a second injury.

ConclusionsKnee injuries are common in sports. Despite

the advances made in surgical techniques and rehabilitation interventions, return to sport rates are poorer than previously thought, and the risk of re-injury or failure after knee surgery is greater than expected. The development of the Sports Knee

Injury Performance Profile allows the clinician to consistently monitor knee function, track progress throughout rehabilitation, and incorporate targeted, personalized interventions to achieve optimal sports performance and function while potentially reducing the risk of re-injury or failure. The implementation of established return to activity criteria provides a platform to ensure that athletes are fully rehabilitated and can begin to introduce loads needed to participate in their sport or activities. Consistent implementation of this profile will allow clinicians to track individual patient progress and to assess trends in their patients over time.

References1. Jacobs JJ, Andersson GB, Bell J, Weinstein SL, Dormans

JP, Gnatz SM, et al. The burden of musculoskeletal diseases in the United States. Rosemont: American Academy of Orthopaedic Surgeons; 2008.

2. Yelin EH. Medical expenditures panel survey 1996-2006. Rockville: Agency for Healthcare Research and Quality; 1996.

3. Gage BE, McIlvain NM, Collins CL, Fields SK, Comstock RD. Epidemiology of 6.6 million knee injuries presenting to United States emergency departments from 1999 through 2008. Acad Emerg Med. 2012;19(4):378-85. http://dx.doi.org/10.1111/j.1553-2712.2012.01315.x. PMid:22506941.

Table 1. IKDC2000 cutoff scores for normal ranges for age- and sex-specific groups215.

Age Group Normal IKDC2000 cutoff

18-24 Men: 89.7Women: 83.9

25-34 Men: 86.2Women: 82.8

35-50 Men: 85.1Women: 78.5

51-65 Men: 74.7Women: 69.0

Figure 1. Algorithm for passing return to activity criteria.

Sports knee injury performance profile

351 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

4. Ingram JG, Fields SK, Yard EE, Comstock RD. Epidemiology of knee injuries among boys and girls in US high school athletics. Am J Sports Med. 2008;36(6):1116-22. http://dx.doi.org/10.1177/0363546508314400. PMid:18375784.

5. Powell JW, Barber-Foss KD. Injury patterns in selected high school sports: a review of the 1995-1997 seasons. J Athl Train. 1999;34(3):277-84. PMid:16558577.

6. Buckwalter JA, Saltzman C, Brown T. The impact of osteoarthritis: implications for research. Clin Orthop Relat Res. 2004;427(Suppl):S6-15. http://dx.doi.org/10.1097/01.blo.0000143938.30681.9d. PMid:15480076.

7. Griffin LY, Agel J, Albohm MJ, Arendt EA, Dick RW, Garrett WE, et al. Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg. 2000;8(3):141-50. PMid:10874221.

8. Kim S, Bosque J, Meehan JP, Jamali A, Marder R. Increase in outpatient knee arthroscopy in the United States: a comparison of National Surveys of Ambulatory Surgery, 1996 and 2006. J Bone Joint Surg Am. 2011;93(11):994-1000. http://dx.doi.org/10.2106/JBJS.I.01618. PMid:21531866.

9. Murphy L, Schwartz TA, Helmick CG, Renner JB, Tudor G, Koch G, et al. Lifetime risk of symptomatic knee osteoarthritis. Arthritis Rheum. 2008;59(9):1207-13. http://dx.doi.org/10.1002/art.24021. PMid:18759314.

10. Kern D, Zlatkin MB, Dalinka MK. Occupational and post-traumatic arthritis. Radiol Clin North Am. 1988;26(6):1349-58. PMid:3051099.

11. Brown TD, Johnston RC, Saltzman CL, Marsh JL, Buckwalter JA. Posttraumatic osteoarthritis: a first estimate of incidence, prevalence, and burden of disease. J Orthop Trauma. 2006;20(10):739-44. http://dx.doi.org/10.1097/01.bot.0000246468.80635.ef. PMid:17106388.

12. Barber-Westin SD, Noyes FR. Objective criteria for return to athletics after anterior cruciate ligament reconstruction and subsequent reinjury rates: a systematic review. Phys Sportsmed. 2011;39(3):100-10. http://dx.doi.org/10.3810/psm.2011.09.1926. PMid:22030946.

13. Griffin LY, Agel J, Albohm MJ, Arendt EA, Dick RW, Garrett WE, et al. Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies. J Am Acad Orthop Surg. 2000;8(3):141-50. PMid:10874221.

14. Frobell RB, Lohmander LS, Roos HP. Acute rotational trauma to the knee: poor agreement between clinical assessment and magnetic resonance imaging findings. Scand J Med Sci Sports. 2007;17(2):109-14. PMid:17394470.

15. Frobell RB, Roos HP, Roos EM, Hellio Le Graverand MP, Buck R, Tamez-Pena J, et al. The acutely ACL injured knee assessed by MRI: are large volume traumatic bone marrow lesions a sign of severe compression injury? Osteoarthritis Cartilage. 2008;16(7):829-36. http://dx.doi.org/10.1016/j.joca.2007.11.003. PMid:18206394.

16. Røtterud JH, Sivertsen EA, Forssblad M, Engebretsen L, Arøen A. Effect of meniscal and focal cartilage lesions on patient-reported outcome after anterior cruciate ligament reconstruction: a nationwide cohort study from Norway and Sweden of 8476 patients with 2-year follow-up. Am J Sports Med. 2013;41(3):535-43. http://dx.doi.org/10.1177/0363546512473571. PMid:23371474.

17. Cox CL, Huston LJ, Dunn WR, Reinke EK, Nwosu SK, Parker RD, et al. Are articular cartilage lesions and meniscus tears predictive of IKDC, KOOS, and Marx activity level outcomes after anterior cruciate ligament reconstruction? A 6-year multicenter cohort study. Am J Sports Med. 2014;42(5):1058-67. http://dx.doi.org/10.1177/0363546514525910. PMid:24647881.

18. Lewis DW, Chan D, Fisher O, Lechford R, Mintowt-Czyz WJ, Lewis MWD. Incidence of meniscal and chondral injuries at the time of ACL reconstruction, and their relationship with outcome at 2 years. J Bone Joint Surg Br. 2012;94-B(Supp IX):41.

19. Swenson DM, Collins CL, Best TM, Flanigan DC, Fields SK, Comstock RD. Epidemiology of knee injuries among U.S. high school athletes, 2005/2006-2010/2011. Med Sci Sports Exerc. 2013;45(3):462-9. http://dx.doi.org/10.1249/MSS.0b013e318277acca. PMid:23059869.

20. Abrams GD, Frank RM, Gupta AK, Harris JD, McCormick FM, Cole BJ. Trends in meniscus repair and meniscectomy in the United States, 2005-2011. Am J Sports Med. 2013;41(10):2333-9. http://dx.doi.org/10.1177/0363546513495641. PMid:23863849.

21. Arøen A, Løken S, Heir S, Alvik E, Ekeland A, Granlund OG, et al. Articular cartilage lesions in 993 consecutive knee arthroscopies. Am J Sports Med. 2004;32(1):211-5. http://dx.doi.org/10.1177/0363546503259345. PMid:14754746.

22. Curl WW, Krome J, Gordon ES, Rushing J, Smith BP, Poehling GG. Cartilage injuries: a review of 31,516 knee arthroscopies. Arthroscopy. 1997;13(4):456-60. http://dx.doi.org/10.1016/S0749-8063(97)90124-9. PMid:9276052.

23. Flanigan DC, Harris JD, Trinh TQ, Siston RA, Brophy RH. Prevalence of chondral defects in athletes’ knees: a systematic review. Med Sci Sports Exerc. 2010;42(10):1795-801. http://dx.doi.org/10.1249/MSS.0b013e3181d9eea0. PMid:20216470.

24. Piasecki DP, Spindler KP, Warren TA, Andrish JT, Parker RD. Intraarticular injuries associated with anterior cruciate ligament tear: findings at ligament reconstruction in high school and recreational athletes. An analysis of sex-based differences. Am J Sports Med. 2003;31(4):601-5. PMid:12860552.

25. Logerstedt DS, Snyder-Mackler L, Ritter RC, Axe MJ, Godges J. Knee pain and mobility impairments: meniscal and articular cartilage lesions. J Orthop Sports Phys Ther. 2010;40(6):A1-35. http://dx.doi.org/10.2519/jospt.2010.0304. PMid:20511698.

26. Hjelle K, Solheim E, Strand T, Muri R, Brittberg M. Articular cartilage defects in 1,000 knee arthroscopies. Arthroscopy. 2002;18(7):730-4. http://dx.doi.org/10.1053/jars.2002.32839. PMid:12209430.

27. Curl WW, Krome J, Gordon ES, Rushing J, Smith BP, Poehling GG. Cartilage injuries: a review of 31,516 knee arthroscopies. Arthroscopy. 1997;13(4):456-60. http://dx.doi.org/10.1016/S0749-8063(97)90124-9. PMid:9276052.

28. Arøen A, Løken S, Heir S, Alvik E, Ekeland A, Granlund OG, et al. Articular cartilage lesions in 993 consecutive knee arthroscopies. Am J Sports Med. 2004;32(1):211-5. http://dx.doi.org/10.1177/0363546503259345. PMid:14754746.

29. Widuchowski W, Widuchowski J, Trzaska T. Articular cartilage defects: study of 25,124 knee arthroscopies.

Logerstedt D, Arundale A, Lynch A, Snyder-Mackler L

352 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

Knee. 2007;14(3):177-82. http://dx.doi.org/10.1016/j.knee.2007.02.001. PMid:17428666.

30. Johnson-Nurse C, Dandy DJ. Fracture-separation of articular cartilage in the adult knee. J Bone Joint Surg Br. 1985;67(1):42-3. PMid:3968141.

31. Keays SL, Newcombe PA, Bullock-Saxton JE, Bullock MI, Keays AC. Factors involved in the development of osteoarthritis after anterior cruciate ligament surgery. Am J Sports Med. 2010;38(3):455-63. http://dx.doi.org/10.1177/0363546509350914. PMid:20051501.

32. Li RT, Lorenz S, Xu Y, Harner CD, Fu FH, Irrgang JJ. Predictors of radiographic knee osteoarthritis after anterior cruciate ligament reconstruction. Am J Sports Med. 2011;39(12):2595-603. http://dx.doi.org/10.1177/0363546511424720. PMid:22021585.

33. Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of contralateral and ipsilateral anterior cruciate ligament (ACL) injury after primary ACL reconstruction and return to sport. Clin J Sport Med. 2012;22(2):116-21. http://dx.doi.org/10.1097/JSM.0b013e318246ef9e. PMid:22343967.

34. Lind M, Menhert F, Pedersen AB. The first results from the Danish ACL reconstruction registry: epidemiologic and 2 year follow-up results from 5,818 knee ligament reconstructions. Knee Surg Sports Traumatol Arthrosc. 2009;17(2):117-24. http://dx.doi.org/10.1007/s00167-008-0654-3. PMid:18974970.

35. Ellis HB, Matheny LM, Briggs KK, Pennock AT, Steadman JR. Outcomes and revision rate after bone-patellar tendon-bone allograft versus autograft anterior cruciate ligament reconstruction in patients aged 18 years or younger with closed physes. Arthroscopy. 2012;28(12):1819-25. http://dx.doi.org/10.1016/j.arthro.2012.06.016. PMid:23102671.

36. Leys T, Salmon L, Waller A, Linklater J, Pinczewski L. Clinical results and risk factors for reinjury 15 years after anterior cruciate ligament reconstruction: a prospective study of hamstring and patellar tendon grafts. Am J Sports Med. 2012;40(3):595-605. http://dx.doi.org/10.1177/0363546511430375. PMid:22184280.

37. Webster KE, Feller JA, Leigh WB, Richmond AK. Younger patients are at increased risk for graft rupture and contralateral injury after anterior cruciate ligament reconstruction. Am J Sports Med. 2014;42(3):641-7. http://dx.doi.org/10.1177/0363546513517540. PMid:24451111.

38. Hui C, Salmon LJ, Kok A, Maeno S, Linklater J, Pinczewski LA. Fifteen-year outcome of endoscopic anterior cruciate ligament reconstruction with patellar tendon autograft for “isolated” anterior cruciate ligament tear. Am J Sports Med. 2011;39(1):89-98. http://dx.doi.org/10.1177/0363546510379975. PMid:20962336.

39. Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of Second ACL Injuries 2 Years After Primary ACL Reconstruction and Return to Sport. Am J Sports Med. 2014;42(7):1567-73. http://dx.doi.org/10.1177/0363546514530088. PMid:24753238.

40. Shelbourne KD, Gray T, Haro M. Incidence of subsequent injury to either knee within 5 years after anterior cruciate ligament reconstruction with patellar tendon autograft. Am J Sports Med. 2009;37(2):246-51. http://dx.doi.org/10.1177/0363546508325665. PMid:19109531.

41. Kamath GV, Murphy T, Creighton RA, Viradia N, Taft TN, Spang JT. Anterior Cruciate Ligament Injury, Return to Play, and Reinjury in the Elite Collegiate Athlete: Analysis of an NCAA Division I Cohort. Am J Sports Med. 2014;42(7):1638-43. http://dx.doi.org/10.1177/0363546514524164. PMid:24981340.

42. Nepple JJ, Dunn WR, Wright RW. Meniscal repair outcomes at greater than five years: a systematic literature review and meta-analysis. J Bone Joint Surg Am. 2012;94(24):2222-7. http://dx.doi.org/10.2106/JBJS.K.01584. PMid:23318612.

43. Lyman S, Hidaka C, Valdez AS, Hetsroni I, Pan TJ, Do H, et al. Risk factors for meniscectomy after meniscal repair. Am J Sports Med. 2013;41(12):2772-8. http://dx.doi.org/10.1177/0363546513503444. PMid:24036573.

44. Tengrootenhuysen M, Meermans G, Pittoors K, van Riet R, Victor J. Long-term outcome after meniscal repair. Knee Surg Sports Traumatol Arthrosc. 2011;19(2):236-41. http://dx.doi.org/10.1007/s00167-010-1286-y. PMid:20953762.

45. Vanderhave KL, Moravek JE, Sekiya JK, Wojtys EM. Meniscus tears in the young athlete: results of arthroscopic repair. J Pediatr Orthop. 2011;31(5):496-500. http://dx.doi.org/10.1097/BPO.0b013e31821ffb8d. PMid:21654455.

46. Paxton ES, Stock MV, Brophy RH. Meniscal repair versus partial meniscectomy: a systematic review comparing reoperation rates and clinical outcomes. Arthroscopy. 2011;27(9):1275-88. http://dx.doi.org/10.1016/j.arthro.2011.03.088. PMid:21820843.

47. Solheim E, Øyen J, Hegna J, Austgulen OK, Harlem T, Strand T. Microfracture treatment of single or multiple articular cartilage defects of the knee: a 5-year median follow-up of 110 patients. Knee Surg Sports Traumatol Arthrosc. 2010;18(4):504-8. http://dx.doi.org/10.1007/s00167-009-0974-y. PMid:19865812.

48. Minas T, Gomoll AH, Rosenberger R, Royce RO, Bryant T. Increased failure rate of autologous chondrocyte implantation after previous treatment with marrow stimulation techniques. Am J Sports Med. 2009;37(5):902-8. http://dx.doi.org/10.1177/0363546508330137. PMid:19261905.

49. Pestka JM, Bode G, Salzmann G, Südkamp NP, Niemeyer P. Clinical outcome of autologous chondrocyte implantation for failed microfracture treatment of full-thickness cartilage defects of the knee joint. Am J Sports Med. 2012;40(2):325-31. http://dx.doi.org/10.1177/0363546511425651. PMid:22056348.

50. Ardern CL, Taylor NF, Feller JA, Webster KE. Fifty-five per cent return to competitive sport following anterior cruciate ligament reconstruction surgery: an updated systematic review and meta-analysis including aspects of physical functioning and contextual factors. Br J Sports Med. 2014;48(21):1543-52. http://dx.doi.org/10.1136/bjsports-2013-093398. PMid:25157180.

51. Ardern CL, Taylor NF, Feller JA, Webster KE. Return-to-sport outcomes at 2 to 7 years after anterior cruciate ligament reconstruction surgery. Am J Sports Med. 2012;40(1):41-8. http://dx.doi.org/10.1177/0363546511422999. PMid:21946441.

52. Gobbi A, Francisco R. Factors affecting return to sports after anterior cruciate ligament reconstruction with patellar tendon and hamstring graft: a prospective clinical investigation. Knee Surg Sports Traumatol Arthrosc. 2006;14(10):1021-8. http://dx.doi.org/10.1007/s00167-006-0050-9. PMid:16496124.

Sports knee injury performance profile

353 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

53. Lee DY, Karim SA, Chang HC. Return to sports after anterior cruciate ligament reconstruction - a review of patients with minimum 5-year follow-up. Ann Acad Med Singapore. 2008;37(4):273-8. PMid:18461210.

54. Osti L, Liu SH, Raskin A, Merlo F, Bocchi L. Partial lateral meniscectomy in athletes. Arthroscopy. 1994;10(4):424-30. http://dx.doi.org/10.1016/S0749-8063(05)80194-X. PMid:7945639.

55. Rangger C, Kathrein A, Klestil T, Glötzer W. Partial meniscectomy and osteoarthritis. Implications for treatment of athletes. Sports Med. 1997;23(1):61-8. http://dx.doi.org/10.2165/00007256-199723010-00006. PMid:9017860.

56. Jørgensen U, Sonne-Holm S, Lauridsen F, Rosenklint A. Long-term follow-up of meniscectomy in athletes. A prospective longitudinal study. J Bone Joint Surg Br. 1987;69(1):80-3. PMid:3818740.

57. Neyret P, Donell ST, DeJour D, DeJour H. Partial meniscectomy and anterior cruciate ligament rupture in soccer players. A study with a minimum 20-year followup. Am J Sports Med. 1993;21(3):455-60. http://dx.doi.org/10.1177/036354659302100322. PMid:8346763.

58. Mithoefer K, Gill TJ, Cole BJ, Williams RJ, Mandelbaum BR. Clinical Outcome and Return to Competition after Microfracture in the Athlete’s Knee: An Evidence-Based Systematic Review. Cartilage. 2010;1(2):113-20. http://dx.doi.org/10.1177/1947603510366576. PMid:26069542.

59. Steadman JR, Miller BS, Karas SG, Schlegel TF, Briggs KK, Hawkins RJ. The microfracture technique in the treatment of full-thickness chondral lesions of the knee in National Football League players. J Knee Surg. 2003;16(2):83-6. PMid:12741420.

60. Namdari S, Baldwin K, Anakwenze O, Park M-J, Huffman GR, Sennett BJ. Results and performance after microfracture in National Basketball Association athletes. Am J Sports Med. 2009;37(5):943-8. http://dx.doi.org/10.1177/0363546508330150. PMid:19251677.

61. Harris JD, Walton DM, Erickson BJ, Verma NN, Abrams GD, Bush-Joseph CA, et al. Return to Sport and Performance After Microfracture in the Knees of National Basketball Association Players. Orthop J Sports Med. 2013;1(6). http://dx.doi.org/10.1177/2325967113512759.

62. Mithoefer K, Peterson L, Saris DBF, Mandelbaum BR. Evolution and current role of autologous chondrocyte implantation for treatment of articular cartilage defects in the football (Soccer) player. Cartilage. 2012;3(1 Suppl):31S-6S. http://dx.doi.org/10.1177/1947603511406532. PMid:26069604.

63. Van Assche D. Return to sport after cartilage repair: opportunities and pitfalls for rehabilitation. Proceedings of the International Cartilage Research Society, 2013 Sept 15-18; Ismir, Turkey. Los Angeles: Sage Publications; 2013. p. 1-3.

64. Rugg CM, Wang D, Sulzicki P, Hame SL. Effects of prior knee surgery on subsequent injury, imaging, and surgery in NCAA collegiate athletes. Am J Sports Med. 2014;42(4):959-64. http://dx.doi.org/10.1177/0363546513519951. PMid:24519183.

65. Kujala UM, Kettunen J, Paananen H, Aalto T, Battié MC, Impivaara O, et al. Knee osteoarthritis in former runners, soccer players, weight lifters, and shooters. Arthritis

Rheum. 1995;38(4):539-46. http://dx.doi.org/10.1002/art.1780380413. PMid:7718008.

66. Takeda H, Nakagawa T, Nakamura K, Engebretsen L. Prevention and management of knee osteoarthritis and knee cartilage injury in sports. Br J Sports Med. 2011;45(4):304-9. http://dx.doi.org/10.1136/bjsm.2010.082321. PMid:21357577.

67. Øiestad BE, Engebretsen L, Storheim K, Risberg MA. Knee osteoarthritis after anterior cruciate ligament injury: a systematic review. Am J Sports Med. 2009;37(7):1434-43. http://dx.doi.org/10.1177/0363546509338827. PMid:19567666.

68. Kurtz S, Ong K, Lau E, Mowat F, Halpern M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am. 2007;89(4):780-5. http://dx.doi.org/10.2106/JBJS.F.00222. PMid:17403800.

69. Flanigan DC, Everhart JS, Pedroza A, Smith T, Kaeding CC. Fear of reinjury (kinesiophobia) and persistent knee symptoms are common factors for lack of return to sport after anterior cruciate ligament reconstruction. Arthroscopy. 2013;29(8):1322-9. http://dx.doi.org/10.1016/j.arthro.2013.05.015. PMid:23906272.

70. Kim SG, Nagao M, Kamata K, Maeda K, Nozawa M. Return to sport after arthroscopic meniscectomy on stable knees. BMC Sports Sci Med Rehabil. 2013;5(1):23. http://dx.doi.org/10.1186/2052-1847-5-23. PMid:24257295.

71. Paterno MV, Rauh MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of contralateral and ipsilateral anterior cruciate ligament (ACL) injury after primary ACL reconstruction and return to sport. Clin J Sport Med. 2012;22(2):116-21. http://dx.doi.org/10.1097/JSM.0b013e318246ef9e. PMid:22343967.

72. Shelbourne KD, Gray T, Haro M. Incidence of subsequent injury to either knee within 5 years after anterior cruciate ligament reconstruction with patellar tendon autograft. Am J Sports Med. 2009;37(2):246-51. http://dx.doi.org/10.1177/0363546508325665. PMid:19109531.

73. van Eck CF, Schkrohowsky JG, Working ZM, Irrgang JJ, Fu FH. Prospective analysis of failure rate and predictors of failure after anatomic anterior cruciate ligament reconstruction with allograft. Am J Sports Med. 2012;40(4):800-7. http://dx.doi.org/10.1177/0363546511432545. PMid:22238055.

74. Arendt E, Dick R. Knee injury patterns among men and women in collegiate basketball and soccer. NCAA data and review of literature. Am J Sports Med. 1995;23(6):694-701. http://dx.doi.org/10.1177/036354659502300611. PMid:8600737.

75. Myklebust G, Engebretsen L, Braekken IH, Skjølberg A, Olsen OE, Bahr R. Prevention of anterior cruciate ligament injuries in female team handball players: a prospective intervention study over three seasons. Clin J Sport Med. 2003;13(2):71-8. http://dx.doi.org/10.1097/00042752-200303000-00002. PMid:12629423.

76. Ryan J, Magnussen RA, Cox CL, Hurbanek JG, Flanigan DC, Kaeding CC. ACL reconstruction: do outcomes differ by sex? A systematic review. J Bone Joint Surg Am. 2014;96(6):507-12. http://dx.doi.org/10.2106/JBJS.M.00299. PMid:24647508.

77. Dunn WR, Spindler KP, Amendola A, Andrish JT, Bergfeld JA, Flanigan DC, et al. Predictors of activity level 2 years after anterior cruciate ligament reconstruction (ACLR):

Logerstedt D, Arundale A, Lynch A, Snyder-Mackler L

354 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

a Multicenter Orthopaedic Outcomes Network (MOON) ACLR cohort study. Am J Sports Med. 2010;38(10):2040-50. http://dx.doi.org/10.1177/0363546510370280. PMid:20709944.

78. Spindler KP, Huston LJ, Wright RW, Kaeding CC, Marx RG, Amendola A, et al. The prognosis and predictors of sports function and activity at minimum 6 years after anterior cruciate ligament reconstruction: a population cohort study. Am J Sports Med. 2011;39(2):348-59. http://dx.doi.org/10.1177/0363546510383481. PMid:21084660.

79. Mayr HO, Weig TG, Plitz W. Arthrofibrosis following ACL reconstruction--reasons and outcome. Arch Orthop Trauma Surg. 2004;124(8):518-22. http://dx.doi.org/10.1007/s00402-004-0718-x. PMid:15480713.

80. Paulos LE, Rosenberg TD, Drawbert J, Manning J, Abbott P. Infrapatellar contracture syndrome. An unrecognized cause of knee stiffness with patella entrapment and patella infera. Am J Sports Med. 1987;15(4):331-41. http://dx.doi.org/10.1177/036354658701500407. PMid:3661814.

81. Shelbourne KD, Patel DV, Martini DJ. Classification and management of arthrofibrosis of the knee after anterior cruciate ligament reconstruction. Am J Sports Med. 1996;24(6):857-62. http://dx.doi.org/10.1177/036354659602400625. PMid:8947412.

82. Ericsson YB, Roos EM, Dahlberg L. Muscle strength, functional performance, and self-reported outcomes four years after arthroscopic partial meniscectomy in middle-aged patients. Arthritis Rheum. 2006;55(6):946-52. http://dx.doi.org/10.1002/art.22346. PMid:17139641.

83. Logerstedt D, Lynch A, Axe MJ, Snyder-Mackler L. Symmetry restoration and functional recovery before and after anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 2013;21(4):859-68. http://dx.doi.org/10.1007/s00167-012-1929-2. PMid:22349604.

84. Palmieri-Smith RM, Thomas AC, Wojtys EM. Maximizing quadriceps strength after ACL reconstruction. Clin Sports Med. 2008;27(3):405-24, vii-ix. http://dx.doi.org/10.1016/j.csm.2008.02.001. PMid:18503875.

85. Van Assche D, Staes F, Van Caspel D, Vanlauwe J, Bellemans J, Saris DB, et al. Autologous chondrocyte implantation versus microfracture for knee cartilage injury: a prospective randomized trial, with 2-year follow-up. Knee Surg Sports Traumatol Arthrosc. 2010;18(4):486-95. http://dx.doi.org/10.1007/s00167-009-0955-1. PMid:19820916.

86. Hartigan EH, Axe MJ, Snyder-Mackler L. Time line for noncopers to pass return-to-sports criteria after anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther. 2010;40(3):141-54. http://dx.doi.org/10.2519/jospt.2010.3168. PMid:20195019.

87. Mithoefer K, Hambly K, Logerstedt D, Ricci M, Silvers H, Della Villa S. Current concepts for rehabilitation and return to sport after knee articular cartilage repair in the athlete. J Orthop Sports Phys Ther. 2012;42(3):254-73. http://dx.doi.org/10.2519/jospt.2012.3665. PMid:22383103.

88. Myer GD, Paterno MV, Ford KR, Quatman CE, Hewett TE. Rehabilitation after anterior cruciate ligament reconstruction: criteria-based progression through the return-to-sport phase. J Orthop Sports Phys Ther. 2006;36(6):385-402. http://dx.doi.org/10.2519/jospt.2006.2222. PMid:16776488.

89. Thomeé R, Kaplan Y, Kvist J, Myklebust G, Risberg MA, Theisen D, et al. Muscle strength and hop performance

criteria prior to return to sports after ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2011;19(11):1798-805. http://dx.doi.org/10.1007/s00167-011-1669-8. PMid:21932078.

90. Chmielewski TL, Stackhouse S, Axe MJ, Snyder-Mackler L. A prospective analysis of incidence and severity of quadriceps inhibition in a consecutive sample of 100 patients with complete acute anterior cruciate ligament rupture. J Orthop Res. 2004;22(5):925-30. http://dx.doi.org/10.1016/j.orthres.2004.01.007. PMid:15304261.

91. Hurd WJ, Axe MJ, Snyder-Mackler L. A 10-year prospective trial of a patient management algorithm and screening examination for highly active individuals with anterior cruciate ligament injury: Part 1, outcomes. Am J Sports Med. 2008;36(1):40-7. http://dx.doi.org/10.1177/0363546507308190. PMid:17940141.

92. Jong SN, van Caspel DR, van Haeff MJ, Saris DB. Functional assessment and muscle strength before and after reconstruction of chronic anterior cruciate ligament lesions. Arthroscopy. 2007;23(1):21-8. http://dx.doi.org/10.1016/j.arthro.2006.08.024. PMid:17210423.

93. Eitzen I, Holm I, Risberg MA. Preoperative quadriceps strength is a significant predictor of knee function two years after anterior cruciate ligament reconstruction. Br J Sports Med. 2009;43(5):371-6. http://dx.doi.org/10.1136/bjsm.2008.057059. PMid:19224907.

94. Logerstedt D, Lynch A, Axe MJ, Snyder-Mackler L. Pre-operative quadriceps strength predicts IKDC2000 scores 6 months after anterior cruciate ligament reconstruction. Knee. 2013;20(3):208-12. http://dx.doi.org/10.1016/j.knee.2012.07.011. PMid:23022031.

95. Ingersoll CD, Grindstaff TL, Pietrosimone BG, Hart JM. Neuromuscular consequences of anterior cruciate ligament injury. Clin Sports Med. 2008;27(3):383-404, vii. http://dx.doi.org/10.1016/j.csm.2008.03.004. PMid:18503874.

96. Keays SL, Bullock-Saxton JE, Keays AC, Newcombe PA, Bullock MI. A 6-year follow-up of the effect of graft site on strength, stability, range of motion, function, and joint degeneration after anterior cruciate ligament reconstruction: patellar tendon versus semitendinosus and Gracilis tendon graft. Am J Sports Med. 2007;35(5):729-39. http://dx.doi.org/10.1177/0363546506298277. PMid:17322130.

97. Anderson AF, Dome DC, Gautam S, Awh MH, Rennirt GW. Correlation of anthropometric measurements, strength, anterior cruciate ligament size, and intercondylar notch characteristics to sex differences in anterior cruciate ligament tear rates. Am J Sports Med. 2001;29(1):58-66. PMid:11206258.

98. Aune AK, Holm I, Risberg MA, Jensen HK, Steen H. Four-strand hamstring tendon autograft compared with patellar tendon-bone autograft for anterior cruciate ligament reconstruction. A randomized study with two-year follow-up. Am J Sports Med. 2001;29(6):722-8. PMid:11734484.

99. Feller JA, Webster KE. A randomized comparison of patellar tendon and hamstring tendon anterior cruciate ligament reconstruction. Am J Sports Med. 2003;31(4):564-73. PMid:12860546.

100. Gobbi A, Mahajan S, Zanazzo M, Tuy B. Patellar tendon versus quadrupled bone-semitendinosus anterior cruciate ligament reconstruction: a prospective clinical investigation

Sports knee injury performance profile

355 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

in athletes. Arthroscopy. 2003;19(6):592-601. http://dx.doi.org/10.1016/S0749-8063(03)00393-1. PMid:12861197.

101. McLeod MM, Gribble P, Pfile KR, Pietrosimone BG. Effects of arthroscopic partial meniscectomy on quadriceps strength: a systematic review. J Sport Rehabil. 2012;21(3):285-95. PMid:22234935.

102. Witvrouw E, Bellemans J, Verdonk R, Cambier D, Coorevits P, Almqvist F. Patellar tendon vs. doubled semitendinosus and gracilis tendon for anterior cruciate ligament reconstruction. Int Orthop. 2001;25(5):308-11. http://dx.doi.org/10.1007/s002640100268. PMid:11794266.

103. Ardern CL, Webster KE, Taylor NF, Feller JA. Hamstring strength recovery after hamstring tendon harvest for anterior cruciate ligament reconstruction: a comparison between graft types. Arthroscopy. 2010;26(4):462-9. http://dx.doi.org/10.1016/j.arthro.2009.08.018. PMid:20362824.

104. Keays SL, Bullock-Saxton JE, Newcombe P, Keays AC. The relationship between knee strength and functional stability before and after anterior cruciate ligament reconstruction. J Orthop Res. 2003;21(2):231-7. http://dx.doi.org/10.1016/S0736-0266(02)00160-2. PMid:12568953.

105. Samuelsson K, Andersson D, Karlsson J. Treatment of anterior cruciate ligament injuries with special reference to graft type and surgical technique: an assessment of randomized controlled trials. Arthroscopy. 2009;25(10):1139-74. http://dx.doi.org/10.1016/j.arthro.2009.07.021. PMid:19801293.

106. Myer GD, Ford KR, Barber Foss KD, Liu C, Nick TG, Hewett TE. The relationship of hamstrings and quadriceps strength to anterior cruciate ligament injury in female athletes. Clin J Sport Med. 2009;19(1):3-8. http://dx.doi.org/10.1097/JSM.0b013e318190bddb. PMid:19124976.

107. Myer GD, Ford KR, Khoury J, Succop P, Hewett TE. Biomechanics laboratory-based prediction algorithm to identify female athletes with high knee loads that increase risk of ACL injury. Br J Sports Med. 2011;45(4):245-52. http://dx.doi.org/10.1136/bjsm.2009.069351. PMid:20558526.

108. Roewer BD, Di Stasi SL, Snyder-Mackler L. Quadriceps strength and weight acceptance strategies continue to improve two years after anterior cruciate ligament reconstruction. J Biomech. 2011;44(10):1948-53. http://dx.doi.org/10.1016/j.jbiomech.2011.04.037. PMid:21592482.

109. Otzel DM, Chow JW, Tillman MD. Long-term deficits in quadriceps strength and activation following anterior cruciate ligament reconstruction. Phys Ther Sport. 2015;16(1):22-8. http://dx.doi.org/10.1016/j.ptsp.2014.02.003. PMid:24933688.

110. Schmitt LC, Quatman CE, Paterno MV, Best TM, Flanigan DC. Functional outcomes after surgical management of articular cartilage lesions in the knee: a systematic literature review to guide postoperative rehabilitation. J Orthop Sports Phys Ther. 2014;44(8):565-A10. http://dx.doi.org/10.2519/jospt.2014.4844. PMid:24955815.

111. Van Assche D, Staes F, Van Caspel D, Vanlauwe J, Bellemans J, Saris DB, et al. Autologous chondrocyte implantation versus microfracture for knee cartilage injury: a prospective randomized trial, with 2-year follow-up. Knee Surg Sports Traumatol Arthrosc. 2010;18(4):486-95. http://dx.doi.org/10.1007/s00167-009-0955-1. PMid:19820916.

112. Kreuz PC, Müller S, Freymann U, Erggelet C, Niemeyer P, Kaps C, et al. Repair of focal cartilage defects with scaffold-assisted autologous chondrocyte grafts: clinical

and biomechanical results 48 months after transplantation. Am J Sports Med. 2011;39(8):1697-705. http://dx.doi.org/10.1177/0363546511403279. PMid:21540360.

113. Ebert JR, Lloyd DG, Wood DJ, Ackland TR. Isokinetic knee extensor strength deficit following matrix-induced autologous chondrocyte implantation. Clin Biomech (Bristol, Avon). 2012;27(6):588-94. http://dx.doi.org/10.1016/j.clinbiomech.2012.01.006. PMid:22341772.

114. Løken S, Ludvigsen TC, Høysveen T, Holm I, Engebretsen L, Reinholt FP. Autologous chondrocyte implantation to repair knee cartilage injury: ultrastructural evaluation at 2 years and long-term follow-up including muscle strength measurements. Knee Surg Sports Traumatol Arthrosc. 2009;17(11):1278-88. http://dx.doi.org/10.1007/s00167-009-0854-5. PMid:19572120.

115. Schmitt LC, Paterno MV, Hewett TE. The impact of quadriceps femoris strength asymmetry on functional performance at return to sport following anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther. 2012;42(9):750-9. http://dx.doi.org/10.2519/jospt.2012.4194. PMid:22813542.

116. Ericsson YB, Roos EM, Dahlberg L. Muscle strength, functional performance, and self-reported outcomes four years after arthroscopic partial meniscectomy in middle-aged patients. Arthritis Rheum. 2006;55(6):946-52. http://dx.doi.org/10.1002/art.22346. PMid:17139641.

117. Roos EM, Roos HP, Lohmander LS, Ekdahl C, Beynnon BD. Knee Injury and Osteoarthritis Outcome Score (KOOS)--development of a self-administered outcome measure. J Orthop Sports Phys Ther. 1998;28(2):88-96. http://dx.doi.org/10.2519/jospt.1998.28.2.88. PMid:9699158.

118. Thorlund JB, Aagaard P, Roos EM. Muscle strength and functional performance in patients at high risk of knee osteoarthritis: a follow-up study. Knee Surg Sports Traumatol Arthrosc. 2012;20(6):1110-7. http://dx.doi.org/10.1007/s00167-011-1719-2. PMid:22037811.

119. Gribble PA, Hertel J, Plisky P. Using the Star Excursion Balance Test to assess dynamic postural-control deficits and outcomes in lower extremity injury: a literature and systematic review. J Athl Train. 2012;47(3):339-57. PMid:22892416.

120. Hewett TE, Paterno MV, Myer GD. Strategies for enhancing proprioception and neuromuscular control of the knee. Clin Orthop Relat Res. 2002;402:76-94. http://dx.doi.org/10.1097/00003086-200209000-00008. PMid:12218474.

121. Paterno MV, Schmitt LC, Ford KR, Rauh MJ, Hewett TE. Altered postural sway persists after anterior cruciate ligament reconstruction and return to sport. Gait Posture. 2013;38(1):136-40. http://dx.doi.org/10.1016/j.gaitpost.2012.11.001. PMid:23219783.

122. Plisky PJ, Rauh MJ, Kaminski TW, Underwood FB. Star Excursion Balance Test as a predictor of lower extremity injury in high school basketball players. J Orthop Sports Phys Ther. 2006;36(12):911-9. http://dx.doi.org/10.2519/jospt.2006.2244. PMid:17193868.

123. Reid A, Birmingham TB, Stratford PW, Alcock GK, Giffin JR. Hop testing provides a reliable and valid outcome measure during rehabilitation after anterior cruciate ligament reconstruction. Phys Ther. 2007;87(3):337-49. http://dx.doi.org/10.2522/ptj.20060143. PMid:17311886.

Logerstedt D, Arundale A, Lynch A, Snyder-Mackler L

356 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

124. Myer GD, Schmitt LC, Brent JL, Ford KR, Barber Foss KD, Scherer BJ, et al. Utilization of modified NFL combine testing to identify functional deficits in athletes following ACL reconstruction. J Orthop Sports Phys Ther. 2011;41(6):377-87. http://dx.doi.org/10.2519/jospt.2011.3547. PMid:21289456.

125. Fitzgerald GK, Lephart SM, Hwang JH, Wainner RS. Hop tests as predictors of dynamic knee stability. J Orthop Sports Phys Ther. 2001;31(10):588-97. http://dx.doi.org/10.2519/jospt.2001.31.10.588. PMid:11665746.

126. Juris PM, Phillips EM, Dalpe C, Edwards C, Gotlin RS, Kane DJ. A dynamic test of lower extremity function following anterior cruciate ligament reconstruction and rehabilitation. J Orthop Sports Phys Ther. 1997;26(4):184-91. http://dx.doi.org/10.2519/jospt.1997.26.4.184. PMid:9310909.

127. Ross MD, Langford B, Whelan PJ. Test-retest reliability of 4 single-leg horizontal hop tests. J Strength Cond Res. 2002;16(4):617-22. PMid:12423195.

128. Wilk KE, Romaniello WT, Soscia SM, Arrigo CA, Andrews JR. The relationship between subjective knee scores, isokinetic testing, and functional testing in the ACL-reconstructed knee. J Orthop Sports Phys Ther. 1994;20(2):60-73. http://dx.doi.org/10.2519/jospt.1994.20.2.60. PMid:7920603.

129. Hopper DM, Strauss GR, Boyle JJ, Bell J. Functional recovery after anterior cruciate ligament reconstruction: a longitudinal perspective. Arch Phys Med Rehabil. 2008;89(8):1535-41. http://dx.doi.org/10.1016/j.apmr.2007.11.057. PMid:18586220.

130. Lephart SM, Perrin DH, Fu FH, Gieck JH, McCue FC 3rd, Irrgang JJ. Relationship between Selected Physical Characteristics and Functional Capacity in the Anterior Cruciate Ligament-Insufficient Athlete. J Orthop Sports Phys Ther. 1992;16(4):174-81. http://dx.doi.org/10.2519/jospt.1992.16.4.174. PMid:18796757.

131. Logerstedt DS, Snyder-Mackler L, Ritter RC, Axe MJ, Godges JJ, Orthopaedic Section of the American Physical Therapist Association. Knee stability and movement coordination impairments: knee ligament sprain. J Orthop Sports Phys Ther. 2010;40(4):A1-37. http://dx.doi.org/10.2519/jospt.2010.0303. PMid:20357420.

132. Noyes FR, Barber SD, Mangine RE. Abnormal lower limb symmetry determined by function hop tests after anterior cruciate ligament rupture. Am J Sports Med. 1991;19(5):513-8. http://dx.doi.org/10.1177/036354659101900518. PMid:1962720.

133. Daniel DM, Malcom LL, Losse G, Stone ML, Sachs R, Burks R. Instrumented measurement of anterior laxity of the knee. J Bone Joint Surg Am. 1985;67(5):720-6. PMid:3997924.

134. O’Donnell S, Thomas SG, Marks P. Improving the sensitivity of the hop index in patients with an ACL deficient knee by transforming the hop distance scores. BMC Musculoskelet Disord. 2006;7(1):9. http://dx.doi.org/10.1186/1471-2474-7-9. PMid:16448576.

135. Xergia SA, Pappas E, Zampeli F, Georgiou S, Georgoulis AD. Asymmetries in functional hop tests, lower extremity kinematics, and isokinetic strength persist 6 to 9 months following anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther. 2013;43(3):154-62. http://dx.doi.org/10.2519/jospt.2013.3967. PMid:23322072.

136. Thorlund JB, Aagaard P, Roos EM. Muscle strength and functional performance in patients at high risk of knee

osteoarthritis: a follow-up study. Knee Surg Sports Traumatol Arthrosc. 2012;20(6):1110-7. http://dx.doi.org/10.1007/s00167-011-1719-2. PMid:22037811.

137. Grindem H, Logerstedt D, Eitzen I, Moksnes H, Axe MJ, Snyder-Mackler L, et al. Single-legged hop tests as predictors of self-reported knee function in nonoperatively treated individuals with anterior cruciate ligament injury. Am J Sports Med. 2011;39(11):2347-54. http://dx.doi.org/10.1177/0363546511417085. PMid:21828364.

138. Logerstedt D, Grindem H, Lynch A, Eitzen I, Engebretsen L, Risberg MA, et al. Single-legged hop tests as predictors of self-reported knee function after anterior cruciate ligament reconstruction: the Delaware-Oslo ACL cohort study. Am J Sports Med. 2012;40(10):2348-56. http://dx.doi.org/10.1177/0363546512457551. PMid:22926749.

139. Holsgaard-Larsen A, Jensen C, Mortensen NHM, Aagaard P. Concurrent assessments of lower limb loading patterns, mechanical muscle strength and functional performance in ACL-patients--a cross-sectional study. Knee. 2014;21(1):66-73. http://dx.doi.org/10.1016/j.knee.2013.06.002. PMid:23835518.

140. Cascio BM, Culp L, Cosgarea AJ. Return to play after anterior cruciate ligament reconstruction. Clin Sports Med. 2004;23(3):395-408, ix. http://dx.doi.org/10.1016/j.csm.2004.03.004. PMid:15262378.

141. Marx RG, Jones EC, Angel M, Wickiewicz TL, Warren RF. Beliefs and attitudes of members of the American Academy of Orthopaedic Surgeons regarding the treatment of anterior cruciate ligament injury. Arthroscopy. 2003;19(7):762-70. http://dx.doi.org/10.1016/S0749-8063(03)00398-0. PMid:12966385.

142. Barber SD, Noyes FR, Mangine RE, McCloskey JW, Hartman W. Quantitative assessment of functional limitations in normal and anterior cruciate ligament-deficient knees. Clin Orthop Relat Res. 1990;(255):204-14. PMid:2347154.

143. Shelbourne KD, Klotz C. What I have learned about the ACL: utilizing a progressive rehabilitation scheme to achieve total knee symmetry after anterior cruciate ligament reconstruction. J Orthop Sci. 2006;11(3):318-25. http://dx.doi.org/10.1007/s00776-006-1007-z. PMid:16721538.

144. Creighton DW, Shrier I, Shultz R, Meeuwisse WH, Matheson GO. Return-to-play in sport: a decision-based model. Clin J Sport Med. 2010;20(5):379-85. http://dx.doi.org/10.1097/JSM.0b013e3181f3c0fe. PMid:20818198.

145. Lentz TA, Zeppieri G Jr, Tillman SM, Indelicato PA, Moser MW, George SZ, et al. Return to preinjury sports participation following anterior cruciate ligament reconstruction: contributions of demographic, knee impairment, and self-report measures. J Orthop Sports Phys Ther. 2012;42(11):893-901. http://dx.doi.org/10.2519/jospt.2012.4077. PMid:22951437.

146. Silbernagel KG, Thomeé R, Eriksson BI, Karlsson J. Continued sports activity, using a pain-monitoring model, during rehabilitation in patients with Achilles tendinopathy: a randomized controlled study. Am J Sports Med. 2007;35(6):897-906. http://dx.doi.org/10.1177/0363546506298279. PMid:17307888.

147. Adams D, Logerstedt DS, Hunter-Giordano A, Axe MJ, Snyder-Mackler L. Current concepts for anterior cruciate ligament reconstruction: a criterion-based rehabilitation

Sports knee injury performance profile

357 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

progression. J Orthop Sports Phys Ther. 2012;42(7):601-14. http://dx.doi.org/10.2519/jospt.2012.3871. PMid:22402434.

148. Sturgill LP, Snyder-Mackler L, Manal TJ, Axe MJ. Interrater reliability of a clinical scale to assess knee joint effusion. J Orthop Sports Phys Ther. 2009;39(12):845-9. http://dx.doi.org/10.2519/jospt.2009.3143. PMid:20032559.

149. Lynch AD, Logerstedt DS, Axe MJ, Snyder-Mackler L. Quadriceps activation failure after anterior cruciate ligament rupture is not mediated by knee joint effusion. J Orthop Sports Phys Ther. 2012;42(6):502-10. http://dx.doi.org/10.2519/jospt.2012.3793. PMid:22523081.

150. Palmieri-Smith RM, Kreinbrink J, Ashton-Miller JA, Wojtys EM. Quadriceps inhibition induced by an experimental knee joint effusion affects knee joint mechanics during a single-legged drop landing. Am J Sports Med. 2007;35(8):1269-75. http://dx.doi.org/10.1177/0363546506296417. PMid:17244901.

151. Eastlack ME, Axe MJ, Snyder-Mackler L. Laxity, instability, and functional outcome after ACL injury: copers versus noncopers. Med Sci Sports Exerc. 1999;31(2):210-5. http://dx.doi.org/10.1097/00005768-199902000-00002. PMid:10063808.

152. Engström B, Gornitzka J, Johansson C, Wredmark T. Knee function after anterior cruciate ligament ruptures treated conservatively. Int Orthop. 1993;17(4):208-13. http://dx.doi.org/10.1007/BF00194180. PMid:8407034.

153. Snyder-Mackler L, Fitzgerald GK, Bartolozzi AR 3rd, Ciccotti MG. The relationship between passive joint laxity and functional outcome after anterior cruciate ligament injury. Am J Sports Med. 1997;25(2):191-5. http://dx.doi.org/10.1177/036354659702500209. PMid:9079172.

154. Hewett TE, Di Stasi SL, Myer GD. Current concepts for injury prevention in athletes after anterior cruciate ligament reconstruction. Am J Sports Med. 2013;41(1):216-24. http://dx.doi.org/10.1177/0363546512459638. PMid:23041233.

155. Chmielewski TL, Hurd WJ, Rudolph KS, Axe MJ, Snyder-Mackler L. Perturbation training improves knee kinematics and reduces muscle co-contraction after complete unilateral anterior cruciate ligament rupture. Phys Ther. 2005;85(8):740-9, discussion 750-4. PMid:16048422.

156. Di Stasi SL, Logerstedt D, Gardinier ES, Snyder-Mackler L. Gait patterns differ between ACL-reconstructed athletes who pass return-to-sport criteria and those who fail. Am J Sports Med. 2013;41(6):1310-8. http://dx.doi.org/10.1177/0363546513482718. PMid:23562809.

157. Ebert JR, Lloyd DG, Ackland T, Wood DJ. Knee biomechanics during walking gait following matrix-induced autologous chondrocyte implantation. Clin Biomech (Bristol, Avon). 2010;25(10):1011-7. http://dx.doi.org/10.1016/j.clinbiomech.2010.07.004. PMid:20692745.

158. Paterno MV, Schmitt LC, Ford KR, Rauh MJ, Myer GD, Huang B, et al. Biomechanical measures during landing and postural stability predict second anterior cruciate ligament injury after anterior cruciate ligament reconstruction and return to sport. Am J Sports Med. 2010;38(10):1968-78. http://dx.doi.org/10.1177/0363546510376053. PMid:20702858.

159. Lewek M, Rudolph K, Axe M, Snyder-Mackler L. The effect of insufficient quadriceps strength on gait after anterior cruciate ligament reconstruction. Clin Biomech (Bristol, Avon). 2002;17(1):56-63. http://dx.doi.org/10.1016/S0268-0033(01)00097-3. PMid:11779647.

160. Di Stasi SL, Logerstedt D, Gardinier ES, Snyder-Mackler L. Gait patterns differ between ACL-reconstructed athletes who pass return-to-sport criteria and those who fail. Am J Sports Med. 2013;41(6):1310-8. http://dx.doi.org/10.1177/0363546513482718. PMid:23562809.

161. Paterno MV, Ford KR, Myer GD, Heyl R, Hewett TE. Limb asymmetries in landing and jumping 2 years following anterior cruciate ligament reconstruction. Clin J Sport Med. 2007;17(4):258-62. http://dx.doi.org/10.1097/JSM.0b013e31804c77ea. PMid:17620778.

162. Ernst GP, Saliba E, Diduch DR, Hurwitz SR, Ball DW. Lower extremity compensations following anterior cruciate ligament reconstruction. Phys Ther. 2000;80(3):251-60. PMid:10696152.

163. Sturnieks DL, Besier TF, Mills PM, Ackland TR, Maguire KF, Stachowiak GW, et al. Knee joint biomechanics following arthroscopic partial meniscectomy. J Orthop Res. 2008;26(8):1075-80. http://dx.doi.org/10.1002/jor.20610. PMid:18327795.

164. Sturnieks DL, Besier TF, Hamer PW, Ackland TR, Mills PM, Stachowiak GW, et al. Knee strength and knee adduction moments following arthroscopic partial meniscectomy. Med Sci Sports Exerc. 2008;40(6):991-7. http://dx.doi.org/10.1249/MSS.0b013e318167812a. PMid:18461009.

165. Bulgheroni P, Bulgheroni MV, Ronga M, Manelli A. Gait analysis of pre- and post-meniscectomy knee: a prospective study. Knee. 2007;14(6):472-7. http://dx.doi.org/10.1016/j.knee.2007.08.003. PMid:17942312.

166. Ebert JR, Robertson WB, Lloyd DG, Zheng MH, Wood DJ, Ackland T. Traditional vs accelerated approaches to post-operative rehabilitation following matrix-induced autologous chondrocyte implantation (MACI): comparison of clinical, biomechanical and radiographic outcomes. Osteoarthritis Cartilage. 2008;16(10):1131-40. http://dx.doi.org/10.1016/j.joca.2008.03.010. PMid:18434214.

167. Andriacchi TP, Mündermann A, Smith RL, Alexander EJ, Dyrby CO, Koo S. A framework for the in vivo pathomechanics of osteoarthritis at the knee. Ann Biomed Eng. 2004;32(3):447-57. http://dx.doi.org/10.1023/B:ABME.0000017541.82498.37. PMid:15095819.

168. Defrate LE, Papannagari R, Gill TJ, Moses JM, Pathare NP, Li G. The 6 degrees of freedom kinematics of the knee after anterior cruciate ligament deficiency: an in vivo imaging analysis. Am J Sports Med. 2006;34(8):1240-6. http://dx.doi.org/10.1177/0363546506287299. PMid:16636348.

169. Gardinier ES, Manal K, Buchanan TS, Snyder-Mackler L. Gait and neuromuscular asymmetries after acute anterior cruciate ligament rupture. Med Sci Sports Exerc. 2012;44(8):1490-6. http://dx.doi.org/10.1249/MSS.0b013e31824d2783. PMid:22330021.

170. Baliunas AJ, Hurwitz DE, Ryals AB, Karrar A, Case JP, Block JA, et al. Increased knee joint loads during walking are present in subjects with knee osteoarthritis. Osteoarthritis Cartilage. 2002;10(7):573-9. http://dx.doi.org/10.1053/joca.2002.0797. PMid:12127838.

171. Childs JD, Sparto PJ, Fitzgerald GK, Bizzini M, Irrgang JJ. Alterations in lower extremity movement and muscle activation patterns in individuals with knee osteoarthritis. Clin Biomech (Bristol, Avon). 2004;19(1):44-9. http://dx.doi.org/10.1016/j.clinbiomech.2003.08.007. PMid:14659929.

Logerstedt D, Arundale A, Lynch A, Snyder-Mackler L

358 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

172. Griffin TM, Guilak F. The role of mechanical loading in the onset and progression of osteoarthritis. Exerc Sport Sci Rev. 2005;33(4):195-200. http://dx.doi.org/10.1097/00003677-200510000-00008. PMid:16239837.

173. Irrgang JJ, Anderson AF, Boland AL, Harner CD, Kurosaka M, Neyret P, et al. Development and validation of the international knee documentation committee subjective knee form. Am J Sports Med. 2001;29(5):600-13. PMid:11573919.

174. Pantano KJ, Irrgang JJ, Burdett R, Delitto A, Harner C, Fu FH. A pilot study on the relationship between physical impairment and activity restriction in persons with anterior cruciate ligament reconstruction at long-term follow-up. Knee Surg Sports Traumatol Arthrosc. 2001;9(6):369-78. http://dx.doi.org/10.1007/s001670100239. PMid:11734876.

175. Kocher MS, Steadman JR, Briggs K, Zurakowski D, Sterett WI, Hawkins RJ. Determinants of patient satisfaction with outcome after anterior cruciate ligament reconstruction. J Bone Joint Surg Am. 2002;84-A(9):1560-72. PMid:12208912.

176. Borsa PA, Lephart SM, Irrgang JJ. Comparison of performance-based and patient-reported measures of function in anterior-cruciate-ligament-deficient individuals. J Orthop Sports Phys Ther. 1998;28(6):392-9. http://dx.doi.org/10.2519/jospt.1998.28.6.392. PMid:9836170.

177. Marx RG, Jones EC, Allen AA, Altchek DW, O’Brien SJ, Rodeo SA, et al. Reliability, validity, and responsiveness of four knee outcome scales for athletic patients. J Bone Joint Surg Am. 2001;83-A(10):1459-69. PMid:11679594.

178. Eitzen I, Moksnes H, Snyder-Mackler L, Engebretsen L, Risberg MA. Functional tests should be accentuated more in the decision for ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2010;18(11):1517-25. http://dx.doi.org/10.1007/s00167-010-1113-5. PMid:20411377.

179. Branch TP, Siebold R, Freedberg HI, Jacobs CA. Double-bundle ACL reconstruction demonstrated superior clinical stability to single-bundle ACL reconstruction: a matched-pairs analysis of instrumented tests of tibial anterior translation and internal rotation laxity. Knee Surg Sports Traumatol Arthrosc. 2011;19(3):432-40. http://dx.doi.org/10.1007/s00167-010-1247-5. PMid:20814662.

180. Hartigan EH, Axe MJ, Snyder-Mackler L. Time line for noncopers to pass return-to-sports criteria after anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther. 2010;40(3):141-54. http://dx.doi.org/10.2519/jospt.2010.3168. PMid:20195019.

181. Murray JRD, Lindh AM, Hogan NA, Trezies AJ, Hutchinson JW, Parish E, et al. Does anterior cruciate ligament reconstruction lead to degenerative disease?: Thirteen-year results after bone-patellar tendon-bone autograft. Am J Sports Med. 2012;40(2):404-13. http://dx.doi.org/10.1177/0363546511428580. PMid:22116668.

182. Risberg MA, Holm I, Tjomsland O, Ljunggren E, Ekeland A. Prospective study of changes in impairments and disabilities after anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther. 1999;29(7):400-12. http://dx.doi.org/10.2519/jospt.1999.29.7.400. PMid:10416180.

183. Mithoefer K, McAdams T, Williams RJ, Kreuz PC, Mandelbaum BR. Clinical efficacy of the microfracture technique for articular cartilage repair in the knee: an evidence-based systematic analysis. Am J Sports Med. 2009;37(10):2053-63. http://dx.doi.org/10.1177/0363546508328414. PMid:19251676.

184. Mithoefer K, Williams RJ 3rd, Warren RF, Wickiewicz TL, Marx RG. High-impact athletics after knee articular cartilage repair: a prospective evaluation of the microfracture technique. Am J Sports Med. 2006;34(9):1413-8. http://dx.doi.org/10.1177/0363546506288240. PMid:16735588.

185. Gobbi A, Karnatzikos G, Kumar A. Long-term results after microfracture treatment for full-thickness knee chondral lesions in athletes. Knee Surg Sports Traumatol Arthrosc. 2014;22(9):1986-96. PMid:24051505.

186. Krych AJ, Robertson CM, Williams RJ 3rd; Cartilage Study Group. Return to athletic activity after osteochondral allograft transplantation in the knee. Am J Sports Med. 2012;40(5):1053-9. http://dx.doi.org/10.1177/0363546511435780. PMid:22316548.

187. Kreuz PC, Steinwachs M, Erggelet C, Lahm A, Krause S, Ossendorf C, et al. Importance of sports in cartilage regeneration after autologous chondrocyte implantation: a prospective study with a 3-year follow-up. Am J Sports Med. 2007;35(8):1261-8. http://dx.doi.org/10.1177/0363546507300693. PMid:17405884.

188. Ebert JR, Robertson WB, Woodhouse J, Fallon M, Zheng MH, Ackland T, et al. Clinical and magnetic resonance imaging-based outcomes to 5 years after matrix-induced autologous chondrocyte implantation to address articular cartilage defects in the knee. Am J Sports Med. 2011;39(4):753-63. http://dx.doi.org/10.1177/0363546510390476. PMid:21257846.

189. Marlovits S, Aldrian S, Wondrasch B, Zak L, Albrecht C, Welsch G, et al. Clinical and radiological outcomes 5 years after matrix-induced autologous chondrocyte implantation in patients with symptomatic, traumatic chondral defects. Am J Sports Med. 2012;40(10):2273-80. http://dx.doi.org/10.1177/0363546512457008. PMid:22922521.

190. Meeuwisse WH, Tyreman H, Hagel B, Emery C. A dynamic model of etiology in sport injury: the recursive nature of risk and causation. Clin J Sport Med. 2007;17(3):215-9. http://dx.doi.org/10.1097/JSM.0b013e3180592a48. PMid:17513916.

191. Czuppon S, Racette BA, Klein SE, Harris-Hayes M. Variables associated with return to sport following anterior cruciate ligament reconstruction: a systematic review. Br J Sports Med. 2014;48(5):356-64. http://dx.doi.org/10.1136/bjsports-2012-091786. PMid:24124040.

192. Schmitt LC, Paterno MV, Hewett TE. The impact of quadriceps femoris strength asymmetry on functional performance at return to sport following anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther. 2012;42(9):750-9. http://dx.doi.org/10.2519/jospt.2012.4194. PMid:22813542.

193. Kiesel K, Plisky PJ, Voight ML. Can Serious Injury in Professional Football be Predicted by a Preseason Functional Movement Screen? N Am J Sports Phys Ther. 2007;2(3):147-58. PMid:21522210.

194. Fitzgerald GK, Axe MJ, Snyder-Mackler L. A decision-making scheme for returning patients to high-level activity with nonoperative treatment after anterior cruciate ligament rupture. Knee Surg Sports Traumatol Arthrosc. 2000;8(2):76-82. http://dx.doi.org/10.1007/s001670050190. PMid:10795668.

195. Gustavsson A, Neeter C, Thomeé P, Silbernagel KG, Augustsson J, Thomeé R, et al. A test battery for evaluating hop performance in patients with an ACL injury and

Sports knee injury performance profile

359 Braz J Phys Ther. 2015 Sept-Oct; 19(5):340-359

patients who have undergone ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2006;14(8):778-88. http://dx.doi.org/10.1007/s00167-006-0045-6. PMid:16525796.

196. Neeter C, Gustavsson A, Thomeé P, Augustsson J, Thomeé R, Karlsson J. Development of a strength test battery for evaluating leg muscle power after anterior cruciate ligament injury and reconstruction. Knee Surg Sports Traumatol Arthrosc. 2006;14(6):571-80. http://dx.doi.org/10.1007/s00167-006-0040-y. PMid:16477472.

197. Björklund K, Andersson L, Dalén N. Validity and responsiveness of the test of athletes with knee injuries: the new criterion based functional performance test instrument. Knee Surg Sports Traumatol Arthrosc. 2009;17(5):435-45. http://dx.doi.org/10.1007/s00167-008-0674-z. PMid:19039577.

198. Barber-Westin SD, Noyes FR. Factors used to determine return to unrestricted sports activities after anterior cruciate ligament reconstruction. Arthroscopy. 2011;27(12):1697-705. http://dx.doi.org/10.1016/j.arthro.2011.09.009. PMid:22137326.

199. Risberg MA, Holm I, Tjomsland O, Ljunggren E, Ekeland A. Prospective study of changes in impairments and disabilities after anterior cruciate ligament reconstruction. J Orthop Sports Phys Ther. 1999;29(7):400-12. http://dx.doi.org/10.2519/jospt.1999.29.7.400. PMid:10416180.

200. Ross MD, Irrgang JJ, Denegar CR, McCloy CM, Unangst ET. The relationship between participation restrictions and selected clinical measures following anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc. 2002;10(1):10-9. http://dx.doi.org/10.1007/s001670100238. PMid:11819015.

201. Mizner RL, Petterson SC, Clements KE, Zeni JA Jr, Irrgang JJ, Snyder-Mackler L. Measuring functional improvement after total knee arthroplasty requires both performance-based and patient-report assessments: a longitudinal analysis of outcomes. J Arthroplasty. 2011;26(5):728-37. http://dx.doi.org/10.1016/j.arth.2010.06.004. PMid:20851566.

202. Clark NC. Functional performance testing following knee ligament injury. Phys Ther Sport. 2001;2(2):91-105. http://dx.doi.org/10.1054/ptsp.2001.0035.

203. Reinke EK, Spindler KP, Lorring D, Jones MH, Schmitz L, Flanigan DC, et al. Hop tests correlate with IKDC and KOOS at minimum of 2 years after primary ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2011;19(11):1806-16. http://dx.doi.org/10.1007/s00167-011-1473-5. PMid:21445595.

204. Irrgang JJ, Snyder-Mackler L, Wainner RS, Fu FH, Harner CD. Development of a patient-reported measure of function of the knee. J Bone Joint Surg Am. 1998;80(8):1132-45. PMid:9730122.

205. Hopper DM, Goh SC, Wentworth LA, Chan DYK, Chau JHW, Wootton GJ, et al. Test-retest reliability of knee rating scales and functional hop tests one year following anterior cruciate ligament reconstruction. Phys Ther Sport. 2002;3(1):10-8. http://dx.doi.org/10.1054/ptsp.2001.0094.

206. Hambly K, Griva K. IKDC or KOOS: which one captures symptoms and disabilities most important to patients who have undergone initial anterior cruciate ligament reconstruction? Am J Sports Med. 2010;38(7):1395-404. http://dx.doi.org/10.1177/0363546509359678. PMid:20351201.

207. Anderson AF, Irrgang JJ, Kocher MS, Mann BJ, Harrast JJ; International Knee Documentation Committee. The International Knee Documentation Committee Subjective Knee Evaluation Form: normative data. Am J Sports Med. 2006;34(1):128-35. http://dx.doi.org/10.1177/0363546505280214. PMid:16219941.

208. Langford JL, Webster KE, Feller JA. A prospective longitudinal study to assess psychological changes following anterior cruciate ligament reconstruction surgery. Br J Sports Med. 2009;43(5):377-81. http://dx.doi.org/10.1136/bjsm.2007.044818. PMid:19019910.

209. Webster KE, Feller JA, Lambros C. Development and preliminary validation of a scale to measure the psychological impact of returning to sport following anterior cruciate ligament reconstruction surgery. Phys Ther Sport. 2008;9(1):9-15. http://dx.doi.org/10.1016/j.ptsp.2007.09.003. PMid:19083699.

210. Myer GD, Martin L Jr, Ford KR, Paterno MV, Schmitt LC, Heidt RS Jr, et al. No association of time from surgery with functional deficits in athletes after anterior cruciate ligament reconstruction: evidence for objective return-to-sport criteria. Am J Sports Med. 2012;40(10):2256-63. http://dx.doi.org/10.1177/0363546512454656. PMid:22879403.

211. Petersen W, Zantop T. Return to play following ACL reconstruction: survey among experienced arthroscopic surgeons (AGA instructors). Arch Orthop Trauma Surg. 2013;133(7):969-77. http://dx.doi.org/10.1007/s00402-013-1746-1. PMid:23604790.

212. Narducci E, Waltz A, Gorski K, Leppla L, Donaldson M. The clinical utility of functional performance tests within one-year post-acl reconstruction: a systematic review. Int J Sports Phys Ther. 2011;6(4):333-42. PMid:22163095.

213. Nawasreh ZH, White K, Logerstedt D, Snyder-Mackler L. Knee Performance and Function at 6 Months Predict Return to Preinjury Activity Level One Year after Anterior Cruciate Ligament Reconstruction. J Orthop Sports Phys Ther. 2014;44(1):A60.

214. Di Stasi S, Myer GD, Hewett TE. Neuromuscular training to target deficits associated with second anterior cruciate ligament injury. J Orthop Sports Phys Ther. 2013;43(11):777-92. http://dx.doi.org/10.2519/jospt.2013.4693. PMid:24175599.

215. Logerstedt D, Di Stasi S, Grindem H, Lynch A, Eitzen I, Engebretsen L, et al. Self-reported knee function can identify athletes who fail return-to-activity criteria up to 1 year after anterior cruciate ligament reconstruction: a delaware-oslo ACL cohort study. J Orthop Sports Phys Ther. 2014;44(12):914-23. http://dx.doi.org/10.2519/jospt.2014.4852. PMid:25347228.

Correspondence David Logerstedt University of the Sciences Department of Physical Therapy 108 Woodland, 600 S 43rd St Philadelphia, PA 19104, USA e-mail: d.logerstedt@usciences.edu

http://dx.doi.org/10.1590/bjpt-rbf.2014.0108

review article

360 Braz J Phys Ther. 2015 Sept-Oct; 19(5):360-368

Critical review of the impact of core stability on upper extremity athletic injury and performance

Sheri P. Silfies1, David Ebaugh1,2, Marisa Pontillo1,3, Courtney M. Butowicz1

ABSTRACT | Background: Programs designed to prevent or rehabilitate athletic injuries or improve athletic performance frequently focus on core stability. This approach is based upon the theory that poor core stability increases the risk of poor performance and/or injury. Despite the widespread use of core stability training amongst athletes, the question of whether or not sufficient evidence exists to support this practice remains to be answered. Objectives: 1) Open a dialogue on the definition and components of core stability. 2) Provide an overview of current science linking core stability to musculoskeletal injuries of the upper extremity. 3) Provide an overview of evidence for the association between core stability and athletic performance. Discussion: Core stability is the ability to control the position and movement of the trunk for optimal production, transfer, and control of forces to and from the upper and lower extremities during functional activities. Muscle capacity and neuromuscular control are critical components of core stability. A limited body of evidence provides some support for a link between core stability and upper extremity injuries amongst athletes who participate in baseball, football, or swimming. Likewise, few studies exist to support a relationship between core stability and athletic performance. Conclusions: A limited body of evidence exists to support the use of core stability training in injury prevention or performance enhancement programs for athletes. Clearly more research is needed to inform decision making when it comes to inclusion or emphasis of core training when designing injury prevention and rehabilitation programs for athletes. Keywords: core stability; neuromuscular control; athletic injuries; athletic performance.

HOW TO CITE THIS ARTICLE

Silfies SP, Ebaugh D, Pontillo M, Butowicz CM. Critical review of the impact of core stability on upper extremity athletic injury and performance. Braz J Phys Ther. 2015 Sept-Oct; 19(5):360-368. http://dx.doi.org/10.1590/bjpt-rbf.2014.0108

1 Department of Physical Therapy & Rehabilitation Sciences, Drexel University, Philadelphia, PA, USA2 Department of Health Sciences, Drexel University, Philadelphia, PA, USA3 Penn Sports Medicine, Good Shepherd Penn Partners, Philadelphia, PA, USAReceived: Mar. 09, 2015 Revised: May 05, 2015 Accepted: May 18, 2015

IntroductionPrevention and treatment of musculoskeletal injuries

in athletes is a principal concern of coaches, medical and fitness professionals, and athletes themselves. It is estimated that greater than 10,000 individuals a day seek medical attention for sports, recreation, and/or exercise related injuries1. The National Collegiate Athletic Association Injury Surveillance System sites over 11,000 injuries per year2. A study utilizing injury data from the International Association of Athletics Federation of World Athletic Championships suggests acute non-contact injuries comprise 13% and overuse injuries 44% of competition injuries3. Junge et al.4 reported that 22% of all documented injuries in the 2008 Summer Olympic Games were non-contact, overuse injuries. At the collegiate level, an estimated one third of all athletic injuries are non-contact in nature, with 20% on average involving the upper extremity2. These data have prompted National and

International associations to recommend future studies to investigate circumstances and characteristics of non-contact injuries in greater detail with a goal of identifying possible risk factors and focusing initiatives toward injury prevention2.

Over a decade ago, core stability was proposed to play an important role in athletic injury and performance5,6. It was hypothesized that poor core stability increased the risk of upper extremity athletic injuries5 and negatively affected athletic performance5,7,8. This hypothesis was readily accepted despite the lack of consensus definition of “core stability” or a robust body of scientific evidence to support it. Today the acceptance of training the “core” as part of injury prevention or rehabilitation programs for athletes is pervasive. However, is there sufficient evidence to support this practice?

Core stability and athletes

361 Braz J Phys Ther. 2015 Sept-Oct; 19(5):360-368

The objectives of this paper are to: 1) open a dialogue on the definition and components of core stability, 2) provide an overview of current scientific evidence linking core stability to musculoskeletal injuries of the upper extremity, and 3) provide an overview of evidence for the association between core stability and athletic performance. Additionally, we will identify clinical tests and measures that might assist in capturing core stability status and discuss gaps in the evidence for the purpose of informing future research.

Definition of the core and core stability

A number of definitions have been proposed to describe the “core”. A commonly accepted definition is the boney skeleton, ligaments, and musculature of the lower spine, pelvis, hips, and proximal lower extremities5,9. When considering overhead athletes, this definition has been expanded to include the boney skeleton, ligaments, and musculature of the shoulder girdle5. Therefore, from this perspective, key core musculature includes muscles in the superficial and deep abdominal wall, pelvic floor, erector spinae, and segmental back muscles, as well as those supporting the pelvic girdle/hip and scapula.

“Core stability” has been defined as the ability to control trunk position and motion for the purpose of optimal production, transfer, and control of forces

to and from the terminal segments during functional activities5. The concept of stability encompasses both static and dynamic control. This includes the ability of the neuromuscular system to keep the trunk in (or return it to) an upright position (static) and control trunk movements (dynamic). This is predominantly accomplished via quick postural responses by the neuromuscular system to both internal and external perturbations (expected or unexpected). This also includes perturbations caused by forces generated from or traveling through the extremities. Both feed-forward and feed-back mechanisms are integrated within the neuromuscular system to respond to these forces10.

A well-performing neuromuscular system is essential for core stability. This system provides stability by relaying available sensory information (position, velocity, force) to the central nervous system (CNS), which then activates appropriate musculature to generate forces quickly and accurately11 (Figure 1). This indicates that core stability is a dynamic process that requires optimal muscle capacity (strength, endurance, power) and neuromuscular control (accurate joint and muscle receptors and neural pathways) that can quickly integrate sensory information and alter motor responses relative to internal and external information.

Scientific evidenceTwo literature searches from January 1990 to

December 2014 were conducted within the CINHAL, MEDLINE, and SPORTDiscus databases. These

Figure 1. A schematic of the components of a well-functioning neuromuscular system. The boxes representing muscle capacity and neuromuscular control include examples of parameters that can be measured to assess these components. The central nervous system (CNS) includes the integration (Σ) of the sensory information and determination of the motor command.

Silfies SP, Ebaugh D, Pontillo M, Butowicz CM

362 Braz J Phys Ther. 2015 Sept-Oct; 19(5):360-368

searches were supplemented by reviewing the reference list of articles that met our criteria. The first search was intended to identify prospective and longitudinal studies that assessed the relationship between core [search terms: core, trunk, lumbopelvic spine] stability [stability, strength, neuromuscular control] and shoulder, elbow, or wrist injury [injury, pain] in athletes [athlete]. We included case control or cohort studies (injured vs. non-injured athletes). However, we did so with the understanding that we could not separate coincidental relationships from causal ones. Systematic reviews were used when available and weighted more heavily in our summary of the evidence. Based upon our operational definition of core stability, we included articles that assessed both sensory and motor aspects of neuromuscular control as well as core muscle strength and endurance. Articles that included interventions had to clearly incorporate specific exercises for and measure changes in core stability within a randomized clinical trial (RCT). The findings of intervention RCTs that focused on prevention of injury and where the injury group was limited to those with non-contact injuries were more heavily weighted in our conclusions. Our literature search identified 64 potential articles; however, this reduced to seven when we applied our criteria for region of injury, subject population, study design, and measured variables of core stability.

The second search was intended to identify articles that assessed the relationship between core stability [same search terms as above] and athletic performance [performance]. We included intervention studies on healthy athletes in which muscle capacity or neuromuscular control training was instituted to determine if changes in performance were associated with changes in specific core stability measures. High quality RCTs and systematic reviews were weighted more heavily in our conclusions. This search resulted in 109 articles that were narrowed to 11 based upon our criteria.

Evidence linking core stability to upper extremity athletic injuries

Deficits in core stability have been proposed to lead to shoulder5,12 or elbow injuries13. Although our search failed to identify any systematic reviews on this proposed relationship, it did identify three recent prospective injury risk studies. Chaudhari et al.14 investigated the association between lumbopelvic control and injuries in baseball players. Lumbopelvic

control was assessed during a single-leg raise test in 347 professional baseball pitchers during spring training. This test was performed in standing with the athlete attempting to keep the waist as level as possible while they slowly lifted one foot up as though they are going to step up onto a curb15 (Figure 2). Days missed because of injury during the season were tracked for each player. They found that pitchers with less control during the single-leg raise task (highest tertile of anterior–posterior lumbopelvic motion) were 3 times more likely to miss at least 30 days than those pitchers demonstrating lower amounts of lumbopelvic motion. Non-contact injuries of the upper extremity and trunk/back accounted for 60% and 14% of the injuries reported over the season, respectively. However, Endo and Sakamoto16 reported no relationship between core muscle endurance (prone bridge, side bridge) and shoulder or elbow injury in junior high school baseball players. Pontillo et al.17 reported on a prospective injury risk study of Division 1 American football players. Their data indicated that players who suffered a shoulder injury during the season could be identified by preseason performance on the Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST). The CKCUEST is performed in

Figure 2. Example of the single leg raise test to assess the ability to control the lumbopelvic region when moving into unilateral stance as described by Chaudhari et al.14.

Core stability and athletes

363 Braz J Phys Ther. 2015 Sept-Oct; 19(5):360-368

a prone plank position where the athlete is asked to alternate periods of upper limb single support to touch one of two lines placed 91.4 cm apart over a 15-second time period18 (Figure 3). Based on their findings, they determined that a cut score of less than 21 touches could identify athletes at risk for future injury. Collectively, these studies suggest that poor core stability (as measured by the CKCUEST and single-leg raise tests) should be considered a potential risk factor for future upper extremity injury.

Two case control and cohort studies of swimmers also lend support to the hypothesized relationship between impaired core stability and upper extremity injuries. Tate et al.19 assessed scapular dyskinesia, core muscle endurance (side-bridge, prone bridge), and the CKCUEST on 236 female youth, high school, or US Masters swimmers. They compared test findings between subjects who reported substantial shoulder disability and pain (Penn Shoulder Score and the sport performance module of the Disability of the Arm, Shoulder and Hand Outcome Measure) and those who did not. Neither the observation of scapular dyskinesia nor reduced core endurance was more predominate in the group with shoulder pain or disability, with the exception of reduced side-bridge endurance20 (Figure 4) for high school age swimmers. Harrington et al.21 also assessed core endurance in swimmers with and without shoulder pain (NCAA Division 1 females, n=37). They reported no significant differences in core endurance for side-bridge and prone bridge between the groups. Together these two studies offer conflicting support for poor core stability being associated with shoulder pain in competitive swimmers.

Based upon the kinetic chain theory5, abnormal neuromuscular control in any portion of the chain could alter forces and biomechanics during upper extremity movements; therefore we included these two recent cohort studies that also assessed standing balance. Radwan et al.22 tested 61 Division III overhead athletes, 14 with current shoulder pain and dysfunction from a non-contact injury. Core stability tests included double leg lowering test (DLLT), Sorensen modified extensor endurance test, and side plank and the single leg balance test (SLBT). Only the SLBT stance time, which assesses static balance, was significantly reduced in the shoulder pain group. Garrison et al.23 also reported significantly decreased dynamic balance in both lead and stance legs, as measured by the Y-balance test24 (Figure 5), in high school and collegiate baseball players with ulnar collateral ligament (UCL) tears.

Their study included 30 male athletes with an UCL tear and 30 non-injured, age-, arm dominance-, experience-, and position-matched controls. Although these studies do not directly support decreased standing balance control as a cause for shoulder injury/pain or UCL tears, they do support the hypothesis of a potential relationship between poor core control, as measured by clinical tests (SLBT, Y-balance), and upper extremity injury.

Is the evidence for an association between poor core stability and upper extremity injury different than that found for the spine and lower extremity injuries?

While not the focus of the review, it seems important to summarize briefly the evidence for an association between core stability status and spine and lower extremity (LE) non-contact injuries. Based on data

Figure 3. Start position for the performance on the Closed Kinetic Chain Upper Extremity Stability Test as described by Pontillo et al.17.

Figure 4. The side-bridge endurance test position as described by Tate et al.19.

Silfies SP, Ebaugh D, Pontillo M, Butowicz CM

364 Braz J Phys Ther. 2015 Sept-Oct; 19(5):360-368

from Hootman et al.2, the percentage of injuries to the spine and LE during practice and games averages 11.5 and 53%, respectively. Thus, it is not surprising that a majority of research related to core stability and injuries has focused on the LE. Several prospective, longitudinal studies from a large cohort of Division 1 collegiate athletes (n= 277) support the relationship between core stability and LE injury25,26. These studies indicate that decreased trunk proprioception and neuromuscular control are predictive of future knee injuries in female collegiate athletes. Using this same cohort of athletes, Cholewicki et al.27 found decreased trunk neuromuscular control (delayed trunk reflexes) to be predictive of future low back injury (LBI). However, neither decreased trunk proprioception nor trunk muscle activation imbalance were predictive of LBI in this cohort28,29. In another large (n=162) prospective study, Nadler et al.30 found an association between hip muscle strength imbalance and LBI in female athletes. A number of studies have suggested that impaired hip muscle strength is associated with LE, particularly knee injuries31,32. Dynamic balance impairment as measured by the Star Excursion Balance Test, Single-leg Hop for Distance, and Lower Extremity Functional Test have also been associated with back, knee, and ankle injuries24,33,34. Work in this area has also advanced to include studies that suggest core stability training can reduce the risk of LE injuries35-37.

While there are studies with stronger and more consistent evidence that support a relationship between core stability and LE or back injuries, these studies are not without limitations. In general, the findings associated with LE injury are weighted to studies that only measured muscle capacity and stronger findings

are associated with knee injuries in female athletes. The primary limitation of these findings is that it is unclear how much poor core stability contributes to injury risk in light of other risk factors.

Evidence linking core stability to athletic performance

Athletic performance can be assessed through functional, agility, speed, accuracy, and power tests that involve the upper extremity, LE, or the entire body. Based on the kinetic chain theory, a “break in the chain”38 should lead to a decrease in optimal force generation or efficiency, and subsequent decrease in performance. Our search on this topic revealed one systematic review by Reed et al.39. Their inclusion criteria were targeted toward core training (isolated or integrated into a rehabilitation program for injured athletes), measurement of sports performance, and subjects under the age of 65 years old. Their search produced 10 RCTs and 14 non-randomized trials. An example of a study included in this review was an eight-week core endurance training protocol completed by Tse et al.8. This non-randomized intervention study investigated the effect of training on various measures of athletic performance (vertical and broad jump, shuttle run, 40-meter sprint, overhead medicine ball throw, and ergometer test). While the authors report significant improvement in the side-bridge endurance, they found no difference between the control group and the group performing core endurance training on any of the performance measures. However, this may be attributed to the fact that only core muscle endurance was trained and not aspects of neuromuscular control.

Figure 5. The Y-balance test performed in the (A) anterior, (B) posterior medial, and (C) posterior lateral directions.

Core stability and athletes

365 Braz J Phys Ther. 2015 Sept-Oct; 19(5):360-368

The diversity of definitions and assessments of core stability, as well as the diversity in core training regimens, hampered summarizing findings of this systematic review. The largest group of studies assessed the effect of core strengthening on LE performance. These studies demonstrated mixed results with 3 of 10 studies reporting increased running performance post core training and 2 reporting no change. However, in general those studies reporting change were conducted using active adults and not trained athletes39. The 6 studies that evaluated aspects of upper extremity performance, suggest that core muscle endurance is not a strong predictor of sports performance. However, a more recent RCT assessing the effects of strength training on nationally ranked junior tennis players (including core muscle exercises) found improvement in service velocity following a 6-week intervention40. Reed et al.39 suggest that isolated training of the core should not be the primary emphasis for programs with the goal of enhancing sports performance. Instead, they propose training tailored to the athlete’s sport (sport-specific training), as studies using these approaches demonstrated at least improved performance in sport-specific tasks (e.g. golf club head speed, bat speed).

Reed et al.39 excluded studies that did not involve core training intervention. There are several non-intervention studies that have investigated the relationship between core stability and general41-43 and specific athletic performance42. Nesser et al.41 investigated the relationship between core stability and performance in Division I football players by measuring: 1) strength, tested by three power lifting exercises; 2) core muscle endurance; and 3) sports performance, tested via sprints of various lengths, countermovement vertical jump, and a shuttle run. Total core strength was defined as the total isometric hold times of the trunk flexion, trunk extension, and left and right side-bridge tests. The authors theorized that increases in core strength would correlate with increased strength and performance measures. Significant correlations were found between total core strength and sprints, agility tasks, 1 repetition maximum squat, and bench press. Okada et al.42 also compared core stability, Functional Movement Screen (FMS), and performance testing in a group of athletic subjects. However, core stability was tested with four endurance tests: sustained flexion, extension, left and right side-bridge. This study was the first to include, amongst the performance tests, an upper extremity performance test consisting of a backwards

overhead medicine ball throw. The authors reported weak to moderate significant correlations between core stability measures and performance. There were no significant correlations between core stability and FMS. It should be noted that, in both studies41,42, the authors only measured core muscle endurance, not neuromuscular control, and the terms “stability” and “strength” were used interchangeably. Sharrock et al.43 used the double leg lowering test (DLLT) to assess muscle capacity of the rectus abdominis and oblique muscles and correlated this with four performance tests: forty-yard dash, T-test, vertical jump, and a medicine ball throw. The medicine ball throw was the only measure that significantly correlated with the DLTT, with an improved score on the double leg lowering correlating with an improved score on the medicine ball throw. Chaudhari et al.44 was the only study we found that assessed the association between neuromuscular control and in season sports performance. They assessed the anterior-posterior motion of the pelvis during the single-leg raise test in 75 Minor League pitchers and tracked their performance (innings pitched, walks + hits/ inning, strike out/inning). The group of pitchers with better lumbopelvic control demonstrated better accuracy (walks + hits/inning) and endurance (innings pitched) with trends toward difference in other measures of game performance.

Collectively, the findings from these studies imply that select measures of core stability are related to athletic performance and function. However, given the study designs, a true causal relationship cannot be strongly inferred and further research is warranted to expand upon this premise.

Limitations and gaps in the literature

Our literature search and subsequent study selection criteria resulted in a small number of higher quality studies that addressed the relationship between core stability and upper extremity injury. Of the few prospective longitudinal studies reviewed, there is evidence to support the proposed relationship. However, sample sizes in these studies were small. More importantly, the amount of risk potentially posed by poor core stability versus other factors such as history of injury, level of recovery, specific shoulder or elbow joint ligament and muscle impairments, reduced joint motion, exposure to the sports activity (pitches throw, swimming strokes), non-orthopaedic conditions, or

Silfies SP, Ebaugh D, Pontillo M, Butowicz CM

366 Braz J Phys Ther. 2015 Sept-Oct; 19(5):360-368

environmental conditions (altitude, extreme heat, or cold) has not been directly compared. Examples of the amount of risk poor core stability might possess are provided by Cholewicki et al.27, who reported a larger risk for future low back injury (LBI) being associated with the history of a LBI (Odds Ratio [OR] 2.84) than risk associated with decreased trunk neuromuscular control (OR 1.02). Zazulak et al.25 also reported that a history of LBI was the only significant factor associated with LE injuries in male athletes. Prior injuries predicting future injury generated the hypothesis that prior injury somewhere in the kinetic chain is associated with future injuries.

The study design of the majority of core stability cohort or intervention studies linked to an athletic injury does not allow us to determine if core stability deficiencies were present prior to injury, a consequence of decondition from the injury, or if the outcome of rehabilitation can be directly associated with changes in core stability alone. Based on the literature reviewed, there is little direct evidence for poor core stability as a cause of or the predominant risk factor for athletic injuries. In addition, the role of pain in muscle inhibition, altered proprioception, disrupted neural processing speed, or cognitive processing cannot be eliminated from studies that assessed the association of core stability to athletes who were currently recovering from an injury45-47. Therefore caution is recommended in interpreting findings from these studies.

Many of the articles assessing the effect of core stability on sports performance do not focus solely on a competitive athletic population. In particular, many studies used recreationally active students and adults to assess the role of core stability in injury or performance, which may represent greater effect size than on trained athletes. Therefore, it is difficult to directly translate the findings to competitive or highly trained athletes39.

Our review was also limited to studies that addressed at least one aspect of core stability as we operationally defined it. Therefore, studies that solely assessed joint ranges of motion, pain, or self-reported measures of disability as risk factors for athletic injury were not included as part of the review.

ConclusionsCore stability is a component of many, if not all,

athletic conditioning, prevention, or rehabilitation programs, despite the lack of strong evidence of a direct contribution to injury prevention or enhanced

performance. Where a contribution has been demonstrated, the amount of risk potentially posed by poor core stability has not been systematically evaluated in conjunction with other identified injury risk factors. Although not specifically reviewed as part of this paper, there is strong evidence for the role of history of prior injury25,27 and level of recovery from prior injury as risk factors for future injury48-50. Other factors associated with upper extremity injury, specific to the joint or region (e.g. muscle impairment, limited or asymmetric joint motion) and those factors associated with environment or exposure (number of pitches, swimming stroke type) related to the sports activity itself, have not been investigated in conjunction with core stability. We included descriptions of clinical tests that have demonstrated potential value in predicting upper extremity injuries and provided references for their reliability. These tests serve as a starting point for clinicians and researchers focused on the treatment of upper extremity athletic injuries. Future studies should be prospective, strive for larger sample sizes, and consider assessing the relationship between risk factors for known specific injuries and exposure to determine which factors are most relevant to achieving the primary goal of reducing the number and severity of athletic injuries. This information would allow coaches, medical and fitness professionals, and athletes themselves to focus on programs designed for prevention and rehabilitation of athletic injuries.

AcknowledgementsThis work was supported in part by a Legacy

Fund Grant from the Sports Physical Section of the American Physical Therapy Association. The content of this manuscript is solely the responsibility of the authors and does not necessarily represent the official views of the American Physical Therapy Association or granting agency.

References1. Centers for Disease Control and Prevention - CDC. CDC

Injury Research Agenda. In: Fleming DW, Binder S, editors. Atlanta: National Center for Injury Prevention and Control, CDC; 2002.

2. Hootman JM, Dick R, Agel J. Epidemiology of collegiate injuries for 15 sports: summary and recommendations for injury prevention initiatives. J Athl Train. 2007;42(2):311-9. PMid:17710181.

3. Alonso JM, Tscholl PM, Engebretsen L, Mountjoy M, Dvorak J, Junge A. Occurrence of injuries and illnesses during the 2009 IAAF World Athletics Championships. Br

Core stability and athletes

367 Braz J Phys Ther. 2015 Sept-Oct; 19(5):360-368

J Sports Med. 2010;44(15):1100-5. http://dx.doi.org/10.1136/bjsm.2010.078030. PMid:21106775.

4. Junge A, Engebretsen L, Mountjoy ML, Alonso JM, Renström PA, Aubry MJ, et al. Sports injuries during the Summer Olympic Games 2008. Am J Sports Med. 2009;37(11):2165-72. http://dx.doi.org/10.1177/0363546509339357. PMid:19783812.

5. Kibler WB, Press J, Sciascia A. The role of core stability in athletic function. Sports Med. 2006;36(3):189-98. http://dx.doi.org/10.2165/00007256-200636030-00001. PMid:16526831.

6. Kibler WB. The role of the scapula in athletic shoulder function. Am J Sports Med. 1998;26(2):325-37. PMid:9548131.

7. Stanton R, Reaburn PR, Humphries B. The effect of short-term Swiss ball training on core stability and running economy. J Strength Cond Res. 2004;18(3):522-8. PMid:15320664.

8. Tse MA, McManus AM, Masters RS. Development and validation of a core endurance intervention program: implications for performance in college-age rowers. J Strength Cond Res. 2005;19(3):547-52. PMid:16095402.

9. Putnam CA. Sequential motions of body segments in striking and throwing skills: descriptions and explanations. J Biomech. 1993;26(Suppl 1):125-35. http://dx.doi.org/10.1016/0021-9290(93)90084-R. PMid:8505347.

10. Borghuis AJ, Lemmink KA, Hof AL. Core muscle response times and postural reactions in soccer players and nonplayers. Med Sci Sports Exerc. 2011;43(1):108-14. http://dx.doi.org/10.1249/MSS.0b013e3181e93492. PMid:20508535.

11. Reeves NP, Narendra KS, Cholewicki J. Spine stability: the six blind men and the elephant. Clin Biomech (Bristol, Avon). 2007;22(3):266-74. http://dx.doi.org/10.1016/j.clinbiomech.2006.11.011. PMid:17210212.

12. Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology Part I: pathoanatomy and biomechanics. Arthroscopy. 2003;19(4):404-20. http://dx.doi.org/10.1053/jars.2003.50128. PMid:12671624.

13. Ben Kibler W, Sciascia A. Kinetic chain contributions to elbow function and dysfunction in sports. Clin Sports Med. 2004;23(4):545-52, viii. http://dx.doi.org/10.1016/j.csm.2004.04.010. [viii.] PMid:15474221.

14. Chaudhari AM, McKenzie CS, Pan X, Oñate JA. Lumbopelvic control and days missed because of injury in professional baseball pitchers. Am J Sports Med. 2014;42(11):2734-40. http://dx.doi.org/10.1177/0363546514545861. PMid:25159541.

15. Yedimenko J, Jamison ST, McNally MP, McKenzie CS, Onate JA, Chaudhari A. Intra- and Inter-rater reliability of a single-leg raise test of pelvic sagittal control. In: American College of Sports Medicine Annual Meeting; 2013; Indianapolis, IN.

16. Endo Y, Sakamoto M. Correlation of shoulder and elbow injuries with muscle tightness, core stability, and balance by longitudinal measurements in junior high school baseball players. J Phys Ther Sci. 2014;26(5):689-93. http://dx.doi.org/10.1589/jpts.26.689. PMid:24926133.

17. Pontillo M, Spinelli BA, Sennett BJ. Prediction of in-season shoulder injury from preseason testing in division I collegiate football players. Sports Health. 2014;6(6):497-503. http://dx.doi.org/10.1177/1941738114523239. PMid:25364482.

18. Tucci HT, Martins J, Sposito GC, Camarini PM, Oliveira AS. Closed Kinetic Chain Upper Extremity Stability test (CKCUES test): a reliability study in persons with and without shoulder impingement syndrome. BMC Musculoskelet

Disord. 2014;15(1):1-9. http://dx.doi.org/10.1186/1471-2474-15-1. PMid:24387196.

19. Tate A, Turner GN, Knab SE, Jorgensen C, Strittmatter A, Michener LA. Risk factors associated with shoulder pain and disability across the lifespan of competitive swimmers. J Athl Train. 2012;47(2):149-58. PMid:22488280.

20. McGill SM, Childs A, Liebenson C. Endurance times for low back stabilization exercises: clinical targets for testing and training from a normal database. Arch Phys Med Rehabil. 1999;80(8):941-4. http://dx.doi.org/10.1016/S0003-9993(99)90087-4. PMid:10453772.

21. Harrington S, Meisel C, Tate A. A cross-sectional study examining shoulder pain and disability in Division I female swimmers. J Sport Rehabil. 2014;23(1):65-75. http://dx.doi.org/10.1123/JSR.2012-0123. PMid:23945068.

22. Radwan A, Francis J, Green A, Kahl E, Maciurzynski D, Quartulli A, et al. Is there a relation between shoulder dysfunction and core instability? Int J Sports Phys Ther. 2014;9(1):8-13. PMid:24567850.

23. Garrison JC, Arnold A, Macko MJ, Conway JE. Baseball players diagnosed with ulnar collateral ligament tears demonstrate decreased balance compared to healthy controls. J Orthop Sports Phys Ther. 2013;43(10):752-8. http://dx.doi.org/10.2519/jospt.2013.4680. PMid:24256174.

24. Plisky PJ, Rauh MJ, Kaminski TW, Underwood FB. Star excursion balance test as a predictor of lower extremity injury in high school basketball players. J Orthop Sports Phys Ther. 2006;36(12):911-9. http://dx.doi.org/10.2519/jospt.2006.2244. PMid:17193868.

25. Zazulak BT, Hewett TE, Reeves NP, Goldberg B, Cholewicki J. The effects of core proprioception on knee injury: a prospective biomechanical-epidemiological study. Am J Sports Med. 2007;35(3):368-73. http://dx.doi.org/10.1177/0363546506297909. PMid:17267766.

26. Zazulak BT, Hewett TE, Reeves NP, Goldberg B, Cholewicki J. Deficits in neuromuscular control of the trunk predict knee injury risk: a prospective biomechanical-epidemiologic study. Am J Sports Med. 2007;35(7):1123-30. http://dx.doi.org/10.1177/0363546507301585. PMid:17468378.

27. Cholewicki J, Silfies SP, Shah RA, Greene HS, Reeves NP, Alvi K, et al. Delayed trunk muscle reflex responses increase the risk of low back injuries. Spine (Phila Pa 1976). 2005;30(23):2614-20. http://dx.doi.org/10.1097/01.brs.0000188273.27463.bc. PMid:16319747.

28. Silfies SP, Cholewicki J, Reeves NP, Greene HS. Lumbar position sense and the risk of low back injuries in college athletes: a prospective cohort study. BMC Musculoskelet Disord. 2007;8:129. http://dx.doi.org/10.1186/1471-2474-8-129. PMid:18166132.

29. Reeves NP, Cholewicki J, Silfies SP. Muscle activation imbalance and low-back injury in varsity athletes. J Electromyogr Kinesiol. 2006;16(3):264-72. http://dx.doi.org/10.1016/j.jelekin.2005.07.008. PMid:16129623.

30. Nadler SF, Malanga GA, Feinberg JH, Prybicien M, Stitik TP, DePrince M. Relationship between hip muscle imbalance and occurrence of low back pain in collegiate athletes: a prospective study. Am J Phys Med Rehabil. 2001;80(8):572-7. http://dx.doi.org/10.1097/00002060-200108000-00005. PMid:11475476.

Silfies SP, Ebaugh D, Pontillo M, Butowicz CM

368 Braz J Phys Ther. 2015 Sept-Oct; 19(5):360-368

31. Ireland ML, Willson JD, Ballantyne BT, Davis IM. Hip strength in females with and without patellofemoral pain. J Orthop Sports Phys Ther. 2003;33(11):671-6. http://dx.doi.org/10.2519/jospt.2003.33.11.671. PMid:14669962.

32. Leetun DT, Ireland ML, Willson JD, Ballantyne BT, Davis IM. Core stability measures as risk factors for lower extremity injury in athletes. Med Sci Sports Exerc. 2004;36(6):926-34. http://dx.doi.org/10.1249/01.MSS.0000128145.75199.C3. PMid:15179160.

33. Brumitt J, Heiderscheit BC, Manske RC, Niemuth PE, Rauh MJ. Lower extremity functional tests and risk of injury in division iii collegiate athletes. Int J Sports Phys Ther. 2013;8(3):216-27. PMid:23772338.

34. Olmsted LC, Carcia CR, Hertel J, Shultz SJ. Efficacy of the star excursion balance tests in detecting reach deficits in subjects with chronic ankle instability. J Athl Train. 2002;37(4):501-6. PMid:12937574.

35. Hewett TE, Ford KR, Myer GD. Anterior cruciate ligament injuries in female athletes: Part 2, a meta-analysis of neuromuscular interventions aimed at injury prevention. Am J Sports Med. 2006;34(3):490-8. http://dx.doi.org/10.1177/0363546505282619. PMid:16382007.

36. Hides JA, Stanton WR. Can motor control training lower the risk of injury for professional football players? Med Sci Sports Exerc. 2014;46(4):762-8. http://dx.doi.org/10.1249/MSS.0000000000000169. PMid:24056268.

37. Myer GD, Ford KR, Palumbo JP, Hewett TE. Neuromuscular training improves performance and lower-extremity biomechanics in female athletes. J Strength Cond Res. 2005;19(1):51-60. PMid:15705045.

38. Burkhart SS, Morgan CD, Kibler WB. The disabled throwing shoulder: spectrum of pathology Part III: The SICK scapula, scapular dyskinesis, the kinetic chain, and rehabilitation. Arthroscopy. 2003;19(6):641-61. http://dx.doi.org/10.1016/S0749-8063(03)00389-X. PMid:12861203.

39. Reed CA, Ford KR, Myer GD, Hewett TE. The effects of isolated and integrated ‘core stability’ training on athletic performance measures: a systematic review. Sports Med. 2012;42(8):697-706. http://dx.doi.org/10.1007/BF03262289. PMid:22784233.

40. Fernandez-Fernandez J, Ellenbecker T, Sanz-Rivas D, Ulbricht A, Ferrautia A. Effects of a 6-week junior tennis conditioning program on service velocity. J Sports Sci Med. 2013;12(2):232-9. PMid:24149801.

41. Nesser TW, Huxel KC, Tincher JL, Okada T. The relationship between core stability and performance in division I football players. J Strength Cond Res. 2008;22(6):1750-4. http://dx.doi.org/10.1519/JSC.0b013e3181874564. PMid:18978631.

42. Okada T, Huxel KC, Nesser TW. Relationship between core stability, functional movement, and performance. J Strength Cond Res. 2011;25(1):252-61. http://dx.doi.org/10.1519/JSC.0b013e3181b22b3e. PMid:20179652.

43. Sharrock C, Cropper J, Mostad J, Johnson M, Malone T. A pilot study of core stability and athletic performance: is there a relationship? Int J Sports Phys Ther. 2011;6(2):63-74. PMid:21713228.

44. Chaudhari AM, McKenzie CS, Borchers JR, Best TM. Lumbopelvic control and pitching performance of professional baseball pitchers. J Strength Cond Res. 2011;25(8):2127-32. http://dx.doi.org/10.1519/JSC.0b013e31820f5075. PMid:21760550.

45. Crombez G, Eccleston C, Baeyens F, Eelen P. The disruptive nature of pain: an experimental investigation. Behav Res Ther. 1996;34(11-12):911-8. http://dx.doi.org/10.1016/S0005-7967(96)00058-7. PMid:8990542.

46. Hodges PW. Pain and motor control: From the laboratory to rehabilitation. J Electromyogr Kinesiol. 2011;21(2):220-8. http://dx.doi.org/10.1016/j.jelekin.2011.01.002. PMid:21306915.

47. Luoto S, Taimela S, Hurri H, Alaranta H. Mechanisms explaining the association between low back trouble and deficits in information processing. A controlled study with follow-up. Spine (Phila Pa 1976). 1999;24(3):255-61. http://dx.doi.org/10.1097/00007632-199902010-00011. PMid:10025020.

48. Cholewicki J, Greene HS, Polzhofer GK, Galloway MT, Shah RA, Radebold A. Neuromuscular function in athletes following recovery from a recent acute low back injury. J Orthop Sports Phys Ther. 2002;32(11):568-75. http://dx.doi.org/10.2519/jospt.2002.32.11.568. PMid:12449256.

49. Orchard JW. Intrinsic and extrinsic risk factors for muscle strains in Australian football. Am J Sports Med. 2001;29(3):300-3. PMid:11394599.

50. Ekstrand J, Gillquist J. The avoidability of soccer injuries. Int J Sports Med. 1983;4(2):124-8. http://dx.doi.org/10.1055/s-2008-1026025. PMid:6874174.

Correspondence Sheri P. Silfies Drexel University Rehabilitation Sciences Spine Research Laboratory Three Parkway, Mail Stop 1041, Philadelphia, PA 19102-1192, USA e-mail: silfies@drexel.edu

http://dx.doi.org/10.1590/bjpt-rbf.2014.0110

review article

369 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

Measuring sports injuries on the pitch: a guide to use in practice

Luiz C. Hespanhol Junior1, Saulo D. Barboza1, Willem van Mechelen1, Evert Verhagen1

ABSTRACT | Sports participation is a major ally for the promotion of physical activity. However, sports injuries are important adverse effects of sports participation and should be monitored in sports populations. The purpose of this paper is to review the basic concepts of injury monitoring and discuss the implementation of these concepts in practice. The aspects discussed are: (1) sports injury definition; (2) classification of sports injuries; (3) population at risk, prevalence, and incidence; (4) severity measures; (5) economic costs; (6) systems developed to monitor sports injuries; and (7) online technology. Only with reliable monitoring systems applied in a continuous and long-term manner will it be possible to identify the burden of injuries, to identify the possible cases at an early stage, to implement early interventions, and to generate data for sports injury prevention. The implementation of sports injuries monitoring systems in practice is strongly recommended. Keywords: sports injury; prevalence; incidence; public health surveillance; epidemiological monitoring; costs and cost analysis.

HOW TO CITE THIS ARTICLE

Hespanhol Junior LC, Barboza SD, van Mechelen W, Verhagen E. Measuring sports injuries on the pitch: a guide to use in practice. Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380. http://dx.doi.org/10.1590/bjpt-rbf.2014.0110

1 Department of Public & Occupational Health, EMGO+ Institute for Health and Care Research, VU University Medical Center, Amsterdam, The NetherlandsReceived: Mar. 10, 2015 Revised: May 12, 2015 Accepted: May 25, 2015

IntroductionThe pandemic of physical inactivity is a major public

health problem of the 21st century1-3. Physical inactivity was responsible for 6% to 10% of non-communicable diseases in 2008 and it is a leading risk factor for mortality4, accounting for 5.3 million deaths in the same year5. Initiatives have been proposed worldwide in order to promote physical activity2,6. In Brazil, this is also a matter of concern, since the prevalence of physical inactivity in adults is estimated to be around 40%7. One of the largest initiatives to promote physical activity in Brazil is the Academia da Saúde (Health Gym) project supported by the Brazilian Ministry of Health8-10. This program is aimed at reducing the barriers to the access of physical activity and to decrease the risk of non-communicable diseases by building 4,000 community gyms8,9.

Sports participation may be part of the solution in promoting an active lifestyle, the benefits of which are well known11-15. However, sports injuries are adverse effects of this practice and may hamper participation in physical activities16. In addition, there are substantial costs of sports-related injuries, making these injuries also a societal problem17,18. As sports injuries are a barrier to the promotion of physical activity and result

in costs for society, efforts should be made to prevent them. It is well recognized that the first step towards sports injury prevention is the measurement of the health and societal burden of sports injuries19. This has been done in research, but it is still a challenge to implement on a broad scale in everyday practice. Continuous monitoring of sports injuries should be implemented in any sport environment, whether individual or team sports. Early identification of injury and availability of evidence-based interventions are the key factors for sports injury prevention and treatment, and only with a reliable and valid injury monitoring system is this possible. The purpose of this paper is, therefore, to review the basic concepts of injury monitoring and to discuss the implementation of these concepts in practice in order to provide a guide for those who want to implement sports injury monitoring systems.

What is sports injury?There are many studies addressing the importance

of defining ‘injury’ in research, and this is also an important topic that should be taken into account in practice. In order to truly prevent or manage injuries

Hespanhol Junior LC, Barboza SD, van Mechelen W, Verhagen E

370 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

in the field, firstly it is necessary to define what is considered an injury. Figure 1 exemplifies the course of a musculoskeletal problem (i.e. sports injury) over time. If the definition of injury is based on the symptom “pain”, the injury has lasted 17 weeks (week 2 to 19). However, if the definition is based on time loss (i.e. missing training or competition), the injury has lasted 3 weeks (week 8 to 11). In both cases, one is dealing with the same musculoskeletal problem (Figure 1). However, there are two different interpretations. The grey area above the pain or the time loss threshold represents the severity (discussed later in the paper), or the burden caused by the injury, once the definition is based on these thresholds. It is clear that the grey area above the time loss threshold is much smaller than the grey area above the pain threshold, meaning that these two definitions lead to two very different conclusions about the injury severity or burden.

Sports injury definitionThe term ‘sports injury’ is used to refer to a

variety of musculoskeletal damage caused by sports participation19. However, ‘what is damage?’ may be interpreted and recorded in different ways19. Recently, studies have provided some ‘consensus’ helping to standardize the definition and/or classification of injuries20-28, improving the comparability between studies, settings, sports facilities, injury measurement systems, and also between different time-points. There are general definitions, such as ‘injuries are considered disorders of the musculoskeletal system or concussions’28, and specific definitions, such as injuries requiring medical attention (i.e. any injury that

leads to health care utilization) or injuries leading to time loss (i.e. injuries that hamper the ability to fully participate in sports for at least one training session or competition). Also, there are injury definition recommendations for specific sports: cricket23, football (soccer)24, rugby25, tennis26, horse racing27, athletics22, and running29. Considering ‘what is an injury?’ will depend on the specific purpose of the surveillance, which may vary between different sports or settings. However, it is fundamental to appropriately define what is going to be measured30.

ClassificationMechanism

Different injuries can have different characteristics, causes, and consequences. Therefore, they should be classified in order to elucidate the injury process. The mechanism of the injury drives the initial classification. Acute injuries are those whose onset can be linked to a specific, identifiable and sudden injury event28, while overuse injuries are those with a gradual onset mechanism resulting from repetitive micro-trauma, without a specific identifiable event causing the problem21. This classification may guide the health care approaches regarding prevention, treatment or prognosis.

Subsequent injuriesIt is not uncommon for an athlete to report more

than one injury during a season. Therefore, subsequent injuries should be measured as well. Subsequent injuries can be classified as a new injury (not the same injury as the initial injury, e.g. an injury to another body region) or as a recurrent injury. Recurrent injuries occur in the same body location and usually are of the same nature and/or mechanism. They can be further classified as re-injury (when the injury has fully healed) or as an exacerbation (when the injury has not fully healed)20,31.

According to consequencesMedical attention and time loss classifications are

also very common. They are frequently used to define an injury (as discussed previously). For example, a study involving recreational runners was conducted based on a time loss definition: “[...] any pain of musculoskeletal origin attributed to running and severe enough to prevent the runner from performing at least one training session [...]”32. It could also be that the same study had a definition based on medical

Figure 1. Example of the course of a sports injury over time40. The thresholds (dashed lines) represent the amount of musculoskeletal tissue damage (in percentage) necessary to result in pain, hamper performance, hamper participation in sports, or result in time loss (training sessions or competitions fully missed). The grey area represents the severity or burden related to the injury.

Measuring sports injuries on the pitch

371 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

attention, e.g. “any pain of musculoskeletal origin attributed to running and resulting in a health care professional consultation”.

Although using these classifications (i.e. medical attention and time loss) is important to provide information about injuries, using these classifications as injury definitions raises concern. It is possible that athletes do not consult medical professionals for some minor injuries. Additionally, this definition is strictly dependent on medical staff availability, which may not be a reality in many settings. This could result in an underestimation of the number and burden of injuries. Similar reasoning can be used for the application of a time loss definition. Minor injuries are no longer registered or monitored in the injury registration system if they cause no sport time loss (Figure 1).

Minor injuries are not severe in nature; however, they frequently occur in sports and may pose a large problem. In practice, monitoring ‘minor’ injuries (or complaints) contributes to an early identification of injuries, resulting in the implementation of early interventions to keep these injuries from becoming more severe, lessening the burden on the athlete, team, and/or health care system. Therefore, we suggest using ‘medical attention’ and ‘time loss’ concepts as a classification only and not as criteria to define injury.

Formal and non-formal diagnosisInjuries are commonly classified according to

the body region affected (e.g. ankle) and/or by their nature (e.g. sprain). This helps one to understand which are the most common injuries in a given sport, and therefore guide the prevention and treatment interventions. The best way to do so is to have a formal diagnosis given by a sports health professional or medical staff. However, this is not always possible because of practical/logistic reasons. Therefore, there are other methods to classify such injuries to provide more information about them. Two examples on how to do this in practice are the classifications proposed by Timpka et al.22 and the Orchard Sports Injury Classification System (OSICS)33. In the method of Timpka et al.22, an injury can be classified according to body region (e.g. ankle), type of injury (e.g. sprain), and mode of onset (i.e. sudden or gradual). In the OSICS model, an injury is classified with a code containing 4 characters: the first character relates to a body region, the second relates to a specific tissue affected or the pathology, and the third and the fourth characters further describe the pathology or broaden the diagnosis33,34. For example, the code KJAP means

Knee injury with a Joint sprain involving the Anterior cruciate ligament, although it is a Partial injury. An isolated rupture would be classified as KJAR.

Measuring sports injuriesOnce the number of injuries is identified, it is

time to put this number into context. A number of injuries by itself does not mean much if the number of individuals at risk and/or the sports exposure are not reported. This information will help one to understand the impact/extent of the problem and to make easier comparisons between different time-point measurements in a single population or team, or between different populations or teams. This is important in order to come to conclusions about whether or not the population or team has been reporting more injuries than expected or to be able to generalize the number of injuries to a specific population. Consequently, specific interventions can be discussed and implemented.

Population at risk and exposure timeIndividuals can only be at risk of developing

sports injuries if they participate in sports. It does not make sense to measure the proportion of football injuries in individuals who do not play football, for example. Therefore, the population at risk in sports is the population exposed by the sport investigated. Suppose 300 football players were injured during a season. Think about the impact of these 300 injured football players if the source population consisted of 10,000 or 500 football players (i.e. individuals at risk). The probability of having an injury during one season is, in the first case (300/10,000) 0.03, or 3%. In the second case (300/500), the probability is 0.6 or 60%, a much higher figure. Therefore, to measure the burden of injuries, it is necessary to know the total population at risk, or the source population, who have a possibility of being injured.

Exposure time is also a very important measure and concept. Even if all individuals practice sports in a source population (i.e. the population at risk), differences in exposure may lead to differences in injury risk. Individuals who practice sports once a week for one hour (i.e. sports exposure of one hour per week) are less exposed than individuals who practice five days a week for two hours (i.e. sports exposure of 10 hours per week). The practice of sports is a necessary cause for sports injuries35. This means that, theoretically, those who are more exposed to the sport activity are more likely to develop a sports injury

Hespanhol Junior LC, Barboza SD, van Mechelen W, Verhagen E

372 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

(if all other variables are controlled). For example, if 50 new injuries were registered in a source population comprised of 200 athletes and the total sports exposure time for this population was 5,000 hours of practice, one could say that the injury risk in this population was 10 injuries per 1,000 hours of practice. However, if the exposure time was 2,000 hours, the injury risk would be 25 injuries per 1,000 hours of practice, which is a risk 2.5 times higher although the number of injuries is the same. Calculations using the entire source population (i.e. population at risk) or the sports exposure are discussed later in the paper.

PrevalencePrevalence is the number of people with a given

health problem (i.e. the number of cases) in a defined population at any given point in time (Equation 1)36. In sports, prevalence is usually reported at a specific point in time (e.g. in the middle of the season) - what is known as ‘point prevalence’. However, in some reports, prevalence is also defined as the period prevalence (e.g. entire season). Prevalence is often used to report the overall extent of the sports injury problem. Suppose a sports manager wants to measure how many football players are injured exactly in the middle of a season. It is known that in this specific time-point, 50 out of 500 football players are injured. The prevalence (Equation 1) of football injuries in the middle of the football season could be 0.1 or 10% in this example.

( )

cases injured individualsPrevalence

entire source population= (1)

IncidenceIncidence is the number of new events that occurred

in a given population at risk during a period of time36. To identify the onset of events (e.g. injuries) and then to be certain that the events are new, a continuous (i.e. longitudinal) measurement is needed. Incidence can be expressed as a proportion (i.e. incidence proportion or risk) by dividing the number of new injured participants (i.e. the number of cases) by the total number of individuals at risk (i.e. the entire source population) during a period of time (Equation 2)37. As an athlete may have more than one injury over a period of time (e.g. a season), the clinical incidence can also be calculated. Clinical incidence (Equation 3) is the number of events (i.e. the number of new injuries) divided by the total number of individuals at risk (i.e. the entire source population)37.

( )

newcases newinjured individuals

Incidence proportionentire source population

= (2)

( )

number of events newinjuries

Clinical incidenceentire source population

= (3)

Incidence can also be expressed as incidence density (or incidence rate), i.e. the number of events (NOTE: participants can have more than one injury over a period of time) by the exposure (i.e. person-time) of the sport investigated (Equation 4)38. Exposure refers to the period from the beginning to the end of the measurement for non-injured individuals. For injured individuals, the exposure is from the beginning of the measurement until the time the injury was identified (i.e. time-to-injury). Person-time is an epidemiological term often used to describe exposure, and it means that the exposure of each individual was calculated and then added (i.e. the sum of person-time exposure) to the incidence density calculation37.

In sports, the exposure can be expressed in such terms as hours of participation, days (training or competition), or km. The incidence density is usually expressed by the number of events per 1,000 or 10,000 person-time exposure. Even though different types of exposure units are described, efforts are needed to achieve a common measure. For instance, a study in field hockey reported an incidence density of 7.87 injuries per 1,000 games, and 3.7 injuries per 1,000 training sessions39. Although this information gives the impression that more injuries were identified during games than during training sessions, this conclusion is misleading, because the exposure unit is not the same. A game could have lasted 1.2 hours and a training session could have lasted 5 hours, but they will still count as 1 unit for games and 1 unit for training sessions, making the comparability between the incidence densities problematic. Therefore, the authors suggest that the exposure unit should be expressed using hours of participation in order to facilitate the comprehension and comparison between different sports (e.g. field hockey and football) and types of participation (i.e. training or competition), unless a relevant reason justifies otherwise.

( )( )

. . number of events newinjuries

Incidencedensitytotal exposure e g hours of sports participation

= (4)

Consider a population of 500 football players. Suppose 70 new injuries were identified in 50 athletes, and the total exposure (i.e. the sum of injured and non-injured person-time exposure) was 20,000 football hours

Measuring sports injuries on the pitch

373 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

(i.e. both training and competition). The incidence proportion (Equation 2) of this example is 10% (50 new cases divided by 500 individuals at risk) and the incidence density (Equation 4) is 0.0035 (70 new injuries divided by 20,000 hours) or 3.5 injuries per 1,000 hours of sport exposure (0.0035 multiplied by 1,000). Note that the incidence density takes into account the number of injuries, which is suitable since an athlete commonly has more than one injury during a certain period of time (e.g. a season).

Prevalence and incidence applicationsPrevalence rather than incidence is used to describe

the overall burden or extent of the sports injury problem. If the question is ‘How many athletes are expected to have sports injuries?’, the recommended measure would be prevalence. However, most sports managers are more interested in the risk of sports injuries. In this case, incidence proportion is the best option to answer the following question: ‘What is the risk of athletes being injured?’. If the athletes can have more than one injury during a period of time and one wants to know ‘what the frequency of injuries is in a certain population’, then the clinical proportion is a good measure. Incidence density is widely used to answer the following question: ‘How many injuries would be expected for a certain amount of exposure?’37. This is an interesting question, because an individual cannot have a sports injury if he or she is not exposed to the sport being investigated.

The issue of measuring overuse injuries in sports should also be discussed. By definition, overuse injuries are those injuries with a gradual onset. However, it is very difficult to identify precisely the real onset of these injuries. In addition, the symptoms of an overuse injury could present as a sudden onset, whilst the course of the injury is actually a long-term process. This phenomenon makes things even more difficult40. Therefore, it has been suggested that the mean prevalence, calculated based on the time-point prevalences repeatedly measured over time, is a better measure of the sports injury magnitude than incidence from an overuse injury perspective40,41.

SeverityMeasuring injury severity is essential to understand

the extent to which sports injuries affect health19. Different aspects are used to determine the severity of sports injuries such as: nature of injury, duration, medical attention, sports time loss, working time loss, permanent damage, and costs of sports injuries42.

This emphasizes the importance of appropriate injury monitoring and classification.

The nature of a sports injury is an indication of its severity. A concussion is more likely to be more severe than a blister. A similar reasoning occurs with the anatomical location of injuries. A blister on the foot or toe of a runner has different consequences than the same injury in a rower. Despite the nature and anatomical location, the extent of symptoms and other consequences of an injury are also crucial. Individual characteristics, the energy involved at the moment of injury occurrence, and the injury mechanism are examples of how the same injury in individuals from the same source population may lead to a different classification of severity.

Mapping the duration of injury also contributes to the measure of severity. For this and other reasons, continuous monitoring (i.e. longitudinal data) is essential. An ankle sprain might be considered more severe than an Achilles tendinopathy in the short term. However, the overuse mechanism of the Achilles tendinopathy might lead to a longer recovery period than an ankle sprain that had an acute mechanism. Therefore, in the long-term, the Achilles tendinopathy may result in greater consequences to the athlete, leading to a higher severity classification than an ankle sprain.

Medical attention and time loss are also examples of severity. An injury that requires medical attention is more severe than an injury that does not. Similarly, if an athlete is not able to participate fully in normal sport activities due to an injury, the time loss indicates the severity of this injury. From a societal perspective, injuries occurring during sports participation may have consequences during other activities. Therefore, working time loss can also be used as a measure of severity, since it is not uncommon that people are not able to work because of a sports injury.

Most athletes recover from sports injuries without a permanent disability (residual symptoms)42. However, injuries like concussions with brain damage, spinal injuries, or eye injuries may leave permanent damage. Injuries that cause permanent damage are clearly more severe than injuries that do not. The costs of sports injuries are also important to determine severity, and the discussion about costs can be found in the next section.

Economic costsThe costs of sports injuries are usually described

as a measure of injury severity42. In general, a more severe injury leads to higher monetary costs because

Hespanhol Junior LC, Barboza SD, van Mechelen W, Verhagen E

374 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

of such things as medical consultations, medications, medical devices, and productivity loss42. All costs related to sports injuries are most commonly taken into account in an economic evaluation, no matter who pays or receives payment43. This is a societal perspective approach. There are four typical classifications of economic costs from this perspective42-45:

• Direct costs or health care costs: costs related to health care utilization, such as consultations with a general medical practitioner, sports physician, medical specialist (e.g. orthopedic surgeon), physical therapist, massage therapist, alternative therapist, the use of hospital care, medications, and medical devices (e.g. crutches, tape, braces).

• Indirect costs or lost productivity costs: costs related to loss of productivity due to absenteeism from paid or unpaid work (e.g. household work, loss of study time, loss of leisure time) or due to presenteeism (i.e. not being able to perform fully at work as a result of the injury).

• Societal costs: include insurance administration costs, costs related to insurance programs, workers’ compensation costs (i.e. workers may receive wage replacement and/or medical benefits due to sick leave44), and litigation costs (i.e. legal and court costs related to time spent by lawyers and judges, contribution made by legal support services, and overhead expenses).

• Social costs: costs related to the psychological burden of the injury (e.g. depression, social isolation, and economic dependence).

Costs data should be collected and monitored by a reliable and continuous injury registration system42. Besides the challenge, the evidence about economic costs of sports injuries has been growing, especially for direct and indirect costs17,18,46,47. Societal and social costs evidence is less common because they are more difficult to measure and estimate. Moreover, social costs are considered “unquantifiable” because of the difficulty in measuring them42.

Challenges in costs data analysisAn economic evaluation requires the collection of

data on such things as the number of (para)medical consultations, medications taken, number of medical devices used, loss of paid working productivity (in hours or days), loss of studying hours, and loss of leisure

time hours. However, this is not enough. After data collection, it is necessary to transform the number of consultations, loss of productivity, and societal and social consequences into a monetary value.

The Dutch health care system maintains a continuous registration of costs-related data. From a central website48, it is possible to download a full report of all the relevant information about the costs related to health care49. If additional information is necessary, the Dutch Central Bureau of Statistics website50 provides a variety of additional information (e.g. average hours spent during paid work by age and gender51). Therefore, the Dutch system allows a very reliable economic evaluation for those who want to perform such analysis in that country.

In Brazil, differences in socioeconomic groups and availability of medical care and costs (e.g. public and private systems) make the economic evaluation even more challenging. However, the Brazilian public health care system (SUS) also keeps continuous records of health-related data through DATASUS52. Within this database, it is possible to find a plethora of information such as number of health care consultations and hospitalizations, costs, and per capita income. DATASUS may be an important tool to perform economic evaluations on sports injuries in Brazil and should be used more for this purpose.

Sports injury monitoring systemsInjury monitoring has been performed in a variety

of ways in research and practice. It can vary from very simple and non-validated surveys32 to more sophisticated and validated injury management systems28,53. Regardless of the vehicle used to collect the injury data, the aspects discussed previously should be addressed in all of them.

There are several injury monitoring systems that record sports injuries over time in a continuous (i.e. longitudinal) manner and also measure the amount of sports exposure53-56. Some of these systems measure exposure indirectly and provide estimations. For example, a team of 50 players with 20 training sessions and 5 competitions may have 1,250 athlete exposures (50 multiplied by 25). Examples of this approach are56: National Athletic Injury Reporting System (NAIRS), Canadian Athletic Injury/Illness Reporting System (CAIRS), NCAA Injury Surveillance System, Sports Injury Monitoring System (SIMS), National High School Athletic Injury Registry, and Athletic Injury Monitoring System (AIMS). However,

Measuring sports injuries on the pitch

375 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

other injury monitoring systems can measure individual sports exposure directly and may be able to provide more accurate measures based on sports exposure (e.g. incidence density). Examples of this approach are53-56: Athletic Health Care System (AHCS), Sport Injury/Illness Reporting System (SIIRS), Canadian Intercollegiate Sport Injury Registry, the IOC Injury Surveillance System for Multi-Sports Events, Training and Injury Prevention Platform for Sports (TIPPS), and the Sports Injury Tracker.

There is a debate about differences between systems in measuring acute and overuse injuries40,41. Many injuries that occur during tournaments and/or participation in contact sports present an identifiable acute onset, and most of the monitoring systems are effective in identifying these injuries. Because of this, these systems provide reliable information for incidence calculations. However, in many endurance sports, most injuries occur by gradual onset or repetitive movements. The onset and symptoms of overuse injuries are very difficult to record in these systems because they present a gradual and transient mechanism40. In this case, incidence is almost impossible to measure accurately. Therefore, a monitoring system was developed in order to deal properly with overuse injuries41 and was further broadened to monitor any sort of health problems in sports: the Oslo Sports Trauma Research Center (OSTRC) Questionnaire on Health Problems28.

The OSTRC questionnaire28 prospectively registers health problems asking 4 key questions: (1) the extent to which injury, illness, or other health problems have affected sports participation; (2) training volume; (3) running performance; and (4) the extent to which the individual has experienced symptoms. Based on the responses, a severity score ranging from 0 to 100 is created. The health problems are further differentiated into illnesses or injuries. For the purposes of this paper, only the sports injury application will be discussed.

The system is based on weekly prevalence measures, and the mean weekly prevalence with its 95% confidence interval (95% CI) has been recommended to be the summary measure. Moreover, it is possible to identify the first report of an injury, and then incidence calculations for acute injuries are also possible. The developers of the questionnaire recommended that medical staff should do the classification of the injuries28. However, if this is not possible, the tools previously discussed could be used for this purpose. The severity score provides an overview of the injury course over time and also differentiates periods of lower and higher severity (Figure 1).

Due to the ability of the OSTRC questionnaire to deal with both acute and overuse injuries, our research group has been using this questionnaire to collect injury data on a variety of sports. In addition to the OSTRC questionnaire, sport-specific questions about exposure (usually in hours of training and competition) and costs related to injury are also included. Costs data are usually neglected in injury monitoring systems in spite of their well-recognized importance, and then the overall burden of injuries may be underestimated. The English version of the OSTRC questionnaire can be found elsewhere28.

Example of application and implications for practice

An example of how injury data collected by these monitoring systems may be displayed for analysis and interpretation in practice is presented in Figure 2. The black lines represent the duration of the injuries from onset or from the time they are first reported (black circles). The grey area represents the variation in severity over time of each injury in each individual. With this monitoring chart, one can identify the periods when the athletes reported more injuries and/or the severity was worse, for example in weeks 2, 6, and 7 of Figure 2. The implication is that the trainer or the medical staff can analyze what happened during this period (e.g. a specific competition or period in which a specific training program was implemented) and develop a strategy and/or intervention to prevent this from happening again. Moreover, after the action, they can see if the strategy and/or intervention was effective in decreasing the prevalence, incidence, or severity of all or specific injuries while the surveillance is maintained.

A more individual tailored approach could be the early identification of injuries for the implementation of early interventions. This aspect has two implications. Firstly, the early identification and early intervention can prevent a minor injury from becoming a more severe injury with more sports participation, health, and societal consequences. This could be done with the individuals 10 and 16 in Figure 2, because it is clear that in the early stages, the injury severity was not high, but it got worse over time. Maybe this sequence could have been prevented. Secondly, the early identification of an injury leads to an earlier treatment or intervention, which prevents the injury from getting worse and/or avoids permanent damage. Individuals 8 and 20 in Figure 2 are examples of an early identification and intervention leading to a faster recovery.

Hespanhol Junior LC, Barboza SD, van Mechelen W, Verhagen E

376 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

Online technologyThe usage of online technology is becoming a

reality worldwide. It is estimated that more than 40% of the world population used the internet in 201457. In Brazil, more than 50% of the population used the internet in the same year, and this number is growing58. Therefore, there is a lot of opportunity to use e-Health, which means “the usage of information and communication technologies (ICT) for health”59. In sports, e-Health can be used to monitor injuries in a variety of ways. Online platforms have been used widely in sports injury research, since it is possible to create questionnaires and send a link to these questionnaires (usually by email) and the answers can be downloaded afterward.

Sometimes this requires cooperation between sports, medical, and ICT personnel to create an online platform. However, now there are several commercial online platforms in which one can simply imbed a questionnaire and start using it. Another way to collect data in order to monitor injuries is by text messaging (e.g. short message service: SMS). This method has been increasingly and successfully implemented60-63, since more and more people are using mobile phones or other portable devices (m-Health)64.

Advantages of using online platforms include65,66: (1) self-entering data by the participant or athlete eliminating the manual entry by the sports manager, increasing fidelity of the data and decreasing the reporting bias; (2) response fields can be predefined with a reasonable range of possibilities, eliminating errors and out-of-range data; (3) reminders may appear if the individual skips some mandatory questions, eliminating missing data and increasing the accuracy of information; and (4) the possibility of branching questions based on the previous responses, saving time, minimizing the burden of answering the questionnaire, and still maintaining the individuals’ motivation to continue answering the questionnaire over time.

Privacy and confidentiality issues are the major concerns about the usage of online technology64. Privacy is the right of an individual not to have his/her private information exposed, and confidentiality is the permission to access information by authorized individuals only67. An unprecedented amount of an individual’s information can be collected and stored in online platforms, and the ‘terms and conditions of use’ of these platforms cannot violate the privacy and confidentiality rights of the individual. For example, one may have consented to provide information to be used by the team staff, but has not consented for

Figure 2. Example of how sports injury monitoring data may be presented in a population level40. The black lines represent the duration of the injuries since their onset or first report (black circles). The grey area represents the variation of severity over time.

Measuring sports injuries on the pitch

377 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

commercial use of the information by third parties64. These issues must be considered beforehand to avoid misuse of information.

The use of online technology in sports practice is still challenging. Even with the increasing number of internet and portable device users, not all individuals can be reached by such technology. In addition, different populations may use online resources differently, meaning that the questionnaire should target the population of interest (e.g. adolescents or elderly). Another important aspect is the validity of using existing questionnaires on an online platform. Questionnaires created and tested in a paper version may not have the same clinimetric properties of the online version, thus it should be tested in the online environment. Finally, the online technology does not substitute the personal contact between the athlete and the trainer, medical staff, or sports managers, which is invaluable64. It is recommended that both approaches should be used in order to optimize and improve the monitoring of sports injuries28,64.

ConclusionsToday, the development of a system to monitor

injuries in individual or team sports is not only feasible, but also strongly recommended in practice. Many tools have been developed and proven to be implementable and manageable, and they are waiting to be used. This paper reviewed the most important aspects of implementing injury-monitoring systems for sports populations and/or facilities, and we recommend their immediate use. Only with this information collected over the long-term will it be possible to truly identify the burden of injuries; enable early identification of possible cases to prevent them from becoming an injury with greater consequences in sports participation, health and social activities (including work); enable comparisons within or between sports modalities; and providing data for sports injury prevention and intervention. Although plausible considerations may differ between different settings, knowledge provided by continuous injury surveillance in sports practice is the key to the management of sports injuries.

AcknowledgementsWe wish to thank CAPES (Coordenação de

Aperfeiçoamento de Pessoal de Nível Superior) and the Brazilian Ministry of Education for the PhD scholarships (process number 0763/12-8 and 0832/14-6).

References1. Kohl HW 3rd, Craig CL, Lambert EV, Inoue S, Alkandari

JR, Leetongin G, et al. The pandemic of physical inactivity: global action for public health. Lancet. 2012;380(9838):294-305. http://dx.doi.org/10.1016/S0140-6736(12)60898-8. PMid:22818941.

2. Hallal PC, Andersen LB, Bull FC, Guthold R, Haskell W, Ekelund U, et al. Global physical activity levels: surveillance progress, pitfalls, and prospects. Lancet. 2012;380(9838):247-57. http://dx.doi.org/10.1016/S0140-6736(12)60646-1. PMid:22818937.

3. Trost SG, Blair SN, Khan KM. Physical inactivity remains the greatest public health problem of the 21st century: evidence, improved methods and solutions using the ‘7 investments that work’ as a framework. Br J Sports Med. 2014;48(3):169-70. http://dx.doi.org/10.1136/bjsports-2013-093372. PMid:24415409.

4. World Health Organization – WHO. Global health risks: mortality and burden of disease attributable to selected major risks. Geneva: WHO; 2009.

5. Lee IM, Shiroma EJ, Lobelo F, Puska P, Blair SN, Katzmarzyk PT. Effect of physical inactivity on major non-communicable diseases worldwide: an analysis of burden of disease and life expectancy. Lancet. 2012;380(9838):219-29. http://dx.doi.org/10.1016/S0140-6736(12)61031-9. PMid:22818936.

6. World Health Organization – WHO. Global strategy on diet, physical activity and health. Geneva: WHO; 2004.

7. Hallal PC, Victora CG, Wells JC, Lima RC. Physical inactivity: prevalence and associated variables in Brazilian adults. Med Sci Sports Exerc. 2003;35(11):1894-900. http://dx.doi.org/10.1249/01.MSS.0000093615.33774.0E. PMid:14600556.

8. Brasil. Ministério da Saúde. Plano de ações estratégicas para o enfrentamento das doenças crônicas não transmissíveis (DCNT) no Brasil 2011-2022. Brasília: Ministério da Saúde; 2011.

9. Brasil. Ministério da Saúde. Portal da Saúde. Programa academia da saúde [Internet]. Brasília [cited 2015 July 22]. Available from: http://portalsaude.saude.gov.br/index.php/o-ministerio/principal/secretarias/svs/academia-da-saude-svs.

10. Parra DC, Hoehner CM, Hallal PC, Reis RS, Simoes EJ, Malta DC, et al. Scaling up of physical activity interventions in Brazil: how partnerships and research evidence contributed to policy action. Glob Health Promot Educ. 2013;20(4):5-12. http://dx.doi.org/10.1177/1757975913502368. PMid:24323944.

11. Wen CP, Wai JP, Tsai MK, Yang YC, Cheng TY, Lee MC, et al. Minimum amount of physical activity for reduced mortality and extended life expectancy: a prospective cohort study. Lancet. 2011;378(9798):1244-53. http://dx.doi.org/10.1016/S0140-6736(11)60749-6. PMid:21846575.

12. Hamer M, Lavoie KL, Bacon SL. Taking up physical activity in later life and healthy ageing: the English longitudinal study of ageing. Br J Sports Med. 2014;48(3):239-43. http://dx.doi.org/10.1136/bjsports-2013-092993. PMid:24276781.

13. van de Laar RJ, Ferreira I, van Mechelen W, Prins MH, Twisk JW, Stehouwer CD. Lifetime vigorous but not light-to-moderate habitual physical activity impacts favorably on carotid stiffness in young adults: the amsterdam growth and health longitudinal study. Hypertension. 2010;55(1):33-9.

Hespanhol Junior LC, Barboza SD, van Mechelen W, Verhagen E

378 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

http://dx.doi.org/10.1161/HYPERTENSIONAHA.109.138289. PMid:19996070.

14. Sattelmair J, Pertman J, Ding EL, Kohl HW 3rd, Haskell W, Lee IM. Dose response between physical activity and risk of coronary heart disease: a meta-analysis. Circulation. 2011;124(7):789-95. http://dx.doi.org/10.1161/CIRCULATIONAHA.110.010710. PMid:21810663.

15. Almeida OP, Khan KM, Hankey GJ, Yeap BB, Golledge J, Flicker L. 150 minutes of vigorous physical activity per week predicts survival and successful ageing: a population-based 11-year longitudinal study of 12 201 older Australian men. Br J Sports Med. 2014;48(3):220-5. http://dx.doi.org/10.1136/bjsports-2013-092814. PMid:24002240.

16. Verhagen E, Bolling C, Finch CF. Caution this drug may cause serious harm! Why we must report adverse effects of physical activity promotion. Br J Sports Med. 2015;49(1):1-2. http://dx.doi.org/10.1136/bjsports-2014-093604. PMid:25082617.

17. Hupperets MD, Verhagen EA, Heymans MW, Bosmans JE, van Tulder MW, van Mechelen W. Potential savings of a program to prevent ankle sprain recurrence: economic evaluation of a randomized controlled trial. Am J Sports Med. 2010;38(11):2194-200. http://dx.doi.org/10.1177/0363546510373470. PMid:20699429.

18. Collard DC, Verhagen EA, van Mechelen W, Heymans MW, Chinapaw MJ. Economic burden of physical activity-related injuries in Dutch children aged 10-12. Br J Sports Med. 2011;45(13):1058-63. http://dx.doi.org/10.1136/bjsm.2010.082545. PMid:21685503.

19. van Mechelen W, Hlobil H, Kemper HC. Incidence, severity, aetiology and prevention of sports injuries. A review of concepts. Sports Med. 1992;14(2):82-99. http://dx.doi.org/10.2165/00007256-199214020-00002. PMid:1509229.

20. Finch CF, Cook J. Categorising sports injuries in epidemiological studies: the subsequent injury categorisation (SIC) model to address multiple, recurrent and exacerbation of injuries. Br J Sports Med. 2014;48(17):1276-80. http://dx.doi.org/10.1136/bjsports-2012-091729. PMid:23501833.

21. Roos KG, Marshall SW. Definition and usage of the term “overuse injury” in the US high school and collegiate sport epidemiology literature: a systematic review. Sports Med. 2014;44(3):405-21. http://dx.doi.org/10.1007/s40279-013-0124-z. PMid:24242858.

22. Timpka T, Alonso JM, Jacobsson J, Junge A, Branco P, Clarsen B, et al. Injury and illness definitions and data collection procedures for use in epidemiological studies in Athletics (track and field): consensus statement. Br J Sports Med. 2014;48(7):483-90. http://dx.doi.org/10.1136/bjsports-2013-093241. PMid:24620036.

23. Orchard J, Newman D, Stretch R, Frost W, Mansingh A, Leipus A. Methods for injury surveillance in international cricket. J Sci Med Sport. 2005;8(1):1-14. http://dx.doi.org/10.1016/S1440-2440(05)80019-2. PMid:15887896.

24. Fuller CW, Ekstrand J, Junge A, Andersen TE, Bahr R, Dvorak J, et al. Consensus statement on injury definitions and data collection procedures in studies of football (soccer) injuries. Br J Sports Med. 2006;40(3):193-201. http://dx.doi.org/10.1136/bjsm.2005.025270. PMid:16505073.

25. Fuller CW, Molloy MG, Bagate C, Bahr R, Brooks JH, Donson H, et al. Consensus statement on injury definitions and data collection procedures for studies of injuries in

rugby union. Br J Sports Med. 2007;41(5):328-31. http://dx.doi.org/10.1136/bjsm.2006.033282. PMid:17452684.

26. Pluim BM, Fuller CW, Batt ME, Chase L, Hainline B, Miller S, et al. Consensus statement on epidemiological studies of medical conditions in tennis, April 2009. Br J Sports Med. 2009;43(12):893-7. http://dx.doi.org/10.1136/bjsm.2009.064915. PMid:19900956.

27. Turner M, Fuller CW, Egan D, Le Masson B, McGoldrick A, Spence A, et al. European consensus on epidemiological studies of injuries in the thoroughbred horse racing industry. Br J Sports Med. 2012;46(10):704-8. http://dx.doi.org/10.1136/bjsports-2011-090312. PMid:22067282.

28. Clarsen B, Rønsen O, Myklebust G, Flørenes TW, Bahr R. The Oslo Sports Trauma Research Center questionnaire on health problems: a new approach to prospective monitoring of illness and injury in elite athletes. Br J Sports Med. 2014;48(9):754-60. http://dx.doi.org/10.1136/bjsports-2012-092087. PMid:23429267.

29. Yamato TP, Saragiotto BT, Lopes AD. A consensus definition of running-related injury in recreational runners: a modified Delphi approach. J Orthop Sports Phys Ther. 2015;45(5):375-80. http://dx.doi.org/10.2519/jospt.2015.5741. PMid:25808527.

30. Clarsen B, Bahr R. Matching the choice of injury/illness definition to study setting, purpose and design: one size does not fit all! Br J Sports Med. 2014;48(7):510-2. http://dx.doi.org/10.1136/bjsports-2013-093297. PMid:24620038.

31. Hamilton GM, Meeuwisse WH, Emery CA, Shrier I. Subsequent injury definition, classification, and consequence. Clin J Sport Med. 2011;21(6):508-14. http://dx.doi.org/10.1097/JSM.0b013e31822e8619. PMid:21959796.

32. Hespanhol Junior LC, Pena Costa LO, Lopes AD. Previous injuries and some training characteristics predict running-related injuries in recreational runners: a prospective cohort study. J Physiother. 2013;59(4):263-9. http://dx.doi.org/10.1016/S1836-9553(13)70203-0. PMid:24287220.

33. Rae K, Orchard J. The Orchard Sports Injury Classification System (OSICS) version 10. Clin J Sport Med. 2007;17(3):201-4. http://dx.doi.org/10.1097/JSM.0b013e318059b536. PMid:17513912.

34. Finch CF, Orchard JW, Twomey DM, Saad Saleem M, Ekegren CL, Lloyd DG, et al. Coding OSICS sports injury diagnoses in epidemiological studies: does the background of the coder matter? Br J Sports Med. 2014;48(7):552-6. http://dx.doi.org/10.1136/bjsports-2012-091219. PMid:22919021.

35. Malisoux L, Nielsen RO, Urhausen A, Theisen D. A step towards understanding the mechanisms of running-related injuries. J Sci Med Sport. 2014;pii: S1440-2440(14)00140-6. http://dx.doi.org/10.1016/j.jsams.2014.07.014. PMid:25174773

36. Botha JL, Yach D. Epidemiological research methods. Part II. Descriptive studies. S Afr Med J. 1986;70(12):766-72. PMid:3787409.

37. Knowles SB, Marshall SW, Guskiewicz KM. Issues in estimating risks and rates in sports injury research. J Athl Train. 2006;41(2):207-15. PMid:16791309.

38. Verhagen E, van Mechelen W. Sports injury research. New York: Oxford; 2010.

39. Dick R, Hootman JM, Agel J, Vela L, Marshall SW, Messina R. Descriptive epidemiology of collegiate women’s field

Measuring sports injuries on the pitch

379 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

hockey injuries: National Collegiate Athletic Association Injury Surveillance System, 1988-1989 through 2002-2003. J Athl Train. 2007;42(2):211-20. PMid:17710169.

40. Bahr R. No injuries, but plenty of pain? On the methodology for recording overuse symptoms in sports. Br J Sports Med. 2009;43(13):966-72. http://dx.doi.org/10.1136/bjsm.2009.066936. PMid:19945978.

41. Clarsen B, Myklebust G, Bahr R. Development and validation of a new method for the registration of overuse injuries in sports injury epidemiology: the Oslo Sports Trauma Research Centre (OSTRC) overuse injury questionnaire. Br J Sports Med. 2013;47(8):495-502. http://dx.doi.org/10.1136/bjsports-2012-091524. PMid:23038786.

42. van Mechelen W. The severity of sports injuries. Sports Med. 1997;24(3):176-80. http://dx.doi.org/10.2165/00007256-199724030-00006. PMid:9327533.

43. Davis JC, Verhagen E, Bryan S, Liu-Ambrose T, Borland J, Buchner D, et al. 2014 consensus statement from the first Economics of Physical Inactivity Consensus (EPIC) conference (Vancouver). Br J Sports Med. 2014;48(12):947-51. http://dx.doi.org/10.1136/bjsports-2014-093575. PMid:24859181.

44. van Dongen JM, van Wier MF, Tompa E, Bongers PM, van der Beek AJ, van Tulder MW, et al. Trial-based economic evaluations in occupational health: principles, methods, and recommendations. J Occup Environ Med. 2014;56(6):563-72. http://dx.doi.org/10.1097/JOM.0000000000000165. PMid:24854249.

45. Tolpin HG, Vinger PF, Tolpin DW. Ocular sports injuries. Economic considerations. Int Ophthalmol Clin. 1981;21(4):179-201. http://dx.doi.org/10.1097/00004397-198102140-00013. PMid:7309427.

46. Verhagen EA, van Tulder M, van der Beek AJ, Bouter LM, van Mechelen W. An economic evaluation of a proprioceptive balance board training programme for the prevention of ankle sprains in volleyball. Br J Sports Med. 2005;39(2):111-5. http://dx.doi.org/10.1136/bjsm.2003.011031. PMid:15665210.

47. Janssen KW, Hendriks MR, van Mechelen W, Verhagen E. The cost-effectiveness of measures to prevent recurrent ankle sprains: results of a 3-Arm randomized controlled trial. Am J Sports Med. 2014;42(7):1534-41. http://dx.doi.org/10.1177/0363546514529642. PMid:24753237.

48. Zorginstituut Nederland. [Internet]. [cited 2015 July 22]. Available from: http://www.zorginstituutnederland.nl.

49. Zorginstituut Nederland. Handleiding voor kostenonderzoek: methoden en standaard kostprijzen voor economische evaluaties in de gezondheidszorg [Internet]. 2011 [cited 2015 July 22]. Available from: http://www.zorginstituutnederland.nl/binaries/content/documents/zinl-www/documenten/publicaties/overige-publicaties/1007-handleiding-voor-kostenonderzoek/1007-handleiding-voor-kostenonderzoek/Handleiding+voor+kostenonderzoek.pdf.

50. Centraal Bureau voor de Statistiek. [Internet]. [cited 2015 July 22]. Available from: http://www.cbs.nl/nl-NL/menu/home/default.htm.

51. Centraal Bureau voor de Statistiek. Arbeidsdeelname; kerncijfers (12-uursgrens) [Internet]. [cited 2015 July 22]. Available from: http://statline.cbs.nl/Statweb/publication/?DM=SLNL&PA=71738ned&D1=8-10&D2=a&D3=a&D4=0&D5=l&VW=T.

52. Brasil. Ministério da Saúde. Portal da Saúde. DATASUS por dentro 2.0. [Internet]. Brasília. 2008 [cited 2015 July 22]. Available from: http://www2.datasus.gov.br/DATASUS/index.php.

53. Junge A, Engebretsen L, Alonso JM, Renström P, Mountjoy M, Aubry M, et al. Injury surveillance in multi-sport events: the International Olympic Committee approach. Br J Sports Med. 2008;42(6):413-21. http://dx.doi.org/10.1136/bjsm.2008.046631. PMid:18390916.

54. Ekegren CL, Gabbe BJ, Donaldson A, Cook J, Lloyd D, Finch CF. Injuries in community-level Australian football: results from a club-based injury surveillance system. J Sci Med Sport. 2014 [Epub ahead of print]. http://dx.doi.org/10.1016/j.jsams.2014.11.390.

55. Malisoux L, Frisch A, Urhausen A, Seil R, Theisen D. Monitoring of sport participation and injury risk in young athletes. J Sci Med Sport. 2013;16(6):504-8. http://dx.doi.org/10.1016/j.jsams.2013.01.008. PMid:23481535.

56. Meeuwisse WH, Love EJ. Athletic injury reporting. Development of universal systems. Sports Med. 1997;24(3):184-204. http://dx.doi.org/10.2165/00007256-199724030-00008. PMid:9327535.

57. Internet Live Stats. Internet users in the world [Internet]. [cited 2015 July 22]. Available from: http://www.internetlivestats.com/internet-users/.

58. Internet Live Stats. Brazil internet users [Internet]. [cited 2015 July 22]. Available at: http://www.internetlivestats.com/internet-users/brazil/.

59. World Health Organization – WHO. eHealth [Internet]. [cited 2015 July 22]. Available from: http://www.who.int/topics/ehealth/en/.

60. Ekegren CL, Gabbe BJ, Finch CF. Injury reporting via SMS text messaging in community sport. Inj Prev. 2014;20(4):266-71. http://dx.doi.org/10.1136/injuryprev-2013-041028. PMid:24413851.

61. Jespersen E, Holst R, Franz C, Rexen CT, Klakk H, Wedderkopp N. Overuse and traumatic extremity injuries in schoolchildren surveyed with weekly text messages over 2.5 years. Scand J Med Sci Sports. 2014;24(5):807-13. http://dx.doi.org/10.1111/sms.12095. PMid:23800031.

62. Moller M, Attermann J, Myklebust G, Wedderkopp N. Injury risk in Danish youth and senior elite handball using a new SMS text messages approach. Br J Sports Med. 2012;46(7):531-7. http://dx.doi.org/10.1136/bjsports-2012-091022. PMid:22554848.

63. Nilstad A, Bahr R, Andersen TE. Text messaging as a new method for injury registration in sports: a methodological study in elite female football. Scand J Med Sci Sports. 2014;24(1):243-9. http://dx.doi.org/10.1111/j.1600-0838.2012.01471.x. PMid:22537065.

64. Verhagen E, Bolling C. Protecting the health of the @hlete: how online technology may aid our common goal to prevent injury and illness in sport. Br J Sports Med. 2015 [Epub ahead of print]. http://dx.doi.org/10.1136/bjsports-2014-094322. PMid:25614537.

65. Verhagen EA, Clarsen B, Bahr R. A peek into the future of sports medicine: the digital revolution has entered our pitch. Br J Sports Med. 2014;48(9):739-40. http://dx.doi.org/10.1136/bjsports-2013-093103. PMid:24273310.

66. Höher J, Bach T, Münster A, Bouillon B, Tiling T. Does the mode of data collection change results in a subjective knee

Hespanhol Junior LC, Barboza SD, van Mechelen W, Verhagen E

380 Braz J Phys Ther. 2015 Sept-Oct; 19(5):369-380

score? Self-administration versus interview. Am J Sports Med. 1997;25(5):642-7. http://dx.doi.org/10.1177/036354659702500509. PMid:9302469.

67. Ferreira A, Cruz-Correia R, Antunes L, Chadwick D. Access control: how can it improve patients’ healthcare? Stud Health Technol Inform. 2007;127:65-76. PMid:17901600.

Correspondence Evert Verhagen VU University Medical Center EMGO+ Institute for Health and Care Research Department of Public & Occupational Health Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands e-mail: e.verhagen@vumc.nl

http://dx.doi.org/10.1590/bjpt-rbf.2014.0122

review article

381 Braz J Phys Ther. 2015 Sept-Oct; 19(5):381-389

Improving performance in golf: current research and implications from a clinical perspective

Kerrie Evans1, Neil Tuttle1

ABSTRACT | Golf, a global sport enjoyed by people of all ages and abilities, involves relatively long periods of low-intensity exercise interspersed with short bursts of high-intensity activity. To meet the physical demands of full-swing shots and the mental and physical demands of putting and walking the course, it is frequently recommended that golfers undertake golf-specific exercise programs. Biomechanics, motor learning, and motor control research has increased the understanding of the physical requirements of the game, and using this knowledge, exercise programs aimed at improving golf performance have been developed. However, while it is generally accepted that an exercise program can improve a golfer’s physical measurements and some golf performance variables, translating the findings from research into clinical practice to optimise an individual golfer’s performance remains challenging. This paper discusses how biomechanical and motor control research has informed current practice and discusses how emerging sophisticated tools and research designs may better assist golfers improve their performance. Keywords: golf swing; kinematics; exercise programs; movement variability; biomechanics.

HOW TO CITE THIS ARTICLE

Evans K, Tuttle N. Improving performance in golf: current research and implications from a clinical perspective. Braz J Phys Ther. 2015 Sept-Oct; 19(5):381-389. http://dx.doi.org/10.1590/bjpt-rbf.2014.0122

1 School of Allied Health Sciences, Menzies Health Institute Queensland, Griffith University, Gold Coast campus, Queensland, AustraliaReceived: Mar. 17, 2015 Revised: June 12, 2015 Accepted: June 25, 2015

IntroductionThe inclusion of golf in the 2016 Summer Olympic

Games for the first time since 1904 is an indicator of the increasing globalisation of the sport. It is estimated that worldwide between 55 and 80 million people from at least 136 countries play golf1-3, with the more avid golfers playing more than once a week, every week of the year. The vast majority of people who play golf are amateur golfers, with only a very small proportion being considered elite amateurs and fewer still are professional golfers. Irrespective of whether a golfer is an amateur or a professional, the goal is the same – to complete a round of golf in as few strokes (shots) as possible and, from a longevity perspective, continue to enjoy the game as pain and injury free as possible.

The game of golfGolf is a sport that involves a relatively long duration

of low-intensity activity interspersed with short bursts of high-intensity activity. Golf courses vary in length and terrain, so a round of 18 holes can take between 3.5 and 6 hours to play and, if the players are walking, results in a low-moderate intensity form of aerobic

exercise4,5. However, as much as 60% of the time taken to play a round of golf is spent preparing and performing swings, and of this time, 25% is spent putting on the green6. In contrast to the relatively low-intensity demand of the rest of the game, a full swing action requires a rapid expenditure of energy. For example, professional golfers perform a swing with a driver in 1.09 seconds7, with the club head reaching speeds of more than 160 km/hour8. Overall muscle activity when using a 5-iron reaches 90% of maximal voluntary contraction (MVC) for amateurs and 80% for professionals9, and golfers perform an average of 30-40 swings every round with these high levels of intensity10. In contrast to full swings, the putting stroke requires minimal body movement but involves the greatest degree of sustained trunk inclination and sagittal flexion compared with shots with other clubs6. It has been suggested that, particularly when practised for prolonged periods, putting may challenge a golfer’s postural endurance11,12. Researchers and clinicians wanting to optimise performance and prevent golf injury have hypothesised that specific golf exercise programs are necessary to meet the physical demands

Evans K , Tuttle N

382 Braz J Phys Ther. 2015 Sept-Oct; 19(5):381-389

of both full-swing shots and the potential fatigue associated with putting or walking13,14.

Biomechanical investigations of the golf swing

The landmark work of Cochran and Stobbs15 in 1968 employed high-speed filming techniques to examine the components of the golf swing, ball aerodynamics, and equipment dynamics. Since then, there has been a vast range of biomechanical studies that have examined the highly complex, multi-joint movements involved in the golf swing. Researchers have used 2D and 3D methods, including high-speed video16, optoelectronic12,17-19 and electromagnetic motion tracking systems20,21, computer modelling22, force plates23-25, wireless inertial sensors26, and electromyography27-31 to gain insight into and quantify the fundamental elements of the swing. The majority of studies have been conducted in laboratory settings and most have employed indirect measures of golf performance such as club head velocity (CHV) and ball launch characteristics18,23,32,33. Laboratory-based studies have clear advantages, including ease of standardisation, greater environmental control, and the degree of accuracy possible with some indoor motion analysis systems. On the other hand, swinging a golf club indoors surrounded by expensive equipment may not reflect what happens on the golf course, and there is concern that the indirect measures of performance used in laboratory conditions may provide incomplete information about actual golf performance. Some studies have been conducted outdoors and on golf courses6,34; however, more research is needed to examine how golfers perform their swing on the course, over a round of golf, and under competition conditions and how these findings relate to what occurs in laboratory settings. Not only will these types of studies provide ecologically valid biomechanical information, but they will also provide more specific information about the physical demands of the sport and how environmental or other factors, such as pressure or fatigue, affect golf performance.

Due to the importance of the full swing, particularly in driving performance32, and perhaps because of the fact that this stroke could be considered as having the most repeatable intention - to hit the ball as far and straight as possible - most kinematic studies have concentrated on full-swing kinematics. In spite of the golf swing being dynamic by nature, many of these studies have measured parameters (e.g. segmental orientation) at discrete time points

during the swing, such as address, top of backswing, ball contact. Collectively, findings have provided valuable insights into, for example, the magnitude of thorax and pelvis movement when high CHV are produced7,35,36, differences in segmental angular velocities between skilled and less skilled golfers37,38, and the importance of the magnitude, sequencing, and timing of segmental motion35,39,40. The results have helped inform research investigating physical characteristics required for skilled golf performance.

With the increasing awareness of the importance of movement variability in skilled performance41-43, there has been growing interest in investigating the complex segment and intersegmental coordination that occurs during the full swing44-47. Movement variability can be described as the normal variations that occur in motor performance across multiple repetitions of a task48. Historically, movement variability observed in skilled sporting tasks was considered “noise” or error and therefore undesirable. It is now recognised that variability has a functional role and does not necessarily result in outcome variability41,45,49. That is, there is greater understanding of the large number of constraints that interact to shape movement behaviours during sporting endeavours, including body properties, environmental conditions, and tasks, and that highly skilled performers demonstrate the necessary flexibility and adaptability to operate proficiently in a variety of learning and performance contexts42,50.

Movement variability in the downswing of skilled male and female golfers was investigated by Horan et al.51. Despite variability in the kinematics of the thorax and pelvis as well as variability in thorax-pelvis coupling at the midpoint of the downswing and at ball contact, both males and females achieved highly consistent club and hand trajectories at ball contact. Interestingly, females were found to have greater variability in thorax-pelvis coupling than males. While physiological measures were not directly measured, the differences may have been due to differences in factors such as strength or flexibility or that male and female golfers adopted different motor control strategies to achieve consistent performance. Gender-related differences in golf swing kinematics have been observed by other authors38,39,52 supporting the notion that a number of characteristics will influence a golfer’s pattern of movement and coordinative strategies.

The concept that movement variability in individual segmental trajectories during a specific task may not be detrimental to outcome performance as long as the critical ‘end point parameters’ (in the case of the golf swing, club head parameters at ball contact)

Clinical perspective on improving performance in golf

383 Braz J Phys Ther. 2015 Sept-Oct; 19(5):381-389

remain consistent49,53 was supported more recently by Tucker et al.54. These authors found that a group of highly skilled golfers maintained consistency of ball speed despite variability in movement of individual body segments during the swing. Variability of movement of the individual body segments are integrated to produce a reduced variability in the club head trajectory, which in turn results in an even smaller variability in the club head on contact with the ball. Additionally, Tucker et al.54 found that movement variability was

highly individual-specific with different golfers adopting different performance strategies to preserve shot outcome. Taken collectively, emerging evidence supports the notions of 1) inter-player variability, i.e. that individual golfers have individualised swing patterns that are different from the patterns of other golfers (Figure 1), and 2) intra-player variability, i.e. that within their own swing pattern, each individual has variation in the contributions from the many different components (Figure 2).

Figure 1. Full swing by two golfers demonstrating between-individual variations. From left: address position, top of backswing, impact, and follow-through.

Figure 2. The 3D trajectory of the club head of one golfer performing multiple swings demonstrating within-individual variation. The width and colour of the pathway indicate the magnitude and direction of variability. The width at the point of impact is narrower indicating considerably less variability than the backswing and downswing that precede it.

Evans K , Tuttle N

384 Braz J Phys Ther. 2015 Sept-Oct; 19(5):381-389

Clinical implicationsGolf has been described as one of the most complex,

technically demanding and high precision sports that exist55. Clinicians that work with golfers should consider that inter-golfer and intra-golfer variability in swing performance will be affected by task, environment, and organism constraints, all of which interact to determine the patterns of motion that are observed when a golfer swings a club45. Despite an increased understanding of the swing from both biomechanics and neuroscience research, the best way to optimise both swing and outcome performance for an individual golfer remains elusive. From a physical therapist’s perspective, optimising performance in golf requires knowledge of not only the technical and physical requirements of the sport, but also how these domains are interrelated with the fields of psychology, motor learning, and motor control. While recognising the importance of a multimodal approach to optimising golf performance, the following sections focus on the physical requirements of golf and evidence pertaining to whether exercise programs can help golfers improve their performance.

Physical requirements of the golf swingHighly skilled golfers tend to have different physical

characteristics than less proficient golfers56 and factors such age, gender, and history of injury also influence a golfer’s performance on physical tests as well as swing parameters39,57,58. Nevertheless, a combination of mobility, stability, strength, and cardiovascular fitness is frequently recommended for optimal ‘golf fitness’14,59. Kinematic studies have highlighted the importance of adequate flexibility, particularly in the trunk, hips, and shoulders, to achieve the body positions required to optimise CHV52,56,60. For example, reported averages for torso rotation during the backswing for a driver range from 78° to 109° with the pelvis rotating to a lesser extent of between 37° and 64°7,35,52. EMG studies have sought to identify the muscle groups important for golf performance28,29,61-64 and several reviews have been published on this topic65,66. From the collated data, it is apparent that the trunk extensors, hip extensors, and the abdominal muscles all play an important role in producing a powerful efficient golf swing. The efficient transfer of energy from the lower body to the muscle groups of the chest and arms and eventually the hands and club - the “bottom up phenomenon”60 - is important for producing high CHV, but similarly to swing kinematics, a number of

kinetic variables measured during the swing are also highly individual-specific22.

Golfers spend many hours practising. Professional golfers can perform up to 300 swings in a single practice session and hit over 2000 shots per week67,68. To ensure a golfer can meet both the physical and mental demands of playing tournament golf and avoid the detrimental effects that fatigue has been shown to have on performance11,69, exercises aimed at improving a golfer’s cardiovascular fitness have also been advocated14.

In summary, playing golf has very specific physical requirements that have led many researchers, coaches, and clinicians to suggest that physical preparation programs should be undertaken by golfers of all ages and abilities in order to improve performance and prevent golf-related injury. This paper will not focus on the latter but on findings from studies that have investigated whether exercise programs can improve golf performance.

Exercise programs to improve golf performance

Golf-specific exercises have been advocated for many years, with early attempts being largely idiosyncratic and based on personal experience and opinion. For example, three-time Open Championship winner Sir Henry Cotton in 1948 said:

Let me add, that, as far as I know, no data on this subject of specific golf muscle-building has ever been given, and I have had to grope my way along according to my own ideas and following my own observations, endeavouring to build up my golfing muscles to the best of my ability70.

Cotton’s statement reflects the predominant understanding of human performance in the 1940’s: increased muscular strength should result in improved performance. A golf-specific exercise program would therefore be designed to target the specific muscles used in the sport. In their review of strength and conditioning programs for improving fitness in golfers, Smith et al.71 defined golf-specific exercises as those that activate muscles groups that are used in golf in comparable patterns of motor coordination, in similar planes and ranges of movements, with similar speeds, and similar loads on postural muscles. In addition to load, this definition adds coordination, pattern specificity, and speed to the idea of what makes exercises golf-specific. Interestingly, Smith et al.71

Clinical perspective on improving performance in golf

385 Braz J Phys Ther. 2015 Sept-Oct; 19(5):381-389

concluded that the majority of studies included in their review involved reasonably generic exercise programs that did not fulfil the criteria for being golf-specific. The exercises employed ranged from free weights and medicine ball plyometric training in young male golfers (age: 29±7.4 yrs, handicap: 5.5±3.7)72 to strength and flexibility exercises in older recreational golfers (age: 65.1±6.2 yrs of all skill levels)73 to a proprioceptive neuromuscular facilitation stretching program in golfers aged between 47 and 82 years with handicaps ranging from 8 to 3474. Despite the fact that several of the studies reviewed by Smith et al.71 had low methodological scores, it is nevertheless interesting to see that, seemingly irrespective of the type of exercise approach, the duration of the program, the age or skill of the golfer, the majority of studies reported improvements in at least some of the fitness (e.g. muscular strength, flexibility) and golf performance variables (e.g. club head speed, driving distance) that were measured.

Since Smith et al.’s71 2011 review, as well as that of Torres-Ronda et al.75, further studies have investigated the effects of different exercise approaches on parameters, such as club head speed, ball spin, and swing kinematic variables, thought to relate to golf performance. These studies have again been diverse in terms of the exercises prescribed (e.g. ‘isolated core training’76, plyometric training77, combination of maximal strength, plyometric and golf-specific exercises78, different warm up programs79); duration of the program (range 6 weeks80 to 18 weeks78); age and skill level of the golfers (e.g. ~24 years with handicap <580 vs ~47 years with a mean handicap of 11.2±6.178); effect sizes; and methodological quality. Similar to previous work, direct measures of golf performance (e.g. strokes per round, performance during tournaments) are lacking. Overall, the results support the notion that it is more important that a golfer do some form of exercise rather than no exercise, irrespective of what particular type of exercise is undertaken.

Lessons from other areas of clinical researchInterestingly, the conclusion that exercise (generally)

has a beneficial effect for golfers, regardless of the type of exercise, is similar to findings in other areas of sports research81,82 but most notably the low back pain (LBP) field. Historically, most reviews of exercise therapy for patients with LBP conclude that when different types of exercise are compared directly, exercise in general is effective83-85. That is, there does not appear to be one form of exercise that is superior

to another for patients with LBP. What the studies do not tell us, however, by reporting group means, is whether one program is better for a given individual and if so, which one. More recently, studies comparing interventions based on subgrouping of patients and development of clinical prediction rules have been conducted with the aim of more specifically tailoring interventions based on a set of patient characteristics. However, it has proven extremely challenging to develop theoretical and practical frameworks that consider enough of a patient’s biological as well as psychosocial characteristics to determine effective treatment strategies86. Nevertheless, there is preliminary evidence supporting the notion that patients who receive a more individualised treatment approach achieve better outcomes87.

To date, when studies of the effects of exercise programs on golf performance have subgrouped participants, the grouping criteria have been according to handicap, age, or gender. Grouping a golfer based on handicap intuitively makes the most sense – skilled golfers have more consistent swing kinematics than unskilled golfers and therefore any changes post-intervention are more likely to be as a result of the intervention than due to measurement error. However, one only has to look at the player anthropometrics of the Ladies Professional Golf Association’s (LPGA) Top 10 female golfers to recognise that even the best players in the world are reasonably heterogeneous.

Where to from here?There is still much to understand about how to

assist golfers improve their game and avoid injury. It will be important to ensure the validity of the measurements that are being made, consider more sophisticated measures or methods of analysis, and ensure that the outcomes being considered are true indicators of the desired outcomes. Perhaps most importantly, however, is to use measures that reflect the dynamic nature of golf and are capable of taking into consideration individual variation in strategies and responses.

New tools such as a variety of wearable sensors, marker-less motion tracking, and wide field-of-view electromagnetic tracking systems are becoming available that can assist to improve our understanding of the biomechanics and by enabling studies to be carried out on the golf course instead of the laboratory. Alternatively, if laboratory studies continue to be used, it will be important to cross-validate the methodologies to ensure what occurs in the lab actually reflects what

Evans K , Tuttle N

386 Braz J Phys Ther. 2015 Sept-Oct; 19(5):381-389

occurs on the course. Similarly, it will be important to determine how the surrogate measures of performance typically used in the lab relate to performance on the course.

The systems that are currently used in most biomechanics laboratories are able to determine location of points on the body and ground reaction forces at rates of hundreds or even thousands of samples per second and create a 3D reconstruction of the entire movement pattern through time. In spite of the dazzling complexity and accuracy of the data, much of the analyses use simplified variables such as maximum or minimum values of locations, angles, speeds, or accelerations or the values of these parameters at predetermined time points during the swing. One of a relatively small number of studies that evaluated data across the time course of the swing was that of Tucker et al.54. The authors recorded the locations of 14 points on the golfer’s body and club at 400 Hz for 10 swings by each of 16 golfers. For each normalised time point for each marker, a virtual three-dimensional ellipsoid was constructed that would contain the mean location +/- one standard deviation of the position of that marker through the swing. Not only does this type of methodology enable the swings of different individuals to be compared in ways that were not previously possible, but it also enables investigators to evaluate the relative impact of different body locations and/or time points on performance.

As more is understood about individual variation, it may be possible to develop and assess the efficacy of individualised programs for individual golfers. Instead of the more common study design, which compares two (or more) groups and have every member of the group receiving the same intervention, individualised programs could be assessed using a parallel group design. For example, the intervention in one group can be individualised according to an algorithm while the other intervention uses a set protocol87. Perhaps more appropriate, however, to evaluate individual treatment responses would be the use of so called “n-of-one trials”88. The power of this design comes from each intervention option being trialled more than once in a multiple crossover design (e.g. as a minimum - an ABAB or ABBA sequence). One type of intervention being consistently superior in more than one comparison provides much stronger evidence for it being actually superior. An advantage of n-of-one trials is that they are also available to the therapist in clinical practice. Consider for example if two exercise programs have demonstrated benefits, but in a head-to-head comparison neither is superior.

One interpretation of the evidence would be to select one and only change the program if the outcomes were ‘very poor’89. However, by applying an n-of-one design in clinical practice, the therapist no longer has to rely on average results but can determine which of the options is better for each individual golfer at a given time.

ConclusionsDespite the growing body of research investigating

the golf swing, much remains unknown and translating the findings from the biomechanical, physiological, motor learning, and motor control research into clinical practice, where the aim is to assist golfers improve their performance and prevent injury, remains challenging. It is generally well accepted that, in order to improve performance, a multimodal approach is required and both researchers and clinicians need to consider the aforementioned inter-related dimensions in order to help optimise golf performance. There are general principles of exercise that are likely to be of benefit to all golfers, and the study designs employed to date have provided a wealth of information and should inform current and future practice. However, more sophisticated tools and designs are available that are capable of expanding our knowledge of golf and practice, thereby potentially increasing our ability to assist our clients improve their golf performance.

AcknowledgementsThe authors wish to thank Dr Catherine Tucker

and colleagues for allowing use of this image which illustrates some of the findings from their research.

References1. Farrally MR, Cochran AJ, Crews DJ, Hurdzan MJ, Price RJ,

Snow JT, et al. Golf science research at the beginning of the twenty-first century. J Sports Sci. 2003;21(9):753-65. http://dx.doi.org/10.1080/0264041031000102123. PMid:14579870.

2. International Golf Federation. IGF National members [Internet]. 2015. [cited 2015 Mar 17]. Available from: http://www.igfgolf.org/about-igf/nationalmembers/

3. HSBC Group. Golf’s 2020 vison: the HSBC report [Internet]. 2012. [cited 2015 Mar 17]. Available from: http://thefuturescompany.com/wp-content/uploads/2012/09/The_Future_of_Golf.pdf

4. Magnusson ML, Bishop JB, Hasselquist L, Spratt KF, Szpalski M, Pope MH. Range of motion and motion patterns in patients with low back pain before and after rehabilitation. Spine (Phila Pa 1976). 1998;23(23):2631-9. http://dx.doi.org/10.1097/00007632-199812010-00019. PMid:9854763.

Clinical perspective on improving performance in golf

387 Braz J Phys Ther. 2015 Sept-Oct; 19(5):381-389

5. Parkkari J, Natri A, Kannus P, Mänttäri A, Laukkanen R, Haapasalo H., et al. A controlled trial of the health benefits of regular walking on a golf course. Am J Med. 2000;109(2):102-8. http://dx.doi.org/S0002-9343(00)00455-1.

6. Derksen JC, van Riel MP, Snijders CJ. A new method for continuous recording of trunk postures while playing golf. J Appl Biomech. 1996;12:116-29.

7. McTeigue M, Lamb SR, Mottram R, Pirozzolo F. Spine and hip motion analysis during the golf swing. In: Farrally MR, Cochran AJ, editors. Science and Golf II: Proceedings of the World Scientific Congress of Golf; 1994 July 4-8; London: E &FN Spon; 1994. p. 50-8.

8. Egret CI, Vincent O, Weber J, Dujardin FH, Chollet D. Analysis of 3D kinematics concerning three different clubs in golf swing. Int J Sports Med. 2003;24(6):465-70. http://dx.doi.org/10.1055/s-2003-41175. PMid:12905097.

9. Hosea TM, Gatt CJ, Galli KM, Langrana NA, Zawadsky JP. Biomechanical analysis of the golfer’s back. In: Cochran AJ, editor. Science and Golf: Proceedings of the World Scientific Congress of Golf. London: Chapman and Hall, 1990. p. 43-8.

10. Wells GD, Elmi M, Thomas S. Physiological correlates of golf performance. J Strength Cond Res. 2009;23(3):741-50. http://dx.doi.org/10.1519/JSC.0b013e3181a07970. PMid:19387406.

11. Evans K, Refshauge KM, Adams RD, Barrett R. Swing kinematics in skilled male golfers following putting practice. J Orthop Sports Phys Ther. 2008;38(7):425-33. http://dx.doi.org/10.2519/jospt.2008.2617.

12. Horan SA, Evans K, Morris NR, Kavanagh JJ. Swing kinematics of male and female skilled golfers following prolonged putting practice. J Sports Sci. 2014;32(9):810-6. http://dx.doi.org/10.1080/02640414.2013.848999. PMid:24480046.

13. Gosheger G, Liem D, Ludwig K, Greshake O, Winkelmann W. Injuries and overuse syndromes in golf. Am J Sports Med. 2003;31(3):438-43. PMid:12750140.

14. Smith MF. The role of physiology in the development of golf performance. Sports Med. 2010;40(8):635-55. http://dx.doi.org/10.2165/11532920-000000000-00000. PMid:20632736.

15. Cochran AJ, Stobbs J. The search for the perfect swing. Chicago: Triumph Books; 1996.

16. Bradshaw EJ, Keogh JW, Hume PA, Maulder PS, Nortje J, Marnewick M. The effect of biological movement variability on the performance of the golf swing in high- and low-handicapped players. Res Q Exerc Sport. 2009;80(2):185-96. http://dx.doi.org/10.1080/02701367.2009.10599552. PMid:19650383.

17. Beak SH, Choi A, Choi SW, Oh SE, Mun JH, Yang H, et al. Upper torso and pelvis linear velocity during the downswing of elite golfers. Biomed Eng Online. 2013;12(1):13. http://dx.doi.org/10.1186/1475-925X-12-13. PMid:23398693.

18. Joyce C, Burnett A, Cochrane J, Ball K. Three-dimensional trunk kinematics in golf: between-club differences and relationships to clubhead speed. Sports Biomech. 2013;12(2):108-20. http://dx.doi.org/10.1080/14763141.2012.728244. PMid:23898684.

19. Myers J, Lephart S, Tsai YS, Sell T, Smoliga J, Jolly J. The role of upper torso and pelvis rotation in driving performance during the golf swing. J Sports Sci. 2008;26(2):181-8. http://dx.doi.org/10.1080/02640410701373543. PMid:17852693.

20. Tinmark F, Hellstrom J, Halvorsen K, Thorstensson A. Elite golfers’ kinematic sequence in full-swing and partial-swing shots. Sports Biomech. 2010;9(4):236-44. http://dx.doi.org/10.1080/14763141.2010.535842.

21. Neal RJ, Lumsden RG, Holland M, Mason B. Segment interactions: sequencing and timing in the downswing. In: Crews D, Lutz R, editors. Science and Golf V: Proceedings of the World Scientific Congress of Golf; 2008 Mar 24-28; Phoenix: Energy in Motion Inc.; 2008. p. 21-9.

22. Nesbit SM, McGinnis RS. Kinetic constrained optimization of the golf swing hub path. J Sports Sci Med. 2014;13(4):859-73. PMid:25435779.

23. Ball K, Best R. Centre of pressure patterns in the golf swing: individual-based analysis. Sports Biomech. 2012;11(2):175-89. http://dx.doi.org/10.1080/14763141.2012.673007. PMid:22900399.

24. Foxworth JL, Millar AL, Long BL, Way M, Vellucci MW, Vogler JD. Hip joint torques during the golf swing of young and senior healthy males. J Orthop Sports Phys Ther. 2013;43(9):660-5. http://dx.doi.org/10.2519/jospt.2013.4417. PMid:23886577.

25. McNally MP, Yontz N, Chaudhari AM. Lower extremity work is associated with club head velocity during the golf swing in experienced golfers. Int J Sports Med. 2014;35(9):785-8. http://dx.doi.org/10.1055/s-0034-1367010. PMid:24577856.

26. Lai DTH, Hetchl M, Wei XC, Ball K, Mclaughlin P. On the difference in swing arm kinematics between low handicap golfers and non-golfers using wireless inertial sensors. Procedia Eng. 2011;13:219-25. http://dx.doi.org/10.1016/j.proeng.2011.05.076.

27. Lim YT, Chow JW, Chae WS. Lumbar spinal loads and muscle activity during a golf swing. Sports Biomech. 2012;11(2):197-211. http://dx.doi.org/10.1080/14763141.2012.670662. PMid:22900401.

28. Pink M, Jobe FW, Perry J. Electromyographic analysis of the shoulder during the golf swing. Am J Sports Med. 1990;18(2):137-40. http://dx.doi.org/10.1177/036354659001800205. PMid:2343980.

29. Pink M, Perry J, Jobe FW. Electromyographic analysis of the trunk in golfers. Am J Sports Med. 1993;21(3):385-8. http://dx.doi.org/10.1177/036354659302100310. PMid:8346752.

30. Farber AJ, Smith JS, Kvitne RS, Mohr KJ, Shin SS. Electromyographic analysis of forearm muscles in professional and amateur golfers. Am J Sports Med. 2009;37(2):396-401. http://dx.doi.org/10.1177/0363546508325154. PMid:19022991.

31. Silva L, Marta S, Vaz J, Fernandes O, Castro MA, Pezarat-Correia P. Trunk muscle activation during golf swing: Baseline and threshold. J Electromyogr Kinesiol. 2013;23(5):1174-82. http://dx.doi.org/10.1016/j.jelekin.2013.05.007. PMid:23816264.

32. Brown SJ, Nevill AM, Monk SA, Otto SR, Selbie WS, Wallace ES. Determination of the swing technique characteristics and performance outcome relationship in golf driving for low handicap female golfers. J Sports Sci. 2011;29(14):1483-91. http://dx.doi.org/10.1080/02640414.2011.605161. PMid:21988676.

33. Myers J, Lephart S, Tsai YS, Sell T, Smoliga J, Jolly J. The role of upper torso and pelvis rotation in driving performance during the golf swing. J Sports Sci. 2008;26(2):181-8. http://dx.doi.org/10.1080/02640410701373543. PMid:17852693.

Evans K , Tuttle N

388 Braz J Phys Ther. 2015 Sept-Oct; 19(5):381-389

34. Evans K, Horan SA, Neal RJ, Barrett RS, Mills PM. Repeatability of three-dimensional thorax and pelvis kinematics in the golf swing measured using a field-based motion capture system. Sports Biomech. 2012;11(2):262-72. http://dx.doi.org/10.1080/14763141.2012.654502. PMid:22900406.

35. Burden AM, Grimshaw PN, Wallace ES. Hip and shoulder rotations during the golf swing of sub-10 handicap players. J Sports Sci. 1998;16(2):165-76. http://dx.doi.org/10.1080/026404198366876. PMid:9531005.

36. Cheetham PJ, Martin PE, Mottram RE, St. Laurent BF. The importance of stretching the “X-Factor” in the downswing of golf: the “X-factor stretch”. In: Thomas PR, editor. Optimising performance in golf. Brisbane: Australian Academic Press; 2001. p. 192-99.

37. Healy A, Moran KA, Dickson J, Hurley C, Smeaton AF, O’Connor NE, et al. Analysis of the 5 iron golf swing when hitting for maximum distance. J Sports Sci. 2011;29(10):1079-88. http://dx.doi.org/10.1080/02640414.2011.576693. PMid:21678149.

38. Zheng N, Barrentine SW, Fleisig GS, Andrews JR. Swing kinematics for male and female pro golfers. Int J Sports Med. 2008;29(12):965-70. http://dx.doi.org/10.1055/s-2008-1038732. PMid:18563677.

39. Horan SA, Evans K, Morris NR, Kavanagh JJ. Thorax and pelvis kinematics during the downswing of male and female skilled golfers. J Biomech. 2010;43(8):1456-62. http://dx.doi.org/10.1016/j.jbiomech.2010.02.005. PMid:20185139.

40. Horan SA, Kavanagh JJ. The control of upper body segment speed and velocity during the golf swing. Sports Biomech. 2012;11(2):165-74. http://dx.doi.org/10.1080/14763141.2011.638390. PMid:22900398.

41. Bartlett R, Wheat J, Robins M. Is movement variability important for sports biomechanists? Sports Biomech. 2007;6(2):224-43. http://dx.doi.org/10.1080/14763140701322994. PMid:17892098.

42. Davids K, Button C, Bennett SJ. Dynamics of skill acquisition: a constraints-led approach. Champaign: Human Kinetics; 2008.

43. Seifert L, Button C, Davids K. Key properties of expert movement systems in sport : an ecological dynamics perspective. Sports Med. 2013;43(3):167-78. http://dx.doi.org/10.1007/s40279-012-0011-z. PMid:23329604.

44. Broman G, Johnsson L, Kaijser L. Golf: a high intensity interval activity for elderly men. Aging Clin Exp Res. 2004;16(5):375-81. http://dx.doi.org/10.1007/BF03324567. PMid:15636463.

45. Glazier P. Movement variability in the golf swing: theoretical, methodological, and practical issues. Res Q Exerc Sport. 2011;82(2):157-61. PMid:21699094.

46. Knight CA. Neuromotor issues in the learning and control of golf skill. Res Q Exerc Sport. 2004;75(1):9-15. http://dx.doi.org/10.1080/02701367.2004.10609128. PMid:15532356.

47. Langdown BL, Bridge M, Li FX. Movement variability in the golf swing. Sports Biomech. 2012;11(2):273-87. http://dx.doi.org/10.1080/14763141.2011.650187. PMid:22900407.

48. Stergiou N, Decker LM. Human movement variability, nonlinear dynamics, and pathology: is there a connection? Hum Mov Sci. 2011;30(5):869-88. http://dx.doi.org/10.1016/j.humov.2011.06.002. PMid:21802756.

49. Davids K, Glazier P. Deconstructing neurobiological coordination: the role of the biomechanics-motor control nexus. Exerc Sport Sci Rev. 2010;38(2):86-90. http://dx.doi.org/10.1097/JES.0b013e3181d4968b. PMid:20335740.

50. Seifert L, Komar J, Barbosa T, Toussaint H, Millet G, Davids K. Coordination pattern variability provides functional adaptations to constraints in swimming performance. Sports Med. 2014;44(10):1333-45. http://dx.doi.org/10.1007/s40279-014-0210-x. PMid:24895244.

51. Horan SA, Evans K, Kavanagh JJ. Movement variability in the golf swing of male and female skilled golfers. Med Sci Sports Exerc. 2011;43(8):1474-83. http://dx.doi.org/10.1249/MSS.0b013e318210fe03. PMid:21266926.

52. Egret CI, Nicolle B, Dujardin FH, Weber J, Chollet D. Kinematic analysis of the golf swing in men and women experienced golfers. Int J Sports Med. 2006;27(6):463-7. http://dx.doi.org/10.1055/s-2005-865818. PMid:16767611.

53. Whiteside D, Elliott BC, Lay B, Reid M. Coordination and variability in the elite female tennis serve. J Sports Sci. 2015;33(7):675-86. http://dx.doi.org/10.1080/02640414.2014.962569. PMid:25358037.

54. Tucker CB, Anderson R, Kenny IC. Is outcome related to movement variability in golf? Sports Biomech. 2013;12(4):343-54. http://dx.doi.org/10.1080/14763141.2013.784350. PMid:24466647.

55. Ferdinands RED, Kwon YH. Golf. Sports Biomech. 2012;11(2):125-6. http://dx.doi.org/10.1080/14763141.2012.696400. PMid:22900395.

56. Sell TC, Tsai YS, Smoliga JM, Myers JB, Lephart SM. Strength, flexibility, and balance characteristics of highly proficient golfers. J Strength Cond Res. 2007;21(4):1166-71. http://dx.doi.org/10.1519/R-21826.1. PMid:18076270.

57. Lindsay D, Horton J. Comparison of spine motion in elite golfers with and without low back pain. J Sports Sci. 2002;20(8):599-605. http://dx.doi.org/10.1080/026404102320183158. PMid:12190279.

58. Tsai YS, Sell TC, Smoliga JM, Myers JB, Learman KE, Lephart SM. A comparison of physical characteristics and swing mechanics between golfers with and without a history of low back pain. J Orthop Sports Phys Ther. 2010;40(7):430-8. http://dx.doi.org/10.2519/jospt.2010.3152. PMid:20592479.

59. Hellström J. Competitive elite golf: a review of the relationships between playing results, technique and physique. Sports Med. 2009;39(9):723-41. http://dx.doi.org/10.2165/11315200-000000000-00000. PMid:19691363.

60. Nesbit SM, Serrano M. Work and power analysis of the golf swing. J Sports Sci Med. 2005;4(4):520-33. PMid:24627666.

61. Bechler JR, Jobe FW, Pink M, Perry J, Ruwe PA. Electromyographic analysis of the hip and knee during the golf swing. Clin J Sport Med. 1995;5(3):162-6. http://dx.doi.org/10.1097/00042752-199507000-00005. PMid:7670971.

62. Cole MH, Grimshaw PN. Electromyography of the trunk and abdominal muscles in golfers with and without low back pain. J Sci Med Sport. 2008;11(2):174-81. http://dx.doi.org/10.1016/j.jsams.2007.02.006. PMid:17433775.

63. Marta S, Silva L, Vaz J, Bruno P, Pezarat-Correia P. Electromyographic analysis of trunk muscles during the golf swing performed with two different clubs. Int

Clinical perspective on improving performance in golf

389 Braz J Phys Ther. 2015 Sept-Oct; 19(5):381-389

J Sports Sci Coaching. 2013;8(4):779-87. http://dx.doi.org/10.1260/1747-9541.8.4.779.

64. Watkins RG, Uppal GS, Perry J, Pink M, Dinsay JM. Dynamic electromyographic analysis of trunk musculature in professional golfers. Am J Sports Med. 1996;24(4):535-8. http://dx.doi.org/10.1177/036354659602400420. PMid:8827315.

65. Marta S, Silva L, Castro MA, Pezarat-Correia P, Cabri J. Electromyography variables during the golf swing: a literature review. J Electromyogr Kinesiol. 2012;22(6):803-13. http://dx.doi.org/10.1016/j.jelekin.2012.04.002. PMid:22542769.

66. McHardy A, Pollard H. Muscle activity during the golf swing. Br J Sports Med. 2005;39:799-804. http://dx.doi.org/10.1136/bjsm.2005.020271.

67. Jobe FW, Pink MM. Shoulder pain in golf. Clin Sports Med. 1996;15(1):55-63. PMid:8903709.

68. Thériault G, Lachance P. Golf injuries. An overview. Sports Med. 1998;26(1):43-57. http://dx.doi.org/10.2165/00007256-199826010-00004. PMid:9739540.

69. Mathers JF, Grealy MA. Motor control strategies and the effects of fatigue on golf putting performance. Front Psychol. 2014;4:1005. http://dx.doi.org/10.3389/fpsyg.2013.01005. PMid:24454298.

70. Cotton H. This game of golf. London: Country Life; 1948.71. Smith CJ, Callister R, Lubans DR. A systematic review

of strength and conditioning programmes designed to improve fitness characteristics in golfers. J Sports Sci. 2011;29(9):933-43. http://dx.doi.org/10.1080/02640414.2011.571273. PMid:21547836.

72. Fletcher IM, Hartwell M. Effect of an 8-week combined weights and plyometrics training program on golf drive performance. J Strength Cond Res. 2004;18(1):59-62. PMid:14971982.

73. Thompson CJ, Osness WH. Effects of an 8-week multimodal exercise program on strength, flexibility, and golf performance in 55- to 79-year-old men. J Aging Phys Act. 2004;12(2):144-56. PMid:15223883.

74. Jones D. The effects of proprioceptive neuromuscular facilitation flexibility training on the clubhead speed of recreational golfers. In: Farrally MR, Cochran AJ, editors. Science and Golf III: Proceedings of the World Scientific Congress of Golf; 1998 July 20-24. St. Leeds: Human Kinetics; 1999, p. 46-50.

75. Torres-Ronda L, Sánchez-Medina L, González-Badillo JJ. Muscle strength and golf performance: a critical review. J Sports Sci Med. 2011;10(1):9-18. PMid:24149290.

76. Weston M, Coleman NJ, Spears IR. The effect of isolated core training on selected measures of golf swing performance. Med Sci Sports Exerc. 2013;45(12):2292-7. http://dx.doi.org/10.1249/MSS.0b013e31829bc7af. PMid:23698248.

77. Bull M, Bridge M. The effect of an 8-week plyometric exercise program on golf swing kinematics. IJGS. 2012;1(1);42-53.

78. Alvarez M, Sedano S, Cuadrado G, Redondo JC. Effects of an 18-week strength training program on low-handicap golfers’ performance. J Strength Cond Res. 2012;26(4):1110-21. http://dx.doi.org/10.1519/JSC.0b013e31822dfa7d. PMid:21881530.

79. Tilley NR, Macfarlane A. Effects of different warm-up programs on golf performance in elite male golfers. Int J Sports Phys Ther. 2012;7(4):388-95. PMid:23936749.

80. Lamberth J, Hale BD, Knight A, Boyd J, Luczak T. Effectiveness of a six-week strength and functional training program on golf performance. International Journal of Golf Science. 2013;2:33-42.

81. Girold S, Maurin D, Dugué B, Chatard JC, Millet G. Effects of dry-land vs. resisted- and assisted-sprint exercises on swimming sprint performances. J Strength Cond Res. 2007;21(2):599-605. PMid:17530963.

82. Mihalik JP, Libby JJ, Battaglini CL, McMurray RG. Comparing short-term complex and compound training programs on vertical jump height and power output. J Strength Cond Res. 2008;22(1):47-53. http://dx.doi.org/10.1519/JSC.0b013e31815eee9e. PMid:18296955.

83. Hayden JA, van Tulder MW, Malmivaara A, Koes BW. Exercise therapy for treatment of non-specific low back pain. Cochrane Database Syst Rev. 2005;(3):CD000335. http://dx.doi.org/10.1002/14651858.CD000335.pub2. PMid:16034851.

84. Macedo LG, Maher CG, Latimer J, McAuley JH. Motor control exercise for persistent, nonspecific low back pain: a systematic review. Phys Ther. 2009;89(1):9-25. http://dx.doi.org/10.2522/ptj.20080103. PMid:19056854.

85. Macedo LG, Smeets RJEM, Maher CG, Latimer J, McAuley JH. Graded activity and graded exposure for persistent nonspecific low back pain: a systematic review. Phys Ther. 2010;90(6):860-79. http://dx.doi.org/10.2522/ptj.20090303. PMid:20395306.

86. Huijnen IPJ, Rusu AC, Scholich S, Meloto CB, Diatchenko L. Subgrouping of low back pain patients for targeting treatments: evidence from genetic, psychological, and activity-related behavioral approaches. Clin J Pain. 2015;31(2):123-32. http://dx.doi.org/10.1097/AJP.0000000000000100. PMid:24681821.

87. Asenlöf P, Denison E, Lindberg P. Individually tailored treatment targeting motor behavior, cognition, and disability: 2 experimental single-case studies of patients with recurrent and persistent musculoskeletal pain in primary health care. Phys Ther. 2005;85(10):1061-77. PMid:16180955.

88. Senn S. Individual therapy: New dawn or false dawn? Drug Inf J. 2001;35(4):1479-94. http://dx.doi.org/10.1177/009286150103500443.

89. Herbert R, Jamtvedt G, Mead J, Hagen KB. Outcome measures measure outcomes, not effects of intervention. Aust J Physiother. 2005;51(1):3-4. http://dx.doi.org/10.1016/S0004-9514(05)70047-7. PMid:15748119.

Correspondence Kerrie Evans Griffith University School of Allied Health Sciences Gold Coast Campus PMB 50, Gold Coast Mail Centre QLD, 9726, Australia e-mail: kerrie.evans@griffith.edu.au

http://dx.doi.org/10.1590/bjpt-rbf.2014.0120

original article

390 Braz J Phys Ther. 2015 Sept-Oct; 19(5):390-397

Sports injuries profile of a first division Brazilian soccer team: a descriptive cohort study

Guilherme F. Reis1, Thiago R. T. Santos2, Rodrigo C. P. Lasmar1, Otaviano Oliveira Júnior1, Rômulo F. F. Lopes1, Sérgio T. Fonseca2

ABSTRACT | Objective: To establish the injury profile of soccer players from a first division Brazilian soccer team. In addition, we investigated the association between the characteristics of the injuries and the player’s age and position. Method: Forty-eight players from a Brazilian first division soccer team were followed during one season. Descriptive statistics were used to characterize the injury profile. Spearman’s tests were used to verify the association between the number and severity of injuries and the player’s age. Chi-square test was used to verify the association between type of injury and player’s position. Fisher’s exact test was used to verify the association between the severity of injuries and player’s position. Results: The incidence of injuries was 42.84/1000 hours in matches and 2.40/1000 hours in training. The injury severity was 19.5±34.4 days off competition or training. Lower limb was the most common location of injury and most injuries were muscular/tendinous, overuse, non-recurrent, and non-contact injuries. Player’s age correlated with the amount and severity of muscle and tendon injuries. Defenders had more minimal injuries (1-3 days lost), while forwards had more moderate (8-28 days lost) and severe injuries (>28 days lost). Furthermore, wingbacks had more muscle and tendon injuries, while midfielders had more joint and ligament injuries. Conclusion: The injury profile of the Brazilian players investigated in this study reflected regional differences in soccer practices. Results confirm the influence of the player’s age and position on the soccer injuries profile. Keywords: epidemiology; sport; incidence; soccer injuries; physical therapy.

HOW TO CITE THIS ARTICLE

Reis GF, Santos TRT, Lasmar RCP, Oliveira O Jr., Lopes RFF, Fonseca ST. Sports injuries profile of a first division Brazilian soccer team: a descriptive cohort study. Braz J Phys Ther. 2015 Sept-Oct; 19(5):390-397. http://dx.doi.org/10.1590/bjpt-rbf.2014.0120

1 Departamento Médico, Clube Atlético Mineiro, Belo Horizonte, MG, Brazil2 Programa de Pós-Graduação em Ciências da Reabilitação, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, BrazilReceived: Nov. 29, 2014 Revised: Apr. 15, 2015 Accepted: June 29, 2015

IntroductionProfessional soccer requires a high level of financial

investment in structure and maintenance1,2. Several studies have identified financial losses associated with high number of injuries in soccer due to the withdrawal of players from matches1-4. The implementation of preventive measures to reduce soccer injuries has received attention from sports physical therapists5. Documentation of the incidence, severity, and nature of injuries in high-level professional sports is the first step in developing effective preventive strategies6. The occurrence of soccer injuries may be affected by sport-specific and context-specific factors. Therefore, in order to understand the process of soccer injury, we must take into consideration not only the characteristics of the players and their roles, but also the characteristics of the place where the sport is played.

Context-specific factors such as number of matches during a season, weather and, style of play may distinctly affect the nature and incidence of soccer injuries in

different countries2,7. For example, Waldén et al.2 observed that the risk of injuries in matches was significantly greater in English and Dutch teams than in teams from France, Italy, and Spain. Despite the absence of comparative studies, Brazilian soccer players are known to have a different style of playing compared to European players. For example, Brazilian players have a more free-flowing offensive style with more individual plays compared to European players. Unfortunately, few studies have investigated injury profile in Brazilian professional soccer8,9. The most recent study was conducted with a second division Brazilian soccer team9. However, the profile of injury found by this study may be not applicable to first division teams given that Emery et al.10 observed a higher incidence of injuries in first division teams compared to other ones. Thus, the establishment of the injury profile of a Brazilian first division soccer team can contribute to the understanding of the factors

Sports injuries profile of a soccer team

391 Braz J Phys Ther. 2015 Sept-Oct; 19(5):390-397

that have to be considered during the implementation of preventive strategies.

Sport-specific factors, such as the player’s age and position on the soccer field, may also affect the injury profile. Coelho et al.11 observed that the efforts during matches varied according to the field position. Specifically, wingbacks exerted a higher amount of maximum efforts than other players11. These authors also observed that midfielders did not participate in as many maximum efforts as the other players11. The different amount of efforts performed by players according to the field position may also influence the soccer injury profile. Another factor that may influence the soccer injury profile is the athlete’s age. Arnason et al.12 investigated athletes between 16 and 38 years of age and found that the older the player is, the greater the chance of injury. The age factor has been a new focus in soccer studies given the observed increase in soccer players over 30 in professional teams13.

Sport- and context-specific factors should be considered in studies that aim to investigate soccer injury profiles thoroughly. Accordingly, the aim of this study was to establish the injury profile of soccer players from a first division Brazilian team. In addition, a secondary aim was to investigate the characteristics of injuries according to age and field position. This study can enhance the understanding of injuries in soccer players and provide knowledge that can help sports physical therapists to design programs focusing on soccer injury prevention.

MethodSubjects and Experimental Design

This descriptive cohort study was conducted with players from a Brazilian first division soccer team who were followed during one season. The players were considered eligible for this study if they did not

have any musculoskeletal injury before the beginning of the study. The medical staff was responsible for screening out players with musculoskeletal injuries. This study was an open cohort, thus if a player joined or left the team during the season, he was not excluded from the investigation, but the number of days that he was followed were considered in the descriptive and inferential analysis. Thirty-eight male athletes were evaluated, and one athlete was excluded due to injury. Thus, 37 athletes were initially followed. During the season, 12 new athletes joined the team, and none had any musculoskeletal injury. In addition, 13 athletes left the team during the season and consequently were not followed for the entire season. At the end of the season, this study investigated 48 male athletes for 238.3±103.2 days, including 4 goalkeepers, 6 defenders, 7 wingbacks, 20 midfielders, and 11 forwards. The characteristics of this sample are shown in Table 1. All athletes signed an informed consent form. This study was approved by the Research Ethics Committee of Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG, Brazil (ETIC 0493.0.203.000-09).

ProceduresInjury recording followed the guidelines for injury

definitions and data collection procedures in studies on soccer injuries of Fédération Internationale de Football Association (FIFA) Medical Assessment and Research Centre (F-MARC)14. Injury was defined as any physical complaint that results in a player being unable to take part in at least one subsequent soccer training session or match14. Injuries were recorded by the physical therapy team of the club, who was trained to use the F-MARC form at the beginning of the season. The injury event was recorded immediately after it occurred, and the match and training hours were recorded by the team’s physiologist.

Table 1. Characteristics of the athletes according to field position.

Field Position Age (years) Body Mass (kg) Height (cm) BMI (kg/m2)

Goalkeeper (n=4) 21.8 (2.2) 89.97 (2.12) 188.50 (3.19) 25.33 (0.85)

Defender (n=6) 24.8 (4.6) 85.52 (4.39) 187.50 (5.33) 24.33 (1.07)

Wingback (n=7) 25.1 (5.1) 73.03 (1.72) 175.50 (2.12) 23.72 (0.85)

Midfielder (n=20) 25.4 (4.5) 74.83 (8.51) 176.82 (6.06) 23.79 (1.76)

Forward (n=11) 26.4 (4.8) 78.00 (8.08) 176.44 (4.40) 25.01 (8.08)

Total (n=48) 25.2 (4.5) 78.73 (8.51) 179.69 (7.01) 24.35 (1.58)

Age, body mass, height and body mass index (BMI) are shown as mean (standard deviation).

Reis GF, Santos TRT, Lasmar RCP, Oliveira O Jr., Lopes RFF, Fonseca ST

392 Braz J Phys Ther. 2015 Sept-Oct; 19(5):390-397

Injury recording considered the moment at which the injury occurred (match or training), as well as severity, location, type, mechanism and recurrence. Injury severity was defined according to the number of days lost by the player between the day of the injury and the return to full participation in team training, and the availability to be selected to play14. Injury severity was also classified according to the number of days lost: minimal (1-3 days), mild (4-7 days), moderate (8-28 days), and severe (>28 days)14. Location of injury was defined according to the following categories: head/neck, upper limbs, trunk, and lower limbs14. The type of injury was classified as fracture/bone stress, joint (non-bone)/ligament, muscle/tendon, contusions, laceration/skin injury, central/peripheral nervous system, and others14. All muscle strains were confirmed by diagnostic imaging. The mechanism of injury was classified as traumatic, i.e. resulting from a specific and identifiable event, or as overuse, i.e. caused by repeated micro-traumas, even without a simple and identifiable event14. Recurrence was defined as the same type and site of injury recorded in the same season, and that occurred after the player returned to full participation in soccer14. Recurrence was classified as early, when the injury occurred at an interval less than two months; or as late, when it occurred between 2 and 12 months, following return to full participation in soccer14.

Data preparationInjuries were organized in number and percentage

according to location, type, mechanism, recurrence, and whether they occurred with or without contact. The incidence of injury during matches and training was reported as the number of injuries per 1000 hours played. Injury severity was shown both in relation to the mean and standard deviation of lost days, as well as quantity and percentage of injuries according to the severity classification. The quantity and severity (lost days) of injuries were divided by the number of days that each player was monitored. Since a player could enter or leave the team during the study, this normalization procedure was chosen in order to consider differences of monitoring-time of the players in the quantity and severity (lost days) of injuries.

Statistical analysesDescriptive statistics were done in order to

characterize the injury profile. Inferential statistics were performed to investigate the characteristics of injuries according to age and field position. Tests of

association were chosen to investigate the association between the player’s age and the characteristics of injury. Initially, the assumption of normality was verified using the Shapiro-Wilk test, which revealed that these variables were non-normally distributed. Considering this, Spearman’s test was used to verify the association between the player’s age and a) normalized total number of injuries, b) normalized number of muscle/tendon injuries, and c) normalized number of joint/ligament injuries. Spearman’s test was also used to verify the association between the player’s age and a) normalized severity of the total group of injuries, b) normalized severity of muscle/tendon injuries, and c) normalized severity of joint/ligament injuries.

Since the player’s field position is a categorical variable, chi-square and Fisher’s exact test were chosen to investigate the relationship between the player’s position and the characteristics of injury. The chi-square test was chosen to verify the association between player’s position and type of injury since the expected frequency in each cell of the contingency table was greater than 5. Fisher’s exact test was chosen to verify the association between the player’s position and the classification of severity of injuries since the expected frequency in some cells of the contingency table was lower than 5. Furthermore, Cramer’s V test was used to calculate the effect size for both the chi-square and Fisher’s exact test. The interpretation of Cramer’s V test output considered that the closer the value is to 1, the greater the effect size. In addition, when a significant association was found, analysis of adjusted residuals was used to verify which subgroups contributed most to the result. A significant adjusted residual indicates that the cell of the contingency table made a significant contribution to the main statistic. Since the adjusted residual is a z score, if the value lies outside of ±1.96, it indicates that the number of cases in that cell of the contingency table is different than expected, considering p<0.05. Positive adjusted residuals indicate that the cell is over-represented in the sample compared to the expected frequency and negative residuals indicate that the cell is under-represented in the sample compared to the expected frequency. The level of significance (α) was set at 0.05 for all inferential analyses.

ResultsThe season consisted of 334 days, during which

58 matches were played. The number of matches per athlete was 24±15.3, and the training time per athlete was 315±54.8 hours. Seventeen players (3 goalkeepers,

Sports injuries profile of a soccer team

393 Braz J Phys Ther. 2015 Sept-Oct; 19(5):390-397

2 defenders, 9 midfielders, and 3 forwards) did not sustain any injuries, and 31 players (1 goalkeeper, 4 defenders, 7 wingbacks, 11 midfielders, and 8 forwards) sustained some type of injury. Forty-one injuries (0.71 injuries per match) occurred during matches (58.6%), and 29 injuries occurred during training (41.4%). The incidence of injury was 42.84/1000 hours of matches and 2.40/1000 hours of training. The mean of severity of injury was 19.5±34.4 lost days. All injuries occurred in the lower limbs and their characteristics are presented in Table 2. In addition, the distribution of type of injury according to the classification of severity is presented in Table 3. The anatomic location of the strains and sprains is presented in Table 4.

The investigated associations are shown in Figure 1. Spearman’s test showed no evidence of association between player age and total number of injuries (p=0.19) or between age and number of joint/ligament injuries (p=0.51). However, a positive association was observed between age and number of muscle/tendon injuries (ρ=0.33, p=0.02). In relation to severity, no

association was observed between player age and severity of total injuries (p=0.74) or between age and severity of joint/ligament injuries (p=0.14). However, an association was observed between age and severity of muscle/tendon injuries (ρ=0.28, p=0.02).

The goalkeepers were not considered in the investigation of the association between field position and type of injury, because they experienced no muscle/tendon or joint/ligament type of injuries. The chi-square test showed an association between field position and type of injury (χ2 (3) = 10.45, p=0.02). Cramer’s V test showed that this association had a magnitude of 0.40 (p=0.02). The analysis of adjusted residuals showed that the midfielders had the greatest association between field position and joint/ligament type of injury (Z=2.1), while wingbacks had the lowest association (Z=-2.1). Furthermore, the wingbacks showed the greatest association between field position and muscle/tendon type of injury (Z=2.1), while midfielders had the lowest association (Z=-2.1).

Fisher’s exact test showed an association between field position and classification of severity (p<0.01). Cramer’s V test showed a correlation with magnitude of 0.36 (p<0.01). The analysis of adjusted residuals showed that defenders contributed more to the association between field position and minimum injury severity (Z=2.2), while the forwards contributed less to this association (Z=-2.5). Furthermore, the forwards contributed more to the association between field position and moderate injury severity (Z=4.3), while wingbacks (Z=-2.2) and defenders (Z=-2.0) contributed less to this association.

DiscussionThis study characterized the injury profile of a first

division Brazilian Championship team during one season. The characteristics of this injury profile may be explained by sport- and context-specific factors. The injury

Table 3. Distribution of injury types according to classification of severity.

Injury typeClassification of Severity

TotalMinimal(1-3 days)

Mild(4-7 days)

Moderate(8-28 days)

Severe(>28 days)

Muscle and tendon 6 (14.6%) 9 (22.0%) 20 (48.8%) 6 (14.6%) 41 (58.6%)

Joint and ligament 9 (36.0%) 4 (16.0%) 7 (28.0%) 5 (20.0%) 25 (35.7%)

Fracture and bone stress 1 (50.0%) 0 (0%) 1 (50.0%) 0 (0%) 2 (2.9%)

Central/peripheral nervous system 0 (0%) 1 (100%) 0 (0%) 0 (0%) 1 (1.4%)

Others 0 (0%) 1 (100%) 0 (0%) 0 (0%) 1 (1.4%)

Total 16 (22.9%) 15 (21.4%) 28 (40.0%) 11 (15.7%) 70

Percentages are related to the total cases of each row, except the row totals and column totals, which percentages are related to the total amount of injuries.

Table 2. Characteristics of injuries.

Number %

Mechanism

Traumatic 15 21.4

Overuse 55 78.6

Recurrence

Non-recurrent 65 92.9

Early 3 4.3

Late 2 2.9

Contact 14 20.0

Non-contact 56 80.0

The percentages in each characteristic are related to the total number of injuries (70).

Reis GF, Santos TRT, Lasmar RCP, Oliveira O Jr., Lopes RFF, Fonseca ST

394 Braz J Phys Ther. 2015 Sept-Oct; 19(5):390-397

incidence observed during matches (42.84/1000 hours) was greater than the injury incidence reported by the Union of European Football Associations (UEFA) teams (mean of 27.5/1000 hours)15 and by the Japanese first division teams (mean of 21.8/1000 hours)16. A comparison with other Brazilian studies was not possible due to methodological differences, such as the definition of sports injury and incidence rate8,9. The incidence of injury (per 1000 h) during matches found in this study was nearly 18 times greater than that observed during training. The greater incidence

Table 4. Anatomic location of strains and sprains.

Number %

Muscles strained 19 100

Rectus femoris 9 46.37

Hip adductors 5 26.32

Hamstring 3 15.79

Iliopsoas 2 10.53

Joints sprained 24 100

Ankle 12 50.0

Knee 12 50.0

Figure 1. Scatter plot of each correlation investigated.

Sports injuries profile of a soccer team

395 Braz J Phys Ther. 2015 Sept-Oct; 19(5):390-397

of injury during matches has already been shown in other studies2,17. This may be related to the greater competitive pressures on the players during games as opposed to during training, and thus, this can be considered a sport-specific factor18. It is noteworthy that the eighteen-fold relationship found in this study is four to six times greater than the mean relationship reported in other studies19. This difference may be related to the number of matches played during a season2. The mean matches per season for UEFA teams is 3215; and ranges from 30-44 for Japanese league teams16. This differs greatly from the 58 matches played by the team investigated in this study. This suggests that context-specific factors, such as the number of matches per season, can explain differences in the profile of soccer injuries observed in different countries. It is important to highlight that the design of this study does not allow the definition of the causes of the observed injuries.

The majority of injuries were classified as of moderate severity. The severity found (19.5±34.4 lost days) in this study is almost the same as reported in other studies4,17. In addition, all injuries occurred in the lower limbs. Muscle/tendon injuries, followed by joint/ligament, were the most common types of injury. Strain injuries predominated among the muscle/tendon injuries, whereas sprain injuries predominated among joint/ligament injuries. These characteristics are in agreement with other studies15-17. Furthermore, most injuries occurred due to overuse (78.6%). This mechanism of injury is possibly related to the type of demand placed on the musculoskeletal system by soccer practice, and thus a sport-specific factor20. For example, during kicking or cutting maneuvers, the musculoskeletal system has to store part of the elastic energy for subsequent reuse20. This mechanism allows less muscle overload during matches and training. The presence of some biomechanical factor related to the soccer player that interferes with the elastic return capability of the musculoskeletal system (i.e. muscle weakness) may result in greater stress on the tissues, which increases the potential for injury. Therefore, the characteristics of severity, type, and mechanism of injury found in the investigated team may be considered as sport-specific factors.

Most of the injuries found in this study were non-recurrent and non-contact. The recurrence rate (7.1%) was lower than what is reported in the literature (20-25%)19. The predominance of non-contact injuries is reported in other studies and can be related to the higher rate of overuse injuries compared to traumatic

injuries17,18. However, the non-contact injury rate found in this study (80%) is higher than the rates reported in the literature17,18. This high rate suggests the existence of a high demand placed on the musculoskeletal system during soccer actions18,20. Activities such as running and cutting are not only related to the mechanism and type of injury (overuse and muscle/tendon types), but may also help explain the large number of non-contact injuries18,20. Thus, the predominance of non-contact injuries reinforces the importance of implementing preventive programs for soccer players.

The age of the player was positively associated with the quantity and severity of muscle/tendon type of injury. Age has already been previously identified as a risk factor for the development of injuries12. The association found in the present study may be related to physiological factors21,22 that reduce the capability of the musculoskeletal system to deal with stress. Muscle mass in adulthood decreases progressively with age, due to the reduction in the amount and cross-sectional area of muscle fibers21. In addition, tendons lose their capacity to store, return, and transmit energy throughout life22. This phenomenon is more intense in older individuals21, which may have contributed to the observed association of the player’s age to the quantity and severity of injuries. Another factor that could explain this association is the occurrence of prior injuries23. Considering that the muscle/tendon injuries are frequent, older players may have suffered this type of injury during other seasons, which could affect the tissue structure and predispose them to injury recurrence. Future cohort studies should be developed to investigate tissue changes in professional soccer players, in order to identify the role of these factors for injury development. Independent of causal factors, preventive programs and recovery programs after matches should consider different activities according to the player’s age.

The player’s field position influenced the type and the severity of injury. Wingbacks had more muscle/tendon injuries, while midfielders had more joint/ligament injuries. Wingbacks have been reported to perform maximal efforts during matches by means of higher number of sprints11,24. This may be related to tactical patterns of modern soccer, characterized by wingbacks performing defensive and attacking roles in short periods of time24. This may overload muscle and tendon tissues, which could predispose the wingbacks to injuries. The greater number of joint/ligament-type injuries associated with midfielders could be related to their role of linking defense and attack actions.

Reis GF, Santos TRT, Lasmar RCP, Oliveira O Jr., Lopes RFF, Fonseca ST

396 Braz J Phys Ther. 2015 Sept-Oct; 19(5):390-397

This role requires frequent turning and changing of direction, which increases the demands on the joints and ligaments20. Furthermore, this study observed that defenders had more minimal severity injuries, while forwards had more moderate and severe injuries. Di Salvo et al.24 reported that defenders perform fewer sprints during matches and, thus, face fewer physical demands compared to other field positions. This may be related to the lesser severity of the injuries observed in defenders. Moreover, the more moderate injuries observed in forwards could be related to the higher demand for sprints performed by this field position, together with the wingbacks. Another factor that could have contributed to this association was the fact that the investigated forwards tended to be slightly older than the players of other positions. Despite this, the injury profile may be more strongly related to different demands of motions required by the athlete’s position on the field.

The turnover of athletes during the season could be considered a limitation of this study. However, due to the difficulty of following an athlete after leaving, this study controlled for this limitation by weighting the analyses according to the days played by each athlete. The investigation of just one season could also be considered a limitation, nevertheless other studies reported no differences in the injury profiles in different seasons23,25. Furthermore, this study investigated athletes from one team and, thus, features of this team may affect the results. It is noteworthy that the investigated team plays in the first division Brazilian Championship and offers an infrastructure similar to other teams of this division. In addition, other factors not considered by this study may also influence the injury profile, such as training characteristics and previous injuries. Finally, the results of this descriptive cohort can help in the design of future epidemiological studies, such as analytical studies with multiple soccer teams, that could consider the factors investigated in the present study.

ConclusionThis study described the injury profile of soccer

players from a first division Brazilian team. This profile had similarities and differences with other reported profiles of teams from other countries, which may reflect the influence of both sport- and context-specific factors for the development of soccer injury. The quantity and severity of injuries were associated with the player’s age and field position. The results of this study can

enhance the knowledge of injuries in Brazilian soccer and help sports physical therapists to plan preventive programs.

References1. Junge A, Dvorak J, Graf-Baumann T. Football injuries

during the World Cup 2002. Am J Sports Med. 2004;32(1 Suppl):23S-7S. http://dx.doi.org/10.1177/0363546503261246. PMid:14754856.

2. Waldén M, Hägglund M, Ekstrand J. UEFA Champions League study: a prospective study of injuries in professional football during the 2001-2002 season. Br J Sports Med. 2005;39(8):542-6. http://dx.doi.org/10.1136/bjsm.2004.014571. PMid:16046340.

3. Woods C, Hawkins RD, Maltby S, Hulse M, Thomas A, Hodson A, Football Association Medical Research Programme. The Football Association Medical Research Programme: an audit of injuries in professional football--analysis of hamstring injuries. Br J Sports Med. 2004;38(1):36-41. http://dx.doi.org/10.1136/bjsm.2002.002352. PMid:14751943.

4. Woods C, Hawkins R, Hulse M, Hodson A. The Football Association Medical Research Programme: an audit of injuries in professional football-analysis of preseason injuries. Br J Sports Med. 2002;36(6):436-41, discussion 441. http://dx.doi.org/10.1136/bjsm.36.6.436. PMid:12453838.

5. Silva AA, Bittencourt NFN, Mendonça LM, Tirado MG, Sampaio RF, Fonseca ST. Analysis of the profile, areas of action and abilities of Brazilian sports physical therapists working with soccer and volleyball. Rev Bras Fisioter. 2011;15(3):219-26. http://dx.doi.org/10.1590/S1413-35552011000300008. PMid:21829986.

6. Bahr R, Krosshaug T. Understanding injury mechanisms: a key component of preventing injuries in sport. Br J Sports Med. 2005;39(6):324-9. http://dx.doi.org/10.1136/bjsm.2005.018341. PMid:15911600.

7. Waldén M, Hägglund M, Orchard J, Kristenson K, Ekstrand J. Regional differences in injury incidence in European professional football. Scand J Med Sci Sports. 2013;23(4):424-30. http://dx.doi.org/10.1111/j.1600-0838.2011.01409.x. PMid:22092416.

8. Cohen M, Abdalla RJ, Ejnisman B, Amaro JT. Lesões ortopédicas no futebol. Rev Bras Ortop. 1997;32(12):940-4.

9. Palacio EP, Candeloro BM, Lopes AA. Lesões nos Jogadores de Futebol Profissional do Marília Atlético Clube : Estudo de Coorte Histórico do Campeonato Brasileiro de 2003 a 2005. Rev Bras Med do Esporte. 2009;15(1):31-5. http://dx.doi.org/10.1590/S1517-86922009000100007.

10. Emery CA, Meeuwisse WH, Hartmann SE. Evaluation of risk factors for injury in adolescent soccer: implementation and validation of an injury surveillance system. Am J Sports Med. 2005;33(12):1882-91. http://dx.doi.org/10.1177/0363546505279576. PMid:16157843.

11. Coelho DB, Mortimer LÁ, Condessa LA, Morandi RF, Oliveira BM, Marins JCB, et al. Intensidade de jogos de futebol de uma competição real e entre jogadores de diferentes posições táticas. Rev Bras Cineantropometria e Desempenho Hum. 2011;13(5):341-7. http://dx.doi.org/10.5007/1980-0037.2011v13n5p341.

Sports injuries profile of a soccer team

397 Braz J Phys Ther. 2015 Sept-Oct; 19(5):390-397

12. Arnason A, Sigurdsson SB, Gudmundsson A, Holme I, Engebretsen L, Bahr R. Risk factors for injuries in football. Am J Sports Med. 2004;32(1 Suppl):5S-16S. http://dx.doi.org/10.1177/0363546503258912. PMid:14754854.

13. Lavallee D. The Effect of a Life Development Intervention on Sports Career Transition Adjustment. Sport Psychol. 2005;19(2):193-202.

14. Fuller CW, Ekstrand J, Junge A, Andersen TE, Bahr R, Dvorak J, et al. Consensus statement on injury definitions and data collection procedures in studies of football (soccer) injuries. Scand J Med Sci Sports. 2006;16(2):83-92. http://dx.doi.org/10.1111/j.1600-0838.2006.00528.x. PMid:16533346.

15. Ekstrand J, Hägglund M, Waldén M. Injury incidence and injury patterns in professional football: the UEFA injury study. Br J Sports Med. 2011;45(7):553-8. http://dx.doi.org/10.1136/bjsm.2009.060582. PMid:19553225.

16. Aoki H, O’Hata N, Kohno T, Morikawa T, Seki J. A 15-year prospective epidemiological account of acute traumatic injuries during official professional soccer league matches in Japan. Am J Sports Med. 2012;40(5):1006-14. http://dx.doi.org/10.1177/0363546512438695. PMid:22408048.

17. Hawkins RD, Hulse MA, Wilkinson C, Hodson A, Gibson M. The association football medical research programme: an audit of injuries in professional football. Br J Sports Med. 2001;35(1):43-7. http://dx.doi.org/10.1136/bjsm.35.1.43. PMid:11157461.

18. Wong P, Hong Y. Soccer injury in the lower extremities. Br J Sports Med. 2005;39(8):473-82. http://dx.doi.org/10.1136/bjsm.2004.015511. PMid:16046325.

19. Junge A, Dvorak J. Soccer injuries: a review on incidence and prevention. Sports Med. 2004;34(13):929-38. http://dx.doi.org/10.2165/00007256-200434130-00004. PMid:15487905.

20. Fonseca ST, Souza TR, Ocarino JM, Gonçalves GP, Bittencourt NF. Applied biomechanics of soccer. In: Magee DJ, Manske

RC, Zachazewski JE, Quillen WS, editors. Athletic and sport issues in musculoskeletal rehabilitation. St. Louis: Elsevier Saunders; 2011. p. 287-306.

21. Brown M. Effect of aging-growth changes and life span concerns. In: Magee DJ, Zachazewski JE, Quillen WS, editors. Scientific foundations and principles of practive in musculoskeletal rehabilitation. St. Louis: Saunders Elsevier; 2007. p. 305-13.

22. Arampatzis A, Degens H, Baltzopoulos V, Rittweger J. Why do older sprinters reach the finish line later? Exerc Sport Sci Rev. 2011;39(1):18-22. http://dx.doi.org/10.1097/JES.0b013e318201efe0. PMid:21088606.

23. Hägglund M, Waldén M, Ekstrand J. Previous injury as a risk factor for injury in elite football: a prospective study over two consecutive seasons. Br J Sports Med. 2006;40(9):767-72. http://dx.doi.org/10.1136/bjsm.2006.026609. PMid:16855067.

24. Di Salvo V, Gregson W, Atkinson G, Tordoff P, Drust B. Analysis of high intensity activity in Premier League soccer. Int J Sports Med. 2009;30(3):205-12. http://dx.doi.org/10.1055/s-0028-1105950. PMid:19214939.

25. Dauty M, Collon S. Incidence of injuries in French professional soccer players. Int J Sports Med. 2011;32(12):965-9. http://dx.doi.org/10.1055/s-0031-1283188. PMid:22052029.

Correspondence Guilherme Fialho Reis Clube Atlético Mineiro Rodovia MG 424, Km 21, s/n, Bairro Jardim da Glória CEP 33200-000, Vespasiano, MG, Brazil e-mail: guifialhoreis@yahoo.com.br

http://dx.doi.org/10.1590/bjpt-rbf.2014.0121

original article

398 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

Multicenter trial of motion analysis for injury risk prediction: lessons learned from prospective longitudinal

large cohort combined biomechanical - epidemiological studies

Timothy E. Hewett1, Benjamin Roewer2, Kevin Ford4,5,6, Greg Myer2,3,4,5

ABSTRACT | Our biodynamics laboratory group has conducted large cohort biomechanical-epidemiological studies targeted at identifying the complex interactions among biomechanical, biological, hormonal, and psychosocial factors that lead to increased risk of anterior cruciate ligament (ACL) injuries. The findings from our studies have revealed highly sensitive and specific predictors for ACL injury. Despite the high incidence of ACL injuries among young athletes, larger cohorts are needed to reveal the underlying mechanistic causes of increased risk for ACL injury. In the current study, we have outlined key factors that contribute to the overall success of multicenter, biomechanical-epidemiological investigations designed to test a larger number of athletes who otherwise could not be recruited, screened, or tested at a single institution. Twenty-five female volleyball players were recruited from a single high school team and tested at three biodynamics laboratories. All athletes underwent three-dimensional motion capture analysis of a drop vertical jump task. Kinematic and kinetic variables were compared within and among laboratories. Reliability of peak kinematic variables was consistently rated good-to-excellent. Reliability of peak kinetic variables was consistently rated good-to-excellent within sites, but greater variability was observed between sites. Variables measured in the sagittal plane were typically more reliable than variables measured in the coronal and transverse planes. This study documents the reliability of biomechanical variables that are key to identification of ACL injury mechanisms and of athletes at high risk. These findings indicate the feasibility of executing multicenter, biomechanical investigations that can yield more robust, reliable, and generalizable findings across larger cohorts of athletes. Keywords: ACL; adolescents; knee injuries; drop vertical jump; prevention.

HOW TO CITE THIS ARTICLE

Hewett TE, Roewer B, Ford K, Myer G. Multicenter trial of motion analysis for injury risk prediction: lessons learned from prospective longitudinal large cohort combined biomechanical - epidemiological studies. Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409. http://dx.doi.org/10.1590/bjpt-rbf.2014.0121

1 Mayo Clinic, Rochester, MN, USA2 Sports Health & Performance Institute, The Ohio State University, Columbus, OH, USA3 Departments of Physiology and Cell Biology, Orthopaedic Surgery, Family Medicine and Biomedical Engineering, The Ohio State University, Columbus, OH, USA4 Division of Sports Medicine, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, USA5 Department of Pediatrics and Orthopaedic Surgery, College of Medicine, University of Cincinnati, Cincinnati, OH, USA6 Department of Physical Therapy, School of Health Sciences, High Point University, High Point, USAReceived: Feb. 05, 2015 Revised: May 12, 2015 Accepted: July 02, 2015

IntroductionOur multicenter, multidisciplinary research group

has conducted several collaborative, multi-institutional studies that included reliability comparisons of biomechanical and neuromuscular data from three different sites – the Biodynamics Laboratories at Cincinnati Children’s Hospital (CCH or Site A), The Ohio State University (OSU or Site B) and the University of Kentucky (UK or Site C) – using identical data collection, reduction techniques, data processing methods, and data analyses. Reliability studies of this kind, as with any such impactful study, are important

for the establishment of widespread generalizability, reliability, reproducibility, and acceptability of multicenter collected data. The authors have previously tested and measured the longitudinal reliability and validity of all of the data collected during testing from one site at Cincinnati Children’s Hospital (CCH)1. In order to conduct a proper measurement of the validity of these prospective cohort study findings, we track injuries prospectively so that we can effectively use these data for widespread injury risk assessment.

Reliability of a prospective biomech trial

399 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

Long-term objectives of multicenter biomechanical-epidemiologic studies

The primary objectives of our Multicenter Biomechanical-Epidemiologic studies are to determine how individuals become more susceptible to injury, prospectively identifying those athletes who are more susceptible to injury and to determine the underlying mechanistic cause(s) of increased risk at the biomechanical level and to optimize the effectiveness of treatments designed to prevent these injuries. Towards these goals, we test hypotheses related to multiple biomechanical variables: lower extremity bone length and body mass maturational stage; neuromuscular performance; whole limb and whole body posture; trunk, hip, and knee joint loading; and injury risk in subsets of athletes.

Our research group has many ongoing studies and our research interests and activities can be broken down into three areas of study: 1) Mechanistic Studies using In Sim approaches that combine multiple in vivo, in vitro, cadaveric, computer modeling, and animal model approaches to answer the most pertinent questions in our field; 2) High-Risk Individuals Studies using evidence-based medicine (EBM) datasets to determine which athletes are at increased risk for anterior cruciate ligament (ACL) injuries; and 3) Preventive Studies using Randomized Controlled Trial (RCT) designs to determine which interventions decrease risk for ACL injuries in large cohort populations. We also employ dual identifying and preventive studies using EBM techniques and datasets and RCT designs to determine which interventions are most efficacious in specific athletes, both individuals and groups, which are at increased risk for ACL injuries.

School and community-based research partnerships

Over the past two decades, we have collaborated with large public geographic county-based schools. Our primary methods of recruitment were data-driven, state-of-the-art presentations and cutting-edge tools used in areas of particular interest, as they fit nicely into school administrators’ overall objectives. These school administrators included superintendents, athletic directors, principals, teachers, and coaches.

Our primary objectives with these studies have been to collaborate with school administrators, coaches, students, and parents to gain support for our coupled Biomechanical-Epidemiologic studies, to design and develop screening protocols to identify high-risk athletes who demonstrate identifiable neuromuscular

control deficits that put them at risk, and to develop and implement neuromuscular training interventions to decrease injury risk. Our overall objectives for the current theoretical construct include understanding the United States’ National Institute of Health (NIH) funding opportunities; technology options for recruiting and retention; tracking options for study/trial management; tips to help avoid time delays in study implementation and to detail technical research methods and tool options and methods.

Multicenter trial of motion analysis for injury risk prediction in school settings: experimental approach & methods

The goals of our experimental approach are to determine the injury risk predictive role of specific factors such as trunk, hip, and knee position; strength and muscle recruitment at the hip and knee; hip and knee load and neuromuscular control, i.e. adolescent growth and increases in tibia and femur length; and body mass in athletes. Our group utilizes what we term a ‘Top-down & Bottom-Up’ administrative approach to implement these studies. We begin our explorations of the school systems with school administrators including superintendents, athletic directors, and principals. We then contact coaches, athletic trainers (ATs), and teachers to get their full support with these research studies.

Overall couple biomechanical-epidemiologic approach

For over a decade, we have conducted prospective longitudinal large cohort combined biomechanical-epidemiological studies. ACL injury risk has proven to be a complex, multi-faceted problem that involves biomechanical, biological, hormonal, and psychosocial factors. We have tested the hypothesis that measures related to dynamic lower extremity valgus will prove predictive of ACL injury risk in high-risk female athletes. For example, Myer et al.2 demonstrated that female athletes with increased knee recurvatum had significantly increased risk of ACL injury. We also demonstrated that increased lateral trunk displacement following quick-release perturbation was indicative of increased risk of anterior cruciate ligament injury in females, but not males3. In another longitudinal study, we showed that there were changes in both knee joint and general joint laxity with growth and development that differ between females and males4. We have also published our examinations of the contributions of both coronal and sagittal plane

Hewett TE, Roewer B, Ford K, Myer G

400 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

kinematics to dynamic stability of the knee and the reliability of our 3D Motion Analysis measures1.

We utilized a prospective longitudinal design in county-based school-sponsored soccer, volleyball, and basketball teams from multiple school systems that we recruited, tested, and tracked. Female and male subjects from high school and junior high school were screened prior to the start of multiple consecutive soccer, volleyball, and basketball seasons. Graphs depicting the standardized means with standard deviations from the demographic variables of the subject population are shown in Figures 1 and 2.

Subject recruitingFor over two decades, our research group has

recruited hundreds of high school teams that have yielded thousands of soccer, volleyball, and basketball players who were pre-screened, trained, and post-screened5. We faced multiple challenges recruiting soccer players at junior high schools in the public county school systems. Some of the junior high schools did not have organized teams. We have addressed this challenge via recruitment of teams outside the county system

(e.g. non-public, parochial schools located in the same county geographic area) in order to fill in all of our randomized blocks. In addition, we captured those junior high school athletes who went on to play high school soccer, volleyball, and basketball within the county school system.

Multicenter reliability biostatistical analyses: biomechanical data

Careful biostatistical analysis should be performed by experienced biostatisticians and biomechanical profiles should be created for each of the screening movements. Standardized values should be used, as the variables are on different scales with varying mean values. Due to underlying normality assumption, it was necessary to transform some relevant variables to the loge scale. In addition, the correlations between variables needed to be accounted for, in particular maximum hip and knee angles and moments. We continue to examine biostatistical models and will check them against data to determine any emergent predictive profiles. Comparison of mean variables, with and

Figure 1. Time series for hip, knee and ankle angles time-normalized to 100% of stance. Lines represent upper and lower 95% confidence interval bounds.

Reliability of a prospective biomech trial

401 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

without adjustment for potential confounders, should also be the focus of future analyses.

MethodA total of 25 volleyball players from a single High

School team were screened in August of 2011. Testing was completed over two weeks in that month. All subjects provided informed consent approved by the institutional review boards at the University of Cincinnati, Cincinnati, OH, USA, The Ohio State University, Columbus, OH, USA, and University of Kentucky, Lexington, KY, USA (approval number 2011H0075, 022-11, and 08-0573, respectively). Each subject was instrumented with forty-three (43) 9-mm retroreflective markers by a different research assistant at each laboratory site. Markers were placed over the spinous process of C7; the midpoint between the suprasternal notch and the second costal notch of the sternum; the L5-S1 spinal junction; left posterior superior iliac spine; and bilaterally on the shoulders, upper arms, elbows, wrists, anterior superior iliac spines (ASIS), greater trochanters, mid thighs,

medial and lateral knee joint lines, tibial tubercles, distal and lateral shanks (i.e. lower part of leg), and medial and lateral ankles, as shown in Figure 3. Subjects wore a small backpack outfitted with three non-collinearly placed markers. Each subject wore the same make and model of shoes with markers permanently affixed to the heels, dorsal surface of the mid foot, fifth metatarsal, and superior surface of the toe. Marker position and force data were collected using commonly accepted motion analysis techniques. A static trial was recorded with the subject standing in a neutral anatomical alignment with his/her foot placement standardized to the laboratory coordinate system. Subjects performed three drop vertical jump (DVJ) maneuvers from a height of 31 cm. Their feet were initially positioned 35 cm apart, and the subjects were instructed to drop off the plyometric box and perform a maximal vertical jump, reaching up towards a target placed directly overhead of the force plates at the height of their maximum vertical jump, as seen in Figure 3.

Data collected at each of the three sites were obtained using similar equipment and sampling

Figure 2. Time series for hip, knee and ankle moments time-normalized to 100% of stance. Lines represent upper and lower 95% confidence interval bounds.

Hewett TE, Roewer B, Ford K, Myer G

402 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

frequencies. Different personnel collected data and instructed subjects at each site. A detailed equipment list is specified in Table 1.

We had internally verified that 3-D marker position data collected simultaneously on Vicon (VICON, Oxford Metrics Ltd., London, UK) and Motion Analysis (Motion Analysis Corp., Santa Rosa, CA, USA) camera systems using the same 240 Hz sampling frequency and the same data reduction techniques yielded no significant differences in computed joint angles6. Data collection procedures were developed and optimized in order to collect reliable and valid data on a team of athletes (approximately 25 athletes) in under 3 hours. We utilized multiple stations that included separate check-in, anthropometrics, marker placement, instruction, and data collection. This provided an opportunity for a large number of personnel to be appropriately trained in a few key areas instead of a few personnel taking on multiple responsibilities. Data collection forms with trial names and randomization order were produced prior to the data collection session and populated via scripting techniques within the motion capture software.

A two-step process was utilized to check the quality of the marker coordinates and to determine proper tracking identification. First, a technician from each laboratory performed the quality control of each trial detailing any potential errors within a spreadsheet. Potential errors, such as marker misidentification and small gaps, were immediately fixed. Secondly, a senior researcher reviewed the trials and addressed any additional concerns with the data. Gaps in marker position data of less than 10% of the marker sampling frequency (Sites A and B ≤24 frames; Site C ≤20 frames) were interpolated using a cubic spline fill. Due to the inherent high hip and trunk flexion in combination with clothing, small 9mm markers, and the rapid rate of data collection, larger gaps in ASIS marker position data were present in a number of subjects. Based on the results of this study, we have now modified camera placement and include redundant pelvis markers. Gaps in ASIS marker position data greater than 10% but less than 25% of the marker sampling frequency were interpolated using a virtual marker fill based on the fixed relative distance from the contralateral ASIS marker and hip joint center

Figure 3. Example of the marker set used in this study as seen during the drop vertical jump (DVJ) task (left). Computerized representation of the marker used in this study (right).

Table 1. Summary of motion capture data collection equipment and techniques used at each data collection site.

Site A B C

Camera System 10-camera Motion Analysis 8-camera Vicon 18-camera Motion Analysis

Force platforms AMTI (600 x 900mm) Bertec (300 x 600mm) Bertec (600 x 900mm)

Sampling frequency (marker / force)

240 Hz/1200 Hz 240 Hz/1200 Hz 200 Hz/1000 Hz

Data processing software Motion Analysis Cortex Vicon Nexus Motion Analysis Cortex

A, B & C: Cincinnati Children’s Hospital, The Ohio State University, and the University of Kentucky, respectively.

Reliability of a prospective biomech trial

403 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

and the sacrum. Our lab has internally validated this approach and verified that it creates an acceptable amount of root mean square error when joint angle curves are compared between real and virtual filled ASIS marker data. It also creates no clinically relevant differences in peak computed joint angles.

Motion data were subsequently processed through Visual 3D (v4.86, C-motion Inc. Germantown, MD, USA) using batch scripts via the motion capture software and Matlab (vR2012b, Mathworks Inc. Natick, MA, USA). All marker and force data were subsequently filtered using a low-pass fourth-order Butterworth filter, sampling at 12 Hz, and post-processed using the same custom Visual 3D and Matlab coding to compute lower extremity joint Euler angles. Force data and computed kinematic data were used to compute joint moments. All joint kinematic and kinetics data from each trial were exported from Visual 3D and plotted as an additional quality control step. We have found this identifies a small percentage of erroneous data from incorrect model based analyses that would not be identified when batch processing large amounts of data.

Peak hip, knee, and ankle angles and moments were calculated during stance from the DVJ using Visual 3D. Stance was defined as the time period between initial contact and take-off (i.e. when the vertical ground reaction force (GRF) exceeded 10N and subsequently fell below 10 N). The average of three trials was used in the current analysis. A two-way, random-effects model of intraclass correlation coefficients (ICC) were used to compute the reliability of peak angles and moments from trial-to-trial at each site (3,k), between each combination of sites (3,1), and among all three sites (3,k). ICC values were classified as ICC>0.75 = excellent, 0.4≤ICC≤0.75 = good, or ICC<0.4 = poor7. Coefficients of multiple correlation (CMC) were also computed using the methods described by Kadaba et al.8 to measure the variability of joint angle and moment waveforms during stance at each site, between each combination of sites, and among all three sites8. Standard error of the measurement (SEM) for each peak kinematic and kinetic variable was also computed and reported. Subject demographic information was compared across sites using an Analysis of Variance with one repeated measure. A priori significance was set at α<0.05.

ResultsThe average (± standard deviation) age of subjects

at the time of the first testing session (Site A) was 15.3±1.0 years. The average height and mass at the

same time point were 169.3±4.5 cm and 62.3±6.8 kg, respectively. There were no significant changes in height (p=0.248) or body mass (p=0.096) during the study period.

KinematicsThe reliability of peak kinematic variables

among all three sites was rated as excellent (Range: 0.762-0.893; Table 2). There was greater variability in waveforms among all three sites, and CMCs ranged from 0.456 to 0.954. All sagittal-plane waveforms had CMCs >0.9, whereas none of the coronal- or transverse-plane waveforms had CMCs greater than 0.7.

Between sites, there were only four instances in which the reliability of peak kinematics variables was rated as excellent (Table 2). The majority of peak variables were rated as good. Peak ankle dorsiflexion between sites A and B was the only kinematic variable rated as poor; however, it had the greatest CMC value among all between-site comparisons.

Within each site, the reliability of peak kinematic variables from trial-to-trial was consistently rated as excellent. CMCs varied from 0.526 to 0.991 (Table 3). CMCs for each variable were greater in the sagittal plane than the coronal and transverse planes.

KineticsThe reliability of peak kinetic variables among sites

varied greatly (range: –0.112-0.830) (Table 2). ICCs were greatest in the sagittal plane for each variable. CMC values varied from 0.493 to 0.862 and were consistently greatest in the sagittal plane for each variable.

Between sites, there was only one instance in which ICCs were rated as excellent. The remaining comparisons were rated as good or poor. Kinetic waveforms for each variable had CMC values that were either similar or slightly less than the respective kinematic waveforms.

Within each site, the reliability of peak kinetic variables from trial-to-trial was consistently rated as excellent with only five instances in which reliability was rated as good (Table 3). The kinetic waveforms had CMC values similar to their respective kinematic comparisons.

DiscussionIn general, the kinematic data were reliable and

reproducible for use in large multicenter trials. However, the reliability of the kinetic data did not appear to be high, hence, this data may be best fit for use at individual

Hewett TE, Roewer B, Ford K, Myer G

404 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

Tabl

e 2.

Bet

wee

n-sit

e re

liabi

lity

for p

eak

kine

mat

ic a

nd k

inet

ic v

aria

bles

.

AM

ON

G S

ITES

Site

A –

Site

BSi

te B

– S

ite C

Site

A –

Site

C

CM

CIC

C (3

,k)

CM

CIC

C (3

,1)

SEM

CM

CIC

C (3

,1)

SEM

CM

CIC

C (3

,1)

SEM

Join

t Ang

les(

o )

Hip

flex

ion

0.93

2±0.

090.

860

0.93

4±0.

070.

536

5.0

0.97

4±0.

020.

765

3.4

0.95

5±0.

040.

719

4.2

Hip

add

uctio

n0.

456±

0.31

0.85

50.

644±

0.28

0.72

42.

30.

709±

0.25

0.70

02.

10.

638±

0.28

0.57

32.

8

Hip

inte

rnal

rota

tion

0.69

3±0.

130.

843

0.82

3±0.

140.

620

4.0

0.84

7±0.

090.

673

4.1

0.81

3±0.

110.

629

4.7

Kne

e fle

xion

0.94

5±0.

100.

832

0.94

4±0.

100.

550

4.7

0.98

1±0.

020.

525

4.5

0.96

2±0.

070.

762

3.7

Kne

e ab

duct

ion

0.57

8±0.

240.

893

0.81

1±0.

110.

715

2.2

0.79

5±0.

230.

758

2.2

0.81

0±0.

170.

728

2.3

Kne

e in

tern

al ro

tatio

n0.

523±

0.20

0.86

00.

827±

0.15

0.73

52.

90.

806±

0.16

0.54

74.

00.

830±

0.13

0.74

12.

9

Ank

le d

orsi

flexi

on0.

954±

0.05

0.76

20.

948±

0.09

0.78

92.

00.

960±

0.08

0.37

33.

40.

969±

0.03

0.45

13.

5

Ank

le E

vers

ion

0.60

8±0.

210.

777

0.75

6±0.

230.

470

2.7

0.80

4±0.

160.

655

1.9

0.78

6±0.

210.

711

1.7

Join

t Mom

ents

(N*m

*kg-1

)

Hip

flex

ion

0.86

2±0.

140.

830

0.85

1±0.

140.

660

0.18

0.91

7±0.

040.

550

0.22

0.88

6±0.

090.

673

0.15

Hip

add

uctio

n0.

643±

0.13

0.62

60.

722±

0.16

0.55

30.

100.

780±

0.12

0.14

00.

130.

697±

0.12

0.38

40.

10

Hip

inte

rnal

rota

tion

0.70

0±0.

140.

545

0.77

5±0.

150.

605

0.07

0.77

5±0.

120.

293

0.12

0.71

2±0.

160.

140

0.14

Kne

e fle

xion

0.81

8±0.

220.

789

0.86

0±0.

130.

385

0.22

0.93

6±0.

040.

734

0.16

0.87

2±0.

120.

504

0.18

Kne

e ab

duct

ion

0.61

5±0.

090.

620

0.72

9±0.

140.

216

0.11

0.84

7±0.

120.

431

0.13

0.76

5±0.

120.

342

0.13

Kne

e in

tern

al ro

tatio

n0.

493±

0.13

0.69

20.

738±

0.14

0.34

40.

060.

690±

0.19

0.37

00.

070.

729±

0.18

0.61

20.

04

Ank

le d

orsi

flexi

on0.

743±

0.22

0.70

50.

799±

0.15

0.52

60.

130.

916±

0.04

0.63

90.

090.

819±

0.13

0.22

30.

16

Ank

le E

vers

ion

0.54

0±0.

21-0

.112

0.70

6±0.

190.

798

0.05

0.67

3±0.

22-0

.288

0.15

0.59

2±0.

21-0

.250

0.15

CM

C: c

oeffi

cien

t of m

ultip

le c

orre

latio

n; IC

C: i

ntra

-cla

ss c

orre

latio

n co

effic

ient

(mea

n +/

- sta

ndar

d de

viat

ion)

; SEM

: sta

ndar

d er

ror o

f the

mea

sure

men

t.

Reliability of a prospective biomech trial

405 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

Tabl

e 3.

With

in-s

ite, t

rial-t

o-tri

al re

liabi

lity.

Site

ASi

te B

Site

C

CM

CIC

C (3

,k)

SEM

CM

CIC

C (3

,k)

SEM

CM

CIC

C (3

,k)

SEM

Join

t Ang

les(

o )

Hip

flex

ion

0.97

4±0.

020.

908

2.6

0.97

9±0.

010.

900

1.9

0.98

2±0.

020.

947

1.7

Hip

add

uctio

n0.

610±

0.30

0.95

00.

90.

672±

0.25

0.91

61.

30.

526±

0.35

0.89

61.

5

Hip

inte

rnal

rota

tion

0.81

3±0.

190.

963

0.7

0.83

0±0.

130.

920

1.2

0.81

8±0.

170.

946

0.7

Kne

e fle

xion

0.98

7±0.

100.

932

2.3

0.99

1±0.

010.

910

2.0

0.99

1±0.

010.

925

2.3

Kne

e ab

duct

ion

0.81

6±0.

150.

989

0.5

0.82

8±0.

100.

973

0.7

0.89

6±0.

080.

987

0.5

Kne

e in

tern

al ro

tatio

n0.

721±

0.18

0.98

30.

90.

825±

0.07

0.98

30.

80.

725±

0.14

0.97

71.

3

Ank

le d

orsi

flexi

on0.

987±

0.01

0.94

71.

20.

942±

0.22

0.94

21.

40.

989±

0.01

0.92

81.

7

Ank

le E

vers

ion

0.80

1±0.

180.

971

0.8

0.68

4±0.

260.

883

1.4

0.76

6±0.

150.

923

1.1

Join

t Mom

ents

(N*m

*kg-1

)

Hip

flex

ion

0.85

1±0.

260.

806

0.07

0.93

3±0.

050.

784

0.09

0.93

5±0.

040.

896

0.05

Hip

add

uctio

n0.

773±

0.09

0.76

60.

040.

776±

0.15

0.62

80.

060.

785±

0.12

0.67

50.

07

Hip

inte

rnal

rota

tion

0.81

1±0.

160.

833

0.03

0.89

6±0.

070.

827

0.03

0.85

2±0.

190.

856

0.04

Kne

e fle

xion

0.88

9±0.

160.

741

0.09

0.93

2±0.

060.

900

0.08

0.91

7±0.

050.

882

0.07

Kne

e ab

duct

ion

0.66

7±0.

230.

849

0.04

0.74

7±0.

240.

910

0.04

0.77

0±0.

190.

881

0.03

Kne

e in

tern

al ro

tatio

n0.

579±

0.24

0.82

70.

030.

593±

0.20

0.60

30.

050.

542±

0.27

0.79

30.

03

Ank

le d

orsi

flexi

on0.

774±

0.16

0.89

70.

020.

884±

0.08

0.80

30.

030.

893±

0.06

0.82

00.

02

Ank

le E

vers

ion

0.65

8±0.

290.

899

0.05

0.84

7±0.

100.

951

0.03

0.82

5±0.

080.

496

0.08

CM

C: c

oeffi

cien

t of m

ultip

le c

orre

latio

n; IC

C: i

ntra

-cla

ss c

orre

latio

n co

effic

ient

(mea

n +/

- sta

ndar

d de

viat

ion)

; SEM

: sta

ndar

d er

ror o

f the

mea

sure

men

t.

Hewett TE, Roewer B, Ford K, Myer G

406 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

sites to train individuals. This kinetic data may also be useful for biofeedback training. For instance, feedback regarding position and technique during sports-related movements may increase an athlete’s awareness and allow him or her to make adjustments during training. Using real-time kinematic biofeedback may provide an intriguing option for delivering augmented feedback and could maximize the effectiveness of traditional neuromuscular intervention programs. Recent studies with real-time gait retraining have reinforced the concept of providing critical feedback with detailed real-time motion analysis data9-11. Multiple studies support the idea that real-time feedback modified potential risk factors related to different knee pathologies. Both immediate and long-term improvements have been identified9-11.

Challenges of Multicenter Biomechanical-Epidemiologic Studies

Subject RecruitingWe have faced and met many challenges recruiting

subjects (i.e. the athletes) in school systems, but to a greater extent at the junior high school level than the high school level in the county school systems. For example, some of the county junior high schools do not have organized sports teams. We addressed this challenge by recruiting teams from recreational leagues and parochial (religious) schools within the county and adjoining counties in order to capture those athletes who go on to play high school sports within the school system.

Data Quality ControlTeams at all sites completed their data processing

pipeline for the biomechanical analyses. With data collected and processed over multiple sites, it was found that a small percentage of movement trials had incorrectly tracked markers, even though all trials had been inspected by a human operator. Due to the high volume of data, it was not possible to do a more thorough inspection of the raw data; therefore, two data verification steps were added to the processing pipeline. The first step involved a complete tracking quality control step at the home site. The second step processed the marker trajectories using a simplified skeleton model with a few degrees of freedom. When presented with incorrectly tracked marker coordinates, this analysis reported an error because the simplified skeleton was unable to fit the data. Trials where this error was detected were sent back to the

human operator for re-tracking, and the others were processed further into joint kinematics and kinetics. A third quality control step was added at the end of the biomechanics pipeline. A human operator looked at groups of curves representing the main biomechanical variables, each curve representing one trial. Outlying curves were identified and the marker tracking of those trials was re-examined for correctness. If correct, the data was used for further statistical analysis. If not, marker tracking was corrected or, if the data was corrupted or incomplete, the trial was discarded. The authors are currently developing a fourth quality control step using a confidence interval-based approach for automatic detection of outliers.

Peak versus Mean Variable ValuesOur research group normally reports both peak

and mean variable values across the entire stance phase in our studies12. We attempt to mitigate the effects of potential moment artifacts by reporting the peak values averaged across three trials per subject. For example, peak KAM occurs approximately 50ms after initial contact during a run-cut, a time at which joint moment artifacts are likely to occur. Conversely, peak KAM during a DVJ does not always occur soon after initial contact when large artifacts are likely to occur. Considering the stance time of a typical DVJ is approximately 400 msec, the peak KAM would occur closer to 100ms and therefore not located where impact artifacts occur during a run-cut13.

Data FilteringHow one decides to filter and analyze motion

data is both an art and a science that requires careful consideration of both the tasks being analyzed and the outcome variables of interest. For these reasons, there are several subtleties and some possible flaws in other studies that warrant clarification. Our research team understands the benefits of testing the reliability of kinematic and kinetic data at matched cutoff frequencies and we have been filtering our motion data at matched frequencies for several years1,14-16. However, universally dismissing studies that use unmatched cutoff frequencies or suggesting that earlier conclusions should be reconsidered – specifically, those from our 2005 study12 – is unfounded. We must not fail to acknowledge the power of the prospective case-cohort design. Principally, prospective designs prevent investigators from potentially biasing their cohorts because they prospectively treat the data uniformly for all of their subjects: those who eventually

Reliability of a prospective biomech trial

407 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

go on to suffer an injury and those who did not. Thus, if properly designed, prospective cohort data will result in valid and reliable findings.

The effects of filtering may render measured biomechanical variables less reliable as injury prediction tool than previously thought. This is why it is important that authors report the reliability of their data. If investigators do not report the reliability of their measures in their study paper or elsewhere in the literature, their conclusions should be interpreted with caution.

Data Limitations-Differences in Movement tasks-validity, reliability issues

It is likely incorrect for investigators to assume that differences in kinematic and kinetic (moment) calculations for one movement directly relate to all other movements that involve high-impact accelerations. For example, it has been shown that relative loads may vary greatly between a drop vertical jump (DVJ) and a cutting movement. All movement tasks that are subject to large forces and accelerations fall victim to a certain degree of specificity of angles, loads, and artifacts. For example, a run-cut task is subject to much larger frontal-plane forces and segment accelerations than a DVJ task; therefore, Knee Abduction Moment (KAM) measured during a run-cut task is likely more sensitive to cutoff frequency than KAM measured during a DVJ. However, large artifacts are typically reserved for the planes of motion in which these large forces and accelerations occur. For example, Kristianslund et al.17 reported a mean peak KAM between 75-150 Nm during a run-cut task, whereas we reported mean peak KAM between 15-45 Nm during a DVJ17. We also previously compared a DVJ to a jump stop side-cut movement and reported significant differences in KAM and Knee Abduction Angle (KAA) between the two movements16. An analysis of our most recent DVJ data indicate that filtering frequency may have only a small effect on the magnitude of peak KAM, and a negligible effect on the relative ranking of subjects based on peak KAM18.

Validity of Conclusions and Interpretation of Findings

In order to conduct a proper measurement of the validity of investigators’ conclusions from a coupled biomechanical-epidemiologic cohort prospective trial, one would need to examine the fidelity with which injuries were prospectively tracked before a study of any task can be effectively evaluated for injury

risk assessment. There are also many potential bias problems introduced in poorly designed cohort and intervention trials. Potential biases abound such as selection bias, reporting bias, and absence of blinding. For example, in a recent study published as a Level One trial in The American Journal of Sports Medicine, significant limitations in the design of the study may have affected the results and their interpretation19. Each coach and all of the athletes knew whether or not they had been assigned to the intervention program, and all were well aware of the expected outcomes of using the program, which had a track record of reducing injuries. This knowledge could potentially have led to a placebo effect among players using the intervention – there was no placebo or “sham” treatment to blind the researchers or study subjects. In addition, the players on the teams that did not use the intervention were older (almost two years older on average), taller, and heavier than the athletes on the teams that took part in the program. One would expect more injuries in bigger, taller athletes independent of the intervention. At the most basic level, simple physics apply – the bigger the study subject is, the harder he or she will fall.

Injury tracking – an important effector of validity of follow-up

In order to conduct a proper measurement of the validity of our findings and conclusions, one would need to track injuries prospectively before a run-cut task could be effectively used for injury risk assessment. Many studies are not designed properly to answer the questions upon which they speculate. A properly designed study requires an approach that includes apples-to-apples comparisons of groups and to other studies using identical data collection, reduction techniques, injury tracking methods, and analyses.

Replication of any study is important for its tenets to gain widespread acceptability. ACL-injury risk factors have proven to be complex and multifaceted with mechanical, biological, hormonal, and psychosocial components. KAM and KAA are certainly prominent, predictive markers for ACL injury risk, and have been repeatedly validated10,20-23, but are only two of many important factors. We have new data that indicates that KAA may be as strong a predictor as KAM. These data are important as we move forward with our secondary kinematic two-dimensional analyses and develop more comprehensive and generalizable clinic-based predictive models.

Hewett TE, Roewer B, Ford K, Myer G

408 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

Significance of coupled biomechanical-epidemiologic study findings

The findings of these coupled biomechanical-epidemiologic studies should provide a foundation for approaching both the mechanistic questions underlying injury risk disparities between individuals and groups, such as sexes, as well as increase our ability to direct high-risk athletes to effective, neuromuscular interventions targeted at specific, measured deficits related to pubertal growth and development.

We performed these parallel studies at the three sites all within two weeks of one another. The goals of these studies were to develop the reliability across sites in a large cohort in order to conduct large multicenter randomized controlled trials. We tested and cross-validated three different biodynamics laboratories (at OSU, CCH, and UK) to collect data on the same medium-sized cohort of subjects. This resulted in adequate statistical power and allowed us to examine injury events as both secondary and primary outcomes. Though KAA and KAM are prominent markers for ACL injury risk and have been demonstrated repeatedly to predict increased ACL injury risk12,24, but are only two of many potentially important factors. We have new data that indicates that knee abduction angle may be as strong a predictor as KAM. This is important as we move forward with our secondary kinematic 2D analyses and development of more comprehensive and generalizable clinic-based predictive models.

Summary and conclusionsThis extended study method developed with a

multi-institutional, multidisciplinary team will likely yield more robust results with increased generalizability and applicability to diverse populations. The additional analyses will provide a foundation for addressing important mechanistic questions; however, they are extremely costly and time-consuming and require assistance. Nevertheless, the added approaches proposed in this supplement will foster the development of a clinician-friendly assessment tool that will enhance the translation of the study results into use in the medical community.

We suggest future collaborative, multicenter, multi-institutional studies that include apples-to-apples comparison of data grouped across sites using identical data collection, reduction techniques, injury tracking methods, and analyses. Replication of any study is important for establishing widespread acceptability. Injury risk factors have proven to be a complex,

multifaceted problem with biological, hormonal, mechanical, and psychosocial factors. For example, KAM is certainly a prominent marker for ACL injury risk and has been demonstrated repeatedly, but it is only one of many important factors. We have new data that indicates that knee abduction angle may be as strong a predictor as KAM. This is important as we move forward with our secondary kinematic 2D analyses and developing more comprehensive and generalizable clinic-based predictive models.

Future directions and plansOur research consortium continues to utilize a

prospective longitudinal design for school-sponsored soccer and basketball teams from multiple school systems, which are recruited, tested, and tracked. Female and male subjects from high schools and junior high schools are being screened prior to the start of each consecutive soccer, volleyball, and basketball seasons. We have tested the basketball players for several consecutive years. We have previously tested and measured the longitudinal reliability and validity of all of the data collected during testing from one site at CCH1. The biomechanics and sports medicine research communities should continue to utilize these analyses to evaluate both the pre-test profiles as well as to determine the effects of prospective randomized controlled trial study designs. We will conduct sports injury surveillance on all of the athletes for two consecutive years following the athletes’ enrollment into the study.

References1. Ford KR, Myer GD, Hewett TE. Reliability of landing 3D

motion analysis: implications for longitudinal analyses. Med Sci Sports Exerc. 2007;39(11):2021-8. http://dx.doi.org/10.1249/mss.0b013e318149332d. PMid:17986911.

2. Myer GD, Ford KR, Paterno MV, Nick TG, Hewett TE. The effects of generalized joint laxity on risk of anterior cruciate ligament injury in young female athletes. Am J Sports Med. 2008;36(6):1073-80. http://dx.doi.org/10.1177/0363546507313572. PMid:18326833.

3. Zazulak BT, Hewett TE, Reeves NP, Goldberg B, Cholewicki J. Deficits in neuromuscular control of the trunk predict knee injury risk: a prospective biomechanical-epidemiologic study. Am J Sports Med. 2007;35(7):1123-30. http://dx.doi.org/10.1177/0363546507301585. PMid:17468378.

4. Quatman CE, Ford KR, Myer GD, Paterno MV, Hewett TE. The effects of gender and pubertal status on generalized joint laxity in young athletes. J Sci Med Sport. 2008;11(3):257-63. http://dx.doi.org/10.1016/j.jsams.2007.05.005. PMid:17597005.

5. Hewett TE, Xu YY, Ford KR, Khoury JC, Myer GD. Changes in biomechanical hip & trunk control, knee load &

Reliability of a prospective biomech trial

409 Braz J Phys Ther. 2015 Sept-Oct; 19(5):398-409

potential predictors of increased acl injury risk: randomized controlled trial. In: Proceedings of the 37th Annual Meeting of the American Society of Biomechanics; 2013 Sept 4-7; Omaha, NE: Publisher; 2013. page 452.

6. Mcnally MP, Roewer BD, Hewett TE. Inter-rater reliability of two commercial 3d motion capture systems. In: Proceedings of the 37th Annual Meeting of the American Society of Biomechanics; 2013 Sept 4-7; Omaha, NE: Publisher; 2013. page 445.

7. Fleiss JL. The design and analysis of clinical experiments. New York: John Wiley & Sons; 1986. http://dx.doi.org/10.1002/9781118032923.

8. Kadaba MP, Ramakrishnan HK, Wootten ME, Gainey J, Gorton G, Cochran GV. Repeatability of kinematic, kinetic, and electromyographic data in normal adult gait. J Orthop Res. 1989;7(6):849-60. http://dx.doi.org/10.1002/jor.1100070611. PMid:2795325.

9. Hewett TE, Myer GD, Ford KR, Paterno MV, Quatman CE. The 2012 ABJS Nicolas Andry Award: The sequence of prevention: a systematic approach to prevent anterior cruciate ligament injury. Clin Orthop Relat Res. 2012;470(10):2930-40. http://dx.doi.org/10.1007/s11999-012-2440-2. PMid:22744203.

10. Myer GD, Ford KR, Khoury J, Succop P, Hewett TE. Clinical correlates to laboratory measures for use in non-contact anterior cruciate ligament injury risk prediction algorithm. Clin Biomech (Bristol, Avon). 2010;25(7):693-9. http://dx.doi.org/10.1016/j.clinbiomech.2010.04.016. PMid:20554101.

11. Myer GD, Schmitt LC, Brent JL, Ford KR, Barber Foss KD, Scherer BJ, et al. Utilization of modified NFL combine testing to identify functional deficits in athletes following ACL reconstruction. J Orthop Sports Phys Ther. 2011;41(6):377-87. http://dx.doi.org/10.2519/jospt.2011.3547. PMid:21289456.

12. Hewett TE, Myer GD, Ford KR, Heidt RS Jr, Colosimo AJ, McLean SG, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study. Am J Sports Med. 2005;33(4):492-501. http://dx.doi.org/10.1177/0363546504269591. PMid:15722287.

13. Ford KR, Myer GD, Toms HE, Hewett TE. Gender differences in the kinematics of unanticipated cutting in young athletes. Med Sci Sports Exerc. 2005;37(1):124-9. http://dx.doi.org/10.1249/01.MSS.0000150087.95953.C3. PMid:15632678.

14. Ford KR, Shapiro R, Myer GD, Van Den Bogert AJ, Hewett TE. Longitudinal sex differences during landing in knee abduction in young athletes. Med Sci Sports Exerc. 2010;42(10):1923-31. http://dx.doi.org/10.1249/MSS.0b013e3181dc99b1. PMid:20305577.

15. Ford KR, Myer GD, Hewett TE. Longitudinal effects of maturation on lower extremity joint stiffness in adolescent athletes. Am J Sports Med. 2010;38(9):1829-37. http://dx.doi.org/10.1177/0363546510367425. PMid:20522830.

16. Cowley HR, Ford KR, Myer GD, Kernozek TW, Hewett TE. Differences in neuromuscular strategies between landing

and cutting tasks in female basketball and soccer athletes. J Athl Train. 2006;41(1):67-73. PMid:16619097.

17. Kristianslund E, Krosshaug T, van den Bogert AJ. Effect of low pass filtering on joint moments from inverse dynamics: implications for injury prevention. J Biomech. 2012;45(4):666-71. http://dx.doi.org/10.1016/j.jbiomech.2011.12.011. PMid:22227316.

18. Roewer BD, Ford KR, Myer GD, Hewett TE. The ‘impact’ of force filtering cut-off frequency on the peak knee abduction moment during landing: artefact or ‘artifiction’? Br J Sports Med. 2014;48(6):464-8. http://dx.doi.org/10.1136/bjsports-2012-091398. PMid:22893510.

19. Longo UG, Loppini M, Berton A, Marinozzi A, Maffulli N, Denaro V. The FIFA 11+ program is effective in preventing injuries in elite male basketball players: a cluster randomized controlled trial. Am J Sports Med. 2012;40(5):996-1005. http://dx.doi.org/10.1177/0363546512438761. PMid:22415208.

20. Myer GD, Ford KR, Khoury J, Hewett TE. Three-dimensional motion analysis validation of a clinic-based nomogram designed to identify high ACL injury risk in female athletes. Phys Sportsmed. 2011;39(1):19-28. http://dx.doi.org/10.3810/psm.2011.02.1858. PMid:21378483.

21. Myer GD, Ford KR, Khoury J, Succop P, Hewett TE. Development and validation of a clinic-based prediction tool to identify female athletes at high risk for anterior cruciate ligament injury. Am J Sports Med. 2010;38(10):2025-33. http://dx.doi.org/10.1177/0363546510370933. PMid:20595554.

22. Myer GD, Ford KR, Khoury J, Succop P, Hewett TE. Biomechanics laboratory-based prediction algorithm to identify female athletes with high knee loads that increase risk of ACL injury. Br J Sports Med. 2011;45(4):245-52. http://dx.doi.org/10.1136/bjsm.2009.069351. PMid:20558526.

23. Padua DA, Marshall SW, Boling MC, Thigpen CA, Garrett WE Jr, Beutler AI. The Landing Error Scoring System (LESS) Is a valid and reliable clinical assessment tool of jump-landing biomechanics: The JUMP-ACL study. Am J Sports Med. 2009;37(10):1996-2002. http://dx.doi.org/10.1177/0363546509343200. PMid:19726623.

24. Paterno MV, Schmitt LC, Ford KR, Rauh MJ, Myer GD, Huang B, et al. Biomechanical measures during landing and postural stability predict second anterior cruciate ligament injury after anterior cruciate ligament reconstruction and return to sport. Am J Sports Med. 2010;38(10):1968-78. http://dx.doi.org/10.1177/0363546510376053. PMid:20702858.

Correspondence Timothy E. Hewett Mayo Clinic 200 First Street SW RO_Gu_01_28BIOM Rochester, MN,USA 55905 e-mail: timothy.hewett@osumc.edu

http://dx.doi.org/10.1590/bjpt-rbf.2014.0126

original article

410 Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420

Physical therapists’ role in prevention and management of patellar tendinopathy injuries in youth, collegiate, and

middle-aged indoor volleyball athletesKornelia Kulig1, Lisa M. Noceti-DeWit1, Stephen F. Reischl1, Rob F. Landel1

ABSTRACT | Patellar tendinopathy is highly prevalent in all ages and skill levels of volleyball athletes. To illustrate this, we discuss the clinical, biomechanical, and ultrasound imaging presentation and the intervention strategies of three volleyball athletes at different stages of their athletic career: youth, middle-aged, and collegiate. We present our examination strategies and interpret the data collected, including visual movement analysis and dynamics, relating these findings to the probable causes of their pain and dysfunction. Using the framework of the EdUReP concept, incorporating Education, Unloading, Reloading, and Prevention, we propose intervention strategies that target each athlete’s specific issues in terms of education, rehabilitation, training, and return to sport. This framework can be generalized to manage patellar tendinopathy in other sports requiring jumping, from youth to middle age, and from recreational to elite competitive levels. Keywords: physical therapy; patellar tendinopathy; volleyball.

HOW TO CITE THIS ARTICLE

Kulig K, Noceti-DeWit LM, Reischl SF, Landel RF. Physical therapists’ role in prevention and management of patellar tendinopathy injuries in youth, collegiate, and middle-aged indoor volleyball athletes. Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420. http://dx.doi.org/10.1590/bjpt-rbf.2014.0126

1 Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USAReceived: Mar. 14, 2015 Revised: May 27, 2015 Accepted: June 26, 2015

Introduction

Volleyball became an Olympic sport in 1964 and remains one of the 10 most popular sports in the world1. It is estimated that elite volleyball athletes practice anywhere from 7 to 10 hours per week2,3 and play in matches 0.5-1.5 hours per week2,3. With this amount of workload, often heavily relying on jumping, it is not surprising that indoor volleyball players are susceptible to overuse injuries. One of the most frequently reported overuse injuries experienced by indoor volleyball players is patellar tendinopathy. It has been estimated that 45% of male volleyball players experience patellar tendinopathy4 and that male players experience symptoms more frequently than female players. Besides the workload the knee undergoes, suboptimal jumping mechanics may contribute to the development of this problem5.

There is a wide variety of treatment options currently available, including nonsteroidal anti-inflammatory medications6-8, therapeutic ultrasound6-8, cortisone injection6-8, protein-rich plasma (PRP) injections6-8, extracorporeal shockwave therapy9, eccentric

exercises8,10-12, concentric exercises11, heavy slow-resistance training12, and surgical intervention10. At present, there is no consensus on the single optimal treatment for patellar tendinopathy in volleyball players.

The team that treats athletes with patellar tendinopathy may include athletic trainers, physical therapists, massage therapists, chiropractors, and/or acupuncturists. Management strategies may vary based on the practitioner’s discipline and the athlete’s age and level of competition. To illustrate the physical therapist’s role in the management of age-specific and competitive level-specific patellar tendinopathy, we present the cases of a youth (Case 1: Youth), a collegiate (Case 2: Collegiate), and a middle-aged (Case 3: Middle-aged) volleyball athlete, using the EdUReP13 concept to propose intervention strategies within the categories of Education, Unloading, Reloading, and Prevention. These intervention strategies may be utilized to manage patellar tendinopathy in other jumping sports across the age spectrum.

PT’s role in management patellar tendinopathy

411 Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420

Case descriptions

Case 1: YouthCS (initials) is a 14-year-old high school student

who is a left-handed opposite hitter for his club and school volleyball teams. He has a primary complaint of nagging left anterior knee pain. The pain began when he was 13, and the intensity has varied over the last 1.5 years. He describes the pain as a general ache with episodes of sharp pains. He is unable to determine if there are any specific aggravating factors, but does notice the aching during volleyball practice and at school. CS notes that ice and non-steroidal anti-inflammatories are helpful, but admits to using neither consistently. He reached developmental milestones in a typical timeframe and has no significant medical history.

CS currently plays/practices volleyball 3 times per week for 2 hours and competes in 2-day tournaments 1-2 times per month. He does not participate in any regular weight-lifting program. He reports that his symptoms do not limit his participation in any activity, but does notice an increase in overall intensity of symptoms at the end of a tournament.

Case 2: CollegiateMM (initials) is a 19-year-old right-handed

outside hitter who plays at the top competitive level of intercollegiate volleyball. One-third of the way into his second collegiate season, he reported left infrapatellar knee pain with squatting or repeated jumping. He described the pain at that time as a dull ache that intensified (from 0/10 to 6/10) toward the end of practice or a match that initially would resolve 15-20 minutes after stopping the activity. Early management included ice, non-steroidal anti-inflammatory medication, modifying weight-lifting training, using Leukotape or a patellar tendon strap, and reducing the number of jumps during practice. His symptoms improved, but returned when he resumed his “typical” resistance-training program and quantity of jumps in practice. He has had left knee pain intermittently for the last a 3 years that began at the end of his 10-month-long club season. He could “play through” his symptoms, which would resolve after not playing over the summer. He played in several beach tournaments between his first and second years and noticed that his knee would intermittently become painful if he did not adequately warm-up prior to each match. Additionally, he sustained a left grade-2 ankle sprain during the middle of his senior year of high

school that prevented him from playing for 4 weeks. He reported that his ankle felt ~80% recovered upon his return to volleyball.

Case 3: Middle-agedJG (initials) is a 47-year-old male engineer who has

been playing for approximately 24 years. He spends 85% of his 40 to 50-hour workweek sitting down. He plays in a coed recreational indoor volleyball league 3-4 times per week and plays on the beach 1-2 times per month. He performs no other form of structured exercise.

JG reports a complex orthopedic history, beginning with a diagnosis of bilateral patellar tendinopathy 20 years ago. He was treated with only activity modification and continued playing volleyball. Eight years ago, JG underwent a left anterior cruciate ligament (ACL) reconstruction using a bone-patellar tendon-bone autograft. Despite an 8-month regimen of physical therapy, he had persistent anterior knee pain and elected to undergo a TOPAZ procedure (TOPAZ Microdebrider device, ArthroCare, Sunnyvale, CA, USA) to his patellar tendon and a lateral release, requiring an additional 8-10 months of a physical therapist’s guided intervention. The TOPAZ procedure is a radiofrequency coblation applied to the pathological tissue. There is currently no reported use of the TOPAZ procedure in patellar tendon conditions, though its use in plantar heel pain and Achilles tendon pain has been reported14,15. To our knowledge, there are no randomized clinical trials on the efficacy of this treatment. Currently, he reports minimal left knee symptoms. Following the procedures to his left knee and return to volleyball, however, he noticed a worsening of his right patellar tendinopathy. He had no specific intervention for his symptoms until he had a TOPAZ procedure one year ago. He did not attend physical therapy following this procedure, and reports persistent knee pain that limits his ability to play volleyball at his desired level and interferes with stair-climbing and sit-to-stand/stand-to-sit activities. His symptoms have worsened steadily over the last six weeks.

Examination strategies

Movement analysisVideo of each athlete’s approach jump was assessed

in the sagittal and frontal planes to determine if any aberrant movements occurred during the key phases of take-off and landing that might predispose him to overload the anterior knee structures. The two key

Kulig K, Noceti-DeWit LM, Reischl SF, Landel RF

412 Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420

sub-phases of take-off and landing were defined as the instant of initial contact with the floor (IC) and weight acceptance (WA), during which time the athlete’s presumed center of mass was lowered towards the floor. We assessed an additional sub-phase during take-off/propulsion, defined as starting from the lowest position of the presumed center of mass and ending when the feet left the ground. Critical events assessed for IC of take-off and landing included the point of contact (e.g. heel vs. whole foot vs. forefoot), the angle of ankle dorsiflexion and knee and hip flexion, and the position of the athlete’s presumed center of mass relative to the point of contact (e.g. posterior center of mass relative to take-off contact point). Critical events assessed for take-off WA included the amount of hip and knee flexion and dorsiflexion (grossly equal contributions from each joint) and the direction of the center of mass relative to the point of contact (for take-off: lowering towards the ground while moving from being posterior to being directly over the point of contact; and for landing: lowering down a vertical line). Critical events for the propulsion sub-phase include grossly equal contributions in movement from the hip, knee and ankle moving the athlete’s center of mass in a primarily vertical direction.

Objective testingCommonly used clinical tests were performed

on each athlete, including single limb balance with eyes closed, depth of single limb squat, calf strength, repetitive single limb squats, modified gluteus maximus manual muscle test, gluteus medius manual muscle test, forward plank, side plank, knee to wall ankle dorsiflexion test, hamstrings flexibility test, Thomas test, hip internal rotation, and hip external rotation. Primary objective findings for each athlete are listed in Table 1.

Diagnostic ultrasoundGray-scale ultrasound (US) images were obtained at

the distal, middle, and proximal aspects of the patellar tendon using Sonoline Antares (Siemens Medical Solutions USA Inc., Malvern, PA, USA). Longitudinal and transverse images at each tendon interval were taken by a skilled musculoskeletal ultrasonographer with 6 years of experience. The macromorphological and micromorphological characteristics of the patellar tendons were extracted from the images using standard laboratory procedures described elsewhere16. Color Doppler scale was used to ascertain the presence or absence of neovascularization within the tendon.

Biomechanical laboratory assessmentsEach athlete’s spike approach jump was assessed at

the Musculoskeletal Biomechanics Laboratory at the University of Southern California, Los Angeles, CA, USA. After a brief warm-up on a bicycle ergometer, each athlete was video-recorded performing a maximum of 10 volleyball jump take-offs and landings on a force plate. The data were acquired and processed using laboratory established methods described elsewhere17

. The following variables were extracted from the kinematic and kinetic data:

• Lower Extremity Contact Angle (LECA) (degrees) during take-off and at landing: defined as the angle formed between the floor and a line connecting the center of pressure and the L5-S1 marker at the time of first point of contact with the ground and represents the position of the lower extremity at that point in time. The LECA, typically ranging between 61 and 78 degrees17 at landing, provides an estimation of the braking impulse (smaller angle = higher braking impulse) that occurs following the initial contact (Figure 1A and 1B).

Table 1. Relevant objective clinical findings for the youth, collegiate, and middle-aged volleyball athlete.

Single Leg Tests Strength Testing Planks Flexibility Hip Rotation

SLS-eyes closed (sec)

SL Squat (deg)

Calf Strength

(reps)

SL Squats (reps)

Gluteus Maximus (out or 5)

Gluteus Medius

(out of 5)

Forward (sec)

Side (sec)

Knee-wall (cm)

Hamstring (deg)

Thomas Test (deg)

Internal Rotation

(deg)

External Rotation

(deg)

Youth 23/28 55/65 4/14 3/5 4-/4 3+/3+ 50 24/39 12/12 46/38 -15/-5 42/42 45/45

Collegiate 4/14 55/65 23/28 6*/13 4-/4 4/5 70 34/49 12/12 48/32 -15/-20 45/45 50/50

Middle-Aged^ 5/10 62/78 16/18 UA**/2 3+/4 3+/3+ 51 32/40 13/12 65/55 -15/-15 30/30 35/35

First number is the measurement from the involved lower extremity; second number is from the non-involved side. Planks are bilateral, therefore no second number is needed. * with pain; UA. ** unable to perform; ^Left side=non-involved limb (both limbs initially symptomatic).

PT’s role in management patellar tendinopathy

413 Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420

The braking impulse determines the amount of force over time endured by the body. LECA at take-off is consistently smaller than at landing.

• Knee Joint Angular Stiffness (Nm/kg/degrees): joint angular (torsional) stiffness is determined by the slope of the curve formed by joint moment (kinetics) over joint displacement (kinematics). A steeper slope signifies a stiffer joint. The slope is dependent on the moment and the displacement,

thus a negligible change in moment with a decrease in joint displacement will result in a higher angular joint stiffness. A conceptual comparison of the knee joint angular stiffness to a torsional spring is presented on Figure 2A18.

Interpretation of data

Case 1: YouthThe youth volleyball player has a pliable and growing

neuromusculoskeletal system. Video analyses of his jumping patterns in the sagittal and frontal planes demonstrate a consistent pattern without obvious abnormalities. Objective testing showed strength and endurance deficits throughout the lower extremity and mild deficits in hamstring and hip flexor flexibility. Adult normative values were used as youth normative data are not available.

No changes in morphology or vascularization were seen on US imaging of the patellar tendon (Figure 3A); however, there were areas of hyperechocity (brighter area) at the tibial attachment of the patellar tendon. His LECA at take-off is 60 degrees and 75 degrees at landing. Both LECA are similar to a cohort of asymptomatic male volleyball players17. Nevertheless,

Figure 1. Lower extremity contact angle at the time of initial contact with the ground during landing from a jump; (A) the angle is drawn onto an image recreated from a biomechanics laboratory data collection, (B) an angle drawn onto the lower extremity posture on a photo taken on the court.

Figure 2. Knee Joint Torsional Stiffness: (A) Conceptual representation of knee joint torsional stiffness. The arms of the spring represent thigh and lower leg, and the coil of the spring represents the resistance provided by the muscles. The ‘resistance’ is represented by the computed extensor moment and the displacement by the change in joint angle; (B) Knee joint torsional stiffness (Nm/kg/degree) in a cohort of asymptomatic collegiate volleyball athletes representing the box-plot. Values for the cases presented in this case series are represented as: Y - Youth volleyball athlete, C - Collegiate volleyball athlete, and MA - middle -aged volleyball athlete.

Kulig K, Noceti-DeWit LM, Reischl SF, Landel RF

414 Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420

his knee joint angular stiffness is greater than the asymptomatic cohorts for both take-off and landing.

Confirmed by US, which suggests calcific adaptation at the tibial attachment of the patellar tendon, this athlete’s symptoms are likely associated with Osgood-Schlatter’s Disease, resulting from mechanical overload of the patellar tendon at the tibial insertion. This is largely from overloading of bone (in this case the teno-osseous junction) due to his increased knee joint angular stiffness during take-off and landing, suggesting a stiffer weight acceptance strategy, (unpublished laboratory data) (Figure 2B) as well as limitations in strength and flexibility.

Case 2: CollegiateOf the three athletes presented, the collegiate

volleyball player endures the highest volume of jumping activities, leading to a higher cumulative load. Video analysis of his approach jump at take-off and landing did not reveal any gross sagittal or frontal plane deviations. Objective testing revealed limitations in single limb balance, repetitions of single limb squatting (reproduction of pain), gluteus maximus and medius strength, forward and side plank endurance, hamstring flexibility (bilaterally), and hip flexor flexibility.

Longitudinal US images of the right knee revealed a thicker proximal patellar tendon, hypoechoic (darker) areas, and neovascularization (acquired in the Doppler mode) were present. This athlete’s LECA at take-off is approximately 60 degrees, similar to the LECA of a cohort of asymptomatic male volleyball players17. His braking impulse, however, is lower than that cohort. When compared to symptomatic male

volleyball players, his landing LECA and braking impulse are within the ranges of the asymptomatic cohort17. This athlete’s knee angular stiffness was typical of what is seen in asymptomatic jumping athletes (unpublished laboratory data) (Figure 2B).

Based on the results from the examinations and diagnostic US, this collegiate volleyball player is experiencing symptoms associated with patellar tendinosis (degenerative tendinopathy). The presence of hypoechocity suggests degeneration of the tendon, resulting in a more compliant tendon, while the presence of neovascularization suggests a long-standing pathological condition of the patellar tendon (Figure 3B). His LECA, tested when rested, are grossly consistent with the asymptomatic cohort, though his braking impulse at take-off is lower than the cohort, he appears to adjust for his angle at take-off by reducing the time and/or force of braking impulse. It is likely that the volume (number of repetitions and frequency) of his jumping as well as the impairments noted on the objective tests, versus alterations in his jumping mechanics, are the largest contributor to this athlete’s pathology and pain pattern.

Case 3: Middle-agedThe middle-aged athlete must balance life,

societal roles, and his passion for volleyball. He can manipulate his repetitions and frequency of playing more easily than the athlete who still participates in organized competition. Conversely, he may have more non-volleyball related factors distracting him from being able to dedicate significant time to his training and rehabilitation program.

Figure 3. Ultrasound images of the patellar tendon: (A) distal patellar tendon of Case 1: Youth athlete (note brighter signal at the tibial tuberosity); (B) proximal patellar tendon in Case 2: Collegiate athlete (note hypoechocity and neovascularization); (C) proximal patellar tendon in Case 3: Middle-Aged athlete (note hypoechocity in mid-substance of the tendon, a remnant of the donor site for ACL repair).

PT’s role in management patellar tendinopathy

415 Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420

Video analysis of his take-off demonstrates increased knee flexion, with his hip and trunk more posterior. From the anterior view, there is a right trunk lean and the left lower extremity positioned in femoral adduction and internal rotation, while the lateral view shows that the trunk is posterior to his base of support. The anterior view of his landing strategy shows a right trunk lean and he appears to overload his right lower extremity as he absorbs the forces of landing. From the lateral view, he lands more vertically with his initial contact on his heels, which ultimately creates a jarring impact. Objective testing yielded limitations in repetitions for single limb squats (23 inch step), calf strength, single limb balance, degree of single limb squat on the right, gluteus medius and maximus strength, hamstring and hip flexor flexibility, hip internal and external rotation ROM, and forward and side plank endurance.

The proximal aspect of the patellar tendon is thicker and hypoechoic (darker) on US, though there is no neovascularization evident in the color Doppler mode. Quantitatively, the LECA at take-off is approximately 58 degrees, which is similar to a cohort of symptomatic male volleyball players17, and his braking impulse also lies within the range measured in the cohort of symptomatic subjects. His LECA at landing is 75 degrees which is similar to the group of asymptomatic male volleyball players17. The knee angular stiffness were typical of what is seen in asymptomatic jumping athletes (unpublished laboratory data) (Figure 2B).

Based on the collective results from movement analysis, objective testing, diagnostic ultrasonography and biomechanical assessments, this athlete has signs and symptoms consistent with patellar tendinosis. Similar to Case 2: Collegiate, this athlete’s US images indicate tendon degeneration (hypoechocity), a more compliant tendon, and the lack of neovascularization suggests an absence of reparative process within the tendon (Figure 3C). This is likely most related to his take-off and landing mechanics, which place an overload on the patellar tendon.

Intervention planThere is a large range of options in managing an

athlete with patellar tendinopathy. The choice of options is dependent upon multiple factors, including position played, severity/irritability of symptoms, duration of competitive season, chronicity of problem, amount of time left in season, current weight-training regimen

(if any), as well as age. Considering these factors is critical to determining the appropriate management of an athlete with patellar tendinopathy. While pain alleviating interventions (including anti-inflammatories, electrical stimulation, US, phonophoresis, iontophoresis, Platelet Rich Plasma (PRP) or cortisone injections, extracorporeal shockwave therapy and ice) are appropriate and helpful in the short term, it is a disservice to the athlete if the factors contributing to the development of patellar tendinopathy are not addressed.

The EdUReP13 concept is useful in the management of individuals with tendinopathy, including athletes19. The concept stresses Education, Unloading, Reloading, and Prevention13 and has been primarily used in the management of individuals with posterior tibial tendinopathy20-22.

• Education: Education regarding the disease process, pathophysiological changes in the tendon, the intervention plan, and the cyclical nature of tendinopathy is essential. It is especially important that the athlete understand that pain is not synonymous with damage within the tendon, but is a typical reaction in a tendinopathic tendon. Discussing aberrant movement patterns and how to alter them is another key point.

• Unloading: A period of unloading the tendon is necessary, though the duration of unloading may vary due to a multitude of reasons. Clinical experience suggests 2-4 weeks of unloading is optimal, though it is unclear on what time frame is ideal in athletes during their competitive season. As always, there will be a conflict between appropriate unloading and the pressures of returning to competition, and an appropriate balance must be found. Unloading may include direct or indirect forms of modifying activity. Examples of direct forms include: bracing or taping variations. Examples of indirect forms include modifying weight-lifting activities, modifying quantity of jumps, optimizing squatting mechanics, and mechanics during the take-off and landing.

• Reloading: The concept of reloading applies to the patellar tendon itself and addressing strength impairments via resistive exercises in remote regions. There is inconsistent information regarding the preferable way to reload the patellar tendon, but the most consistently utilized is eccentric loading. Visnes et al.23 suggests a slow decline squat on the

Kulig K, Noceti-DeWit LM, Reischl SF, Landel RF

416 Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420

involved lower extremity, using hands and/or the other limb to return to full upright position. Three sets of 15 repetitions should be performed twice daily, beginning on flat land and then progressing to a 25-degree angle wedge. Knee flexion to a minimum of 60 degrees should be emphasized, if pain allows (<5/10 overall), and preferably be an eccentric motion only (Figure 4).

• Prevent: The prevention aspect of the EdUReP concept primarily consists of strategies that address factors contributing to patellar tendon overload. As the previous case studies suggest, this might include appropriate pre-season training (perhaps including eccentric training), improving jump/landing mechanics, and proper adjustment of training volume (whether jumps or resistance training).

Specific interventions for each case

Case 1: Youth

The athlete and his parents were educated regarding the pathophysiology of Osgood-Schlatter’s. They were informed that this pathology is likely a result of mechanical overload at the tibial tubercle, that it is a self-limiting disorder that has a good prognosis, and that pain does not correlate with structural damage. The intervention plan addressed areas that contributed to, but were not specifically at, the painful location (e.g. strength and flexibility of the hip and ankle).

Specific unloading techniques included fat pad unloading during practice and matches. Modifications to strength training were unnecessary, as he was not currently involved in a weight training program; however, repetitive jumping drills (i.e. multiple repetitions of hitting) were eliminated from practice for 3-4 weeks.

Specific isolated reloading of the patellar tendon is not indicated in this athlete as the pathology is not located within the tendon, and eccentric loading would likely aggravate the condition. However, reloading of other body regions is indicated. Exercises for the quadriceps included lateral step ups with a band to increases resistance (Figure 5), forward lunges, forward step ups and step downs, and side lunges with ipsilateral lateral reach. Prevention strategies included active and passive static and dynamic multiplanar hamstring and quadriceps stretches. Additional exercises included double limb (progressing to single limb) bridges, sidelying clams, single limb heel raises, forward step-up with posterior lunge, balance and reach, forward planks, and hurdle jumps.

The therapist discussed the biomechanical laboratory data with the athlete, coach, and athletic trainer. The knee angular joint stiffness was explained using the illustration of a torsional spring in Figure 2A and its representation of concurrent change in knee net joint moment and change in knee angular displacement. For example, a quieter landing strategy would represent similar net joint moment but larger joint displacement. This concept was then implemented during practice by asking the athlete to pay attention to the sound accompanying the jumps, namely “louder” for a stiffer landing and “quieter” for less stiff (softer) landing, the second being desirable.

Case 2: CollegiateThe collegiate outside hitter’s future promises

a lot of jump repetitions, both in the remaining season and his collegiate career. It is important that he understands that his symptoms are a result of tendinopathic changes and that there is a minimal inflammatory response present. He must understand

Figure 4. Slow repeated single limb squat lowering exercise on a decline board providing for eccentric loading to the patellar tendon. This is tissue-specific re-loading.

PT’s role in management patellar tendinopathy

417 Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420

that the tendon has attempted to heal but failed to do so, leaving him with a chronic problem. However, pain is not an indication of acute tissue damage and thus he can work through some level of pain. More importantly, while his symptoms will likely improve with time a significant lessening of pain may not occur during the competitive season; this will largely depend on his ability to control the quantity of jumps and his strength and conditioning program23. In addition, the problem may reoccur, which may be a source of frustration for him.

Since he continued to participate at nearly the same level, with only a slight reduction in the number of jumps during practice, he was instructed to use a patellar tendon strap during weight lifting and used Leukotape to unload the tendon during practice and games. His strength and conditioning program was modified to decrease the quantity of quadriceps dominant exercises, increase the quantity of gluteal strengthening, and alter the squatting pattern to bias a hip dominant (hip hinge) pattern versus a quadriceps dominant (knee forward) pattern. Specific reloading

was accomplished using eccentric loading as described previously.

Interventions to decrease the frequency of recurrences were initiated. Improvement in hamstring flexibility, extensibility of the distal quadriceps (Figure 6), hip extension range of motion, and strength of the hip extensors and abductors were addressed during the season and a maintenance program was initiated for the off-season. Plyometric activities were minimized during the season, since the primary concern was reducing the number and frequency of jumps and not improvement of his jumping mechanics.

Case 3: Middle-agedThis athlete had been dealing with patellar

tendinopathy for several years. Education played a key role in his rehabilitation. He learned about the pathophysiologic changes evident in his diagnostic US, the changes that occur in the musculoskeletal system with age, the link between his movement patterns and the overload they created on the patellar tendon, and that his prognosis depended on his ability

Figure 5. Resistive step-up exercises targeting the knee extensors in an upright position, requiring the control of balance. This is non-tissue specific re-loading. A: Left; B: Right.

Kulig K, Noceti-DeWit LM, Reischl SF, Landel RF

418 Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420

to be “fit for playing” versus using volleyball for fitness. For the interventions to be most beneficial, he needed to understand that specific interventions to the patellar tendon, as well as other regions, were required. The discussion regarding altering his landing mechanics should commence early but with the understanding that significant changes will take time to accomplish. The importance of regular exercise and cardiovascular fitness as a preventative measure is a necessary discussion. It is imperative that he understand that, due to age-related changes in his physiology, it is best to maintain a basic level of flexibility and strength. One of the most important things to address is the time element – finding a concise workout regimen that will be easily adhered to by the middle-aged athlete.

Specific patellar tendon unloading was essential for this athlete, accomplished directly using a patellar tendon strap or Leukotape. Indirect tendon unloading included a stretching program addressing hamstrings, quadriceps, and the calf. Providing an adequate rest period was easier in this athlete because he played at a recreational level, and in total, he took approximately 3 weeks off from volleyball. When the athlete had a significant reduction in symptoms, the athlete began an eccentric patellar tendon loading program as described previously. The athlete began with his foot flat on the ground and progressed to a decline board of at least 25 degrees to decrease the calf contribution during the eccentric (lowering) phase of the squat, increase the load on the patellar tendon, and to stimulate the tenocytes to change the collagen fibers and alter the mechanical properties of the patellar tendon24. He was instructed to perform this exercise twice daily, 3 sets of 15 repetitions (Figure 4). The prevention portion of the EdUReP concept may be the most influential in decreasing the

frequency of recurrence of patellar tendinopathy in this athlete. Manual, static, and dynamic stretching of the quadriceps, hamstrings, and calf is important to help counteract the prolonged positioning of this athlete during his workday. Specific instructions to perform the stretches correctly are imperative to avoid accidently overloading another body region. Additionally, it is best to choose stretches that can be performed easily at home, work, or at the court/beach. Strengthening intervention targeted multiple areas, including trunk stabilization and endurance, hip, ankle, and knee deficits. Though tedious, it is likely ideal to begin a strengthening program that isolates the muscles to ensure adequate recruitment and minimal compensations prior to transitioning into larger, more dynamic movements. Examples of isolated strengthening include sidelying clams and bridging (double-single limb-exercise ball), crunches, and single limb heel raises. These exercises can progress to double-single limb squatting with various height arm reaches and to various sides, multidirectional lunging with and without arm movements, forward and side planks, and balance/agility activities. During the instructional period, proper form is important, and he must understand that pain is expected during the activity. Plyometric activities should be initiated only after pain levels have reduced and more optimal neuromuscular control during dynamic movements are obtained. There are many plyometric activities to choose from; however, appropriate dosage and progression of the quantity of jumps is as important as his take-off and landing mechanics. A gradual transition into a full approach jump is an excellent training tool.

Fitting in the conceptual framework “to Educate”, the therapist and the athlete reviewed the videos of his take-off and landing and discussed the relevance of body position at the moment of contact with the ground (LECA) and the subsequent interaction with the ground, focusing on the degree of knee flexion (knee joint torsional stiffness). The optimal strategies were discussed in light of jump performance. Technique cues were suggested, such as “bring your legs underneath you” in preparation for landing to avoid a smaller LECA and therefore lesser braking impulse. Once in the ground contact phase, optimal rate and amount of knee joint flexion were discussed in light of laboratory data on knee joint torsion stiffness. These concepts were consequently explored during practice.

Figure 6. A passive soft-tissue technique to the distal quadriceps region aiming at improving tissue extensibility.

PT’s role in management patellar tendinopathy

419 Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420

Summary of interventionThe management of patellar tendinopathy in volleyball

players is more complex than the etiology might suggest. The presence of macro- and micromorphological changes in the tendon, the athletes’ age, and their competitive level are only a few of the factors that need to be considered when determining the optimal management of this condition.

The EdUReP concept helps determine a treatment plan for each of these athletes, though not all aspects of the concept are relevant to every case. Education of the pathology and treatment plan was essential for each athlete presented, as was a period of unloading. However, the manner of unloading varied for each

athlete. It was important and necessary to address strength and/or flexibility deficits for all three athletes, though only those with tendinopathic changes on diagnostic ultrasound (the middle-aged and collegiate players) benefitted from an eccentric training program. Each athlete went through a period of reloading, though the type of exercise varied. Specific exercises targeting prevention of further injury or re-injury varied for each athlete, though largely included the broad topics of flexibility, strengthening, and neuromuscular control. For certain athletes, it was important to discuss and alter jumping patterns and changes in lifestyle habits.

A brief synopsis of the similarities and differences in treatments are presented in Table 2.

Table 2. Management synopsis of the youth, collegiate, and middle-aged volleyball athlete.

CASE 1: YOUTH CASE 2: COLLEGIATE CASE 3: MIDDLE-AGED

Edu

catio

n

The following aspects of the education portion were discussed with the athlete

• Condition of the tendon bone interface as the pathology which should recover

The following aspects of the education portion were discussed with the athlete• Condition is not an inflammatory

process• Periods of exacerbation• Demand of the position played• Time of the season, may not be

able to rest as much• May not improve during season

The following aspects of the education portion were discussed with the athlete• Condition is not an inflammatory

process• Periods of exacerbation• Need to change fitness level• Volleyball not making him fit, must

be “fit to play”• Alteration of play and practice to

allow rest

Un-

load

ing • Tape, patellar strap to change stress at

the symptom region• Reduce practice and competition

when symptoms are elevated

• Alteration of play and practice• Alteration of weight training

regimen• Use of tape or strap at the patellar

tendon

• Change of take-off and landing patterns

• Change the level of play with more rest

• Flexibility exercises to reduce stress on tendon

• Possible use of strap or tape

Re-

load

ing

• Due to lack of tendon pathology, the eccentric program is not part of the Youth’s intervention program

• Eccentric loading of patellar tendon, using 3 x15 twice per day working towards use of decline board for 12 weeks

• Eccentric loading of patellar tendon, 3 x15 twice per day working towards use of decline board for 12 weeks

• Long term eccentric use 2-3 times a week

Prev

entio

n

• Long term flexibility program to follow up manual therapy intervention

• Strength training for trunk, hip abduction, hip extension, calf

• Neuromuscular and Movement Re-education to plyometrics

• Athlete to compete through long season without loss of performance

• Additional stretching program for LE of hamstrings, distal quad and long hip flexors

• Specific strength training of hip extensors and abductors, first in isolation and progressed

• In-season jumping activities decreased in practice and in weight training

• Alteration of fitness program, with inclusion of comprehensive lower extremity flexibility program

• Strength training for trunk and lower extremity to reduce demand on quadriceps and patellar tendon

• Progress from more isolated muscle activation to patterns of movement and change towards plyometrics

• Sustaining the change of fitness should ensure continued ability to perform

Kulig K, Noceti-DeWit LM, Reischl SF, Landel RF

420 Braz J Phys Ther. 2015 Sept-Oct; 19(5):410-420

References1. Mughal KU. Top 10 most popular sports in the world [Internet].

2014. [cited 2014 Sept 17]. Available from: sporteology.com/top-10-popular-sports-world/

2. Augustsson SR, Augustsson J, Thomeé R, Svantesson U. Injuries and preventive actions in elite Swedish volleyball. Scand J Med Sci Sports. 2006;16(6):433-40. http://dx.doi.org/10.1111/j.1600-0838.2005.00517.x. PMid:17121646.

3. Bahr R, Bahr IA. Incidence of acute volleyball injuries: a prospective cohort study of injury mechanisms and risk factors. Scand J Med Sci Sports. 1997;7(3):166-71. http://dx.doi.org/10.1111/j.1600-0838.1997.tb00134.x. PMid:9200321.

4. Lian OB, Engebretsen L, Bahr R. Prevalence of jumper’s knee among elite athletes from different sports: a cross-sectional study. Am J Sports Med. 2005;33(4):561-7. http://dx.doi.org/10.1177/0363546504270454. PMid:15722279.

5. Sorenson SC, Arya S, Souza RB, Pollard CD, Salem GJ, Kulig K. Knee extensor dynamics in the volleyball approach jump: the influence of patellar tendinopathy. J Orthop Sports Phys Ther. 2010;40(9):568-76. http://dx.doi.org/10.2519/jospt.2010.3313. PMid:20508329.

6. Andres BM, Murrell GAC. Treatment of tendinopathy: what works, what does not, and what is on the horizon. Clin Orthop Relat Res. 2008;466(7):1539-54. http://dx.doi.org/10.1007/s11999-008-0260-1. PMid:18446422.

7. Peers KHE, Lysens RJJ. Patellar tendinopathy in athletes: current diagnostic and therapeutic recommendations. Sports Med. 2005;35(1):71-87. http://dx.doi.org/10.2165/00007256-200535010-00006. PMid:15651914.

8. Saithna A, Gogna R, Baraza N, Modi C, Spencer S. Eccentric exercise protocols for patella tendinopathy: should we really be withdrawing athletes from sport? A systematic review. Open Orthop J. 2012;6(1):553-7. http://dx.doi.org/10.2174/1874325001206010553. PMid:23248727.

9. Mani-Babu S, Morrissey D, Waugh C, Screen H, Barton C. The effectiveness of extracorporeal shock wave therapy in lower limb tendinopathy: a systematic review. Am J Sports Med. 2015;43(3):752-61. http://dx.doi.org/10.1177/0363546514531911. PMid:24817008.

10. Bahr R, Fossan B, Løken S, Engebretsen L. Surgical treatment compared with eccentric training for patellar tendinopathy (Jumper’s Knee). A randomized, controlled trial. J Bone Joint Surg Am. 2006;88(8):1689-98. http://dx.doi.org/10.2106/JBJS.E.01181. PMid:16882889.

11. Jonsson P, Alfredson H. Superior results with eccentric compared to concentric quadriceps training in patients with jumper’s knee: a prospective randomised study. Br J Sports Med. 2005;39(11):847-50. http://dx.doi.org/10.1136/bjsm.2005.018630. PMid:16244196.

12. Kongsgaard M, Kovanen V, Aagaard P, Doessing S, Hansen P, Laursen AH, et al. Corticosteroid injections, eccentric decline squat training and heavy slow resistance training in patellar tendinopathy. Scand J Med Sci Sports. 2009;19(6):790-802. http://dx.doi.org/10.1111/j.1600-0838.2009.00949.x. PMid:19793213.

13. Davenport TE, Kulig K, Matharu Y, Blanco CE. The EdUReP model for nonsurgical management of tendinopathy. Phys Ther. 2005;85(10):1093-103. PMid:16180958.

14. Erken HY, Ayanoglu S, Akmaz I, Erler K, Kiral A. Prospective study of percutaneous radiofrequency nerve ablation for

chronic plantar fasciitis. Foot Ankle Int. 2014;35(2):95-103. http://dx.doi.org/10.1177/1071100713509803. PMid:24165571.

15. Shibuya N, Thorud JC, Humphers JM, Devall JM, Jupiter DC. Is percutaneous radiofrequency coblation for treatment of Achilles tendinosis safe and effective? J Foot Ankle Surg. 2012;51(6):767-71. http://dx.doi.org/10.1053/j.jfas.2012.08.011. PMid:22974813.

16. Kulig K, Landel R, Chang YJ, Hannanvash N, Reischl SF, Song P, et al. Patellar tendon morphology in volleyball athletes with and without patellar tendinopathy. Scand J Med Sci Sports. 2013;23(2):e81-8. http://dx.doi.org/10.1111/sms.12021. PMid:23253169.

17. Kulig K, Joiner DG, Chang YJ. Landing limb posture in volleyball athletes with patellar tendinopathy: a pilot study. Int J Sports Med. 2015;36(5):400-6. http://dx.doi.org/10.1055/s-0034-1395586. PMid:25607520.

18. Butler RJ, Crowell HP 3rd, Davis IM. Lower extremity stiffness: implications for performance and injury. Clin Biomech. 2003;18(6):511-7. http://dx.doi.org/10.1016/S0268-0033(03)00071-8. PMid:12828900.

19. Reinking M. Tendinopathy in athletes. Phys Ther Sport. 2012;13(1):3-10. http://dx.doi.org/10.1016/j.ptsp.2011.06.004. PMid:22261424.

20. Kulig K, Lederhaus ES, Reischl S, Arya S, Bashford G. Effect of eccentric exercise program for early tibialis posterior tendinopathy. Foot Ankle Int. 2009;30(9):877-85. http://dx.doi.org/10.3113/FAI.2009.0877. PMid:19755073.

21. Bowring B, Chockalingam N. A clinical guideline for the conservative management of tibialis posterior tendon dysfunction. Foot. 2009;19(4):211-7. http://dx.doi.org/10.1016/j.foot.2009.08.001. PMid:20307479.

22. Kulig K, Reischl SF, Pomrantz AB, Burnfield JM, Mais-Requejo S, Thordarson DB, et al. Nonsurgical management of posterior tibial tendon dysfunction with orthoses and resistive exercise: a randomized controlled trial. Phys Ther. 2009;89(1):26-37. http://dx.doi.org/10.2522/ptj.20070242. PMid:19022863.

23. Visnes H, Hoksrud A, Cook J, Bahr R. No effect of eccentric training on jumper’s knee in volleyball players during the competitive season: a randomized clinical trial. Clin J Sport Med. 2005;15(4):227-34. http://dx.doi.org/10.1097/01.jsm.0000168073.82121.20. PMid:16003036.

24. Langberg H, Ellingsgaard H, Madsen T, Jansson J, Magnusson SP, Aagaard P, et al. Eccentric rehabilitation exercise increases peritendinous type I collagen synthesis in humans with Achilles tendinosis. Scand J Med Sci Sports. 2007;17(1):61-6. PMid:16787448.

Correspondence Kornelia Kulig University of Southern California Department of Orthopaedic Surgery at the Keck School of Medicine Division of Biokinesiology and Physical Therapy at the Herman Ostrow School of Dentistry 1540 East Alcazar Street, CHP-155 Los Angeles CA 90089 USA e-mail: kulig@usc.edu

http://dx.doi.org/10.1590/bjpt-rbf.2014.0123

original article

421 Braz J Phys Ther. 2015 Sept-Oct; 19(5):421-428

Male and female runners demonstrate different sagittal plane mechanics as a function of static

hamstring flexibilityD. S. Blaise Williams III1,2, Lee M. Welch3

ABSTRACT | Background: Injuries to runners are common. However, there are many potential contributing factors to injury. While lack of flexibility alone is commonly related to injury, there are clear differences in hamstring flexibility between males and females. Objective: To compare the effect of static hamstring length on sagittal plane mechanics between male and female runners. Method: Forty subjects (30.0±6.4 years) participated and were placed in one of 4 groups: flexible males (n=10), inflexible males (n=10), flexible females (n=10), and inflexible females (n=10). All subjects were free of injury at the time of data collection. Three-dimensional kinematics and kinetics were collected while subjects ran over ground across 2 force platforms. Sagittal plane joint angles and moments were calculated at the knee and hip and compared with a 2-way (sex X flexibility) ANOVA (α=0.05). Results: Males exhibited greater peak knee extension moment than females (M=2.80±0.47, F=2.48±0.52 Nm/kg*m, p=0.05) and inflexible runners exhibited greater peak knee extension moment than flexible runners (In=2.83±0.56, Fl=2.44±0.51 Nm/kg*m, p=0.01). For hip flexion at initial contact, a significant interaction existed (p<0.05). Flexible females (36.7±7.4º) exhibited more hip flexion than inflexible females (27.9±4.6º, p<0.01) and flexible males (30.1±9.5º, p<0.05). No differences existed for knee angle at initial contact, peak knee angle, peak hip angle, or peak hip moment. Conclusion: Hamstring flexibility results in different mechanical profiles in males and females. Flexibility in the hamstrings may result in decreased moments via active or passive tension. These differences may have implications for performance and injury in flexible female runners. Keywords: biomechanics; gender; hamstrings; running.

HOW TO CITE THIS ARTICLE

Williams DSB III, Welch LM. Male and female runners demonstrate different sagittal plane mechanics as a function of static hamstring flexibility. Braz J Phys Ther. 2015 Sept-Oct; 19(5):421-428. http://dx.doi.org/10.1590/bjpt-rbf.2014.0123

1 VCU RUN LAB, Department of Physical Therapy, Virginia Commonwealth University, Richmond, Virginia, USA2 Department of Kinesiology and Health Sciences, Virginia Commonwealth University, Richmond, Virginia, USA3 B. Young Physical Therapy, Fuquay-Varina, North Carolina, USAReceived: Mar. 18, 2015 Revised: May 25, 2015 Accepted: June 30, 2015

IntroductionRunning is one of the most popular competitive,

recreational, and fitness activities worldwide. In fact, running is a component of, or training modus for, most Olympic and non-Olympic sports. In 2012, roughly 51.4 million Americans ran at least once with approximately 29.4 million of these running at least 50 days per year1. The health benefits of running include reducing the risks of (i) chronic disease, (ii) disability, (iii) pain, and (iv) health care costs2-4. However, with the continued popularity of running, there has been a corresponding maintenance in the rate of running-related injuries5. The majority of these injuries can be attributed to overuse3. As a result, these injuries force an estimated 46% to 65% of runners to stop running and seek medical treatment each year.

The highest risk factor for injuries in runners is weekly mileage. In particular, it is believed that the

risk of injury significantly increases as the mileage threshold exceeds 40 miles per week3,6-8. Additionally, higher weekly mileage is correlated with a greater likelihood of muscle tightness, including the hamstrings, which are the most commonly injured multi-joint muscle group in the body9,10. Studies suggest that, as hamstring flexibility decreases, the risk of various running injuries increase11, and that there are significant differences in hamstring flexibility between injured and non-injured athletes12. Some controversy exists regarding improvement of hamstring flexibility and decreasing risk or incidence of running-related injuries. For example, while studies suggest that increasing hamstring flexibility may decrease the risk or incidence of lower extremity overuse injuries13, other studies have demonstrated that hamstring flexibility does not differ between injured and non-injured athletes14. Because

Williams DSB III, Welch LM

422 Braz J Phys Ther. 2015 Sept-Oct; 19(5):421-428

the methodology between these two studies is not consistent, it is difficult to draw specific conclusions regarding the hamstrings’ role in running injury, but it does raise questions regarding the specific effects of hamstring flexibility on running mechanics and injuries. While muscle flexibility may play a role in injury, single anatomical factors are not likely to predict rates or incidences of injuries in runners.

Flexibility has been defined as the ability of muscular tissue to lengthen, given that the articulation travels through the entire movement’s span15. Lower extremity alignment, with respect to hamstring flexibility and its correlation to risk of injury, has been studied extensively12,14,16. In an open chain, the hamstrings are the primary flexors of the knee, while acting as secondary extensors of the hip. During running, the hamstrings act to slow down hip flexion in the last half of the swing phase (just prior to initial contact) and to extend the hip during the stance phase17. Additionally, the hamstrings decelerate tibial extension momentum just before initial contact18. Therefore, simultaneous hip flexion and knee extension during late swing result in substantial elongation and eccentric contraction of the biarticular hamstrings, causing extremely high loads during the elongated position of the hamstrings during late swing19. Due to energy transfer between phases and the important concentric and eccentric functions of the hamstrings, the flexibility of this group of muscles is not only an important factor influencing running biomechanics, but also a potential factor related to injury during running18.

The relationship between hamstring flexibility and injury is poorly understood because the mechanism of tissue damage likely depends on multiple factors, such as joint biomechanics, tissue mechanics, intensity of exercise, fatigue, and tissue structure. It has been shown that simulated hamstring shortening influences gait adversely when the popliteal angle is greater than 15 degrees from full knee extension20. These abnormal characteristics were demonstrated by increases in the parameters of walking effort, posterior pelvic tilt, and knee flexion during the stance phase of gait. These were also associated with decreases in walking speed, stride length, step length, hip flexion, pelvic obliquity and rotation, as well as premature ankle dorsiflexion and plantarflexion in stance20. While normal hamstring inflexibility would not likely be as extreme, some of these biomechanical effects would result from existing hamstring inflexibility.

In addition to the above kinematic and spatiotemporal characteristics, knee joint moment is another

important biomechanical factor that must also be taken into consideration when considering running biomechanics as it relates to static hamstring length. As the hamstring muscles are elongated during late swing prior to initial contact, the moment around the knee is significantly increased. With the hip in 0° extension, maximum knee flexion moment (internal) occurs at full knee extension. With the hip at 90°, there is some variation in position of maximum knee torque with some individuals producing maximum knee torque with the knee near 30-45° and some with the knee at full extension21. Furthermore, those with decreased hamstring flexibility exhibit greater knee flexion moment at short muscle lengths and decreased moment at long muscle lengths when compared to individuals with increased hamstring flexibility22. Regardless, at initial contact during running, the knee is close to the maximum torque and the hamstring is substantially elongated, resulting is high loads on this muscle during late swing and early stance.

Differences between the sexes may also play a role in running biomechanics. It has been shown that female recreational runners, when compared to males, demonstrate significantly greater peak hip adduction, hip internal rotation, and knee abduction angles. Thus, female runners exhibit significantly different lower extremity mechanics at the hip and knee in the frontal and transverse planes23. Additionally, it has been demonstrated that women have less knee flexion angle and more knee valgus angle as well as greater quadriceps activation, and lower hamstring activation as compared to their male counterparts during the stance phase of running, side cutting, and cross cutting24. It is unknown whether changes in flexibility of the hamstrings result in different biomechanical profiles in men compared to women.

While hamstring flexibility as it relates to structure and injury is important and has been addressed, there is a lack of research on the differences in running biomechanics in relation to flexible and inflexible individuals. Additionally, while differences in running biomechanics between male and female runners have been investigated, these dissimilarities have not been normalized to account for differences in flexibility due to sex. These differences could help explain how inflexible individuals compensate during running and why injury so often occurs as a result. They could also help explain if differences in male and female running biomechanics are due to sex or inherent flexibility. Therefore, the objective of this study is to compare the effect of static hamstring length on

Hamstring flexibility in male and female runners

423 Braz J Phys Ther. 2015 Sept-Oct; 19(5):421-428

sagittal plane mechanics in male and female runners. We hypothesize that hamstring flexibility will result in similar changes in running mechanics when compared between males and females.

MethodIndividuals in this study were recruited from the

University, surrounding communities, and local running clubs, resulting in a sample of convenience of runners who were asymptomatic at the time of data collection. Each subject gave their written informed consent for participation in the study, which was approved by the University and Medical Center Institutional Review Board, Greenville, NC, USA (UMCIRB 10-0437). An a priori power analysis was conducted utilizing data consistent with the variables of interest in the current study (α=0.05, β=0.80). Each variable was used independently for the power analysis, and peak hip angle was found to require the largest number of subjects to obtain significance. Based on this analysis, a sample size of 8 subjects per group was established for comparisons with adequate statistical power. In order to account for attrition and protect from type II error, the study included a total of 40 male and female subjects ranging in age from 18-50 years. Participants were placed in groups based on hamstring length, measured as the number of degrees lacking from zero, where zero is full knee extension with the hip at 90 degrees (popliteal angle). All subjects in this study had hamstrings that were classified as either flexible or inflexible. There were 4 groups consisting of 10 individuals in each group: flexible males, inflexible males, flexible females, and inflexible females sampled from a larger group of 99 runners collected in the current study. All subjects with tight hamstrings had a popliteal angle >29° away from zero. All subjects with flexible hamstrings had a popliteal angle <10° away from zero (Table 1). The values of 10 and 29° were chosen, as they were 1 standard deviation from the mean for the previously mentioned group of 99 runners ranging in age from 29 to 81 years. Participants ran

a minimum of 10 miles (16 kilometers) per week for at least 6 months prior to this study. Subjects were excluded from this study if they had any cardiovascular or neurological compromise, current lower extremity musculoskeletal injury, joint replacement, or joint fusion. Runners were not excluded from the study if they had previous lower extremity injuries related to running.

Static hamstring flexibility for both lower extremities was measured by two researchers using a standard goniometer with the subject supine on a mat table. One researcher maintained the knee and hip to be measured in a 90° flexed position and moved the knee into a terminal knee extension position to perform the range of motion measurement. Once terminal knee extension was obtained, the second researcher used a hand-held dynamometer to push the leg being measured with an average force of 10-12 pounds into the patient’s end range (Figure 1). The average of

Table 1. Subject demographics.

N Age (yrs) Mass (kg) Height (m) Miles/week Popliteal angle (°)

Flexible Males 10 27.1 (3.7) 76.2 (10.4) 1.80 (0.08) 15.4 (7.5) 4.1 (3.5)

Inflexible Males 10 31.7 (8.9) 73.8 (7.0) 1.79 (0.06) 21.0 (11.6) 33.5 (2.6)

Flexible Females 10 32.0 (7.6) 64.5 (9.5) 1.67 (0.09) 18.0 (8.0) 3.1 (4.3)

Inflexible Females 10 29.2 (5.5) 60.5 (5.3) 1.70 (0.05) 19.1 (12.4) 33.5 (3.9)

Presented in mean (SD).

Figure 1. Measurement of hamstring flexibility. Measurements were taken with a goniometer modified with extended arms. The stationary arm was held vertical and in alignment with the upper leg. This was verified with a bubble level. The movement arm was held in line with the fibula extended through the lateral malleolus. A second examiner provided consistent force measured with a handheld dynamometer while examiner one recorded the final angle.

Williams DSB III, Welch LM

424 Braz J Phys Ther. 2015 Sept-Oct; 19(5):421-428

3 measurements was taken for each lower extremity. The contralateral leg remained flat (extended) on mat table during each measurement. All subjects included in the study had symmetrical range of motion (±5°) between right and left limbs. Therefore, only the right limb was utilized in all subjects for comparison between groups.

A three-dimensional running analysis was completed on subjects eligible for participation. A standing calibration trial was collected during which static joint (greater trochanters, medial and lateral knees, medial and lateral maleoli, and medial and lateral forefoot) and segment tracking (calcaneus, shank, thigh, and pelvis) retroreflective markers were placed on bilateral lower extremities (Figure 2)25. The static joint markers were used to establish joint centers, segment geometry, and segment coordinate systems. Static markers were removed before the dynamic data collection. During the dynamic data collection, subjects were asked to run along a 16-meter runway at a speed of 3.35 m/s (±5%). Running speed was measured using photocells located 6 meters apart. A fixed running speed was used in order to decrease differences in lower extremity biomechanics and spatiotemporal parameters related to differences in forward velocity. Subjects were instructed to run with their normal

running gait. Kinematic data were collected at 240 Hz with a 9-camera motion analysis system (Qualisys Inc., Glastonbury, CT, USA). Qualisys software was used to reconstruct 3-dimensional coordinates for each marker. Two force plates (AMTI, Watertown, MA, USA) mounted on the floor of the runway recorded ground reaction forces (GRF) at a sample frequency of 1200 Hz. Kinematic data was time synchronized with GRF data at the time of collection. Subjects were required to run across the force plates for a minimum of 10 successful trials for the right lower extremity. A trial was considered successful if the subject ran with a natural gait over the force plates within the given velocity range while striking at least one of the force plates with their entire right foot.

Pelvis, thigh, shank, and foot segments were created using Visual 3D Software (C-motion Inc., Bethesda, MD, USA). Data were analyzed between initial contact and toe-off on the right limb and normalized to 100 data points, with each data point representing 1% of the stance phase of running. A second-order recursive Butterworth filter was used to filter marker data at 12 Hz and GRF data at 50 Hz. For this study, knee motion was defined as the tibia moving relative to the femur, and hip motion was defined as the femur moving relative to the pelvis. Visual 3-D software was used to calculate joint rotations via Cardan sequencing in which motion about the X-axis was defined as flexion/extension at the hip and knee. Joint moments were calculated at the hip and knee. Joint moments were normalized to subject mass and height. Mean joint angle and moment curves were created bilaterally at the hip and knee in the sagittal plane for each group. Peak flexion angles and extension moment values at the hip and knee were calculated. Sagittal plane hip and knee angle at initial contact were also calculated. Data plots were visually assessed for normality and variance homogeneity. Shapiro-Wilk test of normality was used to determine data normality on all variables. Based on the above test, all dependent variables were normally distributed.

Joint angles and joint moments were compared between the groups. These data were analyzed using a 2-factor (sex (df=1), flexibility (df=1), within-subjects (df=36)) analysis of variance (α=0.05) to determine differences between groups for peak knee flexion, peak hip flexion, peak knee extension moment, peak hip extension moment, knee flexion angle at initial contact, and hip flexion angle at initial contact. Post hoc t-tests (α=0.05) were utilized for individual comparisons.

Figure 2. Retroreflective marker placement. A total of 39 markers were placed with at least 3 markers per segment were placed on the pelvis, thighs, shanks, and feet for tracking during running. Static markers were placed over the joints in order to establish anthropometrics and segment coordinate systems.

Hamstring flexibility in male and female runners

425 Braz J Phys Ther. 2015 Sept-Oct; 19(5):421-428

ResultsAll results are presented in Table 2. Males

demonstrated greater peak knee extension moment than females (M:2.80±0.47, F:2.48±0.61 Nm/kg*m). Inflexible runners demonstrated greater peak knee extension moment than flexible runners (In:2.83±0.56, Fl:2.44±0.51 Nm/kg*m).

A significant interaction existed for hip flexion at initial contact (p=0.03). Specifically, flexible females exhibited more hip flexion than inflexible females (p<0.01) and flexible males (p=0.05) (Figure 3). Interestingly, flexible females not only landed in more flexion but also remained in roughly the same degree of flexion during loading response (Δ=0.4°).

No differences existed for knee angle at initial contact or peak knee angle. Similar to hip motion, no differences existed for peak hip angle or peak hip moment.

DiscussionThe purpose of this study was to compare the effect

of static hamstring length on sagittal plane mechanics in male and female runners. Mechanical differences existed primarily in flexible females. This is the first study to demonstrate that differences in flexibility result in different mechanical compensations between males and females. This understanding may help define specific interventions for female runners in an attempt to improve performance or reduce injuries.

At the knee, males exhibited greater peak knee extension moment when compared to females.

Figure 3. Sagittal plane hip angle during stance. Note that flexible females demonstrate greater hip flexion at initial contact that does not exhibit the same flexion absorption as the other groups. FF=flexible females; FM=flexible males; IF=inflexible females; IM=inflexible males.

Table 2. Dependent variables.

Males Females ANOVA (p value)Flexible (n=10) Inflexible (n=10) Flexible (n=10) Inflexible (n=10)

Knee

IC Flexion Angle (º) 12.5 (4.8) 14.8 (3.5) 16.7 (5.9) 14.5 (3.5)S=0.26F=0.98I=0.20

Peak Flexion Angle (º) 43.2 (5.1) 45.1 (6.1) 43.5 (3.2) 45.4 (5.3)S=0.86F=0.24I=0.97

Peak Extension Moment (Nm/kg*m) 2.73 (0.34) 2.86 (0.59) 2.15 (0.49) 2.81 (0.55)

S=0.05F=0.02I=0.11

Hip

IC Flexion Angle (º) 30.1 (9.5)‡ 31.7 (7.4) 36.7 (7.4)†‡ 27.9 (4.6)†S=0.55F=0.13I=0.03

Peak Flexion Angle (º) 35.2 (10.3) 37.2 (8.1) 37.1 (7.4) 31.0 (3.2)S=0.38F=0.40I=0.11

Peak Extension Moment (Nm/kg*m) 1.58 (0.41) 1.69 (0.34) 1.76 (0.40) 1.49 (0.23)

S=0.91F=0.46I=0.09

S=main effects for sex (df=1); F=main effects for flexibility (df=1); I=interaction (df=36). Values in bold represent significant p values for main effects or interactions from the ANOVA. †post hoc difference between flexible females and inflexible females (p<0.01). ‡post hoc difference between flexible females and flexible males (p=0.05).

Williams DSB III, Welch LM

426 Braz J Phys Ther. 2015 Sept-Oct; 19(5):421-428

While differences in running mechanics have been demonstrated between sexes23, the majority of these differences were observed in joint movement (kinematic variables) and in the secondary planes of motion (frontal and transverse). Specifically, females demonstrate significantly greater peak hip adduction, hip internal rotation, and knee abduction angles23. Females also demonstrate less knee flexion angle, associated with greater quadriceps activation and lower hamstring activation when compared to males during running and cutting activities24. Females are often termed as “quad-dominant” and less able to activate their hamstrings25,26. As running is a series of single-leg landings (squats), the hamstrings are necessary to aid in extension moment at the knee by eccentrically controlling anterior motion of the tibia4,26,27. If females have reduced hamstring activity, this may partially explain the reduction in knee extension moment. This further requires that the knee extension moment be produced by the quadriceps and may place increased stress on the patellofemoral joint, a common injury among female runners28. If a runner does not use their hamstrings adequately (magnitude or timing), which may be the case in females, this may explain why females do not produce as much knee extension moment during stance. Further evaluation of hamstring activation in these individuals is necessary to explain this further.

Inflexible runners demonstrated higher peak knee moment than flexible runners. This is consistent with previous work showing that poor hamstring flexibility is associated with higher knee extension moments4. As the hamstrings are eccentrically active in controlling flexion of the knee, decreased length of these muscles may result in passive tension and similar control of knee flexion. Therefore, an individual with inflexible hamstrings could demonstrate increased knee extension moment due to the passive tension of this tight group of muscles. Additionally, as hamstring flexibility decreases, the knee extensors may need to counteract the tighter flexor muscles prior to initial contact, further increasing the extension moment at the knee throughout the stance phase.

Flexible females demonstrated the greatest amount of hip flexion at initial contact (Table 2). Interestingly, the females remained in increased hip flexion during loading response but only flexed an additional 0.4º over this time. This, in combination with a large hip extension moment (1.76 Nm/kg*m) results in increased joint stiffness at the hip joint. While not significant, this group demonstrated a similar pattern at the knee

where the flexible females flexed approximately 4 degrees less than the other groups. Specifically, flexible females demonstrated the least knee flexion excursion from initial contact to peak (Δ=26.8°). This creates a stiffer knee resulting in less shock attenuation and potential increases in impact forces. We suggest that this passive flexibility results in a need for the female runners to stabilize the hip joint. The question remains as to whether this is a positive compensation based on performance or injuries in this group. While many of the runners in both the flexible and inflexible groups had a history of running injuries, the number of subjects in the current study is not adequate to establish causation. A much larger cohort of runners followed prospectively is necessary to establish strong relationships between hamstring flexibility and lower extremity injuries in runners.

Previous research has shown that acute changes in hamstring flexibility result in minimal changes in mechanics during running29. Limited data exists on mechanical characteristics of runners based on hamstring flexibility, independent of intervention. It would be expected that increased flexibility in runners would result in more hip flexion or knee extension at initial contact. Because females are typically quadriceps dominant, increased quadriceps activity along with decreased hamstring activity should biomechanically result in more hip flexion26,27. It would also seem reasonable to assume that the increased flexibility in these females would result in increased knee extension at initial contact. This may result in changes in stride length or stride frequency. While no such changes were recognized in the current study, further studies may focus on the effect of stretching protocols on stride length and stride frequency or the effect of stride manipulation on lower extremity mechanics (i.e. knee extension moments) as they relate to hamstring flexibility. In the current study, we saw no differences in stride length or frequency, which suggested that the differences in knee moment were related to other factors.

Strengthening and facilitating co-activation of the hamstrings has been shown to increase dynamic control of the knee joint30. This would suggest that flexible females may not have good dynamic control of the knee, as there is a lack of activation and/or tension in the hamstrings. Therefore, increasing hip flexion at initial contact could be a neuromuscular compensation, as flexible females attempt to optimize the control of the knee through taking away degrees of freedom at the hip or tightening the muscle by lengthening it over

Hamstring flexibility in male and female runners

427 Braz J Phys Ther. 2015 Sept-Oct; 19(5):421-428

the proximal joint. Further understanding of how males and females respond to stretching or strengthening interventions of the hamstrings is necessary to answer this question.

The current is study is limited by its retrospective nature and the collection of data on a sample of convenience. This study only provides a baseline upon which other randomized, controlled studies can be compared. Further, the subjects in the current study were fairly young and, therefore, not affected by changes in musculoskeletal structure related to aging. It is possible that physiological changes in collagen and neuromuscular control as individuals age may result in further disparity in the biomechanics of running. The risk of type 1 error due to multiple comparisons should be considered in the current study. However, the number of comparisons is relatively small compared to similar biomechanical studies. Further, while there are 6 total comparisons within this study, they are spread across 2 joints (knee and hip), include both kinematics and kinetics, and occur at different times during the stance phase of gait. The lack of control of stride frequency in the current study may also have an impact on the overall utility of the results. However, there were no differences in stride frequency between groups in the current study.

In conclusion, male and female runners respond to landing with different mechanics based on their level of hamstring flexibility. Flexible females demonstrate the lowest knee extension moment and greatest amount of hip flexion, particularly at initial contact. Understanding how these mechanics affect performance and injury patterns may aid in the development of treatment programs focused on strength, increasing passive control, or gait training.

References1. Sports and Fitness Industry Association. 2013 SFIA Sports

and Fitness Participation Topline Report. Silver Spring: SFIA; 2013.

2. Marti B, Vader JP, Minder CE, Abelin T. On the epidemiology of running injuries. The 1984 Bern Grand-Prix study. Am J Sports Med. 1988;16(3):285-94. http://dx.doi.org/10.1177/036354658801600316. PMid:3381988.

3. Fredericson M, Misra AK. Epidemiology and aetiology of marathon running injuries. Sports Med. 2007;37(4-5):437-9. http://dx.doi.org/10.2165/00007256-200737040-00043. PMid:17465629.

4. Messier SP, Legault C, Schoenlank CR, Newman JJ, Martin DF, DeVita P. Risk factors and mechanisms of knee injury in runners. Med Sci Sports Exerc. 2008;40(11):1873-9. http://dx.doi.org/10.1249/MSS.0b013e31817ed272. PMid:18845979.

5. Taunton JE, Ryan MB, Clement DB, McKenzie DC, Lloyd-Smith DR, Zumbo BD. A prospective study of running injuries: the Vancouver Sun Run “In Training” clinics. Br J Sports Med. 2003;37(3):239-44. http://dx.doi.org/10.1136/bjsm.37.3.239. PMid:12782549.

6. Decoster LC, Scanlon RL, Horn KD, Cleland J. Standing and supine hamstring stretching are equally effective. J Athl Train. 2004;39(4):330-4. PMid:15592605.

7. Thacker SB, Gilchrist J, Stroup DF, Kimsey CDJR Jr. The impact of stretching on sports injury risk: a systematic review of the literature. Med Sci Sports Exerc. 2004;36(3):371-8. http://dx.doi.org/10.1249/01.MSS.0000117134.83018.F7. PMid:15076777.

8. Meroni R, Cerri CG, Lanzarini C, Barindelli G, Morte GD, Gessaga V, et al. Comparison of active stretching technique and static stretching technique on hamstring flexibility. Clin J Sport Med. 2010;20(1):8-14. http://dx.doi.org/10.1097/JSM.0b013e3181c96722. PMid:20051728.

9. Wang SS, Whitney SL, Burdett RG, Janosky JE. Lower extremity muscular flexibility in long distance runners. J Orthop Sports Phys Ther. 1993;17(2):102-7. http://dx.doi.org/10.2519/jospt.1993.17.2.102. PMid:8467336.

10. Dalrymple KJ, Davis SE, Dwyer GB, Moir GL. Effect of static and dynamic stretching on vertical jump performance in collegiate women volleyball players. J Strength Cond Res. 2010;24(1):149-55. http://dx.doi.org/10.1519/JSC.0b013e3181b29614. PMid:20042927.

11. Hartig DE, Henderson JM. Increasing hamstring flexibility decreases lower extremity overuse injuries in military basic trainees. Am J Sports Med. 1999;27(2):173-6. PMid:10102097.

12. Jönhagen S, Németh G, Eriksson E. Hamstring injuries in sprinters. The role of concentric and eccentric hamstring muscle strength and flexibility. Am J Sports Med. 1994;22(2):262-6. http://dx.doi.org/10.1177/036354659402200218. PMid:8198197.

13. Hreljac A, Marshall RN, Hume PA. Evaluation of lower extremity overuse injury potential in runners. Med Sci Sports Exerc. 2000;32(9):1635-41. http://dx.doi.org/10.1097/00005768-200009000-00018. PMid:10994917.

14. Hennessey L, Watson AW. Flexibility and posture assessment in relation to hamstring injury. Br J Sports Med. 1993;27(4):243-6. http://dx.doi.org/10.1136/bjsm.27.4.243. PMid:8130961.

15. Aquino CF, Gonçalves GGP, Fonseca ST, Mancini MC. Analysis of the relation between flexibility and passive stiffness of the hamstrings. Rev Bras Med Esporte. 2006;12(4):175-9.

16. Wen DY, Puffer JC, Schmalzried TP. Lower extremity alignment and risk of overuse injuries in runners. Med Sci Sports Exerc. 1997;29(10):1291-8. http://dx.doi.org/10.1097/00005768-199710000-00003. PMid:9346158.

17. Mann RA, Hagy J. Biomechanics of walking, running, and sprinting. Am J Sports Med. 1980;8(5):345-50. http://dx.doi.org/10.1177/036354658000800510. PMid:7416353.

18. Novacheck TF. The biomechanics of running. Gait Posture. 1998;7(1):77-95. http://dx.doi.org/10.1016/S0966-6362(97)00038-6. PMid:10200378.

19. Higashihara A, Ono T, Kubota J, Okuwaki T, Fukubayashi T. Functional differences in the activity of the hamstring muscles with increasing running speed. J Sports Sci.

Williams DSB III, Welch LM

428 Braz J Phys Ther. 2015 Sept-Oct; 19(5):421-428

2010;28(10):1085-92. http://dx.doi.org/10.1080/02640414.2010.494308. PMid:20672221.

20. Whitehead CL, Hillman SJ, Richardson AM, Hazlewood ME, Robb JE. The effect of simulated hamstring shortening on gait in normal subjects. Gait Posture. 2007;26(1):90-6. http://dx.doi.org/10.1016/j.gaitpost.2006.07.011. PMid:16949826.

21. Mohamed O, Perry J, Hislop H. Relationship between wire EMG activity, muscle length, and torque of the hamstrings. Clin Biomech. 2002;17(8):569-79. http://dx.doi.org/10.1016/S0268-0033(02)00070-0. PMid:12243716.

22. Alonso J, McHugh MP, Mullaney MJ, Tyler TF. Effect of hamstring flexibility on isometric knee flexion angle-torque relationship. Scand J Med Sci Sports. 2009;19(2):252-6. http://dx.doi.org/10.1111/j.1600-0838.2008.00792.x. PMid:18384490.

23. Ferber R, Davis IM, Williams DS 3rd. Gender differences in lower extremity mechanics during running. Clin Biomech. 2003;18(4):350-7. http://dx.doi.org/10.1016/S0268-0033(03)00025-1. PMid:12689785.

24. Malinzak RA, Colby SM, Kirkendall DT, Yu B, Garrett WE. A comparison of knee joint motion patterns between men and women in selected athletic tasks. Clin Biomech. 2001;16(5):438-45. http://dx.doi.org/10.1016/S0268-0033(01)00019-5. PMid:11390052.

25. Williams DS, Isom W. Decreased frontal plane hip joint moments in runners with excessive varus excursion at the knee. J Appl Biomech. 2012;28(2):120-6. PMid:21975457.

26. Youdas JW, Hollman JH, Hitchcock JR, Hoyme GJ, Johnsen JJ. Comparison of hamstring and quadriceps femoris electromyographic activity between men and women during

a single-limb squat on both a stable and labile surface. J Strength Cond Res. 2007;21(1):105-11. http://dx.doi.org/10.1519/00124278-200702000-00020. PMid:17313276.

27. Ebben WP. Hamstring activation during lower body resistance training exercises. Int J Sports Physiol Perform. 2009;4(1):84-96. PMid:19417230.

28. Taunton JE, Ryan MB, Clement DB, McKenzie DC, Lloyd-Smith DR, Zumbo BD. A retrospective case-control analysis of 2002 running injuries. Br J Sports Med. 2002;36(2):95-101. http://dx.doi.org/10.1136/bjsm.36.2.95. PMid:11916889.

29. Davis Hammonds AL, Laudner KG, McCaw S, McLoda TA. Acute lower extremity running kinematics after a hamstring stretch. J Athl Train. 2012;47(1):5-14. PMid:22488225.

30. Shields RK, Madhavan S, Gregg E, Leitch J, Petersen B, Salata S, et al. Neuromuscular control of the knee during a resisted single-limb squat exercise. Am J Sports Med. 2005;33(10):1520-6. http://dx.doi.org/10.1177/0363546504274150. PMid:16009991.

Correspondence D. S. Blaise Williams III Department of Physical Therapy West Hospital Building, Basement Virginia Commonwealth University, Richmond, VA 23298, USA e-mail: dswilliams@vcu.edu

http://dx.doi.org/10.1590/bjpt-rbf.2014.0117 429 Braz J Phys Ther. 2015 Sept-Oct; 19(5):429-432

clinical commentary

Clinical commentary of the evolution of the treatment for chronic painful mid-portion Achilles tendinopathy

Håkan Alfredson1,2,3

ABSTRACT | The chronic painful Achilles tendon mid-portion was for many years, and still is in many countries, treated with intratendinous revision surgery. However, by coincidence, painful eccentric calf muscle training was tried, and it showed very good clinical results. This finding was unexpected and led to research into the pain mechanisms involved in this condition. Today we know that there are very few nerves inside, but multiple nerves outside, the ventral side of the chronic painful Achilles tendon mid-portion. These research findings have resulted in new treatment methods targeting the regions with nerves outside the tendon, methods that allow for a rapid rehabilitation and fast return to sports. Keywords: rehabilitation; tendinosis; eccentric training.

HOW TO CITE THIS ARTICLE

Alfredson H. Clinical commentary of the evolution of the treatment for chronic painful mid-portion Achilles tendinopathy. Braz J Phys Ther. 2015 Sept-Oct; 19(5):429-432. http://dx.doi.org/10.1590/bjpt-rbf.2014.0117

1 Department of Community Medicine and Rehabilitation, Sports Medicine Unit, Umeå University (UMU), Umeå, Sweden2 Pure Sports Medicine Clinic, London, UK3 The Institute of Sport Exercise & Health (ISEH), University College London Hospitals (UCLH), London, UKReceived: Feb. 26, 2015 Revised: May. 18, 2015 Accepted: June. 22, 2015

BackgroundChronic painful mid-portion Achilles tendinopathy

is a relatively common condition among recreational and elite athletes, but it is also seen in non-active individuals. It is most common between the age of 36 and 60 and very rare among individuals younger than 25 years. The etiology is unknown, but an altered lipid profile with high cholesterol levels has been found in 1/3 of the patients1. Excessive dorsiflexion in the ankle joint2 and low calf muscle strength have also been suggested as possible etiological factors. Conservative treatment with different loading regimens is the first line of treatment, and if that fails, surgical treatment is instituted. For surgical treatment, intratendinous revision via tenotomy followed by 4-6 months of rehabilitation has been the most commonly used procedure worldwide.

The purpose of this clinical commentary is to show how the results of research on the basic science for this condition has resulted in a completely new treatment strategy with major advantages for the patients.

In the 1990s, the Sports Medicine Unit in Umeå, Sweden, as in most other countries, used intratendinous revision surgery to treat patients with chronic painful mid-portion Achilles tendinopathy. Patients not responding to conservative management

were treated with open surgery, including excision of macroscopically abnormal tendon tissue via a central longitudinal tenotomy, followed by immobilization in a cast for 2-6 weeks, with a total 4-6 months rehabilitation period.

By coincidence, our group at the Sports Medicine Unit in Umeå tried a modified version of the Stanish et al.3 model for eccentric calf muscle training. We used a level of loading that was causing pain in the tendon during the exercise and the exercises were done at a slow pace, in contrast to pain-free exercises and gradually increased speed. We got surprisingly good clinical results. To achieve good clinical results after applying painful heavy loading on a chronic painful Achilles tendon was completely opposite to previous thinking around treatments of chronic painful tendons, and the good clinical results4 led to research into the pain mechanisms involved in chronic painful mid-portion Achilles tendinopathy.

Painful eccentric calf muscle trainingOur group designed an eccentric training regimen

modified from the Stanish et al.3 model to be tried on patients suffering from chronic painful mid-portion

Alfredson H

430 Braz J Phys Ther. 2015 Sept-Oct; 19(5):429-432

Achilles tendinosis. The training program included eccentric training over a step – 3x15 reps with straight and flexed knee performed 2 times/day, 7 days/week, for 3 months4. The method was tested in scientific studies4-6, and the overall results were very good, with around 80% satisfied and pain-free patients. After a while, we found out that high-level athletes, especially runners and jumpers who wear spiked shoes, did not have such good results with this treatment. Also, we found it to be of significant importance to establish that the patients had a correct diagnosis before the start of treatment. A partial rupture has to be excluded, because using eccentric training on a partially ruptured Achilles can further damage the tendon, possibly causing a lengthening of the tendon, that is known to be very difficult to treat.

Ultrasound follow-ups were performed on patients with chronic Achilles tendinopathy and very interestingly showed that in the successfully treated patients the Achilles tendon thickness had decreased over time, and the structure looked more normal sonographically7. Consequently, it appeared that painful eccentric calf muscle training had the potential to remodel the tendinosis tendon. From these research projects, where high painful loads were applied to the thick and painful Achilles tendons, we also learned that tolerating these high eccentric loads clearly show that the Achilles tendinosis tendon is not what had previously been thought: a so-called degenerative and weak tendon. Instead, it might very well be a strong tendon!

New research on tendon histology and imaging

We could not explain the background to the good clinical results achieved with painful eccentric training, and this led to extensive research together with Professor Sture Forsgren’s group at the Anatomy Department and Dr Lars Öhberg at the Department of Radiology at Umeå University. Using ultrasound+Doppler, we found high blood flow inside and outside the ventral side of the Achilles tendon mid-portion in patients with chronic painful mid-portion Achilles tendinopathy, but not in normal Achilles tendons8 (Figure 1). In a following study, ultrasound+Doppler-guided biopsies were taken from the region with high blood flow inside and outside the Achilles mid-portion in patients with chronic painful tendinosis. Immune-histochemical analyses showed nerves in close relation to blood vessels outside the tendon, but very few nerves inside the tendon9.

An interesting observation was that these were mainly sympathetic nerves, but also a few sensory nerves9. To try to trace the pain, ultrasound+Doppler-guided injections of small volumes of the local anesthetic xylocain+Adrenaline were administered, targeting the regions with high blood flow outside the tendon. This temporarily cured the tendon pain10. These findings clearly indicated that the pain in mid-portion Achilles tendinopathy comes from the nerves located on the ventral side of the Achilles, and that the nerves can indirectly be found by using ultrasound+Doppler to find the regions with high blood flow (blood vessels with accompanying nerves).

Ultrasound+Doppler-guided sclerosing polidocanol injections

The new research findings related to the reduction of pain at the regions of highest blood flow led to the invention of a new treatment method: ultrasound+Doppler-guided injections of the sclerosing substance polidocanol, targeting the regions with high blood flow and nerves outside the tendon. This type of treatment showed good clinical results with significantly lowered pain scores (VAS) during Achilles tendon loading activity in pilot studies and in a randomized placebo-controlled study11,12. Ultrasound+Doppler 2-year follow-ups of patients treated with sclerosing polidocanol injections showed decreased tendon thickness and improved structure (less irregular structure with less hypo-echoic regions) over time13, indicating a high potential in the soft tissues outside the ventral side of the Achilles tendon. The limitations with ultrasound+Doppler-guided polidocanol injections are that it is technically demanding, having a relatively long learning curve, and that often multiple4,5 injection treatments are needed.

Figure 1. Ultrasound and Doppler examination showing a thickened Achilles tendon mid portion with irregular structure and high blood flow outside and inside the ventral side of the Achilles tendon.

The chronic painful Achilles

431 Braz J Phys Ther. 2015 Sept-Oct; 19(5):429-432

Ultrasound+Doppler-guided mini-surgical scraping

To try to overcome the problems with the technically demanding polidocanol injection treatment, our group at the Sports Medicine Unit in Umeå invented a mini-surgical scraping treatment. Guided by the ultrasound+Doppler findings, a minor surgical procedure is performed under local anesthesia. Using a longitudinal lateral mini (1 cm) incision, the ventral side of the tendon is scraped in the regions with high blood flow and nerves14,15. This is a one stage and more radical approach to interfere with the nerves accompanying the blood vessels on the ventral side of the Achilles. Because there is no intratendinous treatment associated with this procedure, a relatively fast (4-6 weeks) rehabilitation can be used. The patients start walking with full weight bearing the first day after the operation and rapidly progress to functional tendon loading. There is no specific eccentric training regimen, but instead, there is a general build-up of training, depending on the requirements for the individual’s tendon loading activity (high-level activity to non-activity). The clinical results are very good with significantly lowered pain scores (VAS) during Achilles tendon loading activity and return to pre-injury activity levels, without any major side effects. In the 1-2 year follow-up of these individuals, the results remain positive, and the use of this method has been increased. We now have operated on large numbers of patients with chronic AT and at different activity levels, including professional athletes15. For reasons still unknown, high-level athletes seem to do best after this procedure. Patients with low physical activity level showed good clinical results in about 70% of cases, while among high-level athletes the success rate was more than 90%15.

Recently, focus has been placed on the plantaris tendon, located in close relation to the medial Achilles. There seems to be a subgroup of patients suffering from chronic painful mid-portion Achilles tendinopathy, where a thickened plantaris tendon is involved16. These patients have both mid-portion Achilles tendinopathy with high blood flow on the ventral side of the tendon and a closely located plantaris tendon (demonstrated with ultrasound) with also a localized high blood flow (Doppler) on the medial side of the Achilles. These patients most often complain of having pain located on the medial side of the Achilles, where the medial soleus inserts. It is our observation that if the plantaris tendon is involved there is often a poor response to eccentric training. This can theoretically

be explained by the fact that the plantaris tendon, known to be stronger and stiffer than the Achilles17, can cause a compression on the medial Achilles during the movements in the eccentric treatment regimen. When we noticed that the plantaris tendon could be involved, we changed the surgical technique from using a lateral incision to always using a medial incision to allow for an accurate evaluation of the relationship between the plantaris and Achilles tendons18 (Figure 2). If a plantaris tendon involvement is found, then the plantaris tendon is released proximally and distally, and 4-6 cm of its length are taken out.

Very recently, we have noticed that there is a minor group of patients who have plantaris-related pain without also having mid-portion Achilles tendinopathy (verified with ultrasound+Doppler examination) (non-published data). These patients do very well after plantaris tendon removal alone. To study the innervation patterns of the plantaris tendon, immune-histochemical examinations were performed in a large number of plantaris tendons and surrounding fibrous connective and fat that were taken out from patients with mid-portion Achilles tendinopathy and plantaris involvement18. Although the results related to innervation patterns have not been published yet, they show that most sensory nerves are found in the peritendinous connective tissue between the Achilles and plantaris tendon, but in about 1/3 of the plantaris tendons, there are also nerves inside the plantaris tendon that may be a co-factor in the medial pain.

ConclusionsNon-operative treatment with painful eccentric

training is the first line of treatment for chronic painful mid-portion Achilles tendinopathy. Our research on the innervation patterns in patients with chronic painful mid-portion Achilles tendinopathy has shown that there are no (or very few) nerves inside the chronic painful Achilles tendon mid-portion. Instead,

Figure 2. A thickened plantaris tendon located close to the thickened Achilles tendon mid-portion in a patient with chronic painful mid-portion Achilles tendinopathy+plantaris tendon involvement.

Alfredson H

432 Braz J Phys Ther. 2015 Sept-Oct; 19(5):429-432

the nerves are found outside the ventral side of the tendon. This knowledge has led to the invention of a new mini-invasive surgical treatment, combined with a fast rehabilitation, to be used on the patients who have a poor result with eccentric training. With the use of this method, there is a very good chance of cure from chronic painful mid-portion Achilles tendinopathy and return to full activity, including Achilles tendon-demanding professional sports, within 4-6 weeks after surgery.

References1. Beeharry D, Coupe B, Benbow EW, Morgan J, Kwok S,

Charlton-Menys V, et al. Familial hypercholesterolaemia commonly presents with Achilles tenosynovitis. Ann Rheum Dis. 2006;65(3):312-5. http://dx.doi.org/10.1136/ard.2005.040766. PMid:16176995.

2. Nawoczenski DA, Barske H, Tome J, Dawson LK, Zlotnicki JP, DiGiovanni BF. Isolated gastrocnemius recession for achilles tendinopathy: strength and functional outcomes. J Bone Joint Surg Am. 2015;97(2):99-105. http://dx.doi.org/10.2106/JBJS.M.01424. PMid:25609435.

3. Stanish WD, Rubinovich RM, Curwin S. Eccentric exercise in chronic tendinitis. Clin Orthop Relat Res. 1986(208):65-8. PMID: 3720143.

4. Alfredson H, Pietilä T, Jonsson P, Lorentzon R. Heavy-load eccentric calf muscle training for the treatment of chronic Achilles tendinosis. Am J Sports Med. 1998;26(3):360-6. PMid:9617396.

5. Mafi N, Lorentzon R, Alfredson H. Superior short-term results with eccentric calf muscle training compared to concentric training in a randomized prospective multicenter study on patients with chronic Achilles tendinosis. Traumatol Arthrosc. 2001;9(1):42-7. http://dx.doi.org/10.1007/s001670000148.

6. Fahlström M, Jonsson P, Lorentzon R, Alfredson H. Chronic Achilles tendon pain treated with eccentric calf-muscle training. Knee Surg Sports Traumatol Arthrosc. 2003;11(5):327-33. http://dx.doi.org/10.1007/s00167-003-0418-z. PMid:12942235.

7. Öhberg L, Lorentzon R, Alfredson H. Eccentric training in patients with chronic Achilles tendinosis: normalised tendon structure and decreased thickness at follow up. Br J Sports Med. 2004;38(1):8-11, discussion 11. http://dx.doi.org/10.1136/bjsm.2001.000284. PMid:14751936.

8. Öhberg L, Lorentzon R, Alfredson H. Neovascularisation in Achilles tendons with painful tendinosis but not in normal tendons: an ultrasonographic investigation. Knee Surg Sports Traumatol Arthrosc. 2001;9(4):233-8. http://dx.doi.org/10.1007/s001670000189. PMid:11522081.

9. Andersson G, Danielson P, Alfredson H, Forsgren S. Nerve-related characteristics of ventral paratendinous tissue in chronic Achilles tendinosis. Knee Surg Sports Traumatol Arthrosc. 2007;15(10):1272-9. http://dx.doi.org/10.1007/s00167-007-0364-2. PMid:17604979.

10. Alfredson H, Öhberg L, Forsgren S. Is vasculo-neural ingrowth the cause of pain in chronic Achilles tendinosis? An investigation using ultrasonography and colour Doppler, immunohistochemistry, and diagnostic injections. Knee Surg Sports Traumatol Arthrosc. 2003;11(5):334-8. http://dx.doi.org/10.1007/s00167-003-0391-6. PMid:14520512.

11. Ohberg L, Alfredson H. Ultrasound guided sclerosis of neovessels in painful chronic Achilles tendinosis: pilot study of a new treatment. Br J Sports Med. 2002;36(3):173-5, discussion 176-7. http://dx.doi.org/10.1136/bjsm.36.3.173. PMid:12055110.

12. Alfredson H, Öhberg L. Sclerosing injections to areas of neo-vascularisation reduce pain in chronic Achilles tendinopathy: a double-blind randomised controlled trial. Knee Surg Sports Traumatol Arthrosc. 2005;13(4):338-44. http://dx.doi.org/10.1007/s00167-004-0585-6. PMid:15688235.

13. Lind B, Öhberg L, Alfredson H. Sclerosing polidocanol injections in mid-portion Achilles tendinosis: remaining good clinical results and decreased tendon thickness at 2-year follow-up. Knee Surg Sports Traumatol Arthrosc. 2006;14(12):1327-32. http://dx.doi.org/10.1007/s00167-006-0161-3. PMid:16967202.

14. Alfredson H, Öhberg L, Zeisig E, Lorentzon R. Treatment of midportion Achilles tendinosis: similar clinical results with US and CD-guided surgery outside the tendon and sclerosing polidocanol injections. Knee Surg Sports Traumatol Arthrosc. 2007;15(12):1504-9. http://dx.doi.org/10.1007/s00167-007-0415-8. PMid:17879083.

15. Alfredson H. Ultrasound and Doppler-guided mini-surgery to treat midportion Achilles tendinosis: results of a large material and a randomised study comparing two scraping techniques. Br J Sports Med. 2011;45(5):407-10. http://dx.doi.org/10.1136/bjsm.2010.081216. PMid:21349878.

16. Alfredson H. Midportion Achilles tendinosis and the plantaris tendon. Br J Sports Med. 2011;45(13):1023-5. http://dx.doi.org/10.1136/bjsports-2011-090217. PMid:21628352.

17. Lintz F, Higgs A, Millett M, Barton T, Raghuvanshi M, Adams MA, et al. The role of Plantaris Longus in Achilles tendinopathy: a biomechanical study. Foot Ankle Surg. 2011;17(4):252-5. http://dx.doi.org/10.1016/j.fas.2010.08.004. PMid:22017896.

18. Spang C, Alfredson H, Ferguson M, Roos B, Bagge J, Forsgren S. The plantaris tendon in association with mid-portion Achilles tendinosis: tendinosis-like morphological features and presence of a non-neuronal cholinergic system. Histol Histopathol. 2013;28(5):623-32. PMid:23378267.

Correspondence Håkan Alfredson Department of Community Medicine and Rehabilitation Sports Medicine Unit Umeå University - UMU SE-90187 Umeå, Sweden e-mail: hakan.alfredson@umu.se

e d i t o r i a lr u l e s

433 Braz J Phys Ther. 2015 Sept-Oct; 19(5)

INSTRUCTIONS TO AUTHORS

SCOPE AND POLICIES

The Brazilian Journal of Physical Therapy (BJPT) publishes original research articles, reviews, and brief communications on topics related to the professional activity of physical therapy and rehabilitation, including clinical, basic or applied studies on the assessment, prevention, and treatment of movement disorders.

Our Editorial Board is committed to disseminating quality scientific investigations from many areas of expertise.

The BJPT follows the principles of publication ethics included in the code of conduct of the Committee on Publication Ethics (COPE).

The BJPT accepts the following types of study, which must be directly related to the journal’s scope and expertise areas:

a) Experimental studies: studies that investigate the effect(s) of one or more interventions on outcomes directly related to the BJPT’s scope and expertise areas.

The World Health Organization defines a clinical trial as “any research study that prospectively allocates human participants or groups of humans to one or more health-related interventions to evaluate the effect(s) on health outcome(s)”. Clinical trials include single-case experimental studies, case series, non-randomized clinical trials, and randomized clinical trials. Randomized controlled trials (RCTs) must follow the CONSORT (Consolidated Standards of Reporting Trials) recommendations, which are available at: http://www.consort-statement.org/consort-statement/overview0/.

The CONSORT checklist and Statement Flow Diagram, available at http://www.consort-statement.org/downloads/translations, must be completed and submitted with the manuscript.

Clinical trials must provide registration that satisfies the requirements of the International Committee of Medical Journal Editors (ICMJE), e.g. http://clinicaltrials.gov/ and/or http://www.anzctr.org.au. The complete list of all clinical trial registries can be found at: http://www.who.int/ictrp/network/primary/en/index.htmlb) Observational studies: studies that investigate

the relationship(s) between variables of interest

related to the BJPT’s scope and expertise areas without direct manipulation (e.g. intervention). Observational studies include cross-sectional studies, cohort studies, and case-control studies.

c) Qualitative studies: studies that focus on understanding needs, motivations, and human behavior. The object of a qualitative study is guided by in-depth analysis of a topic, including opinions, attitudes, motivations, and behavioral patterns without quantification. Qualitative studies include documentary and ethnographic analysis.

d) Systematic reviews: studies that analyze and/or synthesize the literature on a topic related to the scope and expertise areas of the BJPT. Systematic reviews that include meta-analysis will have priority over other systematic reviews. Those that have an insufficient number of articles or articles with low quality in the Methods section and do not include an assertive and valid conclusion about the topic will not be considered for peer-review analysis. The authors must follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist to format their systematic reviews. The checklist is available at http://prisma-statement.org/statement.htm and must be filled in and submitted with the manuscript. Potential authors are encouraged to read the paper Mancini MC, Cardoso JR, Sampaio RF, Costa LCM, Cabral CMN, Costa LOP. Tutorial for writing systematic reviews for the Brazilian Journal of Physical Therapy (BJPT). Braz J Phys Ther. 2014 Nov-Dec; 18(6):471-480. http://dx.doi.org/10.1590/bjpt-rbf.2014.0077.

e) Studies on the translation and cross-cultural adaptation of questionnaires or assessment tools: studies that aim to translate into and/or cross-culturally adapt foreign questionnaires to a language other than that of the original version of existing assessment instruments. The authors must use the checklist (Appendix) to format this type of paper and adhere to the other recommendations of the BJPT. The answers to the checklist must be submitted with the manuscript. At the time of submission, the authors must also include written permission from the authors of

Editorial Rules

434 Braz J Phys Ther. 2015 Sept-Oct; 19(5)

the original instrument that was translated and/or cross-culturally adapted.

f) Methodological studies: studies centered on the development and/or evaluation of clinimetric properties and characteristics of assessment instruments. The authors are encouraged to use the Guidelines for Reporting Reliability and Agreement Studies (GRRAS) to format methodological papers, in addition to following BJPT instructions.

Important: Studies that report electromyographic results must follow the Standards for Reporting EMG Data recommended by ISEK (International Society of Electrophysiology and Kinesiology), available at http://www.isek-online.org/standards_emg.html.

Ethical and legal aspects Submitting a manuscript to the BJPT implies that

the paper has not been submitted simultaneously to another journal. The papers published in the BJPT are free access and distributed under the terms of Creative Commons Attribution, Non-Commercial License (http://creativecommons.org/licenses/by/3.0/deed.pt_BR), which allows free non-commercial use, distribution, and reproduction into any means, as long as the original format is maintained. The reproduction of part of a manuscript, even partially, including translation to another language, requires prior authorization from the editor.

The authors must cite the corresponding credits. Ideas, data or phrases from other authors without the appropriate citations and with hints of plagiarism will be subject to penalties according to the COPE code of conduct.

If part of the material has been presented in a preliminary format (at a symposium, conference, etc.), the reference of the presentation must be cited as a footnote in the title page.

The use of patient initials, names or hospital registration numbers must be avoided. Patients must not be identified in photographs, except with their express written consent attached to the original article at the time of submission.

Studies in humans must be in agreement with COPE ethical standards and must be approved by the institution’s ethics committee.

Animal experiments must comply with international guidelines (such as those of the Committee for Research and Ethical Issues of the

International Association for the Study of Pain, published in Pain, 16:109-110, 1983).

The BJPT reserves the right not to publish manuscripts that do not adhere to the legal and ethical rules for human and animal research.

Authorship criteria The BJPT accepts submissions of manuscripts

with up to six (6) authors. The BJPT’s authorship policy follows ICMJE requirements for Manuscripts Submitted to Biomedical Journals (www.icmje.org), which state that “authorship credit should be based on 1) substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; 2) drafting the article or revising it critically for important intellectual content; and 3) final approval of the version to be published.” Conditions 1, 2, and 3 should all be met simultaneously. Grant acquisition, data collection, and/or general supervision of a research group do not justify authorship and must be recognized in the acknowledgements.

In exceptional cases, the editors may consider a request for submission of a manuscript with more than six (6) authors. The criteria for analysis include the type of study, potential for citation, quality, and methodological complexity, among other things. In these exceptional cases, each author’s contribution must be described at the end of the text, after the Acknowledgements and right before the References as recommended by the ICMJE and the Guidelines for Integrity of Scientific Activity widely publicized by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (http://www.cnpq.br/web/guest/diretrizes).

All authors are solely responsible for the content of the submitted manuscripts. All published material becomes property of the BJPT, which will retain the copyrights. Therefore, no material published in the BJPT may be reproduced without written permission from the editors. All authors of the submitted manuscript must sign a copyright transfer agreement form valid from the date of the acceptance of the manuscript.

MANUSCRIPT FORM AND PRESENTATION

The BJPT accepts the submission of manuscripts with up to 3,500 words (excluding title page, abstract, references, tables, figures, and legends). The information contained in appendices will be included in the total number of words allowed.

Editorial Rules

435 Braz J Phys Ther. 2015 Sept-Oct; 19(5)

The manuscript must be written preferably in English. Whenever the quality of the English writing hinders the analysis and assessment of the content, the authors will be informed.

It is recommended that manuscripts submitted in/translated into English be accompanied by certification of revision by a professional editing and proofreading service. This certification must be included in the submission. We recommend the following services, not excluding others: - American Journal Experts (www.journalexperts.

com);

- Scribendi (www.scribendi.com);

- Nature Publishing Groups Language Editing (https://languageediting.nature.com/login).

The manuscript must include a title and identification page, abstract, and keywords before the body of the manuscript. References, tables, figures, and appendices should be inserted at the end of the manuscript.

Title and identification page The title of the manuscript must not exceed 25

words and must include as much information about the study as possible. Ideally, the terms used in the title should not appear in the list of keywords. The identification page must also contain the following details:

Full title and short title of up to 45 characters to be used as a legend on the printed pages;

Author: author’s first and last name in capital letters without title followed by a superscript number (exponent) identifying the institutional affiliation (department, institution, city, state, country). For more than one author, separate using commas;

Corresponding author: name, full address, email, and telephone number of the corresponding author who is authorized to approve editorial revisions and provide additional information if needed.

Keywords: up to six indexing terms or keywords in Portuguese and English.

AbstractThe abstract must be concise, not exceeding

250 words in a single paragraph in English, and must be inserted immediately after the title page. Do not include references, footnotes or undefined

abbreviations in the abstract. It must be written in a structured format.

Bullet pointsOn a separate page, the manuscript must identify

three to five phrases that capture the essence of the topic under investigation and the main conclusions of the paper. Each bullet point must be written in a summarized fashion and provide the main contributions of the study to the current literature, as well as the clinical implications (i.e., how the results can influence clinical practice or scientific research in the area of physical therapy and rehabilitation). These points must be presented in a text box in the beginning of the article, after the abstract. Each bullet point must have no more than 80 characters (with spaces).

IntroductionThis part of the manuscript should describe

and define the topic under investigation, explain the relationships with to other studies in the same field, justify the need for the study, and specify the objective(s) of the study and hypotheses, if applicable.

MethodsThis section consists in describing the

methodological design of the study and presenting a clear and detailed report of the study participants and data collection procedures, transformation/reduction, and analysis in order to allow reproducibility of the study. For clinical trials, the participant selection and allocation process must be organized in a flowchart containing the number of participants in each phase as well as their main characteristics (see model of CONSORT flow diagram).

Whenever relevant to the type of study, the author should include the calculation that adequately justifies the sample size for investigation of the intervention effects. All of the information needed to estimate and justify the sample size used in the study must be clearly stated.

The authors must describe the dependent and independent variables; whether the parametric assumptions were met; specify the software used in the data analysis and the level of significance; and specify the statistical tests and their purpose.

Editorial Rules

436 Braz J Phys Ther. 2015 Sept-Oct; 19(5)

ResultsThe results should be presented briefly and

concisely. Pertinent results must be reported with the use of text and/or tables and/or figures. Data included in tables and figures must not be duplicated in the text.

The results must be summarized into self-explanatory graphs or tables using measures of central tendency and variability (e.g. mean (SD) instead of mean±SD); must include measures of magnitude of effect (e.g. effect size) and/or indicators of the precision of the estimates (e.g. confidence intervals); must report the power of the non-significant statistical tests.

DiscussionThe purpose of the discussion is to interpret the

results and to relate them to existing and available knowledge, especially the knowledge already presented in the Introduction. Be cautious when emphasizing recent findings. The data presented in the Methods and/or in the Results sections should not be repeated. Study limitations, implications, and clinical application to the areas of physical therapy and rehabilitation sciences must be described.

ReferencesThe recommended number of references is 30,

except for systematic reviews of the literature. Avoid references that are not available internationally, such as theses and dissertations, unpublished results and articles, and personal communication. References should be organized in numerical order of first appearance in the text, following the Uniform Requirements for Manuscripts Submitted to Biomedical Journals prepared by the ICMJE.

Journal titles should be written in abbreviated form, according to the List of Journals of Index Medicus. Citations should be included in the text as superscript (exponent) numbers without dates. The accuracy of the references appearing in the manuscript and their correct citation in the text are the responsibility of the author(s).

Examples: http://www.nlm.nih.gov/bsd/uniform_requirements.html.

Tables, Figures, and AppendicesAn overall total of five (5) tables and figures is

allowed. Appendices must be included in the number

of words allowed in the manuscript. In the case of previously published tables, figures, and appendices, the authors must provide a signed permission from the author or editor at the time of submission.

For articles submitted in Portuguese, the English version of the tables, figures, and appendices and their respective legends must be attached in the system as a supplementary document. - Tables: these must include only indispensable

data and must not be excessively long (maximum allowed: one A4 page with double spacing). They should be numbered consecutively using Arabic numerals and should be inserted at the end of the text. Small tables that can be described in the text are not recommended. Simple results are best presented in a phrase rather than a table.

- Figures: these must be cited and numbered consecutively using Arabic numerals in the order in which they appear in the text. The information in the figures must not repeat data described in tables or in the text. The title and legend(s) should explain the tables and figures without the need to refer to the text. All legends must be double-spaced, and all symbols and abbreviations must be defined. Use uppercase letters (A, B, C, etc.) to identify the individual parts of multiple figures.

Whenever possible, all symbols should be placed in the legends. However, symbols identifying curves in a graph can be included in the body of the figure, provided this does not hinder the analysis of the data. Figures in color will only be published in the online version. With regard to the final artwork, all figures must be in high resolution or in its original version. Low-quality figures will not be accepted and may result in delays in the process of review and publication.- Acknowledgements: these must include

statements of important contributions specifying their nature. The authors are responsible for obtaining the authorization of individuals/institutions named in the acknowledgements.

Short communications The BJPT will publish one short communication

per issue (up to six a year) in a format similar to that of the original articles, containing 1200 words and up to two figures, one table, and ten references.

Editorial Rules

437 Braz J Phys Ther. 2015 Sept-Oct; 19(5)

ELECTRONIC SUBMISSION

Manuscripts must be submitted, preferably in English, via the website http://www.scielo.br/rbfis. Articles submitted in Portuguese will be reviewed and, if selected for publication, the translation into English of the reviewed version of the manuscript will be the sole responsibility of the authors.

The translated manuscript must be sent within ten days with certification and will be submitted to the BJPT International Editor and proofreader. From volume 19.1 (2015), only English papers will be published.

It is the authors’ responsibility to remove all information (except on the title and identification page) that may identify the article’s source or authorship.

When submitting a manuscript for publication, the authors must include, in addition to the files described above, the following supplementary documents: Cover letter; 2) Conflict of interest statement; and 3) Copyright transfer statement signed by all authors.

THE REVIEW PROCESS

The submissions that meet the journal’s standards and are in accordance with the BJPT editorial policies will be forwarded to the area editors, who will perform an initial assessment and recommend them or not to the chief editor for peer-review. The criteria used for the initial analysis of the area editor include: originality, pertinence, clinical relevance, and methodology. The manuscripts that do not have merit or do not conform to the editorial policies will be rejected in the pre-analysis phase, regardless of the adequacy of the text and methodological quality.

Therefore, the manuscript may be rejected based solely on the recommendation of the area editor without the need for further review, in which case, the decision is not subject to appeal. The manuscripts selected for pre-analysis will be submitted to review by specialists, who will work independently. The reviewers will remain anonymous to the authors, and the authors will not be identified to the reviewers. The editors will coordinate the exchange between authors and reviewers and will make the final decision on which articles will be published based on the recommendations of the reviewers and area editors. If accepted for publication, the articles may be subject to minor changes that will not affect the author’s style. If an article is rejected, the authors will receive a justification letter from the editor. After publication or at the end of the review process, all documentation regarding the review process will be destroyed.

AREAS OF EXPERTISE

1. Physiology, Kinesiology, and Biomechanics; 2. Kinesiotherapy/therapeutic resources; 3. Motor development, acquisition, control, and behavior; 4. Education, Ethics, Deontology, and Physical Therapy History; 5. Assessment, prevention, and treatment of cardiovascular and respiratory disorders; 6. Assessment, prevention, and treatment of aging disorders; 7. Assessment, prevention, and treatment of musculoskeletal disorders; 8. Assessment, prevention, and treatment of neurological disorders; 9. Assessment, prevention, and treatment of gynecological disorders; 10. Assessment and measurement in Physical Therapy; 11. Ergonomics/Occupational Health.

APPENDIX:Checklist for reviewers/authors of studies on the translation and cross-cultural adaptation of

questionnaires/assessment instruments

Instructions to reviewers/authors:

- Stage I: Translation into Portuguese:

3 Did the authors mention the presence of at least two translators? 3 Were the bilingual translators native speakers of Brazilian Portuguese? 3 Did the translators have different professional backgrounds and profiles (i.e. one translator has

knowledge of the concepts assessed by the instrument and the other is not related to the health area)? 3 Did the translators work on the translation independently?

Editorial Rules

438 Braz J Phys Ther. 2015 Sept-Oct; 19(5)

3 Did the authors describe the translator’s questions or changes and the rationale behind the translation?

- Stage II: Synthesis of translation

3 Were the translators involved in the reporting of the process?

3 Were the translated versions compared to the original questionnaire to extract a synthesis of the first Portuguese version of the questionnaire (version I)?

3 Did the authors present a report of the synthesis process containing the questions that required changes and how they were resolved?

3 Was there mention of the process of consensus between the translators?

- Stage III: Back translation

3 Was version I of the translated questionnaire translated back into the original instrument’s language?

3 Were at least two translators involved?

3 Were the bilingual translators native speakers of the original instrument’s language?

3 Did the authors ensure that the translators were not familiar with the original version of the questionnaire?

3 Did the authors ensure that these translators did not have a background in the area of health or information about the concepts explored by the questionnaire or instrument?

- Stage IV: Expert committee

3 Did the Committee include methodologists, health professionals, language professionals, and translators (Stage I and II translators and Stage III back translators)?

3 Were the authors of the original questionnaire contacted and did they grant approval for the cross-cultural adaptation? (Required)

3 Is there mention of the participation of the authors of the original questionnaire during this stage? (Not required)

3 Did the consolidation of a pre-final version consider all reports, translations, and back translations?

3 Is there mention of the aspects that required changes at this stage and of how they were resolved?

3 Were the Committee’s decisions aimed at ensuring semantic, idiomatic, experimental, and conceptual equivalence between the versions?

- Stage V: Pre-test of pre-final version

3 Was the pre-final version tested on at least 30 subjects?

3 Were these subjects part of the target population of the assessed questionnaire or instrument?

3 Did every subject answer the questionnaire or instrument and was each one interviewed to explore their comprehension of each item and answer of the questionnaire? Guillemin et al. (1993) suggest posing the question: “What did you mean?” to assess their understanding of the item.

3 Did the authors report the percentage of uncertainties during this part of the process (pre-final version)? Uncertainties reported by 15 or 20% or more of the sample indicate the need for revision of the questionnaire (Ciconelli et al., 1999; Nusbaum et al., 2001). If the percentage is greater than 15% or if more subjects were included, the translated and adapted version of the questionnaire or instrument must be changed and a new pre-test must be conducted and reported.

3 For original instruments already established in the literature and whose construct has been assessed, the authors should briefly describe the results of this assessment. Otherwise, the authors of the current version must assess the construct using the data from the translation.

3 We recommend that the original instrument be submitted with the manuscript as a separate file.

Editorial Rules

439 Braz J Phys Ther. 2015 Sept-Oct; 19(5)

Checklist – Submission of studies on translations and cross-cultural adaptations and validation Author Reviewer

Items of translation and cross-cultural adaptation Mark with an X

Reported on page no.

Mark with an X

1 - Title mentions that it is a translation and cross-cultural adaptation.2 - Reference to original instrument was included in Methods.3 - Reference to original instrument was included in References.4 - Translated instrument was included in full at the time of submission.5 - Original instrument was submitted in full.6 - Authorization was given by the authors of the original instrument.7 - Guidelines by Beaton et al. (2000) were followed in the translation and adaptation stages and the authors clearly mention the use of this guideline.Translation - 2 translators (1 lay translator and 1 specialized in the area).Meeting of translation committee (synthesis of translation).Back translation - 2 lay translators.Meeting of expert committee.Test of pre-final version (n>30).Rate of comprehension was described in the test of the pre-final version – uncertainties reported by 15 or 20% or more of the sample indicate the need for revision of the questionnaire (Nusbaum et al., 2001).8 - All items of the questionnaire were translated and cross-culturally adapted, including alternative answers and instructions.9 - A clear description was given of the cultural adaptations made during the study.10 - A clear description of the sample characteristics was included in the stages of the study.Measurement properties

Required11 - Was the translated instrument’s reproducibility (test-retest) assessed?12 - Was the sample size adequate for assessment of the reproducibility? (Terwee et al., 2007)13 - Was the translated instrument’s internal consistency assessed?14 - Was the sample size adequate for assessment of the internal consistency? (Terwee et al., 2007)

Recommended15 - Was confirmatory factor analysis of the translated instrument conducted?16 - Was the sample size adequate (Mokkink et al., 2010) for confirmatory factor analysis of the translated instrument?

OR17 - If exploratory factor analysis was not conducted in the original study, was it conducted in the translation study?18 - Was the sample size adequate (Mokkink et al., 2010) for exploratory factor analysis of the translated instrument?

References

- Beaton DE, Bombardier C, Guillemin F, Ferraz MB. Guidelines for the process of cross-cultural adaptation of self-report measures. Spine (Phila Pa 1976). 2000;25(24):3186-3191.

- Ciconelli RM, Ferraz MB, Santos W, Meinão I, Quaresma MR. Tradução para Língua Portuguesa e validação do questionário genérico de avaliação de qualidade de vida SF-36. Revista Brasileira de Reumatologia. 1999;39:143-150.

- Guillemin F, Bombardier C, Beaton D. Cross-cultural adaptation of health-related quality of life measures: literature review and proposed guidelines. J Clin Epidemiol. 1993;46(12):1417-1432.

Editorial Rules

440 Braz J Phys Ther. 2015 Sept-Oct; 19(5)

- Nusbaum L, Natour J, Ferraz MB, Goldenberg J. Translation, adaptation and validation of the Roland-Morris questionnaire. Braz J Med Biol Res. 2001;34(2):203-210.

- Chen WH, Lenderking W, Jin Y, Wyrwich KW, Gelhorn H, Revicki DA. Is Rasch model analysis applicable in small sample size pilot studies for assessing item characteristics? An example using PROMIS pain behavior item bank data. Qual Life Res. 2014 Mar;23(2):485-93.

- Terwee CB1, Bot SD, de Boer MR, van der Windt DA, Knol DL, Dekker J, Bouter LM, de Vet HC. Quality criteria were proposed for measurement properties of health status questionnaires. J Clin Epidemiol. 2007 Jan;60(1):34-42.

PROGRAMA DE PÓS-GRADUAÇÃO EM CIÊNCIAS DA REABILITAÇÃO MESTRADO E DOUTORADO

Recomendado pela CAPES – Conceito 5

O Programa de Pós-graduação em Ciências da Reabilitação tem como base a perspectiva

apresentada no modelo proposto  pela Organização Mundial de Saúde e propõe que as

dissertações e trabalhos científicos desenvolvidos estejam relacionados com o desempenho

funcional humano. Com a utilização de um modelo internacional, espera-se estimular o

desenvolvimento de pesquisas que possam contribuir para uma melhor compreensão do

processo de função e disfunção humana, contribuir para a organização da informação e estimular

a produção científica numa estrutura conceitual mundialmente reconhecida. O Programa de

Pós-graduação em Ciências da Reabilitação tem como objetivo tanto formar como aprofundar o

conhecimento profissional e acadêmico, possibilitando ao aluno desenvolver habilidades para

a condução de pesquisas na área de desempenho funcional humano.

O programa conta com parcerias nacionais e internacionais sedimentadas, e os seus laboratórios

de pesquisa contam com equipamentos de ponta para o desenvolvimento de estudos na área

de Ciências da Reabilitação.

Mais informaçõesFone/Fax: (31) 3409-4781www.eef.ufmg.br/mreab

PHYSIOTHERAPY EVIDENCE DATABASE

Universidade Federal de São Carlos

Programa de Pós-Graduação em Fisioterapia O Programa de Pós-Graduação em Fisioterapia tem como área de

concentração: "Processos de Avaliação e Intervenção em

Fisioterapia". Nosso objetivo é oferecer condições acadêmicas

necessárias para que o aluno adquira um repertório teórico e

metodológico, tornando-se apto a exercer as atividades de docente

de nível universitário e iniciá-lo na carreira de pesquisador.

Os cursos de mestrado e doutorado (stricto sensu) foram os

primeiros criados na área de fisioterapia do país.

Linhas de pesquisa do programa são:

Instrumentação e Análise Cinesiológica e Biomecânica do

Movimento

Processos de Avaliação e Intervenção em Fisioterapia do

Sistema Músculo-Esquelético

Processos Básicos, Desenvolvimento e Recuperação

Funcional do Sistema Nervoso Central

Processos de Avaliação e Intervenção em Fisioterapia

Cardiovascular e Respiratória

Recomendado pela CAPES – Conceito 6

Mais informações

Fone: (16) 3351-8448

www.ppgft.ufscar.br

e-mail ppg-cr@ufscar.br

PHYSIOTHERAPY EVIDENCE DATABASE

ASSOCIAÇÃO BRASILEIRA DE PESQUISAE PÓS-GRADUAÇÃO EM FISIOTERAPIA

ISSN 1413-3555

2015 Sept/Oct; 19(5)

Brazilian Journal of P

hysical Therapy2015 Sept/O

ct; 19(5)

ISSN 1413-3555

2015 Sept/Oct; 19(5)

Editorial329 Editorial

Deborah A. Nawoczenski

Review Article331 Prevention of shoulder injuries in overhead athletes: a science-based approach

Ann M. Cools, Fredrik R. Johansson, Dorien Borms, Annelies Maenhout

340 Aconceptualframeworkforasportskneeinjuryperformanceprofile(SKIPP)andreturntoactivitycriteria(RTAC)David Logerstedt, Amelia Arundale, Andrew Lynch, Lynn Snyder-Mackler

360 CriticalreviewoftheimpactofcorestabilityonupperextremityathleticinjuryandperformanceSheri P. Silfies, David Ebaugh, Marisa Pontillo, Courtney M. Butowicz

369 Measuring sports injuries on the pitch: a guide to use in practiceLuiz C. Hespanhol Junior, Saulo D. Barboza, Willem van Mechelen, Evert Verhagen

381 Improvingperformanceingolf:currentresearchandimplicationsfromaclinicalperspectiveKerrie Evans, Neil Tuttle

Original Articles390 SportsinjuriesprofileofafirstdivisionBraziliansoccerteam:adescriptivecohortstudy

Guilherme F. Reis, Thiago R. T. Santos, Rodrigo C. P. Lasmar, Otaviano Oliveira Júnior, Rômulo F. F. Lopes, Sérgio T. Fonseca

398 Multicenter trial of motion analysis for injury risk prediction: lessons learned from prospective longitudinal large cohort combined biomechanical -epidemiological studiesTimothy E. Hewett, Benjamin Roewer, Kevin Ford, Greg Myer

410 Physical therapists’ role in prevention and management of patellar tendinopathy injuries in youth, collegiate, and middle-aged indoor volleyball athletesKornelia Kulig, Lisa M. Noceti-DeWit, Stephen F. Reischl, Rob F. Landel

421 MaleandfemalerunnersdemonstratedifferentsagittalplanemechanicsasafunctionofstatichamstringflexibilityD. S. Blaise Williams III*, Lee M. Welch

ClinicalCommentary429 Clinicalcommentaryoftheevolutionofthetreatmentforchronicpainfulmid-portionAchillestendinopathy

Håkan Alfredson

Editorial Rules