UNIVERSIDADE DO PORTO

FACULDADE DE DESPORTO

Centro de Investigação em Atividade Física, Saúde e Lazer

Efeitos de um programa de exercícios na sintomatologia lombar e qualidade de vida em

operários

A presente dissertação foi escrita para a obtenção do título de Doutor no âmbito do curso de Doutoramento em Atividade Física e Saúde, da Faculdade de Desporto, nos termos do artigo 81º do Decreto de Lei 74/2006. Orientadores: Prof. Doutor José Carlos Ribeiro

Prof. Doutor Pedro Moreira

Cristina Teresa Torrão de Carvalho Mesquita Porto, Setembro, 2011

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Ficha de catalogação

Mesquita, C.T.T.C. (2011). Efeitos de um programa de exercícios na sintomatologia lombar e qualidade de vida em operários. Porto: C.T.T.C. Mesquita. Dissertação de Doutoramento em Actividade Física e Saúde apresentada na Faculdade de Desporto da Universidade do Porto

PALAVRAS-CHAVE: DOR LOMBAR, OPERÁRIOS, FORÇA E RESISTÊNCIA

MUSCULAR, EXERCICIO ESPECIFICO.

III

Deus não escolhe os capacitados, capacita os escolhidos

Fazer ou não fazer algo só depende de nossa vontade e perseverança

Albert Einstein

Acredita em Ti Mesmo

O homem converte-se aos poucos naquilo que acredita poder vir a ser. Se me

repetir incessantemente a mim mesmo que sou incapaz de fazer determinada

coisa, é possível que isso acabe finalmente por se tornar verdade. Pelo

contrário, se acreditar que a posso fazer, acabarei garantidamente por adquirir

a capacidade para a fazer, ainda que não a tenha num primeiro momento.

Mohandas Gandhi, in 'The Words of Gandhi'

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O trabalho da candidata foi financiado pela bolsa de doutoramento PROTEC do

Instituto Politécnico do Porto e da Fundação para a Ciência e Tecnologia

(SFRH/BD/50183/2009).

Trabalho efectuado em colaboração com o Centro de Investigação em

Atividade Física, Saúde e Lazer (CIAFEL) da Faculdade de Desporto da

Universidade do Porto.

VII

Agradecimentos

Agradeço aos meus orientadores, Prof. Doutor José Carlos Ribeiro e Prof.

Doutor Pedro Moreira pela sua competência científica e pelo apoio prestado na

realização deste trabalho.

À coordenadora da área científica da Fisioterapia da Escola Superior de

Tecnologia da Saúde do Porto, Prof. Doutora Cristina Melo que sempre apoiou

os docentes que estavam e estão a realizar doutoramento mantendo as suas

funções profissionais.

A todos os indivíduos que fizeram parte deste estudo sem os quais teria sido

impossível a realização deste trabalho, os meus sinceros agradecimentos,

assim como, aos Departamentos Médico, de Recursos Humanos e de Higiene

e Saúde Ambiental da empresa.

Aos colegas que ajudaram na recolha de dados, implementação e controle do

programa de exercícios que foram a Bárbara, César, Irene, Joana, Mariana e

Vera.

Um especial e profundo agradecimento às amigas e colegas que me ajudaram

na revisão dos artigos e da tese e que desde o inicio até ao final me apoiaram

dando força, ânimo para manter a perseverança e nunca “pensar” em desistir,

não cito nomes pois elas sabem quem são…

Aos meus pais que foram e sempre serão os pilares da minha existência e

exemplos de coragem, determinação e moralidade.

Aos meus irmãos e queridos sobrinhos que souberam compreender as minhas

ausências.

Aos amigos e família que sempre me apoiaram em todos os meus projectos

pessoais e profissionais, o meu bem-haja.

Ao Rui pelo esforço, paciência, compreensão e amor demonstrado ao longo

desta jornada, o meu muito obrigada.

IX

Índice Geral

Agradecimentos VII

Índice Geral IX

Índice de Figuras XI

Índice de Tabelas XII

Resumo XIII

Abstract XV

Lista de Abreviaturas XVII

Introdução 1

Revisão da literatura 7

Objetivos 17

Material e Métodos 19

Instrumentos 20

Procedimentos 23

Capitulo 1 25

Introduction 28

Methods 29

Results 30

Discussion 31

Conclusion 32

References 32

Capitulo 2 35

Introduction 37

Methods 39

Results 41

X

Discussion 43

Conclusion 45

References 45

Capitulo 3 51

Introduction 54

Methods 55

Results 59

Discussion 60

Acknowledgements 63

References 63

Capitulo 4 69

Introduction 72

Methods 74

Results 77

Discussion 80

Conclusion 83

Acknowledgements 83

Discussão 87

Conclusões 97

Bibliografia Geral 101

Anexos XIX

XI

Índice de Figuras

Figura 1 21

Figura 2 21

Figura 3 22

Figura 4 22

XII

Índice de Tabelas

Capitulo 1

Tabela 1 31

Tabela 2 31

Capitulo 2

Tabela 1 40

Tabela 2 42

Tabela 3 43

Tabela 4 43

Capitulo 3

Tabela 1 57

Tabela 2 60

Capitulo 4

Tabela 1 75

Tabela 2 78

Tabela 3 78

Tabela 4 79

Tabela 5 80

XIII

RESUMO

As lesões músculo-esqueléticas estão entre as doenças mais referidas pelos trabalhadores europeus. Um Inquérito Europeu sobre Condições de Trabalho (2005) revelou que 20% dos trabalhadores queixavam-se de problemas e dores musculares nas costas. Os distúrbios lombares foram identificados como um risco elevado em muitas indústrias, devido à incidência e prevalência de lombalgia ocupacional elevadas sendo um dos fatores de limitação do sistema locomotor.Cada vez se torna mais pertinente prevenir estas disfunções e reduzir a sintomatologia músculo-esquelética (SME). Também, quanto mais alta for a perceção que os indivíduos têm da sua qualidade de vida (QV) resultará numa melhor funcionalidade e num melhor desempenho profissional.

Esta tese foi constituída por quatro estudos, o estudo I, foi a adaptação para a população portuguesa de um instrumento válido e fiável que avalie a SME, tendo-se optado pelo standardized Nordic musculoskeletal questionnaire

(NMQ); o estudo II, analisou a SME existentes no início e após 11 e 21 meses de intervenção; o estudo III, foi a avaliação da força e resistência dos extensores e flexores lombares; e o estudo IV, verificou a percepção da QV relacionada com a saúde durante todo o período de intervenção.

A versão em português do NMQ mostrou ser válida revelando bons coeficientes de fiabilidade (estudo I). No estudo II, pode-se concluir que um programa de exercícios específicos melhorou a SME na região lombar durante os 21 meses, nas variáveis: "problemas nos últimos 12 meses", "limitações nos últimos 12 meses" e "problemas nos últimos 7 dias". Houve melhorias significativas na força muscular e resistência dos extensores, medidos 11 meses após o início da intervenção; ao comparar os dois grupos, as principais diferenças foram verificadas nos flexores lombares e força de extensores (estudo III). Relativamente à QV verificou-se que um programa de exercícios específicos, a longo prazo, modificou positivamente a perceção dos indivíduos em relação à sua saúde.

Palavras-chave : saúde ocupacional, NMQ, fiabilidade, validade, operários, sintomas músculo-esqueléticos, força e resistência muscular, exercícios específicos, qualidade de vida, SF-36.

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ABSTRACT

Musculoskeletal disorders are among the most widespread illnesses reported by European workers. According to European Working Conditions Survey (2005), about 20% of EU workers complain of back problems and muscular pains. In fact, low back pain (LBP) constitutes the major cause of work absence, as it is one of the causes of limitation of the locomotor system. LBP are especially high in manual work industries. The importance of prevention and decrease the musculoskeletal symptomatology and improved quality of life (QoL), resulting in better professional performance and functionality is well Know.

This thesis comprises four studies, study I, the adaption to the Portuguese population of an instrument to assess musculoskeletal symptoms, the standardized Nordic musculoskeletal questionnaire (NMQ); study II, that

measures the musculoskeletal symptomatology (MSS) changes after 21months intervention; study III, to assess the strength and resistance of the extensors and flexors of the trunk; and the study IV to verify the perception of health related QoL throughout the intervention period.

The Portuguese version of NMQ seems to be valid revealing good coefficients of reliability (study I).In the study (II), it can be concluded that a specific exercise program improved MSS in the low back region throughout the 21 months, in all variables: “troubles in the last 12 months”, “limitations in the last 12 months” and “troubles in the last 7 days”. There were significant improvements in extensor muscle strength and resistance, measured 11 months after following the exercise program (study III). In the long term, a low back specific exercise program modified positively the QoL of workers (study IV). After 21 months of following the exercise program, the dimensions physical functioning, role-physical, bodily pain, social functioning, role-emotional and mental health have improved significantly.

Keywords: occupational health, NMQ, reliability, validity, workers, musculoskeletal symptoms, muscle strength and resistance, specific exercises, QoL, SF-36.

XVII

Lista de Abreviaturas

cm Centímetros

EU European Union

ICC Intraclass Correlation Coefficient

IMC Índice de massa corporal

Kg Quilograma

Kgf Quilograma força

LBP Low back pain

LME Lesões músculo-esqueléticas

M1 Momento 1

M2 Momento 2

M3 Momento 3

MSD Musculoskeletal disorders

MSS Musculoskeletal symptomatology

MSS Musculoskeletal symptoms

NMQ Standardized Nordic musculoskeletal questionnaire

OMS Organização Mundial de Saúde

QNM Questionário Nórdico músculo-esquelético

QoL Quality of life

QV Qualidade de vida

Sf-36 – v2 Short Form Health Survey – versão 2

SME Sintomatologia músculo-esquelética

VAS Visual Analogue Scale

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Introdução

A Organização Mundial de Saúde (OMS) caracterizou as lesões relacionadas com o trabalho como doenças multifatoriais, devido aos diferentes fatores de risco envolvidos, tais como de organização do trabalho, alterações físicas, psicossociais e socioculturais, assim como ergonómicas, contribuindo para a causa destes problemas (WHO, 1985). Uma das principais controvérsias em volta da sintomatologia músculo-esquelética relacionada com o trabalho é a sua natureza multifatorial. Alguns centros de estudo não estão de acordo na relação entre os fatores de risco múltiplos e individuais no desenvolvimento desta doença (WHO, 1985). Contudo, os distúrbios músculo-esqueléticos são cada vez mais frequentes, tornando-se assim num dos principais problemas dos países industrializados (Airaksinen et al., 2006; Bigos et al., 2009; Borenstein, 2000). Representam uma das principais causas de morbilidade e têm sido descritos, como sendo os sintomas mais habituais de dor severa prolongada e de incapacidade física na população ativa (Airaksinen et al., 2006; Bigos et al., 2009; IJzelenberg & Burdorf, 2004; Meerdinga, IJzelenberga,

Koopmanschapb, Severensc, & Burdorfa, 2005; Rulgulies & Krause, 2005).

Afetam muitos trabalhadores, refletindo um enorme impacto na produtividade, com consequências económicas substanciais e inerentes repercussões no bem-estar social e económico dos trabalhadores, assim como das suas famílias (Airaksinen et al., 2006;Bigos et al., 2009; Butler & Johnson, 2011; Gundewall, Lilequist, & Hansson, 1993; Juul-Kristensen & Jensen, 2005). São vários os estudos que consideram que nas últimas décadas tem havido um aumento de disfunções músculo-esqueléticas (Harrington, 1994; IJzelenberg & Burdorf, 2004; Kuorinka, Alaranta, & Erich, 1995; Morken et al., 2003; Tveito,

Hysing, & Eriksen, 2004).

A European Foundation for the Improvement of Living and Working Conditions (Giaccone, 2007), destaca que Portugal é o terceiro país na UE no

qual os trabalhadores mais faltam devido a lesões músculo-esqueléticas. Em 2001, o National Institute for Occupational Safety and Health baseando-se em

diversas publicações construiu um modelo conceptual para as lesões músculo-esqueléticas. Neste modelo foram determinados possíveis efeitos resultantes da aplicação de cargas. Podem ser de origem externa ou forças internas resultantes dos efeitos dinâmicos e gravitacionais. Estas cargas aplicadas criam respostas internas dos tecidos muscular, ligamentar e nas superfícies articulares. Conforme a dimensão da carga e dos fatores individuais,

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organizacionais ou sociais, os resultados podem desencadear efeitos de adaptação (aumentos na força, resistência e aptidão física ou serem prejudiciais (tais como dor ou mesmo lesões estruturais nos tendões, nervos, músculos, articulações ou tecidos de suporte), que podem resultar em sintomas dolorosos, disfunção ou incapacidade (Byrns, Reeder, Jin, & Pachis, 2004; Keyserling, Sudarsan, Martin, Haig, & Armstrong, 2005; Roffey, Wai, Bishop,

Kwon, & Dagenais, 2010; Wai, Roffey, Bishop, Kwon, & Dagenais, 2010).

Os trabalhadores são, muitas vezes, sujeitos a movimentos repetitivos e vibratórios, ao levantamento e transporte de pesos, a posturas incorretas por períodos de tempo prolongados e por vezes a longas horas de trabalho (Ala-Mursula, Vahtera, Pentti, & Kivimäki, 2004; Akbar Alipour, Mostafa Ghaffari, Batoul Shariati, Irene Jensen, & Eva Vingard, 2008; Dembe, Erickson, Delbos, & Banks, 2005; Dovrat & Katz-Leurer, 2007; Guo, 2002; Hussain, 2004; Häkkänen, Viikari-Juntura, & Martikainen, 2001; Jansen, Morgenstern, & Burdorf, 2004; Juul-Kristensen & Jensen, 2005; Shimizu, Horie, Nagata, & Marui, 2004; Tveito et al., 2004). Estes fatores colocam os tecidos moles em tensão, surgindo, progressivamente, as lesões músculo-esqueléticas (Bonde et

al., 2005; Jansen et al., 2004; Kuorinka & Patry, 1995).

A sintomatologia músculo-esquelética pode ainda surgir ou ser exacerbada se o trabalho desenvolvido implicar a exposição a temperaturas baixas. Alguns autores, Piedrahíta, Punnett, & Shahnavaz (2004) verificaram uma elevada prevalência de sintomatologia músculo-esquelética (SME) nos trabalhadores de áreas muito frias (2ºC), especialmente na região lombar, pescoço e ombros. Outros autores, referem que o frio diminui a performance muscular, levando, progressivamente, a um aumento de tensão e posterior fadiga precoce (Dovrat & Katz-Leurer, 2007). Por outro lado, a carga psicossocial a que o operário é sujeito, acrescida de um fraco suporte social e baixa satisfação profissional desenvolvem um mecanismo de stress que leva

ao aumento do tónus muscular e à ativação dos recetores da dor potenciando a dor músculo-esquelética (Besler & Can, 2003; Bonde et al., 2005; Cherry,

Meyer, Chen, Holt, & McDonald, 2001; Hoogendoorn et al., 2002)

Segundo a European Foundation for the Improvement of Living and Working Conditions (Giaccone, 2007), as lesões músculo-esqueléticas mais

frequentes nos trabalhadores da EU são a lombalgia (25%) e as dores musculares generalizadas (23%). Os distúrbios músculo-esqueléticos podem ser mensuráveis através da sintomatologia referida por parte dos operários, sendo considerado como sintomatologia a presença de dor, sofrimento ou

3

desconforto. Afeta todas as regiões anatómicas, tanto da coluna vertebral como dos membros superiores ou inferiores (Enthoven, Skargren, Carstensen, & Oberg, 2006; Juul-Kristensen & Jensen, 2005; Kuorinka et al., 1987; Punnett &Wegman, 2004). No entanto, é a lombalgia a condição que implica maior morbilidade e incapacidade, compreendendo custos financeiros consideráveis afetando 58 a 84% dos adultos ativos (Airaksinen et al., 2006; Alexopoulos, Burdorf, & Kalokerinou, 2003; Alexopoulos, Tanagra, Konstantinou, & Burdorf, 2006; Alipour, Ghaffari, Shariati, Jensen, &Vingard, 2008; Bongers, Ijmker, van den Heuvel, & Blatter, 2006; Deyo et al., 1998; Dunn, Jordan, & Croft, 2006; Dunning et al., 2010).

A lombalgia pode restringir a função com consequências pessoais, interpessoais e sociais, como perda de independência, e incapacidade em executar diversas atividades na vida social, podendo interferir ainda com atividades básicas como estar de pé, caminhar e vestir-se, diminuindo a qualidade de vida, assim como as muitas atividades relacionadas com o desempenho profissional (Ceran & Özcan, 2006; Hilfiker et al., 2007; Loisel,

2005; van Tulder, Malmivaara, & Koes, 2007).

A estabilidade e os movimentos permitidos à coluna lombar são determinados pelas estruturas osteoligamentares e musculares do tronco, desempenhando os músculos, ainda, um importante papel protetor sobre as estruturas passivas da coluna vertebral. Quando estas estruturas, por qualquer motivo, se encontram enfraquecidas, os segmentos lombares ficam suscetíveis a lesão (Arokoski, Valta, Airaksinen, & Kankaanpää, 2001; Stevens et al., 2006). Para além dos fatores físicos, diversos estudos comprovam que os fatores psicossociais inerentes ao emprego, como autoridade para decisão, exigência psicológica do trabalho, apoio de supervisores, insatisfação e insegurança do emprego contribuem para o decréscimo do estado de saúde dos trabalhadores (Arnold, Witzeman, Swank, McElroy & Keck Jr, 2000; Edwards, Van Laar, Easton, & Kinman, 2009; Ferreira, 2000b; Moffett, Torgerson, Bell-Syer, Jackson, & Llewlyn-Phillips, 1999). Este tipo de fatores parece potenciar a progressão da dor e incapacidade ao longo do tempo, enquanto os fatores físicos estão mais relacionados com a fase aguda do problema (Lamers, Meerding, Severens, & Brouwer, 2005; Tavafian, Jamshidi,

Mohammad, & Montazeri, 2007).

As convicções que o indivíduo tem acerca da sua dor, levam a que tenha medo do movimento/nova lesão, redução da função e da atividade e consequente exacerbação para uma incapacidade crónica (Urquhart et al.,

4

2008; Vlaeyen, Kole-Snijders, Boeren, & van Eek, 1995). O indivíduo perceciona então uma menor qualidade de vida, que segundo a OMS condiciona a perceção do indivíduo a sua condição de vida, dentro do contexto de cultura e valores em que se insere, das suas metas, expetativas e padrões sociais (Brox et al., 2008; Claiborne, Vandenburgh, Krause& Leung, 2002). De acordo com uma revisão sistemática, van Tulder et al., (2007) de facto as lesões músculo-esqueléticas estão associadas a uma diminuição da qualidade

de vida.

Nas últimas décadas, o exercício tem sido relatado como uma mais-valia no tratamento da dor lombar, parecendo auxiliar pacientes com lombalgia crónica no retomar das atividades normais no seu emprego (Rainville et al., 2004). A realização de programas de prevenção de lesões, (Salinas et al., 2002), como a promoção para a saúde e a realização de exercício físico, têm como objetivo reduzir os possíveis fatores de risco (Eriksen et al., 2002), contribuindo para a redução dos custos diretos com as lesões, bem como para

o aumento da produtividade e qualidade de vida (Salinas et al., 2002).

Os programas de exercício têm provado ser mais eficazes na prevenção e tratamento da dor lombar do que as terapias convencionais, resultando numa redução de sintomatologia dolorosa e maior funcionalidade, diminuindo o absentismo por dor lombar (Moffett et al., 1999). Numa recente revisão os autores encontraram uma forte evidência entre os programas de exercício e a prevenção de problemas lombares (Bigos et al., 2009). Num outro estudo verificaram que existe suporte para que se possa afirmar que os programas de exercício melhoram a flexibilidade e força muscular ao nível do ráquis (Rainville et al., 2004). Contudo, ainda persiste uma certa controvérsia relativamente aos efeitos do exercício, Daltroy et al., (1997) não verificaram efeitos positivos na sua intervenção em trabalhadores industriais. Por outro lado, num estudo mais recente, Brox et al., (2008) verificaram que os programas de exercício eram efetivos na redução de dor e funcionalidade, mas apenas a curto prazo, e IJzelenberg, Meerding, & Burdorf (2007) não verificaram melhoras significativas com o seu programa. Estes resultados poderão ser devidos a problemas de comunicação ou à insatisfação e altas expectativas criadas (Goldby, Moore,

Doust, & Trew, 2006; Sherman, Cherkin, Erro, Miglioretti, & Deyo, 2005).

Um programa de exercícios bem estruturado deverá levar à diminuição de sintomatologia, diminuição de dor e aumento de força que permita aos indivíduos realizarem as suas tarefas com menor esforço, resultando numa melhoria da qualidade de vida (Airaksinen et al., 2006; Arnold, Witzeman,

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Swank, McElroy& Keck Jr, 2000; Carroll & Whyte, 2003; Lang, Liebig, Kastner, Neundörfer& Heuschmann, 2003; Moffet, 1999).

Apesar de as guidelines europeias não recomendarem o tipo e intensidade do exercício, estas preconizam que os programas deverão ser realizados tendo em conta as tarefas e movimentos repetidos que os indivíduos realizam durante o seu trabalho (Airaksinen et al., 2006; Burton et al., 2006). Os trabalhadores deverão receber instruções de como se efetuam os exercícios, devendo-se reforçar a ideia de que os fatores físicos, sociais e mentais são os alicerces da qualidade de vida (Airaksinen et al., 2006; Burton

et al., 2006).

Assim, com este trabalho pretendeu-se avaliar os efeitos de um programa de exercícios específicos em indivíduos operadores de armazém da indústria alimentar durante 21meses.

O programa de intervenção considerou a sintomatologia músculo-esquelética, força e resistência dos músculos da região lombar e a qualidade

vida.

Uma vez que são vários os objetivos deste trabalho, optou-se por apresentar uma breve revisão bibliográfica, os objetivos e os métodos, seguida de quatro capítulos com os diversos estudos resultantes. Segue-se uma

discussão geral e por fim as principais conclusões.

7

Revisão da literatura

Lesões músculo-esqueléticas

Desde o início do século XVIII, as lesões músculo-esqueléticas (LME) foram reconhecidas como tendo por base fatores etiológicos e ocupacionais. No entanto, só a partir da década de 1970 é que os fatores ocupacionais foram estudados utilizando métodos epidemiológicos, e os estudos que relacionavam o trabalho com esses fatores começaram a aparecer regularmente na literatura científica internacional. Desde então, a evidência resultante do desenvolvimento de mais de seis mil artigos científicos publicados apenas abordam a importância da ergonomia no local de trabalho (Bernard, 1997). No entanto, a relação entre as lesões músculo-esqueléticas relacionadas com o trabalho e diversos fatores, continua a ser um assunto de debate (Bernard, 1997). O mesmo tipo de controvérsia tem sido tema de estudo no âmbito de outras patologias, nomeadamente os problemas pulmonares e o cancro, ambos com causas multifatoriais (Bernard, 1997).

Com o mercado cada vez mais competitivo, hoje em dia a produtividade é a palavra de ordem, e as empresas procuram diferentes estratégias para sobreviver a esta nova realidade (Tuomi, Vanhala, Nykyri, & Janhonen, 2004). Algumas seguem a estratégia da melhoria da qualidade, modificando-se na sua produtividade e na sua estrutura organizacional. Porém, as dificuldades encontradas na implementação de uma melhor qualidade, devem-se sobretudo, à escassez de recursos humanos especializados em que as máquinas são indispensáveis e o homem é considerado apenas mais um elemento do sistema de produção, tendo este que se adaptar às mudanças do processo, muitas vezes inadequado às suas características individuais (Costa, 2003). Na maioria dos postos de trabalho cada sujeito desempenha as suas atividades específicas limitadas por um determinado período de tempo, quase sempre reduzido, induzindo os trabalhadores a desempenhar as suas funções no tempo devido, mesmo quando isso coloque em risco a sua saúde (Costa, 2003). Este tipo de convicção leva muitas vezes a incapacidades e limitações funcionais nas atividades de vida diária, bem como profissional, restringindo a participação do indivíduo na sociedade (Meijsen & Knibbe, 2007; van

Nieuwenhuyse et al., 2006)

Num contexto de trabalho, observa-se que as desordens músculo-esqueléticas, nomeadamente ao nível lombar, cervical e membros superiores,

8

são um problema de saúde com impacto importante (Bongers, Ijmker, van den Heuvel& Blatter, 2006; Klussmann, Gebhardt, Liebers, & Rieger, 2008), que conduz a custos elevados em cuidados de saúde, salários perdidos devido a períodos de baixa laboral e redução da produtividade (Côté, Cassidy, Carroll, &

Kristman, 2004; Szabo, 2001).

As desordens músculo-esqueléticas são consideradas um problema multifatorial já com identificação de principais fatores de risco: físicos, psicossociais e individuais. A nível físico, a realização de tarefas que exijam níveis elevados de força, o grande número de repetições de um determinado movimento, a vibração e as posturas incorretas foram os principais fatores responsáveis pelo surgimento de sintomatologia músculo-esquelética nesta área (Alexopoulos, Tanagra, Konstantunou, & Burdof, 2006; Bongers et al.,

2006; Goldsheyder, Nordin, Weiner, & Hiebert, 2002).

Dentro dos fatores psicossociais, estudos realizados em contexto empresarial revelam que estes se prendem com fatores como: os altos grau de exigência no local de trabalho, o baixo apoio social recebido, assim como o insuficiente apoio entre colegas, pouca autonomia relativamente às tarefas e horários atribuídos, o elevado stress psicológico e também a baixa satisfação (Lotters, Franche, Hogg-Johnson, Burdorf, & Pole, 2006; McClelland & McCubbin, 2008; Nahit et al., 2003). Os sintomas depressivos, a perceção de baixa condição física e de saúde, foram considerados preditores significativos de maior número de dias de baixa médica e, parecem constituir fatores de risco importantes para incapacidade laboral prolongada (Alexopoulos et al., 2006; Arnold et al., 2000; Lotters et al., 2006).

Numa revisão sistemática, May (2010) identificou a osteoartrite e a dor lombar crónica como os dois problemas músculo-esqueléticos mais prevalentes na população em geral. Esta caracteriza-se pela elevada frequência, estando associada a elevados custos para a sociedade, diretos e indiretos. Estes resultados epidemiológicos proporcionam uma imagem da realidade que justifica a utilização de estratégias de autogestão a fim de minimizar estes problemas (Airaksinen et al., 2006; Bigos et al., 2009; Bongers et al., 2006; Gundewall, Liljeqvist, & Hansson, 1993; Kent & Keating, 2005; Porter & Gyi, 2002; Trainor & Wiesel, 2002). Como definição de autogestão entenda-se uma ligação entre profissionais de saúde e indivíduos com necessidades nesse sentido, bem como atividades de promoção da saúde independente (May, 2010). Estratégias de autogestão independentes, como o exercício e a automedicação, são praticadas por indivíduos na população em geral sendo o

9

exercício uma estratégia eficaz na gestão de dor lombar crónica e osteoartrite, sem que no entanto não esteja claro o que é “o exercício ideal”. Contudo, o exercício, suportado pelo aconselhamento e educação, deve estar no cerne das estratégias de autogestão para dor lombar crónica (Brox et al., 2008; Burton et al., 2006; Cancelliere, Cassidy, Ammendolia, & Côté, 2011; Giaccone, 2007; Holmstrom & Ahlborg, 2005; May, 2010; May & Rosedale, 2009; Moses, Heestand, Doyle, & O'Sullivan, 2006; T. H. Tveito, M. Hysing, & H. R. Eriksen,

2004; van Oostrom et al., 2009).

Lombalgia (etiologia, fisiopatologia)

A etiologia da dor lombar é muitas vezes atribuída às tarefas e condições de trabalho (Bigos et al., 2009). A combinação do profundo esforço físico e de intensidade, posturas incorretas, exposição aos condicionamentos ambientais e a tempo de recuperação insuficiente contribuem para o aumento de lombalgias, tanto de repetição como o aparecimento de situações agudas (Arokoski et al., 1999; Borenstein, 2000; Goldsheyder et al., 2002; Piedrahíta et

al., 2004).

Chaffin e Park (1973) verificaram que a sintomatologia lombar, incluindo lesões, foi três vezes mais prevalente nos trabalhadores que apresentavam um nível de força inferior ao necessário para a execução das suas tarefas laborais. Na maioria dos casos, é difícil identificar uma causa anátomo-patológica específica para a origem da lombalgia (Fritz, Erhard, & Hagen, 1998; Hicks, Fritz, Delitto, & McGill, 2005; O'Sullivan et al., 2006). Segundo Fritz (1998) os indivíduos com diagnósticos de lombalgia sem etiologia específica são

usualmente incluídos no grupo das lombalgias de origem mecânica.

A lombalgia de origem mecânica é um termo que descreve a dor lombar resultante do esforço físico e que é aliviada com o repouso. Deve-se, geralmente, a disfunções na musculatura posterior do tronco, tendões e ligamentos e pode ser agravada em atividades como levantar pesos, permanecer em posições estáticas prolongadas, tanto na posição de pé como sentada. Indivíduos com este tipo de lombalgia referem sentir um “peso” e uma sensação dolorosa que piora ao final do dia em decorrência de atividades e esforço físico (Cholewicki & McGill, 1996; Imamura, Kaziyama, & Imamura, 2001). A estabilidade dada à coluna vertebral durante a realização dos mais variados movimentos no quotidiano é garantida, principalmente, pelo sistema muscular (Lee et al., 1999; Norris, 1995; O'Sullivan, 2000; Richardson, Jull,

10

Toppenberg, & Comerford, 1992). Quando este falha, ou se encontra enfraquecido, há um aumento da sobrecarga sobre as articulações e ligamentos espinhais (Hodges, 1999). Assim, será mais provável que ocorra uma lesão a nível da coluna lombar (Richardson et al., 1992). Krajcarski et al. (1999) verificaram que a pré-ativação dos músculos extensores do tronco podem servir para reduzir a deslocação do disco intervertebral aquando do movimento de flexão rápido e em carga. A diminuição da força e da resistência dos músculos do tronco surge como um factor de risco primário na ocorrência da lombalgia (Critchley, 2002). Vários estudos verificaram que indivíduos com disfunção da coluna lombar apresentam, na maior parte dos casos, uma diminuição significativa da força e da resistência dos músculos estabilizadores da coluna, comparativamente a indivíduos saudáveis (Arokoski, Valta, Kankaanpää, & Airaksinen, 2004; Costa & Palma, 2005; Gonçalves & Barbosa, 2005; Ismaeil, Hosseini, Salavati, Farahini, & Arab, 2005; Moffroid, 1997; Sung, 2003; Udermann, Mayer, Graves, &Murray, 2003). Os músculos extensores e flexores do tronco são importantes estabilizadores da coluna vertebral, contudo os músculos profundos com inserções nas apófises vertebrais lombares proporcionam uma maior estabilidade intersegmentar, pelo que os músculos multífidos e o transverso abdominal (via fáscia toracolombar) parecem desempenhar o papel principal na estabilização da coluna lombar (Arokoski et al., 2004; Costa & Palma, 2005; Critchley, 2002). De facto, não só a força muscular mas também a resistência parecem estar relacionadas com o aparecimento de dor na região lombar (Arokoski et al., 1999; Arokoski, Valta, Airaksinen, & Kankaanpaa, 2001; Hodges, 1999; Maher et al., 2005; Nourbakhsh & Arab, 2002; O'Sullivan et al., 2006; Roussel et al., 2006; Yang, Marras, & Best, 2011). Os investigadores atribuem a diminuição da resistência dos extensores do tronco encontrada em doentes com lombalgia, a vários fatores, tais como: alto nível metabólico do músculo resultante de tensão prolongada; grande proporção de fibras do tipo II nos músculos para-espinhais, especialmente os multífidos; descondicionamento físico; desequilíbrio na coordenação muscular e inadequada distribuição da força muscular extensora (Arokoski et al., 1999; Arokoski et al., 2001; Hodges, 1999; Maher et al., 2005; Nourbakhsh & Arab, 2002; O'Sullivan et al., 2006; Roussel et al., 2006; Yang et

al., 2011).

Segundo Trainor (2002) o rácio de força entre extensores/flexores do tronco deveria ser de 1.3/1. Estudos têm revelado que pacientes com lombalgia têm este rácio alterado comparativamente à população normal (Lee et al., 1999) verificando-se uma relação de 1.2/1 a 1.5/1 em indivíduos assintomáticos

11

(propensos à aquisição da doença) e de 1.0/1 em alguns casos de indivíduos com lombalgia crónica (Costa, 2003). A falta de suporte dado pela musculatura extensora do tronco pode ocorrer devido à fraqueza muscular, associada,

muitas vezes ao sedentarismo.

Num estudo realizado com o objetivo de investigar a associação entre dezassete fatores mecânicos e a ocorrência de dor lombar concluiu-se que, a diminuição da força e resistência musculares do tronco, estavam associados à ocorrência de lombalgia; os fatores estruturais como a lordose lombar, tilt

pélvico, discrepância no tamanho dos membros, comprimento dos abdominais, isquiotibiais e iliopsoas não estavam relacionados com a ocorrência de dor lombar (Nourbakhsh & Arab, 2002). Alguns estudos concluíram que os músculos mais envolvidos na estabilização da coluna lombar são os oblíquos do abdómen e o transverso abdominal em co-ativação com o eretor da espinha (Richardson, Jull, Toppenberg, & Comerford, 1992; Trainor & Wiesel, 2002). Os músculos abdominais oblíquos, especialmente os oblíquos externos, rapidamente aumentam os níveis de ativação em resposta ao movimento rápido. Quando os níveis de pré-ativação são baixos o tronco fica rígido exercendo-se forças compressivas no disco e estruturas moles adjacentes. Algumas lesões ocorrem devido a erros de controlo motor (Krajcarski, Potvin, & Chiang, 1999). Estes são eventos aleatórios, mas são mais prováveis em pessoas com um sistema de controlo motor pobre (Brereton & McGill, 1999). Assim, uma lesão na região lombar pode ocorrer mesmo numa tarefa simples se não houver aviso de sobrecarga.

A resistência é importante porque com tarefas repetitivas os músculos entram em fadiga (McGill, Childs, &Liebenson, 1999). McGill, Sharratt, &Seguin (1995) observaram que as pessoas têm diferentes capacidades em suportar uma carga nas mãos e respirar "arduamente".Vários autores acreditam que uma condição física pobre associada à fraqueza, quer dos músculos abdominais quer dos extensores do tronco, são fatores importantes no desenvolvimento e persistência de lombalgia (Besler & Can, 2003; Rantanen, Airaksinen, & Penttinen, 1994). Outros autores vão mais longe e salientam mesmo o importante papel da musculatura extensora na prevenção de lombalgia (Arokoski et al., 2001; Arokoski, Valta, Kankaanpaa, & Airaksinen, 2004; Hodges & Richardson, 1998; Peltonen et al., 1998; Rissanen et al., 2002; Roussel et al., 2006). Alguns estudos sugerem que indivíduos que possuem músculos fortes, principalmente os extensores lombares, sofrem menos desta patologia (Besler & Can, 2003; Ng, Richardson, Kippers, & Parnianpour, 1998).

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Por outro lado, outros autores afirmam que o enfraquecimento dos músculos do tronco não está relacionado com a incidência de dor lombar (Johannsen et al.,

1995; Mostardi, Noe, Kovacik, & Porterfield, 1992).

A realização de movimentos repetitivos, ou aquisição de certas posturas viciosas, como é o caso da maioria dos indivíduos, pode levar a um maior desenvolvimento de determinados músculos em detrimento de outros, gerando

desequilíbrios musculares (Comerford & Mottram, 2001; Rissanen et al., 2002).

Potvin & O’Brien (1998) constataram que a fadiga é resultado de uma mudança nos padrões de recrutamento dos músculos do tronco, estes, que atuam como estabilizadores, durante um movimento prolongado de rotação e flexão, passam a funcionar como antagonistas, exigindo mais força e mais rapidamente entram em fadiga. A postura sentada leva à inatividade que pode ser prejudicial (Bernard, 1997; Besler & Can, 2003). A falta de movimento leva a um acúmulo de metabolitos, que provavelmente aceleram a degeneração dos discos e aumentam a probabilidade de estrangulamento do disco (Bigos et al., 2009; Brereton & McGill, 1999; Dunn, Jordan, & Croft, 2006). As posturas de condutores de máquinas, também podem levar a problemas músculo-esqueléticos na região cervical, lombar, ombros e membros superiores. No local de trabalho, em pé e sentado são as duas formas básicas de posturas (Fathallah, Marras, & Parnianpour, 1997; Gagnon & Smyth, 1992). Essas posturas têm vantagens específicas e desvantagens para a mobilidade, exercícios de força, consumo de energia, sistema circulatório, coordenação e controle de movimento (Friedrich, Karnzl, Heller, Kirtley, & Cermak, 2000; Marras, Lavende, Fergunson, Splittstoesser, & Yang, 2010). A estabilidade e os movimentos permitidos à coluna lombar são determinados pelas estruturas osteo-ligamentares e musculares do tronco, desempenhando o músculo, ainda, um importante papel protetor sobre as estruturas passivas da coluna vertebral. Quando estas estruturas, por qualquer motivo, se encontram enfraquecidas, os segmentos lombares ficam suscetíveis a lesão (Arokoski et al., 2001; Stevens et al., 2006). Muitas vezes, a dificuldade em manter dupla tarefa, pode ser importante para a compreensão de que os músculos necessários para evitar deformações na coluna estão permanentemente a ser requisitados para a ventilação, podendo comprometer a elasticidade pulmonar (McGill, Sharratt, &

Seguin, 1995).

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Qualidade de vida

Sendo a região lombar uma importante zona de suporte e de transferência de forças, as alterações acompanhadas de dor terão impacto na qualidade de vida do indivíduo, pela diminuição da função física e deterioração da saúde no geral. A presença da dor quer seja pontual ou constante, induz no indivíduo uma situação de desconforto, comprometendo as atividades da vida diária, reduzindo a sua participação nas atividades sociais e lúdicas, nas atividades familiares e ainda na atividade laboral, com todas as consequências que daí

advêm (Claiborne et al., 2002; Galukande, Muwazi, & Mugi, 2005).

A perceção que o indivíduo tem acerca da dor, leva a que reduza os movimentos pela antecipação da dor ou eventual lesão. Esta condição leva à redução da função e da atividade, e consequentemente à exacerbação da incapacidade, com evolução desta para uma condição crónica (Urquhart et al., 2008; Vlaeyen et al., 1995). Este ciclo induz uma menor qualidade de vida, que segundo a OMS resulta da perceção do indivíduo sobre a sua condição de vida, dentro do contexto de cultura e valores em que se insere, e das suas metas, expetativas e padrões sociais (Brox et al., 2008; Claiborne et al., 2002). Esta evidência foi reforçada por uma recente revisão realizada por van Tulder et al. (2007), onde referem que de facto as lesões músculo-esqueléticas estão associadas a uma diminuição da qualidade de vida.

Para além dos fatores físicos, diversos estudos comprovam que os fatores psicossociais inerentes ao trabalho, como autoridade para decisão, exigência psicológica do trabalho, apoio de supervisores, insatisfação e insegurança do emprego têm também o seu contributo para o decréscimo do estado de saúde dos trabalhadores (Arnold et al., 2000; Edwards et al., 2009; Ferreira, 2000b; Moffett et al., 1999). Este tipo de fatores parece potenciar a progressão da dor e incapacidade ao longo do tempo, estando os fatores físicos mais relacionados com a fase aguda do problema (Lamers et al., 2005; Tavafian et al., 2007).

A saúde relacionada com a qualidade de vida é uma vertente multidisciplinar que mede a capacidade de um indivíduo face às diferentes funções, emoções do seu quotidiano e ao impacto da dor nas suas atividades diárias (Claiborne et al., 2002). A satisfação do indivíduo, isto é, a avaliação do mesmo relativamente aos seus cuidados de saúde de acordo com as expetativas iniciais, é uma forma subjetiva importante de medida do estado de saúde. A redução dos sintomas subjetivos leva a um aumento da qualidade de

14

vida e do bem-estar, condições essenciais para o conceito de saúde (Hemingway, Stafforf, Stansfeld, Shipley, & Marmot, 1997; Lang, Liebig, Kastner, Neundörfer, & Heuschmann, 2003; Sculco, Paup, Fernhall, & Sculco,

2001).

O exercício aumenta a qualidade de vida, resultando num aumento da funcionalidade e performance dos indivíduos (Airaksinen et al., 2006; Claiborne, Vandenburgh, Krause, & Leung, 2002). Percebe-se assim a importância da reabilitação quer dos extensores quer dos abdominais do tronco quando se fala em alcançar a máxima performance possível (Essendrop, Maul,

Läubli, Riihimäki, & Schibye, 2002).

Importância dos programas de exercício físico

O comportamento natural do ser humano é mudar a postura muitas vezes. Mesmo durante o sono, há uma necessidade de ajustes de postura. Nenhuma posição deve ser mantida por um longo período de tempo sem desconforto considerável. Embora possa vir a ser um problema, a prevenção é, de longe, o tratamento de escolha. Os efeitos combinados da comunidade médica, trabalhadores e administradores são necessários para causar algum impacto sobre este problema (Keyserling, Martin, Sudarsan, Haig, & Armstrong, 2005; Pope, Goh, & Magnusson, 2002; Poppel, Hooftman, & Koes, 2004). De facto vários são os estudos que demonstram melhorias nas escalas globais de dor, assim como nas estratégias de lidar com síndromes lombares (Andersen et al., 2010; Bigos et al., 2009; Borenstein, 2000; Brox et al., 2008; Byrne, Doody, & Hurley, 2006; Carroll, Rick, Pilgrim, Cameron, & Hillage, 2010; Ceran & Ozcan, 2006; Costa & Palma, 2005; Denis, St-Vincent, Imbeau, Jette, & Nastasia, 2008; Descarreaux, Normand, Laurencelle, & Dugas, 2002; Gerr et al., 2005; Hildebrandt & Neufer, 2000; Hlobil et al., 2005; Holmstrom & Ahlborg, 2005; Johannsen et al., 1995; Kaser et al., 2001; Lee et al., 1999; Maher, 2000; McGill, Childs, & Liebenson, 1999; Moffroid, 1997; Moseley, 2002; Rainville, Hartigan, Jouve, & Martinez, 2004; Rainville, Hartigan, Martinez, et al., 2004; Stevens et al., 2006; Tuncel, 2006; Tveito & Eriksen, 2009; Tveito et al., 2004;

Udermann, Mayer, Graves, & Murray, 2003).

Foram realizados vários estudos onde se verificou que os indivíduos na presença de dor subaguda respondem restringindo a atividade física para se protegerem da dor e de possíveis lesões ao nível da coluna, sendo esta, uma reação de medo normal em pacientes sintomáticos (Brox, Storheim, Holm,

15

Friis, & Reikeras, 2005). Todo este processo vai condicionar a qualidade de vida do indivíduo ao impedi-lo de realizar as suas tarefas e atividades diárias, sociais e laborais da forma habitual, devido a uma consequente diminuição da

funcionalidade (Rainville et al., 2004).

A prevenção/tratamento através de classes de exercícios tem evidenciado resultados mais eficientes relativamente ao tratamento conservador, apresentando não só redução da dor ao nível lombar e da incapacidade, mas também menores custos, com menor necessidade de recorrer aos serviços de saúde e menor absentismo laboral por dor lombar (Merkesdal & Mau, 2005). Tudo isto se traduz em aumento de qualidade de vida para o indivíduo, proporcionando-lhe através do exercício o aumento do seu desempenho a nível profissional, melhorando também a sua funcionalidade (Claiborne et al., 2002). Pelo que um programa de exercícios bem estruturados leva, a longo prazo, a uma redução da dor lombar (Merkesdal & Mau, 2005). Estes mesmos programas de exercícios específicos para a região lombar têm-se demonstrado eficazes na diminuição da dor, reduzindo assim o desempenho necessário exigido pelas atividades diárias, assim como na incapacidade (Lang et al., 2003), induzindo assim uma melhoria significativa da qualidade de vida nos indivíduos (Merkesdal & Mau, 2005; van Poppel, Hooftman, & Koes, 2004).

Morken et al. (2003) verificaram que mais de um terço dos sintomas músculo-esqueléticos relacionados com o trabalho podia ser evitado. Uma das formas seria um programa de intervenção para a lombalgia através do exercício físico (Airaksinen et al., 2006; Maher et al., 2005; Tveito et al., 2004). Alguns estudos relatam que uma elevada satisfação por parte do indivíduo, no que se refere à sua saúde ocupacional, pode estar relacionada com uma melhor compreensão e adesão ao tratamento (NORA, 2001; Rainville et al.,

2004).

Alguns empregadores têm vindo a implementar medidas para reduzir a carga de trabalho aos seus colaboradores na tentativa de reduzir a incidência de sintomatologia dolorosa e doenças relacionadas com o trabalho de forma a reduzir o absentismo, assim como os custos decorrentes. Para além dessas medidas têm feito ajustes ergonómicos no local de trabalho que podem consistir em programas educativos de educação ou formação. Este tipo de intervenção consiste no ensino de manuseamento e levantamento de cargas, incluindo a prescrição de suportes lombares e programas de exercícios

(Airaksinen et al., 2006; Brox et al., 2008; van Poppel et al., 2004).

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Objetivos

Os objetivos deste estudo foram avaliar os efeitos de um programa de exercícios específicos a médio e longo prazo, em operários de um armazém de distribuição da indústria alimentar. Para que se pudesse concretizar estes

objetivos foi necessário:

� Adaptar para a população portuguesa um instrumento que avaliasse a sintomatologia músculo-esquelética tendo-se optado pelo standardized

Nordic musculoskeletal questionnaire;

� Analisar a sintomatologia músculo-esquelética ao nível das regiões do pescoço, ombros, cotovelos, mãos/punhos, torácica, lombar,

ancas/coxas, joelhos e pés/tornozelos, durante 21 meses;

� Medir a força máxima e resistência dos flexores e extensores lombares,

durante 11 meses;

� Avaliar a perceção da saúde relacionada com a qualidade de vida nas dimensões Função Física, Desempenho Físico, Dor Física, Saúde em Geral, Vitalidade, Função Social, Desempenho Emocional e Saúde

mental, durante 21 meses.

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Material e Métodos

Amostra

A população utilizada neste estudo incluiu 557 trabalhadores do sexo masculino de um armazém de uma empresa de distribuição de alimentos na cidade do Porto. Todos os trabalhadores, do sexo masculino, estavam envolvidos em uma rotina de tarefas sobrecarga e / ou movimentos repetitivos e eles trabalharam sob baixas temperaturas (entre 0 º e 4 º C) durante todas as estações do ano. De acordo com as normas da empresa, todos os trabalhadores usavam roupas de proteção para o frio (blusão, luvas e botas) e cintas de apoio lombar. Os critérios de seleção foram enviados para a empresa (equipa de Medicina do Trabalho e equipa de recursos humanos).

A empresa apresentou uma lista de trabalhadores elegíveis organizados em ordem alfabética de 249 trabalhadores, correspondendo a 45% da população. Aleatoriamente dividiu-se em dois grupos (125 no grupo intervenção e 124 no grupo controlo). De seguida foi solicitado aos trabalhadores que se voluntariassem para participar no estudo, tendo que dar um consentimento por escrito. Os voluntários foram 112 para o grupo intervenção e 117 para o grupo controlo; no início do estudo a amostra foi de

n=229 equivalente a 41% da população.

Incluíram-se os indivíduos que preenchessem os seguintes critérios: um contrato para três ou mais anos e que realizassem o mesmo tipo de tarefa (montagem e desmontagem de paletes). Excluíram-se os indivíduos que: a) eram obrigados a rodar postos de trabalho; b) absentismo no último ano devido a dor nas costas; c) tivessem dor forte nas costas (VAS ≥ 5) no último ano; d) tivessem realizado tratamento (conservador ou cirúrgico) à região lombar durante o último ano, e) se existisse qualquer tipo de patologia diagnosticada

que impedisse a prática exercício físico (Sculco et al., 2001).

Da primeira para a segunda avaliação houve uma perda total de 37,5% dos indivíduos, 29.4% no grupo de intervenção e 44,4% no grupo controlo, assim no momento 2 ficaram 151 trabalhadores dos quais 79 no grupo de intervenção e 72 no de controlo. Do segundo para o terceiro momento de avaliação houve uma perda de 34,2% dos indivíduos, 38,5% do grupo

intervenção e 39,2% do grupo controlo.

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Desde o primeiro ao terceiro momentos de avaliação, as perdas nos grupos de intervenção e controlo foram de 57% e 60%, respetivamente. Depois

de 21 meses a amostra ficou reduzida a aproximadamente 17% da população.

Estas perdas foram de trabalhadores que deixaram a empresa, a mudanças do local de trabalho, não responderem aos questionários e,

nalgumas situações, à falta de motivação para continuar no estudo.

A Tabela 1 mostra os valores de média, desvio padrão, mínimo e máximo para a idade (anos), altura (cm), peso (kg) e índice de massa corporal (IMC) dos trabalhadores incluídos em grupos intervenção e controlo no

Momento 1, antes da intervenção.

Tabela 1: Valores de média, desvio padrão, mínimo e máximo de idade (anos), altura (cm), peso (kg) e IMC dos trabalhadores dos grupos de intervenção e de controlo.

Instrumentos

Questionário de Saúde Geral

Este questionário teve como objetivo fazer a caraterização dos indivíduos, quanto às variáveis demográficas, assim como em relação a alguns hábitos dos indivíduos (Anexo 1).

Questionário Nórdico Músculo Esquelético

Para avaliar a sintomatologia músculo-esquelética dos indivíduos usou-se o Questionário Nórdico músculo-esquelético validado para a população

n=229

Grupo de Intervenção

n=112

Grupo de controlo

n=117

média±dp min Max média±dp min Max

Idade (anos) 34.41±8.36 20 49 33.05±10.19 18 56

Altura (cm) 173.0±0.07 160.0 188.0 178.0±0.09 159.0 188.0

Peso (kg) 76.54±10.44 55 95 81.07±16.84 60 110

IMC (kg/m 2) 25.57 21.48 26.91 25.58 23.81 31.16

21

portuguesa (Mesquita, Ribeiro, & Moreira, 2010). A primeira parte do QNM consiste em questões de escolha dicotómica (Sim ou Não) acerca da ocorrência de sintomas em nove regiões anatómicas. Cada operário deve relatar a ocorrência de SME tendo em consideração os 12 meses e os 7 dias anteriores ao dia do preenchimento do questionário, bem como, relatar se nos últimos 12 meses sentiu alguma limitação nas atividades funcionais pessoais e

ocupacionais (Anexo 2).

Dinamómetro Eletrónico

Para a mensuração da força máxima isométrica foi utilizado o dinamómetro eletrónico isométrico (Globus Ergometer, Globus, Codigné, Italy) para a medição da força máxima isométrica dos grupos musculares flexor e extensor do tronco. É um instrumento de fácil instalação e manuseamento que avalia a força em quilograma força (Kgf) e da resistência, em segundos (Seg). O dinamómetro eletrónico isométrico apresenta uma elevada fiabilidade inter-sessão ICC=0.94 e inter-observador ICC=0.98 (Dankaerts, O'Sullivan, Burnett,

Straker, & Danneels, 2004).

Foram utilizados mosquetões e uma banda de suporte adjacente ao dinamómetro (Fig.1, 2 3 4) para a realização dos testes e, ainda, um

cronómetro Swatch® para controlar os períodos de repouso.

Figura. 1 Figura. 2

22

Figura. 3 Figura. 4

Short Form Health Survey – versão 2 (Sf-36 – v2)

Para a avaliação da qualidade de vida foi utilizado o questionário de auto preenchimento validado para a população portuguesa (Ferreira, 2000a, 2000b). Este é um questionário genérico de estado de saúde desenhado para avaliar o impacto da doença sobre a qualidade de vida (Ware & Sherbourne, 1992). O SF-36 mede o estado de saúde segundo oito dimensões: Função Física (10 itens), Desempenho Físico (4itens), Dor Física (2itens), Saúde em Geral (5itens), Vitalidade (4itens), Função Social (2itens), Desempenho Emocional

(3itens) e Saúde Mental (5itens).

A avaliação da limitação da Função Física é quantificada pela capacidade do indivíduo executar tarefas leves (tomar banho, vestir-se sozinho, caminhar), tarefas moderadas (levantar ou pegar em sacos de mercearia, subir um lanço de escadas) ou tarefas mais violentas como desportos radicais. Para a avaliação do Desempenho Físico e Emocional a medição é realizada em detrimento da quantidade e tipo de trabalho executado, da limitação das tarefas executadas habitualmente e da necessidade de redução do tempo de trabalho.

23

Relativamente à Função Social do indivíduo, são cotadas a quantidade e a qualidade das atividades sociais realizadas e o impacto da limitação física e emocional sobre essas mesmas atividades. A dor corporal é classificada segundo a intensidade e o incómodo que causa e ainda a forma como intervém nas atividades do paciente. Quanto à Saúde Geral, esta é avaliada através de uma escala que descreve o estado de saúde da pessoa relativamente à condição atual, a resistência à doença e ainda a aparência saudável. A Vitalidade permite captar as diferenças de bem-estar, tendo em conta os níveis de energia e de fadiga. A avaliação da Saúde Mental corresponde às questões dirigidas para a ansiedade, depressão, controlo comportamental e emocional

assim como bem-estar psicológico.

Este questionário apresenta 10 questões com várias alíneas, cada uma com uma cotação que traduz a quantidade de cada dimensão. Cada alínea foi traduzida numericamente e o posterior somatório traduz um resultado que varia entre “0”, que corresponde à pior qualidade de vida e “100”, que corresponde à

melhor qualidade de vida possível (Anexo 3).

Procedimentos

Inicialmente, foram realizadas várias visitas às instalações do armazém para conhecer o tipo de tarefas executadas pelos trabalhadores, fotografar e filmar as diferentes atividades realizadas ao longo de um dia de trabalho. Perceber quais os principais problemas dos indivíduos, pedindo a sua colaboração no futuro projeto, dando sugestões. Após a avaliação dos riscos e gestos mais repetidos, foi criado um programa de exercícios (Anexo 4).

Este programa incluiu oito exercícios de fácil execução para promover alongamento e fortalecimento dos tecidos moles responsáveis pela estabilidade da coluna vertebral, especialmente a estabilidade lombar. O programa de exercícios salientou mais o fortalecimento dos extensores lombares e foi criado para ser executado diariamente com duração entre cinco a nove minutos, no início do tempo de trabalho e preferencialmente no posto de trabalho.

Para motivar os trabalhadores a aderir ao programa e segui-lo, houve várias sessões de formação e cartazes que ilustravam o programa de exercícios. Paralelamente um grupo de fisioterapeutas esteve presente diariamente nas primeiras duas semanas, no início de cada turno de trabalho (07h30, 15h30 e 23h30). Após os 15 dias, as visitas passaram a ser em dias alternados durante mais duas semanas. Nas quatro semanas seguintes passou-se a fazer as visitas duas e uma vez por semana. No final das oito

24

semanas passou-se a fazer visitas quinzenais durante todo o período em que se realizou o estudo.

Estas visitas visaram a educação na realização dos exercícios, correção de eventuais erros de execução e responder a dúvidas e perguntas dos trabalhadores quanto ao programa de exercícios e à sua saúde em geral. A eficácia do programa foi avaliada em três momentos: antes da aplicação do programa de exercícios (M1), após 11 meses (M2) e no final, após 21 meses (M3).

O grupo controlo participou nos pré e pós testes. Após a conclusão da intervenção foi-lhes oferecido o mesmo programa de intervenção. O estudo foi realizado entre Fevereiro de 2005 e Março de 2007.

O estudo foi realizado com autorização da empresa, e de acordo com o protocolo entre as instituições envolvidas. Todos os participantes forneceram consentimento informado antes de entrar no estudo, de acordo com a Declaração de Helsínquia.

O estudo foi aprovado pela Comissão de Ética da Escola Superior de Tecnologia da Saúde do Instituto Politécnico do Porto.

Capitulo 1

Portuguese Version of the Standardized Nordic

musculoskeletal questionnaire: cross cultural and r eliability

27

28

29

30

31

32

33

Capitulo 2

An exercise program decreases low back symptoms of workers

(SUBMETIDO PARA PUBLICAÇÃO NO Scandinavian Journal of Work, Environment & Health)

37

ABSTRACT

Background

Musculoskeletal symptoms are associated with pain, problems and functional limitations.

Specific exercise can improve daily life activities and well-being, resulting in better professional

performance and functionality.

Aim

The purpose of this study was to evaluate the effect of following a 21-month exercise program

on the musculoskeletal symptoms of warehouse workers.

Methods

The population included 557 warehouse male workers from a food distribution company in

Oporto/Portugal. Upon application of the selection criteria, 249 workers were deemed eligible,

which were randomised in two groups (125 in the intervention group and 124 in the control

group). Then, subjects were asked to volunteer for the study, being the sample formed by 229

workers (112 in the intervention group and 117 in the control group). All subjects completed the

Portuguese version of the Nordic Musculoskeletal Questionnaire at baseline (M1) and at 11(M2)

and 22(M3) months of follow-up. The exercises were executed in the company facilities once a

day for eight minutes. Data were analysed using SPSS® 17.0 for Windows®.

Results

The most common symptom, with higher proportion across all points of assessment, was the

low back region, followed by the neck, in both groups before intervention. In the intervention

group, improvements were statistically significant in the low back, in the variable “troubles in the

last 12 months”, at M1/M2 (p=0.000) and M1/M3 (p=0.000); in the variable “limitations in the last

12 months”, at M1/M2 (p=0.001) and M1/M3 (p=0.000); and in the variable “troubles in the last 7

days”, at M1/M3 (p=0.01). In the control group there were statistically significant differences at

M1/M3 (p=0.029), although these differences resulted from increased symptoms.

Conclusion

It can be concluded that the implementation of a 21-month low back specific exercise program

decreased low back pain symptoms of warehouse workers.

Keywords: occupational health, musculoskeletal symptoms, specific exercises, Nordic

questionnaire.

INTRODUCTION

Musculoskeletal disorders (MSD) are very common and can even be considered as one

of the main problems in industrialised countries (1).In fact, they represent the most common

cause of chronic incapacity (2, 3). The National Institute for Occupational Safety and Health

defined musculoskeletal symptoms (MSS) as a group of conditions involving the nerves,

tendons, muscles, and supporting structures such as inter vertebral discs (4). Pain is workers’

38

most reported problem and one of the most common causes of work absence (5, 6). According

to (7) low back pain (LBP) (25%) and muscle pain (23%) account for the two major MSD

affectingEUworkers. LBP is the major cause of morbidity and disability, involving considerable

financial costs and affecting 58%-84% of the working population (4, 5,8-15).

Punnett et al. (2005) have verified that about 37% of LBP is associated with exposure to

risk factors (16). Moreover, LBP is considered to depend from different aspects, resulting from

the interaction of physiological, psychological and social factors (17). The physical ergonomic

features of work are frequently mentioned as risk factors for the occurrence of LBP, including

heavy work, repetitive motion patterns, lifting of carrying heavy weight or other forceful manual

tasks, asymmetric body postures (either dynamic or static); movements with trunk flexion or

torsion, forced or involving accumulated compressive forces on vertebral discs, vibration (both

segmental and whole-body), low temperatures, excessive weight on tendons, joints and

muscles, insufficient recovery time of musculoskeletal structures and activity intensity (18-24).

Kasai considered lumbar stability to be a potential cause for LBP (25). The risk of developing

LBP is particularly high when the working environment involves exposure to one or more of

these risk factors.

Low back disorders in warehouses or distribution centres have been identified as an

area of elevated risk in many industries (26), as the incidence and prevalence of occupational

LBP are especially high in manual work industries (26, 27).Common tasks involving manual

work in distribution centres are the assembly and disassembly of pallets, and also the transfer

and stacking of material (boxes or bags) in pallets, which require repetitive movements with

trunk flexion and torsion (28-30). According to Mazloum (2006) weight lifting contributes more to

LBP than any other occupational risk factors (31). Working in wrong postures demands

adequate trunk muscle flexibility and strength (32). In fact, reduced vertebral muscle flexibility

and trunk extension strength are generally associated with LBP and sciatic pain (33-35). MSD

can be measured considering the symptoms reported by workers, such as pain, ache or

discomfort (36-38), affecting all anatomic regions, both spine and extremities (39, 40).

The prevention of LBP and the associated disability is the best attitude to be adopted by

all economic agents and work-related health professionals (1,18, 39-42). Specific exercises

have been shown to prevent and reduce work-related MSD, such as LBP, and the associated

costs (29, 43-48). These exercises aim to restore trunk muscle normal function and have been

shown to be efficient in reducing disability and in increasing performance in individuals with mild

disability (29, 49). These can be important arguments for the implementation of exercise

programs in the work place. These programs include specific exercises which are performed in

the work place to improve workers’ general health and the conditions regarding work activities

and tasks. They promote stretching of shortened muscles and improve motor coordination and

interpersonal relations. Soukup (2001) considered specific exercise to be a common

physiotherapy approach in the prevention of LBP (50).

39

The aim of this study was to evaluate the effects of a specific exercise program

executed before work in the MSS of warehouse workers. Specifically, it aimed to check if a

specific exercise program could decrease MSS in warehouse workers.

METHODS

Subjects

The population used in this study included 557 warehouse urban male workers from a food

distribution company in Oporto/Portugal. All workers were involved in a routine of overcharge

tasks and/or repetitive movements and they worked under low temperatures (between 0º and

4ºC) during all seasons of the year. According to the company norms, all workers wore cold

protective clothing, gloves, boots and lumbar support belts. After informing the clinical physician

and human resources staff on the criteria that would have to be taken into account for subject

selection, the company has provided us with an alphabetically organised list of 249 eligible

workers, corresponding to 45% of the population. The sample was randomised in two groups

(125 in the intervention group and 124 in the control group). Then, subjects were asked to

volunteer to participate in the study under written consent. The sample included 112 volunteers

for the intervention group and 117 for the control group. At baseline the sample was n=229,

corresponding to 41% of the population.

Workers were deemed eligible if they met the following criteria: a) they had a contract

for three or more years; b) they performed the same task type (assembly and disassembly of

pallets). On the other hand, it excluded individuals who: a) were required to rotate work

positions; b) were absent from work because of back pain; c) had severe back pain (VAS ≥ 5) in

the last year; d) had undergo treatment (conservative or surgical) to LBP for the last year; and

e) had been diagnosed with any kind of pathology which could prevent them from participating

in the prescribed exercises (51).

From the first to the second assessment there was a total loss of 37.5% of the subjects,

30% from the intervention group and 44.4% from the control group. From the second to the third

assessment there was a total loss of 34.2% of the individuals, 38.5% from the intervention

group, and 29.2% from the control group. From the first to the third assessment, losses in the

intervention group and in the control group were 57% and 60%, respectively. After 21 months

the sample was reduced to approximately 17% of population. These losses resulted from

workers leaving the company, changing workplace, losing motivation to continue in the study or

not answering the questionnaire.

Table 1 shows values for mean, standard deviation, minimum and maximum for age

(years), height (cm), weight (kg) and body mass index (BMI) of workers included in the

intervention group and in the control group.

40

Table 1: Values for mean, standard deviation, minimum and maximum of age (years), height (cm), weight (Kg) and BMI

of workers included in the intervention group and in the control group.

n=229

Intervention group

n=112

Control group

n=117

mean±sd Min Max mean±sd Min Max

Age

(years) 34.41±8.36 20 49 33.05±10.19 18 56

Height

(cm) 173.0±0.07 160 188 178.0±0.09 159 188

Weight

(Kg) 76.54±10.44 55 95 81.07±16.84 60 110

BMI

Kg/m 2 25.57 21.48 26.91 25.58 23.81 31.16

Instruments

The Portuguese version of the Nordic musculoskeletal questionnaire (NMQ) was used

to evaluate MSS of subjects. This questionnaire has a Kuder-Richardson reliability of 0,855 and

a test-retest reliability in the Cohen’s kappa coefficient test between 0,677 and 1 (52). The NMQ

consists of 27 binary choice questions (yes or no). The questionnaire has three questions

correlating to nine anatomic regions (neck, shoulders, wrists/hands, upper back, low back,

hips/thighs, knees, ankles/feet), addressing three variables: in the first, subjects are asked if

they felt any troubles or pain in the last 12 months; the second variable questions if subjects felt

any work-related limitation in their daily activities in the last 12 months”; the third addresses

troubles or pain felt in the last 7 days. According to the original author of the questionnaire, for

“troubles” we must understand pain, discomfort or aching (36). For a clear identification of

corporal areas, the questionnaire also includes a picture of the human form with nine body

areas shaded and defined (36).

Procedures

The exercise program was implemented in several stages. In a first moment, visits to the

warehouse facilities allowed to know the type of tasks executed by workers and the most

common injuries. Upon evaluation of risks and most repeated gestures, an adequate exercise

program was created. This program included nine easily-executed exercises to promote

stretching and strengthening of soft tissues responsible for spinal stability, especially lumbar

stability. This program was applied, with exercises being executed daily, at the beginning of the

working time, in the company facilities and lasting approximately eight minutes. To motivate

workers to adhere to the program and follow it, there were several training sessions and posters

illustrating the exercise program to execute were distributed in the company facilities.

Facilitators of the program included physiotherapists, who visited the warehouse facilities

each 15 days to correct possible execution errors or to answer doubts and questions from

workers as to the exercise program. The program efficacy was assessed at three moments – at

41

baseline (M1), 11 months after study entry (M2), and 21 months after intervention (M3) – by

application of the NMQ.

The control group participated in the pre- and post-program tests. At the end of the

study this group was offered the possibility of executing the same exercises which were

implemented in the intervention group.

The study was conducted between February 2005 and March 2007, with authorisation

by the company, and according to a protocol between the institutions involved. All participants

provided written informed consent before entering the study. All procedures were in accordance

with the Helsinki Declaration. The study design was approved by the ethics committee of Escola

Superior de Tecnologia da Saúde do Porto, in Portugal.

Statistics

Exploratory data analysis and sample characterisation were performed using descriptive

statistics.

The Q Cochran’s test was used at the different points of assessment to analyse if the

exercise program influenced the intervention group during the study. When values obtained with

this test were below the significance level, the McNemar test was used to check in which

moment (M1-M2; M2-M3; M1-M3) there were statistically significant differences.

The Chi-square test was used to check if there was any association between the

exercise program and the intervention and control groups.

The level of significance was set at 0.05, with 95% confidence intervals. Statistical

analysis was conducted using SPSS® 17.0 for Windows®.

RESULTS

The baseline (M1) symptoms’ proportions were identical in both groups, without

statistical significant differences in any of the variables. The most common symptom, with

higher proportion across all points of assessment, was the low back region, followed by the

neck, in both groups (table 2).As to the intervention group, there was a general reduction in

MSS during the study, in all variables:” troubles in the last 12 months”, “limitations in the last 12

months” and “troubles in the last 7 days”. There was a clear decrease in low back symptoms.

However, there was an increase in symptoms associated with knees and a moderate increase

in symptoms in the neck region, especially in the last 12 months. In the control group there was

a general increase in symptoms, especially in the low back region, where this increase was

higher. Symptoms in the neck also increased significantly, especially in the last 12 months.

42

Table 2 : Proportion of symptoms in the intervention group and in the control group across all points

of assessment (M1, M2, M3) in all regions of the NMQ.

Intervention group

Control group

Troubles in the last 12 months

Limitation in the last 12

months

Troubles in the last 7 days

Regions

Troubles in the last 12 months

Limitation in the last 12 months

Troubles in the last 7 days

M1 M2 M3 M1 M2 M3 M1 M2 M3 M1 M2 M3 M1 M2 M3 M1 M2 M3

% % % % % %

8.3 10.2 19.6 3.1 5.1 4.3 5.3 6.8 5.7 Neck 9.7 8.2 24.2 7.3 6.0 4.8 7.3 6.0 4.8

4.2 6.8 2.2 3.1 3.4 2.2 1.0 3.4 2.2 Shoulders 0.8 2.4 3.2 0.8 3.6 1.6 0.8 3.6 0.0

2.0 0.0 2.2 2.0 0.0 0.0 2.0 0.0 2.2 Elbows 0.8 1.2 3.2 0.8 1.2 0.0 0.0 0.0 0.0

9.4 8.5 8.7 6.3 6.8 0.0 6.3 8.5 4.3 Wrists/Hands 5.6 3.6 8.0 5.7 6.9 4.8 4.9 3.6 3.2

3.1 3.4 2.2 2.1 1.7 0.0 1.0 1.7 0.0 UpperBack 2.4 6.0 7.8 0.8 2.4 3.1 1.6 4.8 4.6

29.0 14.5 10.9 20.0 7.9 6.5 14.6 14.5 6.5 LowBack 24.0 32.1 46.9 12.1 17.9 17.5 23.4 25.0 21.9

7.3 1.7 0.0 4.2 1.7 0.0 2.1 1.7 0.0 Hips/Thighs 4.8 7.2 4.8 2.4 4.8 3.2 4.0 3.6 4.8

5.2 13.6 8.7 4.2 6.8 2.2 3.1 10.2 2.2 Knees 5.6 7.2 9.5 2.4 2.4 3.1 4.0 2.4 6.3

2.1 6.8 0.0 1.0 5.1 2.1 2.1 6.8 0.0 Ankles/Feet 3.2 1.2 4.8 3.2 1.2 0.0 1.6 1.2 1.6

The Cochran’s Q test to independent samples used across all assessments for all

regions (knees, shoulders, elbows, wrists/hands, upper back, low back, hips/thighs and

ankles/feet) only showed statistically significant results for the low back region in the three

variables: “troubles in the last 12 months” (p=0.000); “limitations in the last 12 months”

(p=0.000) and “troubles in the last 7 days” (p=0.030), in the intervention group. In the control

group, the same test was used for the three assessments and for all regions, being results

statistically significant for the low back region, for the variable “troubles in the last 7 days”

(p=0.039). Subsequently, the McNemar test was used to verify in which moment there were

statistically significant differences (table 3).Results have shown statistically significant

differences in the variable ‘troubles in the last 12 months’ for the intervention group at M1/M2

(p=0.000), and M1/M3 (p=0.000). As to the variable ‘limitations in the last 12 months’,

differences in the intervention group were statistically significant at M1/M2 (p=0.001) and M1/M3

(p=0.000). In the variable 'troubles in the last 7 days', in the intervention group, there were

statistically significant differences at M1/M3 (p=0.01), whereas in the control group there were

statistically significant differences at M1/M3 (p=0.029), although these differences resulted from

increased symptoms, which did not occur in the intervention group.

43

Table 3 : McNemar test proof values for both groups across all points of assessment.

The chi-square test was used to verify the association between the exercise program

and symptoms in the different regions (neck, shoulders, elbows, wrists/hands, upper back, low

back, hips/thighs, knees and ankles/feet), but the results obtained did not show statistical

evidence that there is a relation between symptoms and the specific exercise program, either in

the intervention group or in the control group, at baseline (table 4). However, results in table 4

show that in the intervention group there is some dependency in two of the variables for the low

back region. The variable “troubles in the last 12 months”, at M2 (p=0.019) and M3 (p=0.000);

and in the variable ‘troubles in the last 7 days’ at the final assessment (p=0.033).

Table 4 : Chi-square test proof values for both groups across all points of assessment.

Intervention group Region

Control group

M1 M2 M3 M1 M2 M3

p p p Low back p p p

NS 0.019 0.000 Troubles in the last 12 months

NS NS NS

NS NS NS Limitations in the last 12 months

NS NS NS

NS NS 0.033 Troubles in the last

7 days NS NS NS

DISCUSSION

At baseline, the sample was homogeneous, without significant differences as to weight,

height and BMI. The greatest proportion of problems reported was from the low back, as a

result of the type of tasks executed by workers participating in this study: prepare and

disassemble pallets, make picking, drive pallet trucks standing with body turned to the right,

typical tasks executed in warehouses. These results are consistent with other studies (19, 28,

42, 48, 53,54). Increased flexion with trunk rotation, combined with repetitive tasks, provoke

posterior soft-tissue stretch and tension, leading to MSD. These effects stimulate

mechanoreceptors, causing fatigue and discomfort in the low back area. Several authors have

Intervention group Region

Control group

M1-M2 M2-M3 M1-M3 M1-M2 M2-M3 M1-M3

p p p Low back P p p

0.000 NS 0.000 Troubles in the last 12 months NS NS NS

0.001 NS 0.000 Limitations in the last 12 months NS NS NS

NS NS 0.010 Troubles in the

last 7 days NS NS 0.029

44

suggested that noniceptive pain is generated by ischemic muscle tension (20, 30, 53,55-57).

Nevertheless, although the low back is the most affected region, symptoms have decreased

during this study, being differences statistically significant between M1 and M2 and between M2

and M3. These results are similar to the ones obtained in Moffett, where a specific exercise

program led to improved condition in individuals with LBP (55). From M2 to M3 there was no

statistical evidence of a decrease in MSS in the low back region, probably as a result of

increased anxiety motivated by changes in the company direction and in working shifts, which

have caused workers some discomfort. According to Feyer, dissatisfaction has been associated

with self-reported symptoms (57). Harkness defends that work-related stress and psychosocial

conditions, such as dissatisfaction and relationship with supervisors and colleagues, are

associated with work-related MSD (58).

With a decrease in reported LBP symptoms in the last 12 months, there was also a

decrease in reported situations of symptoms in shoulders and wrists/hands and an increase of

symptoms affecting the neck. This can result from incorrect delimitation of body regions by

subjects and the possibility that they can be identifying pain in the wrong area. Other possible

explanation is that the pain felt in the shoulder and wrists/hands regions was in fact a result of

cervical irradiating pain, which became centralised as a benefit of executing the exercise

program, which included specific exercises for these body regions (57).

The greatest proportion of problems reported as provoking higher limitation to personal

and work-related activities in the last 12 months in the control group was the low back, which

shows that besides being the most frequent symptom, LBP was also the most incapacitating.

These results are consistent with several studies which refer that LBP is the major cause of

pain, diminished work capabilities, limitation, resulting in work-absenteeism, substantial health-

care related expenses and productivity losses (10, 16, 31, 42, 53, 59-63). In the intervention

group there was a decrease in reported limitations due to MSS, being differences statistically

significant from M1 to M3, with individuals with LBP showing increased functional capacity

following participation in the exercise program, similarly to other studies (22, 33, 43, 64-66).

Moseley (2002), Waddel and Burton (2001), Arokoski (2004) and O’Sullivan (2006) refer that

following a specific exercise program reduces LBP intensity and improves functional disability in

sub-acute and chronic low back patients. In Kasai, a strengthening exercise program, designed

to increase low back flexibility, has contributed to improve subjects’ functional ability (67).

According to Friedrich, full benefits can only be realised if the exercises are performed regularly

and consistently (68). In fact, exercise effects on functional ability only persist if they are

executed for long periods (69).

Throughout the 21-month follow-up there were no statistically significant differences in

any variable in the regions neck, shoulders, elbows, wrists/hands, upper back, thighs/hips,

knees and ankles/feet, although the proportion of neck-related symptoms must be taken into

account when designing new exercise programs. Together with the low back, the neck is a

transition region where instability problems can occur, with pain and functional limitation. As to

45

MSS pain intensity in the different regions, there were no statistically significant differences to

conclude that there were any changes throughout the study.

A limitation of this study was the impossibility of controlling subjects’ tasks, resting time,

presence of a second subject, eating habits and leisure and sports activities executed by

subjects in non-working time. Other limitation was the high number of losses, which can lead to

errors in the results obtained. However, these limitations are difficult to control in real life

situations, although the whole team has been always interested and paying attention to

motivate subjects to participate and to understand the importance of this study.

As MSD are a major work-related problem, with high disability and reduction of quality

of life, with individuals experiencing pain daily, efforts should be directed towards prevention of

this situation. As such, we suggest carrying out more and longer experimental studies, which

implement prevention strategies, including ergonomic studies which help reducing these

problems.

CONCLUSION

It can be concluded that a specific exercise program improved MSS in the low back

region throughout the 21 months, in all variables: “troubles in the last 12 months”, “limitations in

the last 12 months” and “troubles in the last 7 days”.

References

1. Airaksinen O, Brox JI, Cedraschi C, Hildebrandt J, Klaber-Moffett J, Kovacs F, et al.

Chapter 4. European guidelines for the management of chronic nonspecific low back pain. Eur

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Capitulo 3

Effect of a specific exercise program on strength a nd resistance levels of lumbar muscles of warehouse wo rkers.

(EM PUBLICAÇÃO NO International Journal of Occupational Medicine and Environmental Health)

53

Abstract

Low back pain is one of the major causes of limitation of the locomotor system and one of the most common reasons for searching medical assistance. Different studies have come to the conclusion that patients with low back pain present more weakness in trunk extensor and flexor muscles. Several lines of evidence have shown the importance of implementing exercise programmes specifically directed to workers.

The aim of this study was to verify the influence of a specific exercise program on strength and resistance levels of lumbar flexors and extensors in warehouse

workers.

Study Design

The population used in this randomized controlled trial included 557 warehouse male workers from a food distribution company in Oporto/Portugal. Upon application of the selection criteria, 98 workers were deemed eligible, which were randomized in two groups: 57 were assigned to the intervention group and 41 to the control group. The intervention included 9 easily-executed exercises to promote stretching and strengthening of lumbar region, being executed daily, at the beginning of the working time, in the company facilities and lasting 8’. Trunk muscles´ voluntary strength and resistance were measured using an isometric electronic dynamometer (Globus Ergometer, Globus, Codigné, Italy) at baseline and eleven months after implementing the exercise program. Data were analysed using SPSS®, version 17.0.

After implementation of the exercise program, in the intervention group, all variables increase, significant differences were observed in muscle strength and resistance values (p=0.014 and p=0.006, respectively), as well as in the ratio extensors/flexors (p=0.037). In the control group, all variables decrease being statistically significant decrease of trunk flexors strength level (p=0.009).

The results of this study suggest that a specific exercise intervention program can increase trunk extensors strength and resistance.

Key words strength, resistance, trunk muscles, exercise

54

Introduction

Low back pain (LBP) is the main cause of incapacity in industrialized countries

[1-6]. Epidemiological studies relate the incidence of LBP in approximately 60%

of industrial workers throughout their lives [7]. In fact, LBP constitutes the major

cause of work absence, as it is one of the causes of limitation of the locomotor

system, and one of the most common reasons for searching medical

assistance. As a consequence, LBP is responsible for a growth in social costs

and a reduction in productivity and in the ability to perform everyday tasks. This,

in turn, results in employee replacement by other workers and originates

temporary or even definitive retirement [8-10]

It is generally accepted that prolonged, static sitting postures, such as those

adopted during driving, are more likely to aggravate a preexisting LBP condition

or instigate the development of a new one [11, 12]. In fact, adopting a poor

posture, combined with the effects of vibration and prolonged driving times,

have been identified as sources of increased risk of low back injuries ranging

from disk herniations to general musculoskeletal strains and sprains [13-15].

De Carvalho et al. (2010) have shown that in automobile sitting, with no

lumbar support, the lumbar spine flattens completely in sitting and yet maintains

near standing levels of intervertebral joint angles at L5/S1 [16]. This situation is

highly suggestive of large strains at the posterior aspect of the intervertebral

disks at L4/L5. This is not surprising, as this segment is often referred to as one

of the most common levels of lumbar disk herniation. Generally this is due to

abnormalities in the posterior muscles, tendons and ligaments of the trunk and it

can be attributed to various physical activities, such as lifting weight and

remaining in a standing or sitting position for long periods [17, 18, 19].

The musculoskeletal system, above all, guarantees stability to the spine

in everyday tasks [20, 21]. When it is weakened, spinal joints and ligaments can

became overloaded, increasing the probability of injury incidents at the lumbar

spine. Muscle weakness proceeds from disuse, remaining in certain positions

for long periods or even from tiredness caused by repetitive gestures, resulting

in an excessive transfer of load to the spine structures, causing pain [17, 20, 22-

24]. There is also evidence suggesting that muscle weakness is one of the risk

55

factors for LBP [25-30]. The importance of rehabilitating the trunk muscles to

maintain the lumbar lordosis is clear, as it seems to have a protective effect on

the structures of the spine in different postures. Taking these considerations

into account, more relevance has been given to implement the exercise

program specifically directed to workers, not only to decrease LBP [31-34] but

also to prevent it [30, 33, 35-37].

Systematically reviewing the literature of all interventions performed in

workplaces, Tveito et al. verified that physical exercise has a documented effect

on lumbar pain prevention, muscle strength and resistance [34]. On the other

hand, van Poppel et al. concluded that there is very limited evidence as to the

benefits of applying an exercise program [38]. The aim of this study was to

verify the influence of an 11-month specific exercise program on the strength

and resistance levels of lumbar flexors and extensors in warehouse workers.

Methods

Study Design

This study was a randomized controlled trial.

Sample

The population used in this study included 557 warehouse male workers

from a food distribution company in Oporto/Portugal. All workers were involved

in a routine of overcharge tasks and/or repetitive movements and they worked

under low temperatures [between 0º and 4ºC) during all seasons of the year.

According to the company norms, all workers wore cold protective clothing,

gloves, boots and lumbar support belts.

After informing the clinical physician and human resources staff on the

criteria that would have to be taken into account for subject selection, the

company has provided us with an alphabetically organized list of 143 eligible

workers, corresponding to 25% of the population. The sample was randomized

in two groups (72 in the intervention group and 71 in the control group). Then,

subjects were asked to volunteer to participate in the study under written

56

consent. The sample included 57 volunteers for the intervention group and 41

for the control group. At baseline the sample was n=98, corresponding to 17%

of the population.

This study included all male workers who did not oppose to being

measured as to their maximal isometric strength and resistance of trunk flexors

and extensors and who completed the exercise program. Subjects were

excluded if they met at least one of these criteria: a) presented a clinically

diagnosed pathology which prevented them from executing the exercises or the

strength and resistance tests [39]; b) had been submitted to abdominal or

lumbar-pelvic surgery [26, 40]; c) suffered any musculoskeletal injury or chronic

illness [40]; d) were taking any medication which could influence the viscous

elastic properties of soft tissue [41]; e) were taking pain killers or AINS [41]; f)

had been under back pain treatment for the last year[20]; g) were unable to

maintain a correct posture during measurement of muscle strength and

resistance[21]; h) reported LBP [39, 42, 43]; or i) practiced regular physical

exercise [44].

There were 26 losses at the end of the research: 15 (26.32%) from the

intervention group and 11 (26.83%) from the control group, being the sample at

the end of the program reduced to 72 workers, 42 in the intervention group and

30 in the control group. These losses resulted from workers leaving the

company, changing workplace or giving up from participating in the study before

the end of the program.

Individual characteristics of the sample for age, weight, height and Body

Mass Index (BMI) are presented in table 1.

57

Table 1.Sample characteristics

Instruments

An isometric electronic dynamometer (Globus Ergometer, Globus, Codigné,

Italy) was used to measure resistance (in seconds) and maximal isometric

strength (in Kgf) of trunk flexors and extensors. According to Robinson et al, the

Intraclass Correlation Coefficient (ICC) of this instrument is 0.93, in the test-

retest for the maximal isometric strength, 0.93 in the Pearson Correlation

Coefficient and 0.85 in the test-retest for the isometric resistance [45]. Generic

health status survey questionnaires were used to select and characterize the

sample.

Procedures

The exercise program was implemented in several stages. In a first moment,

visits to the warehouse facilities allowed to know the type of tasks executed by

workers and the most common injuries. Upon evaluation of risks and most

repeated gestures, an adequate exercise program was created. This program

included nine easily-executed exercises to promote stretching and

strengthening of soft tissues responsible for spinal stability, especially lumbar

stability. This program was applied, with exercises being executed daily, at the

beginning of the working time, in the company facilities and lasting

approximately eight minutes (appendix 1). To motivate workers to adhere to the

program and follow it, there were several training sessions and posters

Sample

N=98

Intervention group

(n=57)

Control group

(n=41)

Mean±sd Minimum Maximum Mean±sd Minimum Maximum

Age (years) 33.5±8.17 20 49 27.4±6.25± 20 45

Weight (kg) 77.0±11.10 56.00 104.00 78.1±14.65 57.00 110.00

Height (cm) 175±7.4 161 194 175±9.3 150 187

BMI (kg/m2) 25.2±2.05 21.6 27.6 25.6±1.69 25.3 31.5

58

illustrating the exercise program to execute were distributed in the company

facilities.

Facilitators of the program included physiotherapists, who visited the

warehouse facilities each 15 days to correct possible execution errors or to

answer doubts and questions from workers as to the exercise program. The

program efficacy was evaluated in two moments – at baseline and 11 months

following participation in the program.

All evaluations were preceded by a 5 minute warming up, which involved some

callisthenic exercises [46-49]. Then individuals were positioned in the test

position. For this, an 8 cm wide band was placed around the subjects’

shoulders, just below the medial end of the clavicles and horizontally connected

with the dynamometer by a steel cable [28, 50]. To increase stability, pelvic

supports were placed by the fourth and fifth lumbar vertebrae and on the inferior

third of the thighs. Individuals were asked to stand on a nonslip surface, with

their back positioned against a pelvic supporting board as trunk flexors strength

was measured and their front against the board as trunk extensors strength was

evaluated [28, 50, 51]. A short training in the test position, which consisted of 3

submaximal contractions for flexion or extension of the trunk, depending on the

test, was performed prior to measurements. This warming up period allowed

subjects to get used to the equipment, learning how to use it.

After a rest of 1 minute, individuals were encouraged to produce their maximal

strength for flexion or extension of the trunk. Then, in the same position,

resistance tests were made at 60% of their maximum voluntary contraction,

both for trunk flexors and the extensors [52, 53]. During the execution of muscle

contractions, verbal encouragement was constantly given, in order to stimulate

both the maximal strength and period of time in which the individuals endured

the resistance test. The interval between strength and resistance tests was 15

minutes [54].

The control group participated in the pre- and post-program tests. At the end of

the study this group was offered the possibility of executing the same exercises

which were implemented in the intervention group.

59

The study was conducted between February 2005 and March 2007, with

authorization by the company, and according to a protocol between the

institutions involved. All participants provided written informed consent before

entering the study. All procedures were in accordance with the Helsinki

Declaration. The study design was approved by the ethics committee of Escola

Superior de Tecnologia da Saúde do Porto, in Portugal.

Statistics

Descriptive and inferential statistics were used for results analysis. The

student’s t test for independent samples was used to analyze differences

between mean values in both groups. To analyze differences between mean

values in each group before and after the exercise program, the student’s t test

for paired samples was used. The level of significance was set at 5%. Statistical

analysis was conducted using SPSS® 17.0 for Windows®.

Results

Results in table 2 illustrate an increase in all variables after implementation of

the exercise program during 11 months, in the intervention group, being results

statistically significant for trunk extensors strength (p=0.014), trunk extensors

resistance (p=0.006) and the ratio between trunk extensors/flexors strength

(p=0.037).

In the control group there was a statistically significant decrease of trunk flexors

strength level (p=0.009). Both the increase in flexors’ resistance and the

decrease in extensors’ strength and resistance were not statistically significant.

As to the ratio between trunk extensors/flexors strength in the control group,

there was a decrease, but without statistical significance.

60

Table 2.Statistical results of the student’s t test for paired samples between moments 1 and 2: proof value

to the intervention group and the control group.

Intervention Control

Variables Moment 1 Moment 2 P value Moment 1 Moment 2 P value

SFle (Kgf) 72.07 ± 14.33 73.39 ± 14.42 0.257 63.49 ± 20.94 58.81 ± 18.40 0.002

RFle (Sec) 42.43 ± 15.58 44.31 ± 15.89 0.259 42.71 ± 19.45 45.17 ± 17.06 0.464

SExt (Kgf) 79.48 ± 15.94 83.29 ± 13.73 0.014 65.74 ± 18.42 61.90 ± 20.10 0.069

RExt (Sec) 51.57 ± 17.60 58.69 ± 15.38 0.006 62.41± 18.46 61.79± 18.97 0.859

Ratio 1.10 ± 0.25 1.16 ± 0,21 0.037 1.12 ± 0,30 1.08 ± 0.27 0.312

SFle – Trunk flexors strength; RFle – Trunk flexors resistance; SExt – Trunk extensors strength; RExt –

Trunk extensors resistance; Ratio between trunk extensors/flexors strength

Discussion

Several studies have documented the association between chronic LBP

and decreased muscle performance [13-15, 20, 27, 50]. In this study, we have

used isometric tests to evaluate lumbar muscles’ resistance and strength levels,

as they are quite easy to teach and perform, which allows applying them to a

great number of subjects. Besides, according to Brown and Weir, the isometric

strength test provides predictive information about occupational injuries

associated with dynamic activities. Furthermore, the isometric strength test has

been shown to be more reliable. However, one should not forget that the

isometric contraction occurs at a certain specific angle that can be slightly

associated with strength values in other joints positions [46]. Despite all these

arguments, disagreement arises as to the isometric test capacity to predict

dynamic performance. Taking this into account, it would be important to carry

out new studies to quantify strength and resistance dynamics.

All strength and resistance measurements were taken with individuals in

a standing position as, according to Rantanen et al [50] and Rantanen and

NyKvist [51] in this position there is a decrease in the compressive strength

upon the lumbar column, generated by the psoas muscle. Only male workers

have been included in this study, as, according to Ebben and Jensen, there are

differences of strength between genders [55].

61

Although several studies address exercise programs very similar to ours

as to intensity and duration and in the methods adopted to measure muscle

strength and resistance, none of them included all these aspects. Strength and

resistance levels of lumbar extensors have improved after the exercise

programme. These results are consistent with those obtained in the studies of

Mannion et al. and Gundewall et al., which have used a specific exercise

program, executed twice a week, with a duration between 10 and 20 minutes

[39, 56]. Moffroid also verified improvement in trunk extensors strength and

resistance levels after following an exercise program for 6 weeks [57]. However,

this program only included exercises for the lumbar extensors. Koumantakies et

al. observed an increase in strength, not only at the extensors but also at the

lumbar flexors, after implementing a 15 minutes exercise program, applied

specifically to the lumbar region [52]. In a study by Holmstrom and Ahlborg, the

lack of improvement concerning trunk muscle strength and the small increase in

lumbar extensor muscle resistance were not seen as significant [44]. These

results were probably due to the fact that the exercise program adopted global

callisthenic exercises only for 3 months and, according to Cohen and Narrow,

with these conditions improvements in strength and resistance are only shown

after 6 to 8 months of exercise [58]. even affirms that, in spite of the exercise

showing improvements in the trunk muscles’ resistance, intervention

programmes lasting for many months are most effective in improving physical

performance [57]. Although in the intervention group there were no statistically

significant differences in trunk flexors’ strength levels after implementing the

exercise program (although it has increased), in the control group there was a

statistically significant decrease in the strength of these muscles. These

changes were in decrease way, which can show the importance of the applied

programme in preventing atrophy of the trunk flexors. The decrease in strength

values in the control group could be explained by the constant use of lumbar

support belts, which, in the long run, promotes abdominal muscle weakness

[59]. Nevertheless, the influence of lumbar support belts in muscle strength is

still a very controversial issue and, because of that, it should be considered in

future studies. The increased strength and resistance verified in the intervention

group can also be justified by the decrease in pain perception and by

psychological improvement during the programme [39, 52].

62

Analysing the results, statistically significant differences were verified

between groups as to trunk extensors muscle strength. The increase of

registered strength in the intervention group, when compared to the control

group, is consistent with the studies of Mannion et al., which have used the

same methodology for the same measurement of strength and with an intensity

and duration of exercises very similar to the present study [39].

According to Trainor and Wiesel the ratio between trunk

extensors/flexors strength is 1.3/1 [60]. Studies have revealed that patients with

back pain have this ratio altered comparing to the normal population and that a

relation of 1.2/1 to 1.5/1 can be verified in individuals without symptoms (but

likely to get LBP) and of 1.0 in same cases of individuals with back pain [20,

61]. The results of this study have shown a significant increasing change in the

initial ratio (intervention group) of 1.09/1 to 1.15/1 eleven months after following

the exercise program. This change can be seen as having a protective nature

as, according to Lee et al., (1999) the increase in the extensors/flexors strength

ratio has revealed a biggest solidity in preventing future episodes of back pain

[20]. There were also ratio changes when comparing the intervention group with

the control group (intervention group ratio - control group ratio). There are no

experimental studies which evaluate changes in the strength ratio following an

intervention, which calls to the importance of new studies to analyse this

question in more detail.

This study allowed to evaluate the efficiency of a specific exercise

program in warehouse workers. There were significant improvements in

extensor muscle strength and resistance, measured eleven months after

following the exercise program. When comparing both groups, the main

differences were verified in lumbar flexors and extensors strength.

Acknowledgements

This study was supported by a grant from Fundação para a Ciência e

Tecnologia and Instituto Politécnico do Porto (SFRH/BD/50183/2009).

The authors thank all participants in this study for their time and interest.

63

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Capitulo 4

Effect of an exercise program on the quality of lif e of warehouse workers (EM PUBLICAÇÃO NO Applied Research in Quality of Life)

71

ABSTRACT

Background

Low back problems are associated with decreased quality of life. Specific

exercises can improve quality of life, resulting in better professional

performance and functionality.

Aim

The purpose of this study was to evaluate the effect of following a 21-month

exercise program on the quality of life of warehouse workers.

Methods

The population included 557 male warehouse workers from a food distribution

company in Oporto, Portugal. Upon application of the selection criteria, 249

workers were deemed eligible, which were randomized into two groups (125 in

the intervention group and 124 in the control group). Then, subjects were asked

to volunteer for the study, the sample being formed by 229 workers (112 in the

intervention group and 117 in the control group). All subjects completed the SF-

36 questionnaire prior to beginning the program and on the 11th and 21st months

following it. The exercises were executed in the company facilities once a day

for eight minutes. Data were analyzed using SPSS® 17.0 for Windows®.

Results

After 11 months of following the exercise program, there was an increase in all

scores for the experimental group, with statistically significant differences in the

dimensions physical functioning (0.019), bodily pain (0.010), general health

(0.004), and role-physical (0.037). The results obtained at the end of the study

(21 months) showed significant improvements in the dimensions physical

functioning (p=0.002), role-physical (p=0.007), bodily pain (p=0.001), social

functioning (p=0.015), role-emotional (p=0.011), and mental health (p=0.001). In

the control group all dimensions showed a decrease in mean scores.

Conclusion

It can be concluded that the implementation of a low back specific exercise

program has changed positively the quality of life of warehouse workers.

Keywords: occupational health, workers, quality of life, SF-36, specific

exercises.

72

INTRODUCTION

Health and well-being at work are the main focuses that the European

Working Conditions Observatory will advocate to the next years (Giaccone,

2007). Musculoskeletal disorders are among the most widespread illnesses

reported by European workers. According to the fourth European Working

Conditions Survey, carried out in 2005, about 20% of EU15 workers complain of

back problems and muscular pains (Giaccone, 2007). Low back pain (LBP) is

considered one of the major causes of disability (Deyo et al., 1998). After an

initial episode of LBP, 44% to 78% of people suffer a relapse of pain and 26%-

37% have a relapse of work absence. There is little scientific evidence on the

prevalence of chronic non-specific LBP: best estimates suggest that the

prevalence is approximately 23%; 11%12% population is disabled by LBP and

specific causes are unknown (Airaksinen et al., 2006).

It is well-known that the low back region is an important area for support

and transfer of force activities (van Tulder, Malmivaara, & Koes, 2007). In fact,

LBP is a common reason for reduced participation in social and leisure

activities, as well as in professional tasks (Brox, Storheim, Holm, Friis, &

Reikeras, 2005; Galukande, Muwazi, & Mugisa, 2005). Different studies have

reported that chronic LPB, besides being an economic burden to companies, is

a serious public health problem, being more costly than cancer treatment

(Steenstra, Anema, Bongers, de Vet, & van Mechelen, 2003). In fact,

musculoskeletal problems are assumed to be associated with decreased quality

of life (QoL). In specific working populations, the prevalence of musculoskeletal

disorders can be as high as 22%40%, according to a review by van Tulder et

al., (2007).

Exercise programs have proved more efficient than conventional

therapies in the prevention and treatment of LBP, resulting not only in the

reduction of pain and disability but also in lower costs, decreased healthcare

needs, and reduced absenteeism from work (Moffett, Torgerson, Bell-Syer,

Jackson, & Llewlyn-Phillips, 1999). In systematic literature reviews, Bigos et al.,

(2009) present strong evidence that exercise programs are effective in

preventing episodes of back problems. In another study, Rainville et al., (2004)

recognized that there is evidence supporting the use of exercise as a

73

therapeutic tool to improve impairments in back flexibility and strength. In fact,

several studies have observed improvements in global pain ratings and in

behavioral and cognitive aspects of back pain syndromes. Exercise programs

have been shown to promote improved QoL, resulting in better professional

performance and functionality (Airaksinen et al., 2006; Claiborne, Vandenburgh,

Krause, & Leung, 2002).

Interventional preventive measures have been tested in randomized

controlled trials, but results have been controversial. Daltroy et al., (1997) found

that back schools are not an effective intervention of industrial low back injury.

On the other hand, Brox et al., (2008) also noted that back schools were

effective in reducing pain and disability in the short-term, but not in the long-

term. Ijzelenberg, Meerding & Burdorf (2007) did not observe significant

differences in worksite prevention programs for LBP. Probably the lack of

communication with a professional might introduce negative expectations and

dissatisfaction (Goldby, Moore, Doust, & Trew, 2006; Sherman, Cherkin, Erro,

Miglioretti, & Deyo, 2005).

A well-structured exercise program can lead to long-term improvements

for back pain sufferers, (Norris, 1995) diminishing pain, disability, and the effort

required to execute daily activities (Lang, Liebig, Kastner, Neundörfer, &

Heuschmann, 2003) and resulting in improvements in health-related QoL

(Airaksinen et al., 2006; Arnold, Witzeman, Swank, McElroy, & Keck, 2000;

Carroll & Whyte, 2003). According to European guidelines for prevention of LBP

(Burton et al., 2006), physical exercise is recommended for prevention of LBP,

for prevention of recurrence of LBP, and for prevention of recurrence of sick

leave due to LBP (Level C).

As there is no recommendation for the type and intensity of exercise, the

exercise program used in this study was designed specifically for this population

after carefully analyzing all movements and tasks that workers performed

throughout the working day. This study intends to contribute a deeper

knowledge about the relation between exercise programs performed in the

workplace and health-related QoL, taking into account cost benefit, as well as

the characteristicsof the company and itsemployees. Workers received

instructions on the type of exercises they would perform, as well as training

74

activities, which reinforced the idea that physical, social, and mental well-being

are the foundations of QoL (Burton et al., 2006).

The purpose of this study is to evaluate the effect of following a long-term

specific exercise program on health-related QoL of warehouse workers. This

assessment was made by analyzing if the exercise, performed on a daily basis,

improved dimensions of physical functioning, physical role limitations, bodily

pain, social functioning, emotional role limitations, and mental health after 11

and 21 months of following the exercise program.

METHODS

Subjects

The population used in this study included 557 urban, male warehouse

workers from a food distribution company in Oporto, Portugal. All workers were

involved in a routine of overcharge tasks and/or repetitive movements and

worked in low temperatures (between 0º and 4ºC) during all seasons of the

year. According to the company norms, all workers wore cold protective

clothing, gloves, boots, and lumbar support belts.

After informing the clinical physician and human resources staff on the criteria

that would have to be taken into account for subject selection, the company

provided us with an alphabetically organized list of 249 eligible workers,

corresponding to 45% of the population. The sample was randomized into two

groups (125 in the intervention group and 124 in the control group). Then,

subjects were asked to volunteer to participate in the study and give

underwritten consent. The sample included 112 volunteers for the intervention

group and 117 for the control group. At baseline, the sample was n=229,

corresponding to 41% of the population.

Workers were deemed eligible if they met the following criteria: a) they

had a contract for three or more years; and b) they performed the same task

type (assembly and disassembly of pallets. On the other hand, it excluded

individuals who: a) were required to rotate work positions; b) were absent from

work because of back pain; c) had severe back pain (VAS ≥ 5) in the last year;

d) had undergone treatment (conservative or surgical) for LBP in the last year;

75

and e) had been diagnosed with any kind of pathology, which could prevent

them from participating in the prescribed exercises (Sculco, Paup, Fernhall, &

Sculco, 2001).

From the first evaluation moment to the second, there was a total loss of

37.5% of the subjects, 30% from the intervention group and 44.4% from the

control group. From the second to the third evaluation moment there was a total

loss of 34.2% of the individuals, 38.5% from the intervention group, and 29.2%

from the control group. From the first to the third evaluation moment, losses in

the intervention group and in the control group were 57% and 60%,

respectively. After 21 months the sample was reduced to approximately 17% of

the population. These losses resulted from workers leaving the company,

changing workplace, losing motivation to continue in the study, or not answering

the questionnaire.

Table 1 shows values for mean, standard deviation, minimum and

maximum for age (years), height (cm), weight (kg), and body mass index (BMI)

of workers included in the intervention group and in the control group.

Table 1: Values for mean, standard deviation, minimum and maximum of age (years), height (cm), weight

(Kg), and BMI of workers included in the intervention group and in the control group.

n=229 Intervention group

n=112 Control group

n=117 mean±sd min max mean±sd min max

Age (years) 34.41±8.36 20 49 33.05±10.19 18 56

Height (cm) 173.0±0.07 160.0 188.0 178.0±0.09 159.0 188.0

Weight (Kg) 76.54±10.44 55 95 81.07±16.84 60 110

BMI (Kg/m2) 25.57 21.48 26.91 25.58 23.81 31.16

Instrumentation

Health-related QoL was measured using the Short Form Health Survey

(SF-36) self-administered questionnaire, which is a generic health status survey

questionnaire designed to assess the impact of illness on a patient’s QoL (Ware

& Sherbourne, 1992). The SF-36 was translated for the Portuguese population

by Ferreira and yields an 8-dimension profile (Ferreira, 2000a): physical

functioning, role limitations due to physical problems, bodily pain, vitality,

general health perceptions, social functioning, role limitations due to emotional

problems, and mental health. The SF-36 reports the patients' perceived QoL

using scores ranging from zero to 100, zero being the worst score and 100 the

76

best score. The SF-36 has been extensively used in studies addressing patients

with chronic back disorders (Picavet & Hoeymans, 2004). The validity and

reliability of the Portuguese translation of the SF-36 is well documented

(Ferreira, 2000b).

Procedures

The exercise program was implemented in several stages. In the first

evaluation, visits to the warehouse facilities allowed investigation of the types of

tasks executed by workers and the most common injuries. Upon evaluation of

the risks and most repeated gestures, an adequate exercise program was

created. This program included nine easily executed exercises to promote

stretching and strengthening of the soft tissues responsible for spinal stability,

especially lumbar stability. This program was applied, with exercises being

executed daily in the company facilities at the beginning of work and lasting

approximately eight minutes. To motivate workers to adhere to the program and

follow it, there were several training sessions, and posters illustrating the

exercise program were distributed in the company facilities.

Facilitators of the program included physiotherapists, who visited the

warehouse facilities every 15 days to correct possible execution errors or to

answer doubts and questions from workers about the exercise program. The

program efficacy was evaluated in three moments—prior to (M1), at 11 months

(M2), and at 21 months (M3) following participation in the program—by

application of the SF-36 questionnaire.

The control group participated in the pre- and post-program tests. At the

end of the study this group was offered the possibility of executing the same

exercises that were implemented in the intervention group.

The study was conducted between February 2005 and March 2007 with

authorization by the company and according to a protocol between the

institutions involved. All participants provided written, informed consent before

entering the study. All procedures were in accordance with the Helsinki

Declaration. The study design was approved by the ethics committee of Escola

Superior de Tecnologia da Saúde do Porto, in Portugal.

77

Statistics

Exploratory data analysis and sample characterization were performed

using descriptive statistics. Therefore, to check the existence of statistically

significant differences between the data analyzed, before and after

implementing the exercise program, the repeated measures test and the

Friedman ANOVA test were used. The student’s t test for paired samples was

used to analyze differences between mean values in both groups. To analyze

differences between mean values in both groups at the different moments, the

student’s t test for independent samples was used. The level of significance

was set at 0.05, with 95% confidence intervals. Statistical analysis was

conducted using SPSS® 17.0 for Windows®.

RESULTS

Results in table 2 indicate that at baseline, workers in both groups had a

good perception of their QoL. Mean scores of the SF-36 are generally near or

above 80%. However, the analysis does not show statistically significant

differences between groups. It can be observed that the physical functioning

dimension obtained the best mean scores throughout the study in the

intervention group, while both groups showed lower scores in the general health

dimension. The bodily pain dimension obtained the lowest score in the control

group while in the intervention group the worst score obtained was in the vitality

dimension (table 2).

After 11 months of follow-up, groups showed statistically significant

differences in the dimensions physical functioning (0.002), role-physical (0.006),

and bodily pain (0.000) (table 2). At the end of the exercise program, all

dimensions showed increased scores in the intervention group, with the

exception of general health, which obtained a lower score. The control group

obtained the best mean values in the dimensions role-emotional and role-

physical, while lower scores were obtained for the dimensions bodily pain,

vitality, and general health. Nevertheless, it can be observed that mean values,

in all dimensions, decreased throughout the 21-month period in the control

group.

78

Table 2: Values obtained for the 8 dimensions of SF-36 in the form of means and standard deviations, in the intervention group and in the control groups at the three evaluation moments; proof values obtained in the student’s t test for independent samples, between the intervention and control groups, in each evaluation moment.

**P<0.01 and ***P<0.001

When analyzing subjects’ health-related QoL, results have shown that

there were significant differences between the three evaluation moments in

almost all variables, both in the intervention and control groups, as reported in

table 3.

Table 3: Differences between the three evaluation moments in the intervention group and in the control group obtained using the Friedman ANOVA test.

Variables

Intervention group

(P value)

Control group

(P value)

Physical functioning * **

Role-physical * NS

Bodily pain ** NS◊

General health NS *◊

Vitality NS ***

Social functioning * *

Role-emotional * NS

Mental health ** **

*P<0.05, **P<0.01, and ***P<0.001 ◊ Repeated Measures test

In the second evaluation moment (after 11 months of follow-up) there

was an increase in all dimensions for the intervention group, although only

scores for dimensions physical functioning (0.019), bodily pain (0.010), general

health (0.004), and role-physical (0.037) are significant, whereas in the control

group all dimensions showed a decrease in mean scores, with scores in

dimensions physical functioning (0.049) and role-physical (0.006) being the

ones with statistical significance (table 4).

Variables

M1 M2 M3

Intervention group

mean ± sd

Control group

mean ±sd

p value

Intervention group

mean ± sd

Control group

mean ± sd

p value

Intervention group

mean ± sd

Control group

mean ± sd

p value

Physical functioning 91.02±11.325 90.25±11.209 NS 94.22±9.595 88.11±12.0 20 ** 97.50±5.028 84.15±15.481

***

Role-physical 89.00±15.867 88.38±14.539 NS 92.00±12.974 85.28±14. 616 ** 97.01±7.423 85.00±15.608

***

Bodily pain 74.51±22.158 69.22±21.484 NS 82.74±19.108 66.84±21. 251 *** 89.67±15.001 61.79±20.741

***

General health 70.63±13.535 73.04±15.944 NS 76.20±14.364 71.44±16. 531 NS 73.37±11.521 64.84±15.416

**

Vitality 69.11±20.261 74.17±20.798 NS 74.17±17.309 71.82±19. 367 NS 76.04±16.237 63.23±18.866

**

Social functioning 85.30±19.609 85.73±17.669 NS 87.99±16.538 83.91±17. 468 NS 94.39±11.492 78.05±18.68

9 ***

Role-emotional 89.12±15.103 90.10±14.189 NS 93.93±12.555 90.55±13. 018 NS 96.39±8.234 89.18±13.12

5 **

Mental health 78.30±17.470 78.70±18.597 NS 80.44±17.486 81.22±16. 014 NS 89.28±11.097 76.86±19.08

1 ***

79

From the beginning of the study to the end, after 21 months, all

dimensions of the SF-36 have increased in the intervention group, with

differences being statistically significant, except for dimensions general health

and vitality. In the control group, mean values decreased, with scores obtained

in dimensions role-emotional and mental health being not statistically

significant.

Table 4: Values for mean, standard deviation of SF-36 and proof values obtained in the student’s t test for paired samples in the intervention group and in the control group between the first (1st) and second (2nd) and the first (1st) and third (3rd) moments of evaluation.

Variables

Intervention Group Control Group

M2 M1 M3 M2 M1 M3

mean ± sd pvalue mean ± sd pvalue mean ± sd mean ± sd pvalue mean ± sd Pvalue mean ± sd

Physical functioning 94.22±9.595 * 91.02±11.325 ** 97.50±5.028 88.11±12.020 * 90.25±11.209 ** 84.15±15.481

Role-physical 92.00±12.974 NS 89.00±15.867 ** 97.01±7.423 85.28±14.616 ** 88.38±14.539 ** 85.00±15.608

Bodily pain 82.74±19.708 * 74.51±22.158 ** 89.67±15.001 66.84±21.251 NS 69.22±21.484 ** 61.79±20.741

General health 76.20±14.364 ** 70.63±13.535 NS 73.37±11.521 71.44±16.531 NS 73.04±15.944 ** 64.84±15.416

Vitality 74.17±17.309 NS 69.11±20.261 NS 76.04±16.237 71.82±19.367 NS 74.17±20.798 ** 63.23±18.866

Social functioning 87.99±16.538 NS 85.30±19.609 * 94.39±11.492 83.91±17.468 NS 85.73±17.669 ** 78.05±18.689

Role-emotional 93.93±12.555 * 89.12±15.103 * 96.39±8.234 90.55±13.018 NS 90.10±14.189 NS 89.18±1 3.125

Mental health 80.44±17.486 NS 78.30±17.470 * 89.28±11.097 81.22±16.014 ** 78.70±18.597 NS 76.86±19.081

*P<0.05, **P<0.01, and ***P<0.001

From the second to the third moment of evaluation (11th to 21st months),

the intervention group showed statistically significant differences in the

dimension mental health (0.009), whereas in the control group there was a

statistically significant decrease in all dimensions, except for role-physical (table

5).

Table 5: Values for mean, standard deviation of SF-36 and proof values obtained in the student’s t test for paired samples in the intervention group and in the control group between the second (2nd) and third (3rd) moments of evaluation.

Variables Intervention Group Control Group

M2 mean ± sd

M3 mean ± sd p value M2

mean ± sd M3

mean ± sd p value

Physical functioning 94.22±9.595 97.50±5.028 NS 88.11±12.020 84.15±15.48 1 **

Role-physical 92.00±12.974 97.01±7.423 NS 85.28±14.616 85.00±15.6 08 NS

Bodily pain 82.74±19.708 89.67±15.001 NS 66.84±21.251 61.79±20. 741 **

General health 76.20±14.364 73.37±11.521 NS 71.44±16.531 64.84±15. 416 **

Vitality 74.17±17.309 76.04±16.237 NS 71.82±19.367 63.23±18. 866 **

Social functioning 87.99±16.538 94.39±11.492 NS 83.91±17.468 78.05±18. 689 **

Role-emotional 93.93±12.555 96.39±8.234 NS 90.55±13.018 89.18±13.1 25 *

Mental health 80.44±17.486 89.28±11.097 ** 81.22±16.014 76.86±19.081 *

*P<0.05, **P<0.01, and ***P<0.001

80

DISCUSSION

The sample included young male workers (mean age 33-34), with a BMI close

to overweight. Although there is no evidence showing increased weight as a

cause of LBP, several epidemiologic studies showed that there can be a

modest positive association between BMI and LBP (Borenstein, 2000). In fact,

several studies have demonstrated the importance of low back exercise for

spine stabilization, providing better functionality and a consequently better QoL

(Airaksinen et al., 2006; Descarreaux, Normand, Laurencelle, & Dugas, 2002;

Tuncel, Iossifova, Ravelo, Daraiseh, & Salem, 2006; Tuzun, 2007).

In this study, an analysis of the SF-36 dimensions throughout the 21-

month period shows the efficacy of an exercise program, as mean scores

obtained in all dimensions have increased, with results in dimensions physical

functioning, role-physical, bodily pain, social functioning, role-emotional, and

mental health being statistically significant. These results are in accordance with

the results of another study in which the subjective effects of exercise on the

participants’ health and well-being were significantly better in the intervention

group than in the control group (Tveito & Eriksen, 2009). A similar situation

occurred in other studies, where the intervention group tended to have a higher

median baseline physical functioning and bodily pain score on the SF-36

(Santos, Bredemeier, Rosa, Amantéa, & Xavier, 2011).

In the first 11 months of intervention, only three dimensions showed

significant improvement (physical functioning, role limitations physical and

bodily pain) although all of them tended to improve. These results are

consistent with other studies, which have also used pain-specific exercises and

obtained similar results on health-related QoL (Bendix & Bendix, 1997; Carroll &

Whyte, 2003; Walsh & Radcliffe, 2002). In the control group there was a

significant decrease in the dimensions physical functioning and role limitations

physical and a decreasing tendency in the scores of the remaining dimensions.

One possible explanation could be the fact that workers have to execute heavy

tasks all the time and they do not have good motor control. Also, we cannot

forget that 55% of the population suffers episodes of severe back pain every

year. These kinds of factors influence QoL.

81

From the second to the third moment of evaluation there were no

statistically significant differences that showed exercise efficacy on health-

related QoL, with the exception of the dimension mental health in the

intervention group. In the control group there was a steep decrease with

significant differences in all dimensions, except in the dimension role-physical.

A possible explanation for this occurrence could be the fact that during this

period there were changes imposed by the company in terms of working times,

shift work, and increased workload, which could have led to dissatisfaction and

changes in family and social activities. In a large study, Butler & Johnson (2011)

found that workers’ satisfaction with the effectiveness of their health care is

influenced more by reduced perceptions of pain and increased physical

functionality than by the “bedside manner” of health care professionals. In other

words, differences in the type of care provided are important in the early stages

of episodes of back pain but disappear at the 12-month mark. The dominant

influences at 12 months become the workers’ perceptions of the manner in

which they have been treated by the employer. Several studies suggest that

socio-economic and psycho-social factors can negatively affect attitudes and

behaviors (Buchbinder, Jolley, & Wyatt, 2001; Walsh & Radcliffe, 2002)

At the final evaluation (21 months), the intervention group showed

statistically significant differences in all dimensions, except in mental health and

vitality, showing that a specific exercise program can be efficient in increasing

functionality and health-related QoL. These results are consistent with the ones

obtained by Merkesdal & Mau (2005), which have shown that following an

exercise program is efficient in improving daily activities, social relations, and

functional capacity and in diminishing pain, thus contributing to an overall

increase in QoL (Walsh & Radcliffe, 2002). In the intervention group, the

dimension bodily pain improved significantly between evaluation moments, with

individuals feeling less pain, which shows that physical exercise is a good

therapeutic resource in preventing and treating LBP, as it improves weakness

and low isometric resistance of lumbar extensors associated with pain (Pengel,

Herbert, Maher, & Refshauge, 2003). Bendix & Bendix (1997) and Claiborne et

al., (2002) mention that increased activity leads to decreased pain levels and to

better physical performance. This is consistent with the findings obtained in the

82

present study, which show significant improvement in the control group and a

significant decrease in the intervention group at the end of the study.

Improvements in physical function and performance may also result from

the subjects' awareness of the risks they face and their attempt to compensate

these risks with physical exercise. This results in improved physical condition,

increased functionality, and decreased pain, which is in accordance with the

study of Salo et al., (2010), who had similar results in a study applied to women.

At baseline, 55% of the individuals had severe lower back problems, which

reduced the sample to less than half. In the second year, losses were a little

higher than in the first, which could be explained by the fact that during this

period the company demanded more production and changed some

intermediate managers, changes not very well understood by workers.

However, in the study by Santos et al., (2011) there was a loss of 28% of the

sample after nine months of intervention and in the study by Butler & Johnson

(2011) the loss rate was 58% in one year.

Another strong reason for losses throughout the program was the novelty

to do exercise in the company, and also the fact that this was seen as an extra

obligation to the intervention group. Moreover, subjects in the control group did

not seem to understand the importance of their role, despite all the information

and motivation actions taken. The study nature could have also been a

limitation, as it was not possible to control the individuals outside the workplace.

Some factors, such as having more than one job, insufficient rest, holidays, and

non-existence of other entertainment activities, although workplace-

independent, can negatively affect the physical and psychological status of

individuals, as seen in the subjects of this study. The ideal would be to find the

best balance between the costs and benefits for both individuals and companies

(Giaccone, 2007).

This study provides valuable information because it is the first

longitudinal study based on a representative sample of warehouse workers.

Because of the relative insufficiency of evidence on the effectiveness of specific

exercise programs to workers, future trials are needed. In this context, training

institutions and professional organizations should provide continuing education

in pain assessment and management concerning QoL to health professionals at

all levels.

83

CONCLUSIONS

In the long term, a low back specific exercise program positively modified

the quality of life of warehouse workers. After 21 months of following the

exercise program, the dimensions physical functioning, role-physical, bodily

pain, social functioning, role-emotional, and mental health have improved

significantly.

Acknowledgements

This study was supported by a grant from Fundação para a Ciência e

Tecnologia and Instituto Politécnico do Porto (SFRH/BD/50183/2009).

The authors thank all participants in this study for their time and interest.

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Discussão

88

Discussão

Relativamente às caraterísticas da amostra, os grupos mostraram-se

homogéneos no início do estudo não existindo diferenças estaticamente

significativas quanto ao peso, altura e Índice de Massa Corporal (IMC).

Contudo, o IMC da amostra mostrou estar próximo da classificação de excesso

de peso.Apesar de não se ter encontrado evidência que prove que o excesso

de peso seja causa de problemas vertebrais, nomeadamente da região lombar,

vários estudos mostram a existência de correlação moderada entre o IMC e dor

lombar (Borenstein, 2000).

Na amostra, incluíram-se apenas indivíduos do sexo masculino,

principalmente devido às características da força e resistência serem diferentes

entre sexos (Ebben & Jensen, 1998) e também porque as mulheres que

trabalhavam neste armazém tinham tarefas específicas, tais como limpezas e

não realizavam o mesmo tipo de tarefas dos homens.

Neste trabalho utilizou-se para a avaliação da sintomatologia a versão

portuguesa do standardized Nordic musculoskeletal questionnaire (Mesquita et

al., 2010).

As adaptações culturais e linguísticas dos questionários envolvem

processos de tradução e de retroversão para a língua original, assim como a

análise das propriedades psicométricas. Neste estudo estes processos

desenvolveram-se sem dificuldades e estiveram de acordo com as normas do

Medical Outcomes Trust (1997) e do European Group on Health Outcomes

(ERGHO). A validade de conteúdo foi obtida durante o processo de tradução e

retroversão, o qual foi constituído por um painel de juízes: pessoas comuns,

dois tradutores oficiais, um deles bilingue e fisioterapeutas. Este painel tem

como objetivos verificar incongruências ou redundâncias em cada item do

questionário (Beaton & Schemitsch, 2003). A validade de critério foi testada

com o Oswestry disability índex (ODI) tendo-se obtido uma correlação

moderada e positiva para as regiões torácica e lombar, na variável, últimos 7

dias e para a região lombar, variável, limitações em atividades nos últimos 12

meses. Não se conseguiu mais nenhuma correlação, porém ODI mede o

89

impacto de disfunção apenas para a dor lombar, tendo sido uma das limitações

deste estudo. Contudo o ODI foi o questionário que se encontrou em Portugal,

que reunia mais semelhanças com o NQM.

Quanto aos resultados da fiabilidade, estes foram muito bons tendo os

índices de correlação variado entre 0.7 e 1. Estes resultados estão de acordo

com a versão original que foi entre 0.8 e 1(Kuorinka et al., 1987) e com um

trabalho realizado por Palmer, Smith, Kellingray, & Cooper (1999) que

encontrou índices do coeficiente de Kappa igual a 1. Na versão portuguesa

para a população brasileira os coeficientes de correlação para a fiabilidade

também variaram entre 0.63 e 1 (de Barros & Alexandre, 2003). Numa recente

investigação, na Austrália, Dawson, Steele, Hodges, & Stewart, (2010), os

coeficientes de correlação foram de k/kmax=0.71-0.96 e k/kmax=0.76-1.

Relativamente à consistência interna o coeficiente de correlação, Kuder-

Richardson foi de 0.855 indicando ser muito bom (Carmines & Zeller, 1991).

Infelizmente não foi possível comparar este resultado com outros porque nos

estudos consultados não constavam resultados sobre consistência interna.

Cada vez mais se torna imprescindível a existência de instrumentos

validos e fiáveis para que se possa comparar os resultados obtidos a nível

nacional e internacional (MacDermid, Walton, & Law, 2009; Pynsent, 2001).

No início do estudo, antes da intervenção do programa de exercícios

específicos, momento 1 (M1) não se verificaram diferenças estatisticamente

significativas que mostrassem a existência de diferenças entre o grupo de

intervenção e o de controlo ao nível da sintomatologia músculo-esquelética e

da perceção da qualidade de vida. Na generalidade, pode dizer-se que os

grupos de intervenção e de controlo eram homogéneos. Relativamente às

diferenças entre grupos, manhã, tarde e noite, também não se verificaram

diferenças estatisticamente significativas.

Relativamente aosresultados do NMQ, em M1, mostraram que a região

corporal em que os operários relataram maior proporção de sintomas foi a

região lombar, em ambos os grupos. Este facto pode serdevido ao tipo de

tarefas realizadas pelos indivíduos deste estudo: fazer e desfazer paletes, fazer

picking, manobrar empilhadoras em pé, em rotação vertebral quer para a direita

90

quer para a esquerda, manobrar empilhadoras em posição de sentado, tarefas

típicas dos trabalhadores que operam em grandes armazéns.

Estesresultadosestão em concordância com outrosestudos nos quais se

encontraram resultados semelhantes (Alexopoulos, Stathi, & Charizani, 2004;

Alexopoulos et al., 2006; Alipour et al., 2008; Bergman, 2007; Keyserling et al.,

2005; Punnett &Wegman, 2004).

Ao analisar os níveis de força e resistência muscular antes da

implementação do programa de exercícios verificou-se que os grupos de

intervenção e controlo apresentavam valores diferentes e, em algumas

variáveis, força e resistência dos extensores, eram estatisticamente

significativos. Não se encontra explicação para este facto, contudo é de

salientar que o valor do rácio entre a força dos extensores e flexores é de 1.1/1

para o grupo de intervenção e de 1.03/1 para o grupo de controlo. Estes

valores de rácio são relevantes pois, segundo Trainor & Wiesel (2002), os

valores ideais deveriam ser de 1.3/1,pois abaixo deste rácio existe o risco de

lesão na região lombar. Estes valores complementam a sintomatologia

apresentada pelos indivíduos. Estes resultados poderãoser devido ao tipo de

tarefas efetuadas pelos trabalhadores que exigem aumento da flexão com

rotação do tronco, provocando alongamento e tensão dos tecidos moles da

região posterior, podendo levar a problemas músculo-esqueléticos. Estes

efeitos estimulam os mecanorreceptores causando fadiga e desconforto na

região lombar, sendo que a tensão muscular com isquemia têm sido propostas

como originadoras de dor nociceptiva (Feyer et al., 2000; Kaser et al., 2001;

Keyserling et al., 2005; Marras, Granta, & Davis, 1999; Marras, Lavender,

Ferguson, Splittstoesser, & Yang, 2010; Moffett et al., 1999). A reforçar este

facto são os scores apresentados pelo SF-36, que apesar de no geral estarem

muito bons, as dimensões Dor Física e Saúde em Geral apresentam os valores

mais baixos, influenciando a qualidade de vida.

No segundo momento de avaliaçãoverificaram-se melhorias

significativas, na sintomatologia da região lombar em duas das variáveis,

sintomatologia e limitações nos últimos 12 meses. No entanto, em quase todas

as regiões, a sintomatologia no grupo de intervenção diminui sem que as

diferenças fossem estatisticamente significativas. No grupo de controlo a

91

sintomatologia aumentou, principalmente na região lombar, embora as

diferenças não fossem significativas. Entre M2 e M3 não se verificaram

diferenças estatisticamente significativas em nenhum dos grupos, contudo a

tendência anterior manteve-se, o grupo de intervenção a reduzir as queixas e o

grupo de controlo a aumentar. As diferenças estatisticamente significativas

verificaram-se em M1-M3 na região lombar, no grupo de intervenção,

mostrando um aumento da capacidade funcional, em indivíduos com lombalgia,

após um programa de exercícios específicos para a região lombar como

também é referido em diversos estudos (Arokoski et al., 2004; Kuukkanen &

Malkia, 2000; Moseley, 2002; O'Sullivan, Mitchell, Bulich, Waller, & Holte, 2006;

Rainville, Hartigan, Martinez, et al., 2004; Waddell & Burton, 2001). Estes

referem queos programas de exercício específicos podem reduzir a intensidade

da dor lombar e aliviar a incapacidade funcional naqueles que sofrem de dor

lombar subaguda e crónica. Kasai (2006) utilizando um programa de exercícios

de alongamento, desenhados para aumentar a flexibilidade da região lombar,

também obteve aumentos significativos na capacidade funcional dos

indivíduos. Segundo Friedrich, Gittler, Arendasy, & Friedrich (2005) os

benefícios apenas podem ser atingidos se os exercícios forem realizados

regular e consistentemente. Os efeitos dos exercícios na capacidade funcional

subsistem apenas quando os indivíduos continuam o exercício por um longo

período de tempo (Peate, Bates, Lunda, Francis, & Bellamy, 2007).

Ao longo dos 21 meses deste estudo nas regiões do pescoço, ombros,

cotovelos, mãos/punhos, torácica, ancas/coxas, joelhos e pés/tornozelos, não

se verificaram diferenças estatisticamente significativas em nenhuma das

variáveis embora a proporção de sintomatologia ao nível da região do pescoço

seja preocupante e deva ser tida em conta nos próximos programas de

exercício, pois, tal como a região lombar, ela é também uma região de

transição onde pode vir a existir problemas de instabilidade e

consequentemente dor e limitações funcionais.Relativamente à intensidade da

dor devido a SME nas diversas regiões não se verificaram diferenças

estatisticamente significativas para afirmar que se verificaram alterações ao

longo do estudo.

92

Quanto à força e resistência muscular os resultados neste estudo

mostraram que houve aumentos significativos nos extensores, tal como no

estudo de (Moffroid, 1997), apesar de este ter sido um programa de seis

semanas e apenas contemplou fortalecimento dos extensores. Nos flexores, a

força e resistência aumentaram mas as diferenças não foram significativas.

Estes resultados estão mais de acordo com os de (Koumantakis, Watson, &

Oldham, 2005), que após um programa de 15 minutos que era específico para

a região lombar também obtiveram resultados de aumento de força, tanto dos

extensores como dos flexores. O mesmo tipo de resultados foi obtido em

diversos trabalhos, apesar de serem de características diferentes, pois alguns

decorriam apenas duas vezes por semana com uma duração de 15 a 20

minutos (Gundewall, Lilequist, & Hansson, 1993; Mannion, Taimela, Müntener,

& Dvorak, 2001).

Quanto ao rácio alguns autores preconizam que o ideal seria entre 1.2/1

e 1.5/1, pois foram os valores encontrados em população assintomática e 1.1/1

em algumas situações de indivíduos com dor lombar (Lee et al., 1999; Vital,

Melo, Nascimento, & Roque, 2007). Os valores de rácio extensores/flexores,

neste estudo, em M2, foram de 1.16/1 para o grupo de intervenção tendo esta

diferença sido estatisticamente significativa e de 1.08/1 para o grupo de

controlo. Este último rácio aumentou ligeiramente, mas não foi devido ao

aumento da força dos extensores e sim devido a um decréscimo significativo

da força dos flexores. De acordo com os autores acima referenciados, pensa-

se que os indivíduosdeste estudo, estão em risco de ocorrência de lesões

lombares porque ambos os grupos apresentaram rácios abaixo de 1.2/1. O

acentuado decréscimo de força dos flexores poderá ser devido ao uso

continuado dos cintos lombares (Quinn, 2003). Este autor preconiza que

quando existe uma utilização continuada destes cintos de suporte há uma

promoção de fraqueza dos músculos abdominais. Num outro estudo,

transversal, sobre o uso de cintos lombares, Darren & London (2007)

verificaram que o uso dos cintos aumentava a dor lombar, contudo este estudo

foi realizado em condutores de táxi e os autores são cautelosos nas suas

conclusões, porque não tinham um grupo de controlo randomizado e era muito

pequeno relativamente ao experimental.

93

Teria sido interessante verificar-se como estes resultados da força e

resistência evoluiriam em M3, após os 21 meses de intervenção, mas tal não

foi possível devido a avaria do instrumento de medição (Ergometer) e da sua

reparação ter demorado alguns meses. Esta foi a grande limitação deste

estudo porque apenas existem resultados para 11 meses e não para 21 meses,

tal como seria de esperar.

Quanto á perceção da qualidade de vida, em M2, apenas três

dimensões mostraram melhorias significativas, a função física, o desempenho

físico e a dor corporal; todavia, verificou-se uma tendência geral de subida em

todos os scores do SF-36. Estes resultados são semelhantes aos obtidos em

outros estudos sobre qualidade de vida e programas de exercício (Bendix &

Bendix, 1997; Carroll & Whyte, 2003; Walsh & Radcliffe, 2002). Entre M2-M3

não existiram melhorias significativas, exceto na dimensão saúde mental. No

final do programa, o grupo de intervenção melhorou significativamente em

quase todos os scores do Sf-36, exceto na saúde em geral e vitalidade que as

diferenças dos resultados não foram significativas, notando-se, no entanto, um

aumento dos resultados. Estes mostraram que o programa de exercício físico

específico para a região lombar foi positivo para os indivíduos do grupo de

intervenção, que melhoraram a sua qualidade de vida ao longo dos 21 meses.

Tal é consistente com outros estudos que verificaram que o exercício melhora

as relações sociais, atividades da vida diária e na capacidade funcional,

diminuindo a dor e contribuindo assim para um aumento da qualidade de vida

(Merkesdal & Mau, 2005; Pengel, Herbert, Maher, & Refshauge, 2003; Walsh &

Radcliffe, 2002). Os resultados obtidos através do SF-36, que dão a perceção

da qualidade de vida que o indivíduo tem de si mesmo, estão de acordo com os

resultados do NMQ em que se verificou uma diminuição da dor lombar e

consequentemente das limitações nas atividades do dia-a-dia, estando de

acordo com a maioria da literatura que tem vindo a preconizar a importância do

exercício específico realizado no posto de trabalho como forma de prevenção e

de evitar lesões na coluna na lombar (Bendix, Bendix, Lund, Kirkbak, &

Ostenfeld, 1997; Claiborne et al., 2002; Harkness, Macfarlane, Nahit, Silman, &

McBeth, 2003; Santos, Bredemeier, Rosa, Amantea, & Xavier, 2011; Tveito &

Eriksen, 2009).

94

No momento 1, antes da intervenção, verificou-se que 55% da

população já tinham tido problemas severos de lombalgias, em que estiveram

ausentes no último ano mais de um mês e 10% destes já tinham sido

intervencionados cirurgicamente à coluna vertebral. Dos 45% da população

que cumpria os critérios de inclusão e no momento da primeira avaliação

aproximadamente 30% da população referiu dor lombar e a faixa etária foi de

33 anos em média, ou seja, estes números são um pouco alarmantes e pela

literatura revista não existe uma relação de causalidade (Roffey et al., 2010;

Wai et al., 2010) mas sabe-se que a única forma de tentar prevenir e tratar as

lesões músculo-esqueléticas são através de programas de intervenção

específicos para as populações em risco (Airaksinen et al., 2006; Descarreaux

et al., 2002; Tuncel, 2006; Tuzun, 2007).

A generalidade dos estudos de investigação apresenta um conjunto de

limitações associado. Este projeto apresenta igualmente algumas limitações,

nomeadamente o elevado número de perdas, podendo levar à não ocorrência

de alguns resultados esperados, ou à inexistência de resultados significativos,

fruto de algumas dessas limitações. Porém, este tipo de limitações são de difícil

controlo em situações reais, embora toda a equipa de trabalho tenha estado

sempre atenta e empenhada na motivação dos indivíduos para a participação e

importância deste estudo. Todavia, as perdas deste estudo são relativamente

semelhantes às perdas de 28% referidas por Santos et al. (2011) ao fim de

nove meses de intervenção e das de Butler & Johnson (2011), que reportaram

perdas de 58% da amostra ao fim de um ano de intervenção. Eventualmente,

uma outra razão para a desistência do programa, e dos controlos, foi o facto

dealguns indivíduos considerarem que como o programa era executado dentro

e no horário da empresa, os exercícios eram considerados mais uma obrigação

e tarefa por parte da empresa do que um benefício ou vantagem para os

trabalhadores.

Outra limitação foi o não controlo das tarefas, das horas de descanso, da

presença ou não de um segundo emprego, dos hábitos alimentares e das

atividades recreativas ou desportivas dos operários dos dois grupos fora das

horas laborais.

95

Este estudo afigura-se relevante, visto ter sido experimental e de longa

duração, o que permitiu ter acesso a dados concretos acerca dos trabalhadores

portugueses e das suas reais necessidades e problemas. Uma vez que os

distúrbios músculo-esqueléticos são um problema cada vez mais comum entre

a população trabalhadora, causando elevados níveis de incapacidade nos

indivíduos e consequentemente redução da qualidade de vida, passando os

indivíduos a ter que lidar diariamente com a dor, sugere-se que sejam

efetuados mais estudos experimentais de longa duração sobre estratégias

preventivas, englobando também estudos ergonómicos de modo a diminuir

todas estas sequelas. Seria também importante testar e comparar outro tipo de

programas de atividade física de forma a perceber se existiriam diferenças nos

resultados.

Conclusões

98

Conclusões

A adaptação para a população portuguesa do Standardized Nordic

Musculoskeletal questionnaire evidenciou bons índices de correlação de

fiabilidade e de moderada validade.

O programa de exercícios específicos demonstrou ser eficaz na

diminuição da sintomatologia músculo-esquelética, na região lombar, ao longo

de um período de 21 meses, nas suas três variáveis: sintomatologia nos

últimos 12 meses, limitações nos últimos 12 meses e sintomatologia nos

últimos 7 dias, em trabalhadores de armazém.

Nas outras regiões (pescoço, ombros, cotovelos, mãos/punhos, torácica,

ancas/coxas, joelhos e pés/tornozelos, não se verificaram alterações

significativas da sintomatologia, nas suas três variáveis, com a inserção do

programa de exercícios específicos.

O programa de exercícios específicos aplicado em trabalhadores de

armazém, durante 11 meses, mostrou que a força e resistência dos músculos

extensores lombares aumentaram significativamente. Relativamente à força e

resistência dos flexores aumentou, mas não foi demonstrada evidência

estatística.

Quanto à qualidade de vida dos indivíduos, aos quais se aplicou o

programa de exercícios específicos, esta, evidenciou aumentos significativos

nas dimensões: Função Física, Desempenho Físico, Dor Física, Função Social,

Desempenho Emocional e Saúde Mental.

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Anexos

Anexo I

XXI

Questionário de Saúde Geral

1. Tem alguma anormalidade anatómica? □Sim □ Não

� Se respondeu sim, diga qual: _______________________________

2. Pratica algum desporto? □Sim □ Não

� Se respondeu sim diga qual a periodicidade: ____________________

3. Possui alguma lesão ou doença crónica do foro neuro-musculo-esquelético? □Sim □

4. Toma alguma medicação específica? □ Sim □ Não

� Se respondeu sim, especifique: _______________________________

5. Realizou alguma cirurgia à zona abdominal ou lombo-pélvica ou devido a dor lombar?

□Sim □ Não

6. Realizou algum tratamento à coluna lombar no último ano? □Sim □ Não

7. Tem história de dor a nível da coluna lombar? □Sim □ Não

8. Neste momento, sente dor a nível da coluna lombar? □ Sim □ Não

� Se respondeu sim, indique com um X qual a sua severidade, tendo em conta que 0

corresponde a “ausência de dor” e 10 a “dor máxima imaginável”.

0 1 2 3 4 5 6 7 8 9 10

Nome: ________________________________________________ Nº Código: _______

Idade: _______ Sexo: □ Masculino □ Feminino

Preencha o questionário com sinceridade,assinale com uma cruz a hipótese mais adequada.

No caso de surgir alguma dúvida no preenchimento do questionário não hesite em esclarecer

com um dos nossoscolaboradores!!!

A informação fornecida jamais servirá para outros fins que nãoesta investigação.

XXII

9. Possui algumadoença a nível do Sistema Respiratório?□ Sim □ Não

� Se respondeu sim, diga qual: _______________________________

10. Possui algumadoença a nível do Sistema Cardiovascular?□ Sim □ Não

� Se respondeu sim, diga qual: _______________________________

11. Possui algumadoença a nível do Sistema Endócrino ou Renal?□ Sim □ Não

� Se respondeu sim, diga qual: _______________________________

XXIII

Anexo 2

Questionário Nórdico Músculo-esquelético

XXIV

Instruções para o preenchimento

• Por favor, responda a cada questão assinalando um “X” na caixa apropriada: �

• Marque apenas um “X” por cada questão.

• Não deixe nenhuma questão em branco, mesmo se não tiver nenhum problema em

qualquer parte do corpo.

• Para responder, considere as regiões do corpo conforme ilustra a figura abaixo.

Questionário Nórdico Músculo-esquelético

XXV

Idade_____Data de nascimento____/___/___Sexo_______ __Data de hoje____/____/_____

Posto de trabalho_________________________________E stado civil__________________

Nome_______________________________________________________________________

Considerando os últimos 12 meses , teve algum problema (tal como dor, desconforto ou dormência ) nas seguintes regiões:

Responda, apenas, se tiver algum problema

Durante os últimos 12 meses teve que evitar as suas actividades normais (trabalho, serviço doméstico ou passatempos) por causa de problemas nas seguintes regiões:

Teve algum problema nos últimos 7 dias, nas seguintes regiões:

1. Pescoço? Não Sim

1 � 2 �

2. Pescoço?

Não Sim

1 � 2 �

3. Pescoço?

Não Sim

1 � 2 �

4.

5. Ombros?

Não Sim

1 � 2 � , no ombro direito

3 � , no ombro

esquerdo

4 � , em ambos

6. Ombros?

Não Sim

1 � 2 � , no ombro direito

3 � , no ombro

esquerdo

4 � , em ambos

7. Ombros?

Não Sim

1 � 2 � , no ombro direito

3 � , no ombro

esquerdo

4 � , em ambos

8.

9. Cotovelo?

Não Sim

1 � 2 � , no cotovelo direito

3� , no cotovelo

10. Cotovelo?

Não Sim

1 � 2 � , no cotovelo direito

3� , no cotovelo

11. Cotovelo?

Não Sim

1� 2� , no cotovelo direito

3� , no cotovelo

12.

Código:

Questionário Nórdico Músculo-esquelético

XXVI

esquerdo

4� , em ambos

esquerdo

4� , em ambos

esquerdo

4� , em ambos

13. Punho/Mãos?

Não Sim

1� 2� , no punho/mãos direitos

3� , no punho/mãos esquerdos

4� , em ambos

14. Punho/Mãos?

Não Sim

1� 2� , no punho/mãos direitos

3� , no punho/mãos esquerdos

4� , em ambos

15. Punho/Mãos?

Não Sim

1� 2� , no punho/mãos direitos

3� , no punho/mãos esquerdos

4� , em ambos

16.

17. Região Torácica?

Não Sim

1 � 2 �

18. Região Torácica?

Não Sim

1 � 2 �

19. Região Torácica?

Não Sim

1 � 2 �

20.

21. Região Lombar?

Não Sim

1 � 2 �

22. Região Lombar?

Não Sim

1 � 2 �

23. Região Lombar?

Não Sim

1 � 2 �

24.

25. Ancas/Coxas?

Não Sim

1 � 2 �

26. Ancas/Coxas?

Não Sim

1 � 2 �

27. Ancas/Coxas?

Não Sim

1 � 2 �

28.

29. Joelhos?

Não Sim

1 � 2 �

30. Joelhos?

Não Sim

1 � 2 �

31. Joelhos?

Não Sim

1 � 2 �

32.

33. Tornozelo/Pés?

Não Sim

1 � 2 �

34. Tornozelo/Pés?

Não Sim

1 � 2 �

35. Tornozelo/Pés?

Não Sim

1 � 2 �

36.

XXVII

XXVIII

XXIX

XXX

XXXI