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Londrina 2013

CENTRO DE PESQUISA EM CIÊNCIAS DA SAÚDE MESTRADO EM CIÊNCIAS DA REABILITAÇÃO

LUCAS MACIEL RABELLO

COMPARAÇÃO DA ELETROMIOGRAFIA DE SUPERFÍCIE E

ULTRASSONOGRAFIA DE IMAGEM NA ANÁLISE DO

COMPORTAMENTO DO MÚSCULO OBLÍQUO EXTERNO EM

DIFERENTES TAREFAS


Londrina 2013




DIFERENTES TAREFAS

Dissertação apresentada ao Programa de Pós-Graduação em Ciências da Reabilitação (Programa Associado entre Universidade Estadual de Londrina - UEL e Universidade Norte do Paraná - UNOPAR), como requisito parcial à obtenção do título de Mestre em Ciências da Reabilitação.

Orientador: Prof. Dr. Rubens Alexandre da Silva Junior.





DIFERENTES TAREFAS

Dissertação apresentada ao Programa de Pós-Graduação em Ciências da Reabilitação (Programa Associado entre Universidade Estadual de Londrina [UEL] e Universidade Norte do Paraná [UNOPAR]), como requisito parcial à obtenção do título de Mestre em Ciências da Reabilitação.

BANCA EXAMINADORA

___________________________________

Prof. Dr. Rubens Alexandre da Silva Jr. (Orientador)

Universidade Norte do Paraná

____________________________________ Prof. Dr.Rodrigo Franco de Oliveira

(Membro interno) Universidade Norte do Paraná

____________________________________ Prof. Dr. Leandro Ricardo Altimari

(Membro externo) Universidade Estadual de Londrina

Londrina, _____de ___________de _____.

DEDICATÓRIA

Dedido este trabalho à minha família e todos

aqueles que me incentivaram e me apoioaram

até a concretização deste sonho.

AGRADECIMENTOS

Primeiramente, agradeço a Deus. Agradeço a Ele por estar presente durante

toda a minha vida, nos momentos alegres e tristes, nos momentos em que decisões

importantes deveriam ser tomadas e Ele me mostrou o caminho a seguir. Foi Ele

quem ouviu minhas perguntas e me deu todas as respostas (no tempo certo). Meu

Deus, obrigado por abençoar meus passos e de todos que estiveram nesta jornada

comigo. “Não esqueço o que fez por mim./ Entregando sua vida em meu lugar. /

Nunca ninguém, Senhor, me amou de modo assim. / Eu descobri, ao Seu lado é

meu lugar.” – Rosa de Saron)

Aos meus pais, Beth e Heleno, obrigado por me apoiarem durante esses dois

anos de Mestrado (e durante os 26 anos da minha vida) e por estarem ao meu lado

quando aceitei o convite de estudar no Canadá. Tenho certeza que não teria

suportado toda a distância e não teria encarado todos os desafios se vocês não

estivessem tão presentes durante TODOS os dias!

Obrigado a minha Vó Elza e meu Tio Osvaldo por sempre me fazerem sentir

muito especial e fazendo a distância entre a gente tornar-se mínima! Muito Obrigado

por esse amor! E como minha vó disse: “Nunca estivemos tão próximos.”

Agradeço ao meu irmão Mateus e minha cunhada Silvia por também dividirem

esse momento comigo e por me suportarem! E aproveitando, agradeço a Fer. Minha

amiga, minha irmã... tudo!

A minha Família Maciel, tias, tios, primas e primo, muito obrigado! Sei que não

podemos estar juntos sempre, mas nem por isso deixamos de estar próximos!

Agradeço aos meus Avós que guiam meus passos ao lado de Deus e que

tenho certeza que estão vibrando com essa conquista. Obrigado!

Aos meus amigos e amigas de longa data e aos amigos que fiz durante os

dois anos de mestrado, muito obrigado! Sei que muitas vezes tive que abrir mão de

sair com vocês devido aos compromissos (principalmente nas últimas semanas).

Obrigado por estarem comigo a milhares de Km, seja por mensagens ou por Skype!

Vocês sempre me disseram: “Calma, vai dar tudo certo!”. E vocês estavam certos!

Aos meus amigos de Banda (Dirty Harrys). Juliano, Marcos, Zé e meu irmão! E

obrigado aos meus colegas Canadenses!! Em especial a Audrey, Annie Phan,

Annie-Claude, Hugo, Nabil e Alex! Obrigado ao Phillipe Paquette, que foi

fundamental para a realização deste Projeto.

Obrigado aos meus companheiros de Mestrado! Aprendemos juntos,

compartilhamos conhecimentos, alegrias e também momentos difíceis... foram horas

de conversas, de estudos durante dias e noites. Mas também tínhamos nossos

momentos de tranqüilidade nos churrascos e nas “reuniões” na Casa da Cachaça!

Em especial, agradeço o “Grupo”, vocês são pra sempre!

Aos Professores do Mestrado, muito obrigado! Obrigado por ensinarem

“conteúdos”, mas também muito obrigado por ensinarem “valores”. Obrigado a

Coordenação (Prof Fábio e Prof Vanessa).

Aos funcionários do Mestrado, em especial o secretário Gleydson. Sempre

disponível para ajudar. Além de secretário, tornou-se um grande amigo! Obrigado!

Agradeço os Engenheiros e colaboradores que estiveram comigo em

Montreal. Aos engenheiros Phillipe, Youseff (e Seléna), Michel e Daniel. Aos

professores do Instituto, aos alunos de Doutorado e Mestrado e todos os

funcionários. Em especial, obrigado ao engenheiro Hakim por desenvolver o

software para minhas análises e por estar sempre disponível!

Meus amigos de Laboratório. André, Rogério, Ana, Stheace, Camila, Patrícia

e todos os outros que estiveram com a gente durante esses 2 anos. A união de um

grupo nos leva a sonhos muito maiores! As publicações em Revista são

conseqüências de um trabalho bem feito. E obrigado aos professores que nos

orientam!

Agora, um “obrigado” mais do que especial. Professor Rubens, obrigado por

confiar em mim desde o começo. Foi você que confiou em mim e me deu a

oportunidade de realizar sonhos. Muito obrigado por ser mais do que um orientador,

obrigado por ser um Amigo! Compartilhamos nossas alegrias e nossas dificuldades.

E você me proporcionou a oportunidade de viver algo “mágico”! Obrigado por ser tão

diferente dos “outros” e por acreditar em valores a cima do que estamos

acostumados. Obrigado pela oportunidade de experimentar o que você viveu

durante anos em Montreal. A minha responsabilidade era muito grande (visto que

até hoje eles possuem um Banner fixo a parede de um dos seus trabalhos), tentei

não decepcionar! E tenho certeza que esta parceria só esta começando. Estamos

juntos para o que der e vier!

Ao meu orientador em Montreal, Dany Gagnon. Obrigado por me aceitar e

obrigado por aceitar esse desafio. Não foi fácil fazer um projeto em 6 meses, mas

conseguimos (obrigado por acreditar e confiar desde o começo!)! Obrigado por todos

os ensinamentos e por compartilhar todo conhecimento. Aprendi muitas coisas

novas e tive a oportunidade de realizar um trabalho maravilhoso. E que esta parceria

ainda possa ir além!

E ao Professor Christian Larivière que participou do nosso Projeto e orientou

o trabalho, compartilhando seu conhecimento. Obrigado pelos seus ensinamentos e

obrigado por me mostrar visões diferentes de um mesmo conteúdo.

ENFIM, OBRIGADO A TODOS VOCÊS!

“Quem acredita sempre alcança.”

“Todas as vitórias ocultam uma abdicação.”

(Simone de Beauvoir)

RABELLO, Lucas Maciel. Comparação da eletromiografia de superfície e ultrassonografia de imagem na análise do comportamento do músculo oblíquo externo em diferentes tarefas. 2013. 89 folhas. Trabalho de Conclusão de Curso

do Programa de Pós Graduação em Ciências da Reabilitação (Programa Associado entre Universidade Estadual de Londrina [UEL] e Universidade Norte do Paraná [UNOPAR]) – Universidade Norte do Paraná, Londrina, 2012.

RESUMO

A parede abdominal é composta de múltiplos músculos com arquitetura diferente e com o papel de controlar os movimentos do tronco nos três planos e promover a estabilidade da coluna lombar. Todavia, estes músculos estão envolvidos nas patologias comuns da coluna vertebral, como a dor lombar crônica. No processo de reabilitação é essencial avaliar especificamente a função dos músculos abdominais utilizando os sistemas de análise de alta tecnologia como o ultrassom de imagem (USI) e a eletromiografia (EMG) de superficie. A relação entre a atividade elétrica do músculo medida, por meio da EMG, e a espessura muscular, proveniente da medida do USI, permanecer ainda incerta, especialmente para os músculos abdominais superficiais tais como o oblíquo externo.O objetivo do presente estudo foi determinar a associação entre a espessura muscular e a atividade eletromiográfica do músculo oblíquo externo (OE). Dezoito sujeitos foram recrutados para realizar uma contração isométrica em rampa, de intensidade entre 5 à 50% de uma contração voluntária máxima, em três diferentes direções do movimento: flexião, flexão lateral e rotação do tronco. Os sujeitos foram posicionados em posição sentada no dinamômetro e dois eletrodos de EMG foram posicionados superficialmente sobre o músculo OE direito em dois ângulos diferentes (18º e 27º). O transdutor do ultrassom foi posicionado cinco mm abaixo dos eletrodos e as imagens foram registradas simultaneamente com a atividade elétrica do músculo. De acordo com a análise de variância, o músculo oblíquo externo foi mais ativo durante a flexão anterior e a rotação do tronco em comparação a flexão lateral (P < 0,05). Também, o comportamento da EMG entre os níveis de força (5-50%) não foi comparado com as alterações da espessura muscular. Somente para as medidas de EMG, os níveis de força durante a contração em rampa foram significamente diferentes (P < 0,05) entre eles (do menor para o maior). A relação entre a EMG e o USI foi determinada para cada sujeito individualmente devido a alta variabilidade entre os mesmos. A correlação entre as duas medidas variou de fraca a forte para as tarefas avaliadas. O presente estudo conclui que a ultrassonografia de imagem pode ser utilizada para avaliar a atividade do músculo oblíquo externo durante atividades de baixa intensidade (até 30% da CVM). Este resultado implica no uso do ultrassom de imagem no processo de avaliação e intervenção da função dos músculos do tronco em programas de reabilitação. Palavras chave: eletromiografia, ultrassom de imagem, músculos abdominais.

RABELLO, Lucas Maciel. Comparison of surface electromyography and ultrasound imaging in the analysis of the behavior of the external oblique muscle in different tasks. 2013. 89 pages. Trabalho de Conclusão de Curso do

Programa de Pós Graduação em Ciências da Reabilitação (Programa Associado entre Universidade Estadual de Londrina [UEL] e Universidade Norte do Paraná [UNOPAR]) – Universidade Norte do Paraná, Londrina, 2012.

ABSTRACT

The abdominal wall is composed of multiples muscles with different architecture and potential roles in controlling the movements of the trunk in three planes and promote stability of the lumbar spine. Though, those muscles are involved in common pathologies of the spine, as chronic low back pain. During the rehabilitation process, it is essential to assess specifically the function of the abdominal muscles using high-tech analysis system such as ultrasound imaging (USI) and superficial electromyography (EMG). The relationship between electrical muscle activity (measured with EMG) and the muscle thickness (measured with USI) remains still unclear, specially to the superficial abdominal muscle, such as the external oblique. The purpose of the present study was to determine the association between the relative muscular thickness change and the EMG muscular utilization ratio of the external oblique (EO) muscle. Eighteen subjects were recruited to perform ramp isometric, of intensity between 5 to 50% of the maximum voluntary contraction, in three different movement directions: flexion, lateral bending and rotation of the trunk. Subjects were positioned sitting on the dynamometer and two EMG electrodes were placed superficially over the right EO muscle, with different angles (18º and 27º). The US probe was placed five mm above the electrodes and the US images were registred simultaneously with the electrical muscle activity (EMG). According to analysis of variance, the external oblique muscle was more active during the anterior flexion and rotation effort, compared to the lateral bending (P<0,05). Also, the behavior of the EMG between the force levels (5 to 50%) was not compered to the muscle thickness changes (USI). Only for the meaures of the EMG, force levels during the ramp contraction were significant different (P < 0,05) between them (from lowest to highest). The relationship between the EMG and the USI was determined for each subject due the great variance between them. The correlation between the two measures ranged from poor to strong for tasks assessed. The present study concluded that ultrasound imaging can be used to evaluate the activity of the external oblique muscle during low intensity activities (up to 30% of MVC). These results implicate in the use of the ultrasound imaging in the evaluation and intervation process in the function of trubk muscles, specifically the external oblique muscle, in a rehabilitation program. Key words: electromyography, ultrasound imaging, abdominal muscles.

LISTA DE ILUSTRAÇÕES

Figura 1 – Músculos que compõe a parede abdominal .......................................... 23

Figura 2 – Posição do sujeito e do avaliador durante o teste .................................. 50

Figura 3 – Gabarito desenhado pelos autores para padronização da posição

dos eletrodos da EMG e do transdutor do USI ......................................................... 51

Figura 4 – Imagem do US descrevendo os locais utilizados para mensuração

da espessura do músculo oblíquo externo .............................................................. 52

LISTA DE TABELAS

Tabela 1 – Valores de %EMG e %Thickness em 5-50% da contração em

rampa para a direção em flexão ............................................................................... 53

Tabela 2 – Valores de %EMG e %Thickness em 5-50% da contração em

rampa para a direção em rotação ........................................................................... 54

Tabela 3 – Coeficiente de correlação de Pearson entre as médias dos valores

de %EMG e %Thickness em 5-50% da contração em rampa durante a flexão ....... 55

Tabela 4 – Coeficiente de correlação de Pearson entre as médias dos valores

de %EMG e %Thickness em 5-50% da contração em rampa durante rotação ........ 56

LISTA DE ABREVIATURAS E SIGLAS

RA Reto Abdominal / Rectus Abdominis

OE Oblíquo Externo

OI Oblíquo Interno

TrA Transverso do Abdome / Transversus Abdominis

EMG Eletromiografia / Electromyography

USI Ultrassom de Imagem / Ultrasound Imaging

FTL Fáscia Tóraco-lombar

RM Ressonância Magnética

LBP Low Back Pain

MRI Magnetic Resonance Imaging

SEMG Superficial Electromyography

EO External Oblique

IO Internal Oblique

BMI Body Mass Index

CRIR Center of Interdisciplinary Research in Rehabilitation of the Greater

Montreal

mm Milímetros / Millimeters

s Segundos / Second

MVC Maximum Voluntary Contraction

MVIC Maximum Voluntary Isometric Contraction

RMS Root Mean Square

TLF Thoracolumbar Fascia

DLC Dor Lombar Crônica

SUMÁRIO

1 INTRODUÇÃO ....................................................................................................... 12

2 OBJETIVOS.........................................................................................................15

2.1 OBJETIVO GERAL.................................................................................................15

2.2OBJETIVO ESPECÍFICO...........................................................................................15

3 REVISÃO DE LITERATURA - CONTEXTUALIZAÇÃO ........................................ 16

3.1 MÚSCULOS ABDOMINAIS ......................................................................................... 16

3.1.1 Orientação Dos Fascículos Musculares Do Abdome ....................................... 16

3.2 FUNÇÃO DOS MÚSCULOS ABDOMINAIS .................................................................... 17

3.3 PRINCIPAIS PATOLOGIAS DO TRONCO ASSOCIADAS AOS MÚSCULOS ABDOMINAIS ...... 18

3.4 MÉTODOS DE AVALIAÇÃO DA FUNÇÃO DO TRONCO .................................................... 19

3.4.1 Emetromiografia (EMG) .................................................................................... 19

3.4.2 Ultrassom de Imagem (USI) ............................................................................. 20

3.4.2.1 “Thickness” muscular .................................................................................... 21

3.5 Evidências Científicas Entre As Medidas De EMG e USI Na Avaliação Dos

Músculos Abominais.................................................................................................. 22

4 ARTIGO: ......... ....................................................................................................... 26

CONCLUSÃO GERAL .............................................................................................. 57

REFERÊNCIAS ........................................................................................................ 58

ANEXOS ................................................................................................................... 64

ANEXO A – Normas de formatação do periódico Journal of Electromyography

and Kinesiology ......................................................................................................... 65

ANEXO B – Carta de aceite do Comitê de Ética Local e Protocolo .......................... 77

ANEXO C – Termo de Conscentimento Livre e Esclarecido ..................................... 87

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1 INTRODUÇÃO

Os principais problemas associados à disfunção da coluna vertebral,

como a lombalgia crônica de origem não específica, têm relação com os músculos

do tronco, por exemplo, os músculos abdominais. Os quatro músculos que compõe a

parede abdominal, reto abdominal (RA), oblíquo externo (OE), oblíquo interno (OI) e

o transverso do abdome (TrA), são responsáveis por uma variedade de funções

essenciais nas atividades do corpo humano. Estes músculos produzem torque

necessário para realizar os movimentos de flexão, rotação e inclinação lateral da

coluna vertebral1,2, sustentam a cavidade abdominal, preservam a estabilidade da

coluna lombar durante tarefas simples como levantar-se, sentar-se e locomover-se3,4

assim como tarefas mais complexas durante os movimentos dinâmicos e com

sobrecargas5,6 e por fim, auxiliam também na respiração7. Sendo assim, esses

músculos apresentam um papel extremamente importante na prevenção e no

tratamento de doenças e disfunções da coluna vertebral8.

Bergmark (1989)9 propôs uma definição para tais músculos do

tronco quanto a sua funcionalidade. Segundo o autor, estes músculos responsáveis

pelo controle funcional do tronco podem ser classificados em dois grupos: 1) o

primeiro grupo, composto pelos músculos que se inserem diretamente na vértebra

lombar (multífidos, TrA e OI), os quais promovem a estabilidade segmentar da

coluna; e 2) o segundo grupo que consiste de grandes músculos geradores de

torque articular, mas sem inserções diretas na coluna lombar. Estes músculos

controlam os movimentos mais amplos do tronco (em grandes amplitudes de

movimento) e promovem também a estabilidade da coluna vertebral. Os músculos

que compõe este segundo grupo são: RA, OE e eretor da coluna torácica. Para o

interesse do presente trabalho e devido à utilização da eletromiografia de superfície,

somente uma investigação aprofundada do músculo obliquo externo (OE) será

realizada.

Apesar do número crescente de estudos desenvolvidos para avaliar

a funcionalidade do tronco com ênfase na prevenção e intervenção das disfunções

da coluna vertebral, pouco se sabe sobre os mecanismos específicos dos músculos

abdominais quando agindo de forma individual e/ou em conjunto com outras

estruturas passivas e ativas do tronco10. Estudos prévios avaliaram o papel dos

músculos abdominais com uso da eletromiografia (EMG) de superfície durante a

13

execução de diferentes tarefas para melhor entendimento do papel desses

músculos11. Sabe-se que o músculo OE está envolvido na orientação da coluna

vertebral12. Seroussi & Poupe (1987)13 observaram que o músculo OE, por exemplo,

se torna ativo durante o movimento sustentado de inclinação lateral do tronco em

indivíduos saudáveis. McGill (1991)14 observou também com uso da EMG que este

músculo, assim como o OI, participa dos movimentos de rotação do tronco durante

uma tarefa resistida. Outras evidências apontam que os músculos abdominais são

ativos simultaneamente para múltiplas funções do tronco15,16.

Por outro lado, a atividade dos músculos abdominais pode ser

influenciada pela postura adotada pelo indivíduo e, conseqüentemente, pela

estabilidade articular12,17,18. Em um estudo de Snijders et al (1995)19, observou-se

uma maior ativação dos músculos abdominais na posição sentada quando

comparada a posição supina. Porém, os mesmo autores, comparando a posição

sentada versus ortostática, encontraram uma menor ativação dos músculos

abdominais na posição sentada, devido o aumento na estabilidade da articulação

sacroilíaca20. A avaliação dos músculos abdominais na posição sentada é de

fundamental importância visto que o sedentarismo da vida moderna faz com que os

indivíduos permaneçam nesta posição por mais tempo21, levando ao

descondicionamento dos músculos do tronco, à sobrecarga lombar e ocasionando

assim, uma maior incidência de patologias da coluna vertebral22. Portanto, a

necessidade de se avaliar e compreender a função destes músculos para tomadas

de decisões clínicas na reabilitação é de suma importância.

A cada dia novos métodos e protocolos envolvendo a alta tecnologia

surgem para avaliar o papel dos músculos do tronco. Nos últimos anos, métodos de

avaliação desta musculatura, como a ultrassonografia de imagem (USI), tornaram-se

mais difundidos. Este sistema permite avaliar isoladamente o papel de alguns

músculos da parede abdominal, como por exemplo, as ações de um dos principais

músculos, o OE, durante diferentes tarefas motoras específicas23. A confiabilidade e

a validade do uso deste novo método para medidas da geometria muscular, quando

comparada a outras técnicas (ex: EMG, ressonância magnética), têm sido

confirmada na literatura24-27. Entretanto, ainda são necessários mais estudos para

avaliar a utilização da ultrassonografia de imagem para avaliar os músculos

abdominais. As mudanças nas medidas da espessura (thickness) dos músculos da

parede abdominal têm sido correlacionadas com o aumento dos valores (RMS)

14

obtidos com a EMG durante uma contração isométrica submáxima na posição

sentada reclinada28. Todavia, um recente estudo (2007)23 comparando a ativação do

músculo OE na posição supina por meio da EMG e USI, concluiu que as mudanças

na espessura muscular utilizadas como medida de atividade muscular deveriam ser

vistas com precaução na avaliação da funcionalidade do tronco devido a falta de

consistência entre as medidas. Sendo assim, mais estudos são ainda necessários

para melhor compreender o comportamento destes músculos em diferentes

posições, direções do movimento e sob a ação de diferentes intensidades de

contração muscular.

15

2 OBJETIVOS

2.1. Geral

Quantificar a espessura (thickness) muscular com o ultrassom de

imagem e a porcentagem da ativação muscular com a eletromiografia do oblíquo

externo direito durante as contrações unidirecionais em rampa na posição sentada

em indivíduos saudáveis.

2.2. Específicos

Determinar em qual(ais) direção(ões) do movimento o músculo

oblíquo externo apresenta maior ativação. E então para esta(s) direção(ões)

somente:

a) comparar os níveis de contração muscular submáxima para as

principais variáveis (atividade elétrica e thcinkness muscular) com a finalidade de

determinar se as intensidades de contração muscular distinguem tanto nas

mudanças da espessura quanto na ativadade elétrica; e

b) determinar a associação entre as medidas de espessura muscular

e atividade eletromiográfica do músculo oblíquo externo.

.

16

3 REVISÃO DE LITERATURA – CONTEXTUALIZAÇÃO

3.1 MÚSCULOS ABDOMINAIS

A musculatura abdominal pode ser dividida em parede abdominal

lateral, composta pelo oblíquo externo (OE), oblíquo interno (OI), e o transverso do

abdômen (TrA); e parede anterior, composta pelo reto abdominal (RA) e a fáscia

abdominal anterior27.

Em geral, estes músculos são importantes para funcionalidade do

tronco para os diferentes movimentos corporais. Também, eles preservam e auxiliam

na estabilidade da região lombar quanto aos stress e as sobrecargas nas estruturas

passivas da coluna vertebral29. É importante ressaltar que a disfunção desses

músculos pode promover a instabilidade da coluna vertebral, aumentar as

sobrecargas e consequentemente os riscos de lesões nas estruturas ligamentares e

articulares da região lombar. Alguns autores apontam que a instabilidade da coluna

vertebral leva a dor lombar crônica e as incapacidades funcionais em adultos30,31.

3.1.1 Orientação dos Fascículos Musculares do Abdome

A parede abdominal (Figura 1) pode ser dividida em: parede abdominal

lateral e parede abdominal anterior.

Os músculos da parede abdominal lateral podem ser divididos em três

regiões: superior (acima da décima primeira cartilagem costal), medial (entre a

décima primeira cartilagem e a crista ilíaca) e inferior (abaixo da crista ilíaca)35. Os

músculos que compõe a parede abdominal lateral são: OE, OI e TrA.

Em relação a parede abdominal anterior, esta é composta pelo

músculo reto abdominal e pela fáscia abdominal anterior. A linha alba divide a

parede abdominal anterior em direita e esquerda27.

As fibras musculares do OE se originam na borda externa das oito

costelas inferiores e se inserem na linha alba e na metade ou no terço anterior da

crista ilíaca33,34. Alguns autores descrevem a inserção do OE na fáscia toracolombar

(FTL) nos níveis lombares superiores35, enquanto outros autores descrevem a

localização na margem posterior livre34. Biomecanicamente, o músculo OE

17

apresenta três direções de fibras (ventral, lateral e dorsal), sendo cada uma dessas

responsáveis por produzir diferentes forças direcionais. A contração unilateral deste

músculo resulta na rotação do tronco para o lado oposto e quando contraído

bilateralmente, realiza a flexão anterior do tronco e aumenta a pressão

intrabdominal36.

O músculo OI se origina nos dois terços anteriores da crista ilíaca e a

na metade ou no terço lateral do ligamento inguinal, e se insere nas cartilagens

costais inferiores, na linha alba e na sínfise púbica33,34.

Já o músculo TrA se origina na superfície interna da cartilagem das

seis costelas inferiores, da FTL, nos dois terços anteriores da crista ilíaca e no terço

lateral do ligamento inguinal e se insere anteriormente na linha alba e na pelve33,34.

O RA tem a maior espessura de todos os músculos abdominais. Este

músculo se origina no processo xifóide e nas cartilagens costais (da quinta a sétima

costelas) e se insere na sínfise púbica, crista púbica e tubérculo púbico37.

A fáscia abdominal lateral para o músculo RA é um arranjo complexo

de conexões aponeuróticas de cada músculo que compõe a parede abdominal

lateral e o “RA sheath” (compartimento aponeurórico onde o reto abdominal esta

contido)33,34,38. As fibras de cada músculo da parede lateral cruzam a linha média e

se unem às fibras dos músculos que compõe a parede abdominal lateral

contralateral para formar a linha Alba. Esta linha auxilia na distribuição de cargas

entre os lados para parede abdominal27.

3.2 FUNÇÃO DOS MÚSCULOS ABDOMINAIS

Sabe-se que o papel principal dos músculos abdominais é de gerar

força para produzir movimento do tronco e estabilização da coluna vertebral, em

especial da região lombar. Porém, ainda não está bem elucidado os mecanismos de

ação conjunta e individual de cada músculo para cada tipo de movimento do

tronco39. Diversos autores têm estudado a função dos músculos da parede

abdominal anterolateral nos últimos anos. Três modelos predominam para a função

desses músculos em associação com os músculos paraespinhais: 1) a cocontração

entre os músculos flexores e extensores do tronco40,41; 2) a integração de todos os

músculos durante uma tarefa específica42,43, e 3) a função muscular local versus

global9,44,45.

18

Os resultados do trabalho de Gardner-Morse et al (1998)40, mostraram

que os músculos agonistas e antagonistas coativados aumentam a estabilidade da

coluna lombar. Esses achados suportam a hipótese de que os músculos funcionam

não somente como promotores de torque articular durante o movimento do tronco,

mas também como molas estabilizadoras na contenção de sobrecargas articulares

da coluna vertebral41.

Para Bergmark (1989)9, os músculos transverso do abdomem e oblíquo

interno são parte de um grupo muscular capaz de promover a estabilidade

segmentar da coluna. Enquanto que, os músculos reto abdominal e oblíquo externo

são parte de um segundo grupo responsável pelo controle dos movimentos amplos

do tronco além de promoverem a estabilidade da coluna vertebral. Outra teoria,

conforme Richardson et al (1999)44, salienta que os músculos abdominais laterais

são teoricamente responsáveis pelo controle do movimento e por promover a

estabilidade do tronco para atividades funcionais, enquanto que o músculo

transverso do abdome é responsável pelo suporte e proteção da coluna46.

Já a teoria de Panjabi (1992)29,30 sugere que o sistema de estabilidade

da coluna é composto por três subsistemas: 1) Subsistema passivo (vértebras,

facetas articulares, discos intervertebrais, ligamentos espinhais e capsulas

articulares) que promove a estabilidade intrínsica da coluna; 2) Subsistema ativo

(músculos e tendões ao redor da coluna) responsável pela estabilidade dinâmica e

os movimentos da coluna vertebral; e 3) Subsistema neural (central e periférico, tais

como os receptores sensitivos localizados nos ligamentos, tendões e músculos)

associado ao controle motor. Este último subsistema é responsável por avaliar e

determinar os requisitos de estabilidade e coordenação das respostas musculares

do tronco. Para Panjabi, a instabilidade toda da coluna vertebral é presente quando

um ou mais destes subsistemas não funcionam adequadamente ou são

deteriorados.

3.3 PRINCIPAIS PATOLOGIAS DO TRONCO ASSOCIADAS AOS MÚSCULOS ABDOMINAIS

As disfunções lombo-pélvicas, como espondilólise, espondilolistese,

dor pélvica posterior associada à gravidez e dor lombar crônica são associadas com

a disfunção dos músculos do tronco, incluindo os músculos abdominais27.

19

A dor lombar tem sido uma das patologias do tronco de maior estudo e

pesquisa nos últimos anos. Em adultos jovens, o descondicionamento muscular e a

má coordenação motora dos músculos do tronco estão associados à dor lombar

crônica47. A dor lombar crônica é uma patologia comum, com incidência superior a

80%48, e uma prevalência em crescimento contínuo mundialmente49.

Os músculos abdominais têm um importante papel na prevenção e no

processo de intervenção das disfunções da coluna vertebral. Programas de

treinamento de estabilização da coluna lombar, o qual requer a participação

constante desta importante musculatura, têm demonstrado resultados positivos

quanto aos sintomas clínicos (redução da dor, incapacidades e recorrência das

dores) de pacientes com dor lombar crônica50-52. Assim, a utilização de novos

métodos de avaliação desta musculatura, que sejam válidos e fidedignos, é de suma

importância para o diagnóstico e as tomadas de decisões clínicas quanto às

diferentes intervenções propostas para conter a disfunção desta musculatura.

3.4 MÉTODOS DE AVALIAÇÃO DA FUNÇÃO DO TRONCO

Uma das técnicas mais utilizadas para avaliação da ativação muscular

é a eletromiografia (EMG) de superfície. A EMG é definida como o registro da

atividade elétrica muscular. O registro do sinal eletromiografico pelo equipamento é

a soma do potencial de ação de diferentes unidades motoras ativas durante a

contração muscular53. Recentemente outros métodos têm sido empregados na

prática clínica e para pesquisas científicas para avaliação da atividade muscular. Um

desses métodos é a Ultrasonografia de imagem (USI).

Esses dois métodos de avaliação serão abordados nas próximas sessões

deste trabalho.

3.4.1 Eletromiografia (EMG)

A eletromiografia é amplamente utilizada por possibilitar a observação

do comportamento muscular durante atividades funcionais específicas, além de

possibilitar a quantificação da atividade muscular elétrica para descrição e

comparação entre diferentes músculos e indivíduos54,55. Além disso, a EMG pode ser

relacionada com a quantidade de força desenvolvida por um músculo56.

20

Para avaliação dos músculos abdominais alguns autores utilizam a

EMG intramuscular50,57, porém, devido ao alto custo, desconforto do paciente e a

dificuldade de aplicação desta técnica na prática clínica58, a EMG de superfície vem

sendo empregada por diversos autores23,59,60.

A avaliação por meio da eletromiografia de superfície tornou-se um

método popular de investigação da função muscular. Em diversos estudos clínicos, a

EMG é utilizada para analisar a função dos músculos do membro superior, inferior e

tronco61, as disordens do movimento62 e alteraçoes posturais relacionadas as cargas

de trabalho dentro da ergonomia63.

Uma forma de interpretar os sinais provenientes da EMG, é quantificar

os dados brutos em raiz quadrada da média da amplitude do sinal, chamada de:

RMS – Root Mean Square. Esta forma de análise contempla as alterações

fisiológicas do sinal eletromiográfico, e reflete o número de unidades motoras ativas,

além da frequência de disparo dessas mesmas unidades motoras e a forma do

potencial de ação64. Outras formas de se interpretar os sinais da EMG são

destacadas na literatura, principalmente no domínio da frequência65. Todavia,

somente a forma RMS será aplicada no presente estudo.

3.4.2 Ultrassom de Imagem (USI)

O Ultra-ssom de imagem (USI) é utilizado na área médica desde os

anos 50. O principal uso do USI continua sendo na radiologia tradicional, a qual

considera as características morfológicas e a integridade estrutural de vários órgãos

e tecidos. Entretanto, como esta tecnologia foi comprovada como uma forma segura,

portátil, objetiva e relativamente barata para a realização de exames, a diversidade

de aplicações estendeu além da prática médica66.

Em 1968, Ikai e Fukunaga (1968)67 fizeram o primeiro relato de uma

imagem muscular relacionada a reabilitação. Neste estudo, os autores relacionaram

o comprimento e espessura do membro superior (ex: braço) com a força muscular.

Porém, foi o trabalho do Dr Archie Young et al na Universidade de Oxford em 1980

que deu início ao uso do USI pelos fisioterapeutas. A descoberta do seu trabalho foi

como a atrofia dos membros inferiores era substimado com uma fita métrica68.

Desde então, o USI vem sendo usado para a reabilitação musculoesquelética.

21

Em maio de 2006, um simpósio organizado pela US Army-Baylor

University Doctoral Program em San Diego-Tx foi proposto um consenso o qual

declara: “Ultra-som de imagem para reabilitação é um procedimento usado pelo

fisioterapeuta para avaliar a morfologia e função dos músculos e tecidos moles

adjacentes durante os exercícios físicos e tarefas funcionais”69.

O USI pode avaliar a espessura muscular e a área de secção-

transversa. Este método pode determinar a atrofia muscular70,71 e os déficits da

ativação26,28,72. Além disso, a espessura muscular obtida pelo ultrassom pode ser

interpretada com um indicador de geração de força muscular73. Em estudos

anteriores, autores observaram uma relação positiva entre a espessura dos

músculos da mastigação e a magnitude da força da mordida74,75.

Em uma comparação feita entre a ressonância magnética e o USI,

Hides et al (2006)24 observaram que as medidas da espessura muscular do

transverso abdominal e do oblóquo interno, assim como também o deslocamento da

fáscia, eram correlacionados com as medidas obtidas por meio da ressonância

magnética. Em uma revisão sistemática, Hebert et al (2009)76 concluiram que apesar

do USI apresentar uma confiabilidade e precisão adequada para a quantificação da

espessura e da área-transversa dos músculos abdominais e lombares, ainda são

necessários novas pesquisas para aumentar o entendimento da área.

3.4.2.1 Espessura muscular

Considerando-se a espessura relativa dos músculos abdominais, o

músculo RA é o de maior espessura enquanto o músculo TrA é o de menor. Em

indivíduos sem história de dor lombo-pélvica, os músculos RA, OI, OE, e TrA

representam 35%, 28% , 22%, e 13% de toda espessura somada do músculo

abdominal (±2,4% para ±4,8%), respectivamente37. Este padrão é independente do

gênero, local avaliado (esquerda e/ou direita), e região abdominal27.

O exame de Ressonância Magnética (RM) é considerado o padrão-

ouro para avaliar a morfologia muscular. Recentemente, a RM começou a ser

utilizada para avaliar a mudança do “thickness” dos músculos da parede abdominal

lateral durante o respouso24. Porém esta técnica apresenta alto custo e restrições de

uso em determinados pacientes (ex. Pacientes com implantes metálicos) devido ao

campo magnético gerado. Sendo assim, o ultrassom de imagem torna-se uma boa

22

opção para avaliar a morfologia muscular e comportamento de alguns músculos

durante o movimento humano.

3.5 EVIDÊNCIAS CIENTÍFICAS ENTRE AS MEDIDAS DE EMG E USI NA AVALIAÇÃO DOS

MÚSCULOS ABDOMINAIS

A relação entre a medida do thickness muscular com uso do ultrassom

e da ativação muscular pela eletromiografia ainda necessita de novos estudos,

porém, alguns autores apresentam resultados interessantes para diferentes tipos de

contração dos músculos abdominais. Os achados são claramente inconclusivos até

o momento, com uma correlação estatística entre os dois métodos que varia de fraca

a forte (0.14 a 0.93).

Em um estudo realizado por McMeeken et al (2004)26, oberservou-se

uma boa correlação entre o USI e a EMG para o músculo transverso do abdome (R²

= 0.87). Sendo assim, os autores concluíram que a mudança do thickness do

músculo TrA pode ser utilizada para indicar mudanças na atividade elétrica deste

músculo.

Para Hodges et al (2003)28, as medidas da arquitetura muscular por

meio do USI promovem medidas da atividade para menores níveis de contração

muscular (< que 20 ou 30% de uma contração voluntária máxima). Todavia, este

método não pode ser utilizado para diferenciar as atividades musculares em níveis

de força de moderado a alto, em razão que os músculos abdominais apresentam

pequenas mudanças em suas estruturas morfológicas para essas intensidades. Por

fim, estes autores observaram um comportamento diferente do músculo OE quando

comparado ao OI e o TrA durante a contração isométrica da parede abdominal. Os

autores concluíram que, par ao músculo OE, não há uma relação consistente entre a

atividade elétrica muscular (EMG) e a espessura muscular (USI) durante a

flexão/extensão e contração isométrica do tronco.

Em um estudo mais recente realizado por Brown e McGill (2010)73,

concluiu-se que existe uma relação complexa entre a ativação muscular e a

mudança do thickness muscular. Estes autores não encontraram nenhuma relação

entre a USI e a EMG para os músculos OE (r = 0.22) e OI (r = 0.14) durante a

contração isométrica em rampa.

23

Já o estudo de John & Beithe (2007)23 concluiu que a mudança na

espessura do músculo OE caracterizada por medida de atividade muscular deve ser

usada com cautela quando este músculo atua na rotação do tronco como agonista

principal do movimento durante a contração isométrica.

Por fim, ainda é necessário mais estudos na área para melhor entender

a relação entre as duas medidas, principalmente utilizando novos protocolos de

avaliação. O presente trabalho pretende avaliar somente um músculo abdominal, o

OE. Outro aspecto importante é avaliar os dois métodos (USI e EMG) usando um

tipo de contração muscular que promova diferentes intensidades de força (5 a 50%

da contração voluntária máxima), em uma contração do tipo rampa, na qual é

definida como a produção de uma única força progressiva de contração linear de

baixa a alta intensidade (0 a 100%) durante poucos segundos (ex: 5 a 10 s)75. Para

conhecimento autoral, poucos estudos utilizaram este procedimento e compararam

as medidas em diferentes níveis de contração muscular e direções do movimento

como flexão, inclinação lateral e rotação do tronco em um mesmo estudo. Por fim a

postura do individuo durante a avaliação é de suma importância. No presente estudo

foi escolhida a posição sentada com apoio pois esta pode representar mais as

atividades diárias e também por esta se relacionar com a dor lombar crônica70.

24

Ilustrações

25

Figura 1- Músculos que compõem a parede abdominal.

26

ARTIGO

(Artigo completosubmetido no periódico Jounal of Electromyography and Kinesiology no mês de Abril

de 2013)

27

<Title>

External Abdominal Oblique Muscle Thickness Changes Measured Using Ultrasound

Imaging is Not an Appropriate Surrogate Measure of Electromyographic Activity During

Isometric Trunk Contractions

<Authors>

Lucas M. Rabelloa,b,c

; Dany Gagnonc,d

; Christian Larivièrec,e

; Philippe Paquettec,d

; Rubens A.

da Silvaa,b,c*

Affiliation

a. Centre for Health Science Research, Laboratory of functional evaluation and human

motor performance, Universidade Norte do Paraná (UNOPAR), Londrina-PR, Brazil.

b. Master’s Program in Rehabilitation Sciences UEL/UNOPAR, Londrina-PR, Brazil.

c. Pathokinesiology Laboratory, Centre for Interdisciplinary Research in

Rehabilitation of Greater Montreal, Institut de réadaptation Gingras-Lindsay-de-

Montréal, Montreal, Quebec, Canada.

d.School of Rehabilitation, Faculty of Medicine, Université de Montréal, Montreal,

Quebec, Canada.

e. Occupational Health and Safety Research Institute Robert-Sauvé (IRSST) Montreal,

Quebec, Canada.

*Corresponding Author

Rubens A. da Silva, Ph.D.

Centre for Health Science Research, Laboratory of functional evaluation and human motor

performance (LAFUP).

Universidade Norte do Paraná (UNOPAR).

Av. Paris, 675 - Jd. Piza CEP 86041-140 - Cx. P. 401

Londrina-PR, Brazil.

Telephone: 011 55 (43) 3371-7700 #7990

Fax: 011 55 (43) 3371-7721

Email: [email protected]

28

Abstract

This study was conducted to assess the validity of ultrasound imaging (USI) thickness

measures of right external oblique (EO) muscle activity. Eighteen subjects were instructed to

sit on a dynamometer and execute ramp isometric efforts progressing from 0 to 50% of the

maximal voluntary contraction (MVC) in three trunk directions: (1) forward flexion; (2) right

lateral flexion; and (3) left axial rotation. USI and surface electromyography (EMG) of the

EO muscle were measured concomitantly. EMG and USI thickness changes were both

normalized against rest and maximal EMG respectively. Based on the EMG results, the EO

muscle was significantly more activated (p 0.001) during forward flexion (42% on average)

and axial rotation (35%) than during lateral flexion (24%). Non-significant (r = 0.01; P =

0.979) to highly significant (r = 0.98; P < 0.0001) negative and positive Pearson correlations

were observed between EMG and USI for both flexion and rotation directions across

individuals. The USI validity was better related to rotation direction efforts. These results

support the idea that quantitative musculoskeletal ultrasound imaging and EMG of the EO

muscle provides different but complementary information when investigating muscular

recruitment during isometric trunk contractions.

Keywords: Electromyography, ultrasonography, trunk muscle, biomechanics, rehabilitation

29

1. Introduction

Abdominal wall muscle function is often an area of interest within rehabilitation

programs related to lumbar spine stabilization in patients with low back pain (LBP). In

keeping with the mechanical stability of the spine hypothesis (Panjabi, 1992a, Panjabi,

2006b), some evidence suggests that LBP patients can present spinal dysfunctions related to

the trunk neuromuscular system (Dankaerts et al., 2006), potentially leading to unstable spinal

segments and back pain. The abdominal muscles play a crucial role in adequate

neuromuscular control of the lumbar spine because they are involved during various efforts

generated in forward flexion, lateral bending and axial rotation (Marras et al., 1990; McGill,

1991; Thelen et al., 1994).

The function of specific abdominal muscles can be assessed using a variety of

techniques such as intramuscular fine-wire electromyography (EMG) or functional magnetic

resonance imaging (D´hooge B et al., 2013). However, these two techniques are both costly

and uncomfortable and therefore impractical for clinical use. More practical methods such as

surface EMG (De Luca et al., 2012) and more recently, ultrasound imaging (USI) (Whittaker

et al., 2007; Teyhen, 2006a), have been used for assessing the abdominal muscles during

various tasks.

USI has grown in popularity in research and clinical settings as a reliable, non-

invasive technique for assessing abdominal muscle function (McMeeken et al., 2004; Teyhen

et al., 2007b; Costa et al., 2009). This technique has been used to estimate the activity of

transversus abdominis (Hodges et al., 2003; McMeeken et al., 2004) and external and internal

oblique muscles (Hodges et al., 2003) by measuring changes in muscle thickness. However,

the relationship between EMG activity and muscle thickness changes remains unclear in

terms of the abdominal wall muscles (Brown and McGill, 2010), which calls into question the

validity of USI-based thickness measures of muscle activity.

30

As recently discussed by Brown and McGill (2010), “the mechanical interaction

between the abdominal muscle layers makes for complex deformation patterns that differ

dependent upon the relative action of each muscle.” Consequently, the validity of USI

measures as an estimate of muscle activity may depend on the complexity of the tasks as well

as the muscle being investigated. There are some obvious advantages of studying the three

abdominal layers (external and internal obliques and transversus abdominis) at the same time

using USI to understand the relative contribution of each muscle (Rankin et al., 2006).

However, the relationship between external oblique (EO) USI thickness and EMG activity has

seldom been studied (Brown and McGill, 2010; John & Beith, 2007; Hodges et al., 2003),

despite playing a primary role in axial trunk rotation and participating in some movements of

trunk flexion and lateral bending (Peach et al., 1998). As a result, further research is certainly

required.

To date, two studies (Brown and McGill, 2010; Hodges et al., 2003) found no

significant relationship (r correlation of -0.22 and 0.23, respectively) between the two

measures (EMG and USI) during trunk flexion contraction (in both studies) and brace, hollow

and extension trunk efforts (in Brow and McGill only). However, these studies used a small

sample of subjects (5 and 3, respectively), which likely did not accurately represent inter-

individual variations. Neither of these two studies investigated a task involving the primary

role of this muscle (axial rotation), which clearly appears to make a difference according to

the results previously reported by John & Beith (2007). John & Beith (2007) substantiated the

EO USI and EMG relationship in 24 subjects during axial rotation effort and found a

significant linear relationship in 21 of the 24 subject but the strength of this relationship was

undoubtedly different across subjects. However, the axial rotation effort was controlled using

the EO EMG as biofeedback, which is not an ideal method for standardizing the EO

biomechanical demand. The main purpose of this study was therefore to assess the

31

relationship between USI thickness and EMG (concurrent validity) with respect to right EO

muscle activation using a dynamometer to produce isometric efforts in three trunk directions

(forward flexion, right lateral flexion and left axial rotation) with real-time contraction

direction- and velocity-specific visual feedback controlling isometric contraction efforts from

one plane (e.g., axial rotation in the transverse plane) while minimizing efforts in the other

planes (e.g., frontal and sagittal planes) (Larivière et al., (2009). Finally, since the EO muscle

is comprised of many fascicules having different directions and functions (Mirka et al., 1997),

we tested whether previously observed inter-individual variations could be partly explained

by the tested EO fascicule.

2. Methods

2.1. Subjects

Twenty-three men were recruited from the local community using a convenient and

voluntary sampling method. The inclusion criteria for the study were as follows: participants

must be healthy and must not be involved in regular physical activity programs. Subjects were

excluded if they had suffered back pain in the previous year or back pain lasting longer than

one week in previous years; had a history of self-reported injuries, illnesses, musculoskeletal

disorders, systemic–neurological or degenerative disorders or cardiovascular or respiratory

disease. Five of the 23 subjects were excluded at the laboratory due to excessive fat in the

abdominal region and reduced space between the last rib and the iliac crest, making USI much

too difficult. This resulted in a total sample of 18 subjects. The mean characteristics of these

18 subjects were: 25 years of age [Standard Deviation (SD) = 8], height of 1.78 m (SD = 1),

mass of 73 kg (SD = 5), and a body mass index of 23 kg/m2 (SD = 2).

32

The research was conducted at the Institut de réadaptation Gingras-Lindsay-de-

Montréal, a research site of the Centre for Interdisciplinary Research in Rehabilitation of

Greater Montreal (CRIR). The subjects signed the consent form after receiving verbal and

written information about the study. The protocol and consent form were approved by the

local ethics committee (CRIR 716-0312).

2.2. Experimental procedures

All subjects were invited to one evaluation session only. They first underwent a

structured interview conducted by a physiotherapist to collect basic information including

demographics and anthropometric measures, followed by a physical examination.

Subjects were then placed in a sitting position, with their trunk straight, on a

dynamometer. EMG electrodes were attached to the skin while seated on the dynamometer.

The pelvis, legs and thorax segments were stabilized to better isolate the EO biomechanical

demand (Figure 1). Subjects were asked to keep their arms crossed during all tests. Next, they

were instructed to remain at rest while a baseline USI image (EO thickness measures at rest)

was recorded.

To familiarize the subjects with the protocol and visual feedback, three submaximal

contractions were performed in each of the following three directions: (1) forward flexion, (2)

right lateral flexion and (3) left axial rotation of the trunk. Five minutes after the

familiarization period, three isometric maximal voluntary contractions (MVC) were

performed in each direction to record maximal EMG activation for normalization purposes.

Each MVC lasted 8 seconds (s), with 2 minutes (m) of rest between trials. Visual feedback

and verbal encouragement were given to obtain maximal effort.

Ten minutes after the MVCs, the subjects performed three ramp contractions ranging

from 0 to 55% of the MVC in each direction (forward flexion, lateral flexion and axial

33

rotation). The directions were randomly presented. Each submaximal ramp contraction lasted

6 seconds (s), with 1 minute of rest between each trial. In order to obtain stable EMG and USI

measurements, the subjects were required to hold their breath (after an inhalation) during all

the contractions.

2.3. Measurement techniques

Dynamometric, EMG and ultrasound data was synchronized by triggering the data

collection of all instruments with the ultrasound pedal, which was pressed by the ultrasound

operator.

Dynamometry

A 3D isometric dynamometer was used to measure and control the L5/S1 moments

during the tasks (Larivière et al., 2009). This dynamometer is comprised of a tri-axial force

platform (Advanced Mechanical Technology Incorporated, model MC6-6-1000) that records

the force produced on the three axes at a sampling rate of 100 Hz. This equipment allows for

the stabilization of the feet, knees, pelvis and trunk. As explained elsewhere (Larivière et al.,

2009), this dynamometer is combined with visual feedback (3D – feedback), which allows the

subjects to produce the main effort in one direction (e.g., flexion, rotation or lateral bending)

while minimizing the production of force moments in the other directions.

Ultrasound imaging

To assess muscular thickness, a Phillips HD11 1.0.6 ultrasound machine and a 5–12

MHz 50-mm linear array transducer (model L12-5; Philips Medical Systems, Bothell, WA)

were used. The position of the USI transducer was standardized (see Electromyography

section below), a distance which prevented the electrodes from coming into contact with the

34

ultrasound gel. The image gain (85 dB) and depth (7 cm) were standardized to optimally

visualize the muscle fascia boundaries of the EO muscle. A well-trained physiotherapist

experienced in musculoskeletal ultrasound imaging was responsible for holding the

ultrasound transducer and starting the 10-s ultrasound video (sampling rate: 23 Hz) for each

trial using a standardized protocol.

Electromyography

EMG signals were collected at a sampling rate of 2000 Hz with a 16-channel EMG

system (Delsys Inc., Wellesley, MA). This system uses active surface electrode pairs (Model

DE-2.3) composed of two silver bars (10 mm long, 1 mm wide) spaced 10 mm apart. Two

electrode pairs were placed over the right external oblique (EO). As proposed by Mirka et al.,

(1997), the first electrode pair, hereafter called EMG1, was positioned at an angle of 63° from

horizontal (which corresponds to electrode #2 in Mirka et al.) while the second electrode pair,

hereafter called EMG2, was positioned at an angle of 72° from horizontal (which corresponds

to electrode #3 in Mirka et al.). A hole-punched template to mark the position of the two

electrode pairs as well as the placement of the ultrasound transducer was positioned 2.5 cm

from the EO muscle insertion into the lateral region of the rectus abdominus fascia and

identified with the ultrasound system. The vertical distance between EMG1 and EMG2

relative to transducer was 5mm and 8mm, respectively, and the distance of electrodes (EMG1

and EMG2) center to center was 33 mm (see Figure 2). The skin was shaved and abraded with

alcohol before placement of the electrodes. A silver/silver chloride reference electrode was

positioned over the olecranon.

35

2.4 Data analysis

All data processing was performed using Matlab subroutines (Version 7.0, release 14;

MathWorks Inc., Natick, MA). The USI and EMG variables were extracted across contraction

intensities related to each 5% force level (5–50% of the MVC) from each of the trunk

directions, taking into account a 130-m electromechanical delay (van Dieen et al., 1991).

All EMG signals were first bandpass filtered (30 and 450 Hz) to remove high-

frequency noise and ECG artefacts using a zero-phase, eight-order Butterworth filter. As for

the EMG signals recorded during MVCs, a moving root mean square (RMS) processing

method was executed on consecutive 250-m (512 points) time windows (50% overlapped).

For each EMG recording, the peak RMS value across all MVC trials (in all three directions)

represented the maximal EMG activity (RMSMAX). The EMG RMS computed during the

submaximal contractions (RMSSUBMAX), using centered 250-m time windows, was then

normalized to its corresponding RMSMAX value, hereafter called the EMG muscle activation

level, as illustrated in the following equation:

EMG Muscle Activation Level (%) = [(RMSSUBMAX / RMSMAX × 100%)]

The normalized values corresponding to the three trials were then averaged for further

analysis for each direction and electrode (EMG1 and EMG2).

USI images were selected as close as possible to the epochs selected for the EMG

analyses, which led to a maximal error of 0.04 s, given the video sampling rate (23 Hz). Each

image was divided in two sides: the medial side (Thickness-1) related to EMG1 (at an angle

of 63°); and the lateral side (Thickness-2) related to EMG2 (at an angle of 72°). To calculate

the thickness changes, the evaluator marked a 1-cm area (see Figure 3). The mean thickness

across 3 trials was then retained. The USI thickness measures during submaximal contractions

(THICKNESSSUBMAX) for each direction and electrode measurement were normalized relative

36

to the thickness recorded when the subject was asked to relax at the beginning of the protocol

(THICKNESSREST), using the following equation:

USI-based thickness (%) = [(THICKNESSSUBMAX / THICKNESSREST× 100%)]

Based on this equation, 110% means that the muscle thickness was 10% greater than at rest.

2.4.1 Statistical analysis

All statistical analyses were done with SPSS software (version 15.0 for Windows)

with an alpha level of 0.05 indicating statistical significance. The normality of the data was

verified with the Wilk–Shapiro test. Since the data from both measures (USI and EMG)

followed a normal distribution, the analyses were subsequently performed using parametric

statistical tests and the results were presented using mean and Standard Deviation (SD)

values.

To determine which trunk direction activated the EO muscle the most, as assessed

only with EMG1 and EMG2 electrodes, a one-way ANOVA with repeated measures was

carried out to compare EMG muscle activation level values at 50% of the MVC of the ramp

contraction among the three isometric direction efforts.

Considering that USI thickness measures are burdensome, we elected to reject the

lateral bending task based on these EMG results. Subsequently, a one-way ANOVA with

repeated measures was performed to compare EMG muscle activation and USI-based

thickness level values across the 10 intensities (ranging from 5 to 50% of the MVC) for the

isometric forward flexion and left axial rotation contraction directions. A one-way ANOVA

was independently run for each variable (EMG1, EMG2, Thickness-1, Thickness-2). Post-hoc

Tukey tests were applied as required to further identify differences between the intensities for

each direction.

37

To look at inter-individual variability in the EMG/USI relationship in each isometric

flexion and rotation effort direction, Pearson correlation coefficients (r) were calculated

between muscular thickness and EMG variables across the intensities for each participant

individually in order to determine the validity of the USI-based thickness measures of EO

muscle activation.

3. Results

3.1 Differences across isometric movement directions

The mean relative values for EMG1 during forward flexion, right lateral flexion and

left axial rotation were 35.57% (SD = 14.12), 18.41% (SD = 12.95) and 29.03% (SD = 12.13),

respectively. The mean values for EMG2 during forward flexion, right lateral flexion and left

axial rotation were 38.11% (SD = 10.78), 22.99% (SD = 10.23) and 31.44% (SD = 7.04),

respectively. Significant differences (P 0.01) were found for both EMG1 and EMG2

between the three isometric contraction directions. A post-hoc Tukey test revealed significant

differences between the forward flexion and right lateral directions (EMG1 P< 0.001; EMG2

P = 0.027) as well as between the left axial rotation and right lateral directions (EMG1 P<

0.001; EMG2 P = 0.006). As previously stated, the right lateral flexion direction was rejected

for subsequent analyses and only the main isometric contraction directions (flexion and

rotation) were used to determine whether the proposed contraction intensities indeed trigger

distinct muscular thickness and EMG changes (section 3.2 ) and to attempt to further validate

the USI measures (see section 3.3).

38

3.2 Effects of progressing relative isometric contraction intensities

Progressing relative isometric contraction intensities ranging from 5 to 50% resulted in

similar effects during the forward flexion and left axial rotation isometric contraction

directions (See Table 1 and Table 2). For EMG1 (P < 0.01) and EMG2 (P < 0.01), ANOVA

results confirmed that their values progressively increased as significant differences across the

various contraction intensities (5 to 50% of the MVC) were found. Post-hoc analyses revealed

numerous significant differences mostly between low and high forward flexion and left axial

rotation isometric contractions, respectively, for both EMG1 and EMG2 (see Table 1 and

Table 2). No significant differences were found for Thickness-1 and Thickness-2 across the

contraction intensities (5 to 50% of the MVC) during the forward flexion (Thickness-1: P =

0.992; Thickness-2: P = 0.334) and left axial rotation directions (Thickness-1: P = 0.999;

Thickness-2 P = 0.456). However, it should be noted that Thickness-2 tended to increase as

the relative isometric contraction intensity progressed, especially at values less than 30% of

the MVC, but without reaching the significance level (Table 1 and Table 2).

3.3 Validity of USI-based thickness measures of EO muscle activity

Pearson correlation coefficients between EMG1 and Thickness-1, as well as between

EMG2 and Thickness-2, were calculated and reported separately for each subject to better

appreciate the data variability. In terms of the forward flexion direction (Table 3), Pearson

correlation coefficients between EMG1 and Thickness-1 ranged from -0.90 to 0.92 (group

mean r = -0.33), while for the EMG2 and Thickness-2 relationship, values ranged from -0.90

to 0.97 (group mean r = 0.82). Only 5/18 and 11/18 subjects showed a strong correlation (r >

0.75 and P < 0.05) between EMG1 and Thickness-1 and between EMG2 and Thickness-2,

respectively. The left axial rotation direction results (Table 4) are similar to those observed for

forward flexion, ranging from -0.83 to 0.93 for EMG1 and Thickness-1 relationship (group

39

mean r = 0.37) and from -0.59 to 0.98 for EMG2/Thickness-2 relationship (group mean r =

0.97). Only 4/18 and 9/18 participants showed a strong correlation (r > 0.75 and P < 0.05)

between EMG1 and Thickness-1 and between EMG2 and Thickness-2, respectively. Hence,

the validity of USI-based thickness measures of EO muscle activity was better related to the

EMG2 and Thicknness-2 variables in both directions, despite the large variability observed

across subjects.

4. Discussion

The present study assessed muscular activity changes of the right external oblique

(EO) muscle using electromyography and ultrasound image-based thickness measures during

three isometric contraction directions: (1) forward trunk flexion; (2) right lateral flexion; and

(3) left axial rotation. All isometric effort directions were performed in a stabilized sitting

position on a dynamometer to better isolate the EO biomechanical demand relative to planes

of movement. Interestingly, in this standardized and well-controlled protocol, the EO muscle

was more activated only in forward flexion (45% on average) and left axial rotation (35% on

average ) effort directions as compared to the right lateral flexion direction (24% on average).

These two main effort directions (flexion and rotation) were thus retained for subsequent

analyses, which showed that the EO EMG values increases somewhat proportionally with

increases in relative contraction intensities, whereas no clear pattern was established with

regard to EO thickness during the same period. The validity of USI-based thickness measures

of EO muscle activity during low intensity contractions (<50% of the MVC) was accepted

only for the EMG2 and Thicknness-2 relationship for both of these directions, despite

substantial variability across subjects.

The external oblique muscle is involved in different activities of the trunk, such as

flexion (Sheeran et al., 2012), lateral bending (Huang et al., 2001) and axial rotation (Kumar

40

et al., 2001). Some authors (Ng et al., 2002) have demonstrated, however, that the external

oblique can be more activated during lateral bending, which is contrary to the present results.

It is known that abdominal muscle activity can change across different postures (Anderson et

al., 2002), and this could partly explain the differences between our results and those reported

by Ng et al., (2002). Furthermore, Ng et al., (2002) gathered their results during a maximal

effort instead of various submaximal contraction intensities as performed in the present study.

Our subjects were evaluated in a sitting position with the pelvis and lower limbs stabilized,

which might better isolate the biomechanical action of this muscle on each plane of

movement and consequently generate more activity during each specific direction such as in

forward flexion and left axial rotation (Brown and McGill, 2009a).

To determine whether the proposed contractions intensities trigger distinct muscular

thickness and EMG changes, we compared EMG and USI variables across various intensities

(ranging from 5 to 50% of the MVC) for isometric flexion and rotation directions. Previous

studies (Brown and McGill, 2010; John & Beith, 2007; Hodges, 2003), evaluating one or two

directions only, observed a small change in muscular thickness with an increase in the

contraction intensity level, which coincides with the results of the present study. Our results

conclude that only EMG variables presented a somewhat linear increase with a force increase

during forward flexion and axial rotation isometric contractions. The relationship between

EMG and an increase of force is well known in the literature (De Luca, 1997, Lawrence and

De Luca, 1983), even though it changes the pattern depending on the nature of the task (static

or dynamic). As observed in Table 1 and 2, the percentage of EO EMG relative to maximal

increases in contraction intensity (5 to 50% of the MVC), which is indicative of motor unit

recruitment with an increased mechanical load on this muscle. However, this pattern is not

similar to EO thickness during the same period. The explanation for these USI measure results

remains unclear in the literature. A plausible hypothesis could be associated with a

41

mechanical link between the abdominal muscular layers as described by Brown and McGill

(2010), where the shortening and thickening of EO muscle are compromised when the other

abdominal layers are contracted simultaneously. This could directly affect USI changes with

the increase in contraction intensities. In other words, depending on the force generated by the

muscle with the increase in intensity, the stretching force becomes the dominate force

(compared to the deformation force) and the muscle may show a tendency to stretch out and

thus attenuate the USI/force relationship. This may partly explain the results found in the

literature (Ferreira et al., 2004; John & Beith, 2007; Hodges et al., 2003) and those in the

present study, where the EO muscle showed very little increased thickness with high EMG

activity during increases in contraction intensities.

We must remember that USI-based thickness measures are influenced by inter-subject

variability. Our results showed that some subjects presented a positive relationship of

thickness and electrical muscle activity with an increase in contraction intensity, while other

subjects had a negative direction, or even, null correlation. When specifically comparing the

correlation between EMG2 and Thickness-2 measures, we observed 13 and 15 positive

correlations for the forward flexion and left axial rotation directions, respectively. The mean

EMG/USI relationship was r = 0.97 (Table 4), based on the results for the left axial rotation,

which thus supports the validity of EO muscle activity USI-based thickness measures. These

results are consistent with those reported by John & Beith (2007) for this isometric

contraction direction. These authors also demonstrated a significant relationship between an

increase in EO thickness and an increase in EMG activity within the muscle during the left

axial rotation direction for the majority of subjects. Although, the correlations between the

two measures ranged from weak to strong depending on the subjects, we observed that 11

subjects (61% of our sample) presented a significant relationship between EMG2 and

Thickness-2 measures for the left axial rotation effort direction (Table 4), while John & Beith

42

reported that 87% of their sample had a positive correlation between both measures. However,

compared to the study by John & Beith, the advantage of the present study was the use of a

robust experimental protocol to better control the EO biomechanical demand during each

isometric contraction direction in order to minimize EO fascicle compensations in one plane

of movement compared to another. John & Beith only used EO EMG biofeedback to control

the axial rotation effort during all testing, which could limit their validity of measurement.

Ultrasound imaging can provide a visual representation of muscle function as

previously supported (Teyhen et al., 2007). One aspect of muscle function that has been

studied in recent years is muscular electrical activity, and the relationship between changes in

muscular thickness and EMG activity. However, the present study, as well as others before it,

does not clearly support the use of USI measures for quantifying muscular activity of the

trunk muscles, dependent from effort direction and isometric contraction intensity. The

findings are still inconclusive concerning the relationship between these two measures in

terms of the lateral abdominal wall. However, the validity between these two measures can be

accepted in some cases depending on subject variability. Furthermore, some authors suggest

that USI can be used with different applications for research and more specifically for clinical

practice to 1) provide the physical therapist and patient with feedback and 2) to assist physical

therapists in their decision-making process related to exercise prescription and progression

(Teyhen et al., 2007).

Finally, the results of the present study should be interpreted with caution. Only

surface EMG signals were recorded, which is different from some previous studies (Hodges et

al., 2003; McMeeken et al., 2004) that have used intramuscular recordings to capture

electrical muscle activity simultaneously with the measures of USI to assess the muscular

activation of the abdominal muscles. The surface EMG does not make it possible for the

evaluator to place the USI transducer in the same location where the electrical muscle activity

43

was recorded. To minimize these effects, the present study used a device to standardize the

position between the US transducer and the EMG electrodes, as stated previously under

Methods (section 2.2.1). In addition, the results of the present study can neither be generalized

to individuals with impairments or disability (e.g., individuals with low back pain), nor to

women. Finally, in terms of statistical power, the possibility of Type I errors (false findings)

and Type II errors (missed findings) appears unlikely in the present study, except for USI

measures of Thickness-2 with increases in intensity (P = 0.334 for flexion direction and P =

0.456 for rotation direction), which could have reached statistical significance (Type II errors)

with a larger sample of subjects.

5. Conclusion

The results of present study support the idea that quantitative musculoskeletal

ultrasound imaging and EMG of the EO muscle provides different but complementary

information when investigating muscular recruitment during isometric trunk contractions.

Relative EMG activity of the EO muscles, especially of the lateral compartment, is more

responsive to progressive increased isometric trunk contraction intensity than EO muscular

thickness. The association documented only for a small proportion of subjects between the

EMG intensity and muscular thickness of the EO muscle during isometric trunk contractions

remains to be strengthened. In the present study, the validity between two measures was better

accepted for the relationship between EMG2 and thickness-2 during the left axial rotation

direction. Hence, quantitative ultrasound imaging of the abdominal muscles should be used

with caution in clinical practice and in rehabilitation research protocols.

44

Conflict of interest statement

None declared.

Acknowledgement

This study was funded in part by the Fonds de la recherche du Québec-Santé (FRQS). The

equipment and material required for this research project was financed in part by the

Occupational Health and Safety Research Institute Robert-Sauvé (IRSST) and the Canada

Foundation for Innovation (CFI). Dany Gagnon holds a Junior 1 Research Career Award from

the FRQS. Rubens A. da Silva, was funded by from the National Foundation for the

Development of Private Higher Education (FUNADESP, Brazil). The authors thank the

assistance of Hakim Mecheri for help with data processing and analysis. We thank Prof.

Rodrigo Franco (UNOPAR University, Brazil) for his contribution to and comments on the

Master’s degree thesis by Lucas Rabello, upon which this research study is based. We thank

Université de Montréal and UNOPAR for the official collaboration in the international

student exchange program.

45

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49

Figure legends:

Figure 1. Represents the position of the evaluator and the subjects during the test.

Figure 2. Sheet designed by the authors to standardize EMG and USI electrode placement.

EMG1 and EMG2 electrodes were placed at an angle of 63° and 72°, respectively, relative to

horizontal line. Vertical distance between EMG1 and transducer was of 5mm, while for the

EMG2 in relation to transducer was of 8mm. The distance of electrodes (EMG1 and EMG2)

center to center was of 33 mm.

Figure 3. Ultrasound image corresponding to the lateral abdominal wall during the analysis

process using a custom-made Matlab program. USI image was selected as close as possible to

the epochs selected for the EMG analyses. Each image was divided in two sides (white

circles): the right side (Thickness-1) related to EMG1 (at an angle of 63°) and the left side

(Thickness-2) related to EMG2 (at an angle of 72°). The yellow lines (superior and inferior

EO fascias) represent 1-cm area to calculate the Thickness values.

50

Figure 1. Represents the position of the evaluator and the subjects during the test.

51

Figure 2. Sheet designed by the authors to standardize EMG and USI electrode placement.

EMG1 and EMG2 electrodes were placed at an angle of 63° and 72°, respectively, relative to

horizontal line. Vertical distance between EMG1 and transducer was of 5mm, while for the

EMG2 in relation to transducer was of 8mm. The distance of electrodes (EMG1 and EMG2)

center to center was of 33 mm.

52

Figure 3. Ultrasound image corresponding to the lateral abdominal wall during the analysis

process using a custom-made Matlab program. USI image was selected as close as possible to

the epochs selected for the EMG analyses. Each image was divided in two sides (white

circles): the right side (Thickness-1) related to EMG1 (at an angle of 63°) and the left side

(Thickness-2) related to EMG2 (at an angle of 72°). The yellow lines (superior and inferior

EO fascias) represent 1-cm area to calculate the Thickness values.

53

Table 1. EMG Muscle Activation Level (%) and USI-based thickness (%) results from

isometric contraction intensities (5 to 50%) for the forward flexion direction.

Intensities a (%) EMG1

b EMG2

c Thickness-1 Thickness-2

MEAN (SD) MEAN (SD) MEAN (SD) MEAN (SD)

5 3.15 (1.96) 4.23 (1.97) 111.27 (14.85) 112.40 (15.95)

10 3.94 (2.16) 5.23 (2.14) 113.04 (15.58) 115.54 (17.03)

15 6.18 (3.09) 7.30 (2.29) 115.60 (18.42) 120.27 (20.53)

20 8.82 (4.18) 10.22 (2.67) 114.82 (18.53) 123.13 (32.08)

25 11.98 (5.71) 13.88 (4.25) 114.22 (20.15) 125.89 (23.94)

30 15.29 (6.74) 17.30 (4.92) 115.27 (21.19) 127.72 (23.91)

35 20.02 (9.24) 21.57 (6.50) 113.96 (21.73) 127.88 (24.89)

40 24.48 (10.36) 25.35 (9.72) 112.72 (22.99) 128.18 (26.86)

45 30.55 (12.90) 33.05 (10.90) 112.57 (24.61) 129.15 (27.26)

50 35.57 (14.12) 38.11 (10.78) 111.90 (25.05) 128.37 (28.14)

Mean values from 18 subjects with standard deviation (SD). a Significant differences (P < 0.01) between the intensities from one-way ANOVA results for

each EMG variable. No significant difference (P 0.05) was found between intensities for

USI-based thickness values from measures 1 and 2 (one-way ANOVA performed

independently). b,c

For both EMG1 and EMG2, Tukey post-hoc analyses revealed, overall, significant

differences between low and high intensity levels (5 to 50% of the MVC). These differences

are further illustrated in Figure 2 (Figure 2a and 2b for EMG measures; and Figure 2c and 2d

for Thickness measures).

54

Table 2. EMG Muscle Activation Level (%) and USI-based thickness (%) results from

isometric contraction intensities (5 to 50%) for the left axial rotation direction.

Intensities a (%) EMG1

b EMG2

c Thickness-1 Thickness-2

MEAN (SD) MEAN (SD) MEAN (SD) MEAN (SD)

5 3.84 (2.20) 4.76 (1.83) 109.33 (15.60) 116.77 (18.54)

10 5.88 (3.41) 6.98 (2.65) 108.02 (17.36) 120.11 (21.76)

15 7.80 (3.72) 9.31 (3.17) 107.75 (19.42) 122.34 (25.33)

20 10.20 (4.45) 12.41 (3.81) 106.56 (20.77) 125.34 (26.22)

25 12,54 (5,54) 14.58 (3.66) 106.53 (21.50) 127.73 (28.13)

30 15.23 (6.93) 17.92 (5.81) 106.48 (22.89) 128.83 (28.75)

35 18.63 (7.62) 20.42 (5.28) 106.84 (23.83) 129.64 (27.42)

40 21.58 (7.81) 24.54 (6.84) 106.97 (23.33) 131.00 (25.53)

45 25.56 (9.78) 28.71 (7.15) 109.08 (22.32) 133.06 (22.63)

50 29.03 (12.13) 31.44 (7.04) 111.60 (22.67) 135.37 (25.15)

Mean values from 18 subjects with standard deviation (SD). a Significant differences (P < 0.01) between the intensities from one-way ANOVA results for

each EMG variable. No significant difference (P 0.05) was found between intensities for

USI-based thickness values from measures 1 and 2 (one-way ANOVA performed

independently). b,c

For both EMG1 and EMG2, Tukey post-hoc analyses revealed, overall, significant

differences between low and high intensity levels (5 to 50% of the MVC). These differences

are further illustrated in Figure 3 (Figure 3a and 3b for EMG measures; and Figure 3c and 3d

for Thickness measures).

55

Table 3. EMG Muscle Activation Level (%) and USI-based thickness (%) correlation results

from the mean (5 to 50%) value of isometric contraction during the forward flexion direction.

Subject EMG1 vs. Thickness-1 EMG2 vs. Thickness-2

r (P value) r (P value)

1 0.92 (0.001)* 0.67 (0.033)*

2 -0.73 (0.017)* -0.90 (0.000)*

3 0.92 (0.000)* 0.97 (0.000)*

4 -0.92 (0.000)* 0.41 (0.236)

5 0.59 (0.074) 0.82 (0.003)*

6 -0.35 (0.326) -0.30 (0.395)

7 0.38 (0.276) 0.93 (0.000)*

8 -0.25 (0.478) 0.95 (0.000)*

9 -0.74 (0.013)* 0.82 (0.004)*

10 0.92 (0.000)* 0.97 (0.000)*

11 0.26 (0.472) 0.87 (0.001)*

12 0.15 (0.671) 0.95 (0.000)*

13 -0.90 (0.000)* -0.01 (0.979)

14 -0.35 (0.328) -0.88 (0.001)*

15 0.88 (0.001)* -0.18 (0.615)

16 -0.66 (0.038)* 0.88 (0.001)*

17 0.82 (0.003)* 0.19 (0.600)

18 0.28 (0.426) 0.40 (0.258)

Mean -0.33 (0.348) 0.82 (0.004)*

*Significant Pearson correlation coefficient (r) between EMG Muscle Activation Level (%)

and USI-based thickness (%) measures by individual.

56

Table 4. EMG Muscle Activation Level (%) and USI-based thickness (%) correlation results

from the mean (5 to 50%) value of isometric contraction during the left axial rotation

direction.

Subject EMG1 vs. Thickness-1 EMG2 vs. Thickness-2

r (P value) r (P value)

1 -0.27 (0.437) 0.27 (0.433)

2 -0.74 (0.014)* 0.91 (0.000)*

3 0.83 (0.002)* 0.52 (0.120)

4 0.01 (0.970) 0.73 (0.014)*

5 0.43 (0.211) 0.84 (0.002)*

6 -0.005 (0.987) 0.89 (0.000)*

7 0.93 (0.000)* 0.98 (0.000)*

8 -0.55 (0.093) 0.51 (0.131)

9 -0.66 (0.034)* -0.59 (0,070)

10 -0.02 (0.093) 0.85 (0.000)*

11 0.86 (0.001)* 0.81 (0.004)*

12 0.79 (0.005)* 0.95 (0.000)*

13 -0.81 (0.004)* -0.15 (0.660)

14 -0.53 (0.109) 0.67 (0.031)*

15 0.15 (0.673) -0.56 (0.086)

16 0.33 (0.340) 0.84 (0.002)*

17 -0.40 (0.239) 0.11 (0.753)

18 0.47 (0.170) 0.94 (0.001)*

Mean 0.37 (0.285) 0.97 (0.001)*

*Significant Pearson correlation coefficient (r) between EMG Muscle Activation Level (%)

and USI-based thickness (%) measures by individual.

57

CONCLUSÃO GERAL

Esta pesquisa avaliou a utilização de uma nova ferramenta, o

ultrassom de imagem (USI), para avaliação o músculo externo oblíquo (OE). Esta

ferramenta pode ser utilizada por fisioterapeutas para avaliação e reabilitação dos

músculos abdominais em pacientes com diversas patologias, como a lombalgia.

Para estes profissionais utilizarem novas tecnologias, estas devem ser comparadas

ao padrão-ouro de medida da atividade muscular, no caso, a eletromiografia (EMG).

Devido aos poucos estudos e a grande diferença metodológica, a relação entre o

USI e a EMG ainda não esta clara na literatura. A diferença do nosso estudo em

relação aos anteriores foi o protocolo utilizando, no qual os sujeitos foram

posicionados sentados com apoio e foi realizada a contração em rampa (5 a 50% da

contração voluntária máxima [CVM]). Além disso, dois eletrodos foram posicionados

sobre o músculo EO e a medida da espessura muscular foi realizada em regiões

correspondentes a estes eletrodos.

Os resultados do presente estudo suportam a ideia de que o USI

não fornece, necessariamente, a mesma informação em relação a atividade elétrica

muscular captada pela EMG.

Desta forma, sugere-se que as medidas USI sejam utilizadas com

precaução, especialmente no que diz respeito a realização de pesquisas científicas

e na realização de avaliações clínicas para pacientes com alguma patologia.

Principalmente devido a alta variabilidade dos resultados encontrado entre os

sujeitos.

Novas pesquisas são necessárias utilizando um protocolo similar de

avaliação, porém com maior número de participantes. Sendo assim, a correlação

entre a EMG e o USI permanece inconclusiva.

58

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64

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For full instructions on the electronic submission of artwork, please visit: http://ees.elsevier.com/jek.

Graphs

The minimum amount of descriptive text should be used on graphs and drawings (label curves, points,

etc, with single-letter symbols). Descriptive matter should be placed in the figure caption. Scale grids

should not be used in graphs, unless required for actual measurements. Graph axes should be labelled

with variables written out in full, along the length of the axes, with the unit in parentheses (for example,

Time(s)). A table is usually more satisfactory for recording data.

Photographs

Supply glossy, black and white, unmounted prints or 35 mm transparencies, plus two photocopies. A

scale, where appropriate, should be marked on the photographs or included in the caption.

Colour Illustrations

If, together with your accepted article, you submit usable colour figures then Elsevier will ensure, at no

additional charge, that these figures will appear in colour on the web (e.g., ScienceDirect and other sites)

regardless of whether or not these illustrations are reproduced in colour in the printed version. For colour

reproduction in print, you will receive information regarding the costs from Elsevier after receipt of your

accepted article. For further information on the preparation of electronic artwork, please

see http://ees.elsevier.com/jek. Please note: Because of the technical complications which can arise by



72

converting colour figures to 'grey scale' (for the printed version should not opt for colour in print) please

submit in addition usable black and white prints corresponding to all the colour illustrations. Submit

colour illustrations as original photographs high-quality computer prints or transparencies, close to the

size expected in publication, or as 35 mm slides. Polaroid colour prints are not suitable.

REFERENCES

The reference list should be constructed alphabetically. Where more than one reference has the same

first author, use the next named author to construct the list alphabetically. For identical author groups,

list the references by date. References should be cited in the text using the first author name plus the

year of the paper, eg Solomonow et al, 2004, in square brackets. References should be in the following

form:

Journal article

Paivio A, Jansen B, Becker LJ. Comparisons through the mind's eye. Cognition 1975;37(2):635-47

Book

Strunk W, White EB. The elements of style. 3rd ed. New York: Macmillan, 1979

Article or chapter in edited book

Gurman AS, Kniskern DP. Family therapy outcome research: knowns and unknowns. In: Gurman AS,

Kniskern DP, editors. Handbook of family therapy. New York: Brunner/Maazel, 1981:742-75.

Please ensure that references are complete, in that they include where relevant, author's name, article or

book title, volume and issue number, publisher, year and page reference. Journal titles should appear in

full.

UNITS AND ABBREVIATIONS

SI units and their accepted abbreviations should be used.

73

RANDOMISED CONTROLLED TRIALS

All randomised controlled trials submitted for publication in the journal should include a completed

Consolidated Standards of Reporting Trials (CONSORT) flow chart. Please refer to the CONSORT

statement website at http://www.consort-statement.org for more information. The Journal of

Electromyography and Kinesiology has adopted the proposal from the International Committee of Medical

Journal Editors (ICMJE) which require, as a condition of consideration for publication of clinical trials,

registration in a public trials registry. Trials must register at or before the onset of patient enrolment.

The clinical trial registration number should be included at the end of the abstract of the article. For this

purpose, a clinical trial is defined as any research project that prospectively assigns human subjects to

intervention or comparison groups to study the cause-and-effect relationship between a medical

intervention and a health outcome. Studies designed for other purposes, such as to study

pharmacokinetics or major toxicity (e.g. phase I trials) would be exempt. Further information can be

found at www.icmje.org.

ETHICS

Work on human beings that is submitted to the Journal should comply with the principles laid down in

the Declaration of Helsinki; Recommendations guiding physicians in biomedical research involving human

subjects. Adopted by the 18th World Medical Assembly, Helsinki, Finland, June 1964, amended by the

29th World Medical Assembly, Tokyo, Japan, October 1975, the 35th World Medical Assembly, Venice,

Italy, October 1983, and the 41st World Medical Assembly, Hong Kong, September 1989. The manuscript

should contain a statement that the work has been approved by the appropriate ethical committees

related to the institution(s) in which it was performed and that subjects gave informed consent to the

work. Studies involving experiments with animals must state that their care was in accordance with

institution guidelines. Patients' and volunteers' names, initials, and hospital numbers should not be used.

CHECKLIST

Have you told readers, at the outset, what they might gain by reading your paper?

Have you made the aim of your work clear?

Have you explained the significance of your combination?

http://www.consort-statement.org/

http://www.elsevier.com/wps/find/journaldescription.cws_home/30442/www.icmje.org

74

Have you set your work in the appropriate context by giving sufficient background (including a complete

set of relevant references) to your work?

Have you addressed the question of practicality and usefulness?

Have you identified future developments that may result from your work?

Have you structured your paper in a clear and logical fashion?

COPYRIGHT

Upon acceptance of an article, authors will be asked to sign a "Journal Publishing Agreement" (for more

information on this and copyright see http://ees.elsevier.com/jek. Acceptance of the agreement will

ensure the widest possible dissemination of information. An e-mail (or letter) will be sent to the

corresponding author confirming receipt of the manuscript together with a "Journal Publishing

Agreement" form. If excerpts from other copyrighted works are included, the author(s) must obtain

written permission from the copyright owners and credit the source(s) in the article. Elsevier has

preprinted forms for use by authors in these cases : contact Elsevier's Rights Department, Philadelphia,

PA, USA: Tel. (+1) 215 238 7869; Fax (+1) 215 238 2239; e-mail [email protected] .

Requests may also be completed online via the Elsevier homepage

(http://www.elsevier.com/locate/permissions).

AGREEMENTS WITH FUNDING BODIES

Elsevier has established agreements and developed policies to allow authors who publish in this journal

to comply with manuscript archiving requirements of the following funding bodies, as specified as

conditions of researcher grant awards. Please

seewww.elsevier.com/wps/find/authorsview.authors/fundingbodyagreements for full details of the

agreements that are in place for these bodies:

• Arthritis Research Campaign (UK)

• British Heart Foundation (UK)

• Cancer Research (UK)

• Howard Hughes Medical Institute (USA)



http://www.elsevier.com/locate/permissions

http://www.elsevier.com/wps/find/journaldescription.cws_home/30442/www.elsevier.com/wps/find/authorsview.authors/fundingbodyagreements

75

• Medical Research Council (UK)

• National Institutes of Health (USA)

• Wellcome Trust (UK)

These agreements and policies enable authors to comply with their funding body's archiving policy

without having to violate their publishing agreements with Elsevier. The agreements and policies are

intended to support the needs of Elsevier authors, editors, and society publishing partners, and protect

the quality and integrity of the peer review process. They are examples of Elsevier's ongoing

engagement with scientific and academic communities to explore ways to deliver demonstrable and

sustainable benefits for the research communities we serve.

Authors who report research by funding bodies not listed above, and who are concerned that their author

agreement may be incompatible with archiving requirements specified by a funding body that supports

an author's research are strongly encouraged to contact Elsevier's author support team

([email protected]). Elsevier has a track-record of working on behalf of our authors to ensure

authors can always publish in Elsevier journals and still comply with archiving conditions defined in

research grant awards.

PROOFS

One set of page proofs in PDF format will be sent by e-mail to the corresponding author (if we do not

have an e-mail address then paper proofs will be sent by post). Elsevier now sends PDF proofs which can

be annotated; for this you will need to download Adobe Reader version 7 available free

from http://www.adobe.com/products/acrobat/readstep2.html. Instructions on how to annotate PDF

files will accompany the proofs. The exact system requirements are given at the Adobe site:

http://www.adobe.com/products/acrobat/acrrsystemreqs.html#70win. If you do not wish to use the PDF

annotations function, you may list the corrections (including replies to the Query Form) and return to

Elsevier in an e-mail. Please list your corrections quoting line number. If, for any reason, this is not

possible, then mark the corrections and any other comments (including replies to the Query Form) on a

printout of your proof and return by fax, or scan the pages and e-mail, or by post. Please use this proof

only for checking the typesetting, editing, completeness and correctness of the text, tables and figures.

Significant changes to the article as accepted for publication will only be considered at this stage with

permission from the Editor. We will do everything possible to get your article published quickly and


http://www.adobe.com/products/acrobat/readstep2.html

76

accurately. Therefore, it is important to ensure that all of your corrections are sent back to us in one

communication: please check carefully before replying, as inclusion of any subsequent corrections cannot

be guaranteed. Proofreading is solely your responsibility. Note that Elsevier may proceed with the

publication of your article if no response is received.

OFFPRINTS

The corresponding author, at no cost, will be provided with a PDF file of the article via e-mail or,

alternatively, 25 free paper offprints. The PDF file is a watermarked version of the published article and

includes a cover sheet with the journal cover image and a disclaimer outlining the terms and conditions

of use. Additional paper offprints can be ordered by the authors. An order form with prices will be sent to

the corresponding author.

PREPARATION OF SUPPLEMENTARY DATA

Elsevier now accepts electronic supplementary material to support and enhance your scientific research.

Supplementary files offer the author additional possibilities to publish supporting applications, movies,

animation sequences, high-resolution images, background datasets, sound clips and more.

Supplementary files supplied will be published online alongside the electronic version of your article in

Elsevier web products, including ScienceDirect: http://wwww.sciencedirect.com. In order to ensure that

your submitted material is directly usable, please ensure that data is provided in one of our

recommended file formats. Authors should submit the material in electronic format together with the

article and supply a concise and descriptive caption for each file. For more detailed instructions please

visit: http://ees.elsevier.com/jek.

AUTHOR ENQUIRIES

For enquiries relating to the submission of articles (including electronic submission where available)

please visit: http://ees.elsevier.com/jek.

Contact details for questions arising after acceptance of an article, especially those relating to proofs, are

provided after registration of an article for publication.

http://wwww.sciencedirect.com/



77

ANEXO B

Carta de aceite do Comitê de Ética Local e Protocolo.

87

ANEXO C

Termo de Conscentimento Livre e Esclarecido

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