The biomechanics and the production of knowledge in physiotherapy

A biomecânica e a produção do conhecimento em fisioterapia: levantamento baseado nos anais do congresso brasileiro de biomecânica

The biomechanics and the production of knowledge in physiotherapy: survey based on the proceedings of Brazilian congress of biomechanics

Paula Hentschel Lobo da Costa^I; Roberta de Fátima Carreira Moreira^II; Fabiana Almeida Foltran^II; Luiz Fernando Approbato Selistre^II; Kleber Luis Silva Santos^II; Kelli Cristina de Castro^II; Natália Targas Lima^III; Teresinha das Graças Coletta^IV

^IDoutora em Biodinâmica do Movimento Humano, Departamento de Educação Física e Motricidade Humana da UFSCar – São Carlos (SP), Brasil
^IIPrograma de Pós-Graduação em Fisioterapia da UFSCar – São Carlos (SP), Brasil
^IIIDepartamento de Educação Física e Motricidade Humana da UFSCar – São Carlos (SP), Brasil
^IVMestre em Engenharia de Produção, Escola de Engenharia de São Carlos da Universidade de São Paulo (USP) – São Carlos (SP), Brasil

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RESUMO

O aumento gradual da participação da comunidade acadêmica da Fisioterapia nas edições do Congresso Brasileiro de Biomecânica (CBB) é notório. Os Anais do CBB passaram a ser importantes veículos para a divulgação científica em Fisioterapia no Brasil; porém, a caracterização dessa produção ainda não foi feita. O objetivo do presente estudo foi realizar um levantamento bibliográfico dos estudos em Fisioterapia publicados nas edições dos Anais do CBB, desde a primeira edição em 1992 (Anais do IV CBB) até a edição publicada em 2009 (Anais do XIII CBB), a fim de identificar quais especialidades da Fisioterapia têm aplicado o conhecimento em Biomecânica no contexto clínico e/ou científico, além de caracterizar o tipo de pesquisa que se tem desenvolvido. Seis revisores independentes levantaram os estudos pertencentes à área da Fisioterapia e coletaram informações de maneira padronizada através de questionários. Os resultados evidenciaram um grande crescimento da participação das diferentes áreas da Fisioterapia ao longo das dez edições do CBB. Embora os dados sejam positivos em relação à ampliação das pesquisas em Biomecânica, verificou-se uma carência da utilização dos recursos biomecânicos para avaliar efeitos de intervenções em pacientes. Dessa forma, recomenda-se que mais estudos sejam conduzidos em contextos clínicos e com acompanhamento longitudinal, de modo a ampliar a aplicação prática das ferramentas biomecânicas no campo da intervenção, bem como aperfeiçoar a avaliação em Fisioterapia.

Descritores: biomecânica; fisioterapia; pesquisa.

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ABSTRACT

The increasing presence of the Physical Therapy (PT) community in the Brazilian Congress of Biomechanics (CBB) is well known. The Proceedings of the CBB Congresses have turned to important vehicles to scientific publications in Physical Therapy, but the characteristics of these studies have not been focus of analysis. Thus, the purpose of this study was to identify the contribution of PT to the studies published in the Proceedings of the CBB Congresses, from the first edition in 1992 (Proceedings of the IV CBB) to the 2009 edition (Proceedings of the XIII CBB), in order to verify which subareas of expertise in PT are applying the biomechanical knowledge on clinical and/or scientific context and the kind of research being developed. Six independent reviewers collected data related to the PT production according to standardized questionnaires. The results evidenced that the area of PT has increased its publications along the ten CBB Proceedings. Despite positive findings, we noticed a lack of biomechanical studies aimed at investigating interventions in patients. Thus, we can suggest that clinical studies with a longitudinal design could be developed in order to improve the application of biomechanical tools in therapeutic settings and to contribute to evaluation procedures in PT.

Keywords: biomechanics; physical therapy specialty; research.

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INTRODUÇÃO

Todo movimento é um fenômeno mecânico e sempre que uma força atua sobre o corpo humano, direta ou indiretamente, princípios biomecânicos estão envolvidos. O estudo de forças é fundamental para a compreensão de situações estáticas e dinâmicas do movimento humano, seja ele normal ou patológico¹. O estudo de forças que atuam sobre ou no corpo humano é feito pela Biomecânica.

Biomecânica pode ser considerada uma parte inerente à Fisioterapia², pois, ao lidar com disfunções do movimento, a Fisioterapia precisa da descrição desta, feita pela cinemática. Uma cinemática anormal precisa ser explicada pelas forças atuantes sobre o corpo, geradoras do movimento. Para isso, princípios da cinética precisam ser considerados.

A Biomecânica foi considerada como uma área que, em 1984, ainda estava restrita à pesquisa em Fisioterapia nos Estados Unidos¹. No Brasil, não é possível inferir sobre o papel exato da Biomecânica na formação inicial de fisioterapeutas, pois não foram encontrados estudos na literatura sobre esse tema. Ainda em 1984, Devine³afirmou que currículos em Fisioterapia deveriam considerar o desenvolvimento de competências biomecânicas para atuação em áreas de prevenção de disfunções do movimento, avaliação e tratamento de pacientes, a fim de se superar o enfoque estritamente de pesquisa.

O investimento em pesquisa na Fisioterapia tem crescido rapidamente nos últimos anos e um importante marco para esse desenvolvimento foi a criação, em 2005, da Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia⁴. Entretanto, antes disso já era notório o aumento gradual da participação da comunidade acadêmica da Fisioterapia nas edições do Congresso Brasileiro de Biomecânica (CBB), o que refletia o interesse dos pesquisadores pela área. Verificou-se um crescimento gradual tanto do número absoluto de trabalhos, quanto da participação relativa da Fisioterapia nos Anais do CBB, desde a primeira edição dos Anais em 1992, até a publicada em 2009, na qual 56,5% dos estudos originaram-se em Departamentos de Fisioterapia⁵.

Esse crescimento do interesse da Fisioterapia pela pesquisa em Biomecânica teve como consequência a necessidade de espaço para a divulgação de novos conhecimentos e para discussões sobre os avanços científicos e técnicos.

Os Anais do CBB passaram a ser importantes veículos para a divulgação científica em Fisioterapia no Brasil; porém, a caracterização dessa produção ainda não foi feita. As tendências de publicações nas edições dos anais do CBB foram analisadas previamente por Mochizuki et al.⁶, Cotta e Mochizuki⁷; porém, esses estudos não fizeram referência à contribuição relativa de áreas específicas do conhecimento.

Os Anais entre 1992 e 2005 foram avaliados por Cotta e Mochizuki⁷. Os autores focaram a discussão na distribuição dos estudos quanto à metodologia biomecânica utilizada e identificaram uma redução percentual dos estudos sobre instrumentação biomecânica e de revisão bibliográfica, a partir da edição de 2001. Por outro lado, observaram um crescimento dos estudos experimentais, identificando a dinamometria como a metodologia mais utilizada. Não foram feitas considerações sobre quais áreas do conhecimento estavam contribuindo para essa produção.

Também Mochizuki et al.⁶ avaliaram a produção dos anais do CBB de 1992 a 2003, usando um modelo matemático para descrever o ritmo de crescimento da produção e identificaram a região Sudeste como a origem da maior parte das publicações brasileiras.

A qualidade da pesquisa em Fisioterapia publicada em congressos foi analisada por Coury⁸. A tendência ao longo de 20 anos dos estudos destinados à intervenção ergonômica foi avaliada sistematicamente a partir de publicações de 7 Congressos Latino-Americanos de Ergonomia e 12 Congressos Brasileiros de Ergonomia. A autora identificou que apenas uma pequena porcentagem dos estudos abordava medidas de intervenção preventivas e uma porcentagem ainda menor destes apresentava conclusões convincentes.

Com vistas a melhor identificar quais especialidades da Fisioterapia têm aplicado o conhecimento em Biomecânica no contexto clínico e/ou científico, e caracterizar o tipo de pesquisa que se tem feito, o presente estudo apresenta como objetivo realizar um levantamento bibliográfico dos estudos em Fisioterapia publicados nos Anais do CBB, desde a primeira edição em 1992 até a publicada em 2009.

O levantamento das características das pesquisas em Fisioterapia publicadas nos anais do CBB poderá contribuir para identificar as subáreas envolvidas com a Biomecânica e a forma como esta tem contribuído para a atuação profissional na área.

MATERIAIS E MÉTODOS

Estratégia de busca

Foi realizada pesquisa nas edições dos anais do CBB publicadas desde a primeira edição até 2009, o que compreendeu as edições de 1992⁹, 1993¹⁰, 1995¹¹, 1997¹², 1999¹³, 2001¹⁴, 2003¹⁵, 2005¹⁶, 2007¹⁷ e 2009¹⁸.

Para a identificação do estudo como pertencente à área da Fisioterapia, foram inicialmente verificados o título do estudo e a filiação dos autores. Em caso de ausência desses dados, foi consultado o currículo Lattes. Durante essa consulta, considerou-se que se ao menos um dos autores pertencesse a um departamento de Fisioterapia, o estudo seria considerado para análise.

Inicialmente, seis revisores independentes trabalharam coletando dados de todos os estudos que compunham os anais. Todos os estudos foram classificados de acordo com a área do conhecimento a que pertenciam. Os revisores utilizaram dois formulários padronizados que auxiliaram a coleta de dados gerais e específicos sobre os trabalhos publicados. Eventuais dúvidas e discordâncias durante o processo foram solucionadas por meio de consenso.

A seguir, todos os estudos relacionados à Fisioterapia foram selecionados e tiveram seus resumos analisados para identificar o assunto abordado e a subárea específica a que pertenciam.

Critérios de inclusão

Tipos de participantes

Foram selecionados apenas estudos que relataram resultados referentes a seres humanos, independentemente do gênero, faixa etária e condição de saúde.

Tipo de resultados relatados

Foram selecionados os estudos que utilizaram instrumentação específica para avaliação de variáveis biomecânicas em seres humanos.

Extração dos dados

Todos os revisores trabalharam de forma independente, utilizando dois formulários padronizados para a extração dos dados. Inicialmente, através do formulário 1, todos os estudos apresentados nas 10 edições do CBB foram classificados quanto a: 1) edição do CBB a que pertencia; 2) área do conhecimento; 3) instituição à qual, ou às quais, seus autores estavam filiados.

A seguir, por meio do formulário 2, os estudos relacionados à Fisioterapia foram analisados separadamente, sendo então classificados quanto a: 1) instituição de ensino; 2) subárea da Fisioterapia a que pertencia; 3) características da população do estudo, como o perfil dos sujeitos avaliados, número de sujeitos, média de idade e gênero; 4) desenho do estudo, classificado entre dois modelos: transversal e longitudinal; 5) variáveis biomecânicas avaliadas e 6) instrumentação utilizada.

Após a tabulação dos dados, foram criadas novas categorias para facilitar a análise dos resultados. Assim, as instituições de ensino foram agrupadas de acordo com a região geográfica a que pertenciam. Os sujeitos foram categorizados em acometidos e não acometidos de acordo com a presença ou ausência de afecções do sistema musculoesquelético. Em relação à idade, foram estabelecidas 4 categorias de acordo com a seguinte faixa etária: crianças (0 a 15 anos); adultos jovens (de 16 a 29 anos); adultos (30 a 59 anos) e idosos (idade superior a 60 anos). Quanto à instrumentação utilizada, foram usadas quatro categorias baseadas nas variáveis biomecânicas medidas¹⁹: antropometria, cinemetria, eletromiografia, dinamometria e outros (incluindo metodologias de goniometria, eletrogoniometria, manovacuometria, testes clínicos, fleximetria e termometria).

Não foi realizada avaliação da qualidade metodológica dos estudos incluídos, pois havia uma grande variedade de modelos experimentais, o que inviabilizou a padronização dos estudos para uma avaliação objetiva e comparativa da qualidade.

Finalmente, foi realizada uma avaliação geral sobre a organização dos anais considerando: as áreas utilizadas para classificação dos trabalhos; a forma de apresentação dos estudos; a presença de sumário e de índice de autores e o meio de divulgação dos anais.

Análise de dados

Os resultados foram analisados de forma descritiva levando em consideração a distribuição de frequência dos resultados obtidos.

Resultados E discussão

Participação da Fisioterapia

Ao longo das edições do CBB, a Fisioterapia participou de maneira cada vez mais significativa quanto ao total de publicações. Observa-se que a partir do ano de 2001 houve incremento dessa participação. A contribuição da Fisioterapia, de forma geral, passou de 2,4 % do total de estudos em 1992 para 56,5% em 2009 (Tabela 1).

Além do aumento na quantidade de estudos, diferentes áreas da Fisioterapia foram se apresentando nas edições do CBB, demonstrando maior vínculo com a instrumentação biomecânica.

A Ortopedia destacou-se em número de publicações no CBB desde as primeiras edições, seguida pela Ergonomia (participação regular desde 1997) e Neurologia (desde 1999). Os estudos em metodologia de pesquisa em Fisioterapia e a participação de outras áreas como a Fisioterapia respiratória, reumatológica, cardiológica e ginecológica (agrupadas na categoria denominada 'Outras') já é fato desde a edição de 1999 (Figura 1).

Provavelmente o predomínio da Ortopedia se deva à ampla utilização de conceitos e princípios biomecânicos na área para fins clínicos e de ensino, dando suporte à pesquisa e ao desenvolvimento de tecnologia como os dinamômetros isocinéticos.

Características dos sujeitos de pesquisa

Quanto à caracterização dos sujeitos de pesquisa, observou-se que os sujeitos sem acometimentos ou lesões (não acometidos) foram mais pesquisados que aqueles com algum tipo de distúrbio neuromusculoesquelético (Tabela 2). Esse tipo de população passou a predominar na edição do ano de 2003, talvez pela facilidade de recrutamento. Quanto à faixa etária dos sujeitos de pesquisa, verificou-se que, de um modo geral, todas as faixas etárias estiveram presentes nos estudos, contudo houve predomínio da faixa etária composta por adultos jovens (Tabela 2). Além disso, vale ressaltar que na edição de 2009 houve grande quantidade de trabalhos (34%) sem informação quanto à idade, o que dificultou a classificação em populações específicas quanto à faixa etária. A análise das amostras demonstrou que um grande número de estudos utilizou estudantes universitários para a obtenção de dados. O fácil acesso a essa população, sua relativa disponibilidade para participar de protocolos experimentais são fatores que possivelmente contribuíram para tal fato.

Esses resultados demonstram que tem havido pouca aplicabilidade das metodologias biomecânicas no contexto clínico. Tal fato pode estar relacionado à dificuldade de acesso aos equipamentos, à ausência de espaços apropriados para sua utilização nos setores de atendimento, bem como a problemas de acesso relacionados ao transporte e deslocamento de pacientes para laboratórios de universidades. Assim, a afirmação de Devine³continua atual, no sentido de que permanece no Brasil a necessidade de se superar o enfoque estritamente de pesquisa da Biomecânica em Fisioterapia.

Instrumentação utilizada

A instrumentação utilizada nos estudos foi classificada de acordo com a variável biomecânica mensurada. Observou-se que a dinamometria prevaleceu como metodologia de avaliação a partir do ano de 1999 e que a cinemetria passou a ser utilizada de forma mais regular na pesquisa em Fisioterapia na edição de 1997. Porém, a partir de 2005 observou-se um expressivo crescimento do emprego da cinemetria (Figura 2). Neste estudo, a cinemetria incluiu as metodologias de radiografia, ultrassonografia e ressonância magnética, sempre que as informações foram quantificadas, do contrário, quando esses métodos eram empregados apenas para efeito de diagnóstico, os estudos não foram incluídos na análise. A dinamometria incluiu as metodologias de dinamometria isocinética e baropodometria dinâmica. A categoria 'Outros' incluiu: impressão plantar, goniometria, eletrogoniometria, termometria, monofilamentos e manovacuômetro.

Distribuição geográfica dos núcleos de pesquisa

A classificação baseada na localização geográfica das instituições (Figura 3) mostrou que em 1992 e 1993 não houve participação da fisioterapia nacional nas produções do CBB, apenas uma participação internacional em 1992. Porém, a partir de 1999 a produção em Fisioterapia das regiões sudeste e sul começou a se fazer presente nos Anais do CBB, com crescimento rápido ao longo das edições, principalmente no sudeste. A região nordeste passa a publicar nos anais no ano de 1997. No ano de 2005, observou-se a presença de produções científicas das regiões norte e centro-oeste, além da região nordeste ter atingido o auge de sua produção. Nesse ano o congresso foi realizado em João Pessoa (PB), o que pode ter contribuído para esse fato. Desde então, as regiões norte, nordeste e centro-oeste mantém com regularidade sua produção nas edições do CBB. Esse fato foi mais bem avaliado, pois havia o indicativo de que houvesse uma clara relação entre o local sede do congresso e o aumento da publicação dos grupos locais e regiões. No entanto, esse fato não se comprovou nas outras edições dos Anais do CBB.

Há uma parceria internacional na primeira edição em 1992, mas apenas em 1999 houve novamente esse tipo de estudo, mantendo uma regularidade de contribuição a partir de 2003. Essas parcerias internacionais refletem o interesse na formação de recursos humanos em Biomecânica e a busca pelo domínio de novas metodologias de pesquisa. Tais parcerias são importantes e devem ser incentivadas, de modo a aprimorar as pesquisas nacionais e fortalecer as cooperações internacionais para pesquisa na área de Biomecânica aplicada à Fisioterapia.

Desenho dos estudos

A análise do desenho dos estudos demonstrou que em 1992 o único estudo da Fisioterapia era uma parceria internacional e tinha caráter longitudinal. Em 1995, foram identificados um estudo longitudinal e um transversal. A partir de 2001, houve grande predomínio de desenhos transversais de estudos, que passaram a corresponder a 92, 89, 74, 76 e 81 % nos anos de 2001, 2003, 2005, 2007 e 2009, respectivamente. Observou-se que a maioria dos estudos envolveu questões específicas, desenvolvidas em contextos com pouca possibilidade de generalização dos resultados.

Considerações sobre a apresentação dos Anais

O presente estudo não se propõe à avaliação da qualidade metodológica das publicações dos Anais do CBB e nem a sintetizar evidências sobre um aspecto de pesquisa específico. O objetivo foi apresentar um panorama da pesquisa em Biomecânica na Fisioterapia, indicando os caminhos que têm sido traçados de acordo com os documentos avaliados.

Um aspecto muito importante nessa análise foi o levantamento da normatização dos anais. Observou-se que há, de maneira geral, uma carência de normatização, o que se reflete em publicações (tanto impressas, quanto na forma digital) não padronizadas. A classificação dos estudos em áreas da Biomecânica na composição dos Anais precisa ser mais bem definida, pois há estudos metodologicamente semelhantes que se inserem em áreas diferentes no mesmo livro de Anais. O mesmo ocorre na comparação de Anais de edições diferentes. Ainda, um mesmo estudo pode ser incluído em mais de um assunto ou subárea, criando uma classificação por vezes dúbia. A fim de superar essa limitação, nas próximas edições poderia ser utilizado um índice comum para áreas e subáreas, por exemplo, definido a partir de um vocabulário controlado.

Alguns anais estão organizados pela forma de apresentação, outros pelo tipo de publicação e ainda há a organização com base na ordem de inscrição dos estudos no CBB. Esse fato dificultou a classificação dos trabalhos, o uso de instrumentos de busca e, certamente, o acesso aos documentos. Todas as dificuldades relativas à falta de normatização dos anais podem ter afetado os resultados do presente estudo, representando um fator limitante de nossas conclusões.

Anais de eventos elaborados apenas na forma digital têm inúmeras vantagens; porém, caso não sejam construídos a partir de plataformas automáticas, com padronização de templates para os diferentes formatos de publicação (resumos, artigos, completos), ou formas de apresentação (tema oral, pôster, conferência) que utilizem robôs de busca (por palavras-chave, sobrenome do autor, entre outros), tornam a recuperação do documento uma tarefa difícil. Naturalmente, a disseminação do conhecimento depende em grande parte da facilidade de acesso aos documentos por parte dos interessados.

Finalmente, o baixo grau de citação dos estudos, mencionado por Mochizuki et al.⁶ pode ser decorrente da dificuldade de acesso aos documentos devido à deficiente normatização dos anais e não necessariamente pela pouca relevância ou novidade do conhecimento veiculado.

CONCLUSÃO

Houve um crescimento relevante da participação das diferentes áreas da Fisioterapia ao longo das dez edições do CBB incluídas na avaliação proposta por este estudo. Esse crescimento pode refletir: 1) o aumento do interesse pelo uso da Biomecânica na pesquisa em Fisioterapia; 2) um maior domínio dos recursos disponíveis, a partir de parcerias que favorecem a troca de informação e o compartilhamento da instrumentação; 3) um maior acesso às novas tecnologias que permitem aliar informações quantitativas aos dados qualitativos relacionados às avaliações clínicas do movimento humano.

Embora esses resultados sejam positivos em relação à ampliação do uso das ferramentas da Biomecânica nas pesquisas desenvolvidas por departamentos de Fisioterapia, verificou-se uma carência da utilização dessas ferramentas para avaliação objetiva dos efeitos de intervenções fisioterapêuticas em indivíduos com disfunção.

A maioria dos estudos avaliados não foi realizada dentro de um contexto terapêutico. Tal fato foi evidenciado pelo grande número de estudos com desenho transversal e pelo predomínio da participação de indivíduos saudáveis. Assim, é possível reforçar a importância da aplicação prática das competências biomecânicas utilizadas na pesquisa durante a atuação terapêutica. Além disso, enfatiza-se a necessidade de desenvolvimento de ensaios clínicos futuros utilizando as ferramentas biomecânicas disponíveis para avaliação dos efeitos de intervenções clinicas.

Dessa forma, recomenda-se que mais estudos sejam conduzidos em contextos clínicos e com acompanhamento longitudinal de modo a ampliar a aplicação prática das ferramentas biomecânicas no campo da intervenção, bem como aperfeiçoar a avaliação em Fisioterapia.

Ressalta-se a importância de adotar normatização padronizada de publicações visando facilitar a recuperação de dados e o acesso aos documentos publicados, independentemente da forma de divulgação, impressa ou digital.

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17. Anais do XII Congresso Brasileiro de Biomecânica; 2007 Mai 30-02; São Pedro, SP, Brasil. São Paulo: Sociedade Brasileira de Biomecânica; 2007.         [ Links ]

18. Anais do XIII Congresso Brasileiro de Biomecânica; 2009 Jul 28-01; São Paulo, SP, Brasil. São Paulo: Sociedade Brasileira de Biomecânica; 2009.         [ Links ]

19. Amadio AC, Duarte M (Eds). Fundamentos biomecânicos para a análise do movimento humano. São Paulo: EEFEUSP; 1996.         [ Links ]

Scoliometer measurements of patients with idiopathic scoliosis

Scoliometer measurements of patients with idiopathic scoliosis

Daniel M.  Coelho1, Guilherme H.  Bonagamba2, Anamaria S.  Oliveira3

¹Universidade de São Paulo , Ribeirão Preto, SP, Brazil

²Universidade de São Paulo , Ribeirão Preto, SP, Brazil

³USP, School of Medicine of Ribeirão Preto, Department of Biomechanics, Medicine e Rehabilitation of Locomotor System, Ribeirão Preto, SP, Brazil

ABSTRACT

BACKGROUND:

Patients with idiopathic scoliosis are exposed to approximately 25 radiographic examinations of their spine throughout the clinical follow-up using the Cobb angle. Several non-invasive and radiation-free methods have been proposed to measure scoliotic deformities, including the scoliometer.

OBJECTIVES:

To measure the intra- and interrater reliability of the scoliometer measurements, to assess the correlation of the values obtained by the scoliometer measurements with the Cobb angles obtained by radiography, and to assess the sensitivity and specificity of the scoliometer measurements for the different diagnostic criteria for the referral of idiopathic scoliosis.

METHOD:

Sixty-four patients were selected for the study: half with idiopathic scoliosis and half without. The 17 levels of the spine of each volunteer were measured with a scoliometer in the forward bending position. The measurements were performed three times on 42 volunteers by two different raters to obtain data for calculating the reliability values. Anteroposterior radiographs were taken to determine the Cobb angles, which were then compared with the highest trunk rotation value. Sensitivity and specificity were evaluated using radiograph criteria for referral: a Cobb angle of 10º and axial trunk rotation values between 5º and 10º.

RESULTS:

Excellent intrarater reliability values and very good interrater reliability values were obtained. The correlation between the scoliometer measurements and radiograph analyses was considered good (r=0.7, p<0.05). The highest sensitivity value was for a trunk rotation of 5º at 87%.

CONCLUSIONS:

The scoliometer measurements showed a good correlation with the radiographic measurements.

Key words: physical therapy; scoliometer; scoliosis; spine; evaluation

INTRODUCTION

Patients with idiopathic scoliosis are exposed to approximately 25 radiographic examinations of their spine throughout the clinical follow-up using the Cobb angle to measure the magnitude of scoliotic curvature^1-3. These patients' excessive exposure to radiation has been associated with an increased risk of developing breast cancer up to 5.4%⁴.

Several non-invasive and radiation-free methods have been proposed to measure scoliotic deformities^5-8, including the scoliometer^9-11. The scoliometer is an inclinometer that measures the asymmetries between the sides of the trunk in axial rotation degrees. The first attempt to correlate the values of the scoliometer measurements with Cobb angles was performed when developing the device¹². Since then, there has been no consensus regarding the correlation of these values. Mubarak et al.¹³, Amendt et al.⁹ and Pearsall et al.¹⁴stated that the values obtained with the scoliometer had poor or insignificant correlations with the Cobb angles. However, Bunnell¹², Korovessis and Stamatakis¹⁵, Sapkas et al.¹¹ and Griffet et al.¹⁶ found a high correlation between the axial trunk rotation (ATR) values and the Cobb angles.

The consistency of the values obtained by the scoliometer has been evaluated using intra and interrater reliabilities^9,15. Amendt et al.⁹ evaluated 65 patients with scoliosis and found correlation values between 0.86 and 0.97 for the intra and interrater values. Korovessis and Stamatakis¹⁵ evaluated the interrater reliability of the scoliosis measurement values, referring to the vertebral level with the greatest trunk asymmetry, and found reliability values ranging between 0.64 and 0.92. The study by Côté et al.¹⁷ showed that the reliability in determining the level of greatest trunk asymmetry was only 0.25. These authors suggested that methodological and statistical analysis flaws had compromised the conclusions of the earlier studies reporting low correlations.

The precision of the scoliometer test has also been the subject of previous studies^{9,12,15,17-19}. Measurements using the scoliometer require a value that identifies a minimal deformity to determine whether the patient needs clinical treatment¹². The criteria for referral found in the literature ranged between 5ºATR, with a 23% sensitivity¹², and 7.5ºATR, with an 87% sensitivity¹⁸, for Cobb angles greater than 20º. However, there is still no consensus about the diagnostic criteria for referral using scoliometer measurements, with repercussions for the values of the instrument's sensitivity and specificity.

Hence, the purpose of this study was to 1) assess the intra- and interrater reliability of the scoliometer measurements, 2) assess the correlation of the values obtained by the scoliometer measurements with the Cobb angles obtained from radiographs, and 3) measure the sensitivity and specificity of the scoliometer measurements for the different diagnostic criteria for the referral of idiopathic scoliosis using the scoliometer.

METHOD

The participants were enrolled by convenience in a sample of 32 patients with idiopathic scoliosis for the scoliosis group (SG), which was seen at the Clinic of Orthopedics and Spine of the Clinics Hospital of the Medicine School of Ribeirão Preto, Universidade de São Paulo (HCFMRP-USP), Ribeirão Preto, SP, Brazil. The patients were diagnosed as having scoliosis by a spine specialist orthopedic physician after a physical evaluation and radiographic diagnosis. Another 32 volunteers with Cobb angles smaller than 10º were enrolled at the USP as the control group (CG). The weight and height variables were paired based on the scoliosis group. The volunteers' ages were not paired because, considering the study's objective, it was more important to control the structural ratio of the body segments that were studied. All subjects signed the consent form. This study was approved by the Ethics Committee for Research involving Human Beings at the Committee of Ethics in Human Research of the HCFMRP-USP under process number 9164/2006 in 08/28/2006.

The participants in the SG were on average 18.2 years old (±3.9 years), with an average weight of 54.9 kg (±8.7 kg) and height of 1.61 m (±0.78 m). The average age in the CG was 21.1 years (±2.2years), with an average weight of 55.3 kg (±7.6 kg) and average height of 1.60 m (±0.72 m) (Table 1). The SG, comprising 32 volunteers (31 females and 1 male), presented a total of 47 curves in the frontal plane, considering primary and secondary curves. The curves' magnitudes ranged between Cobb angles of 10º and 101º (average of 25.5º±18.4º). Overall, 16 volunteers had curves between 10º and 20º, eight had curves between 21º and 30º, five had curves between 31º and 40º, and three had curves greater than 40º. The CG also comprised 31 females and 1 male.

Table 1 Anthropometric data, mean and standard deviation of the volunteers in the Scoliosis Group and Control Group showing the differences between the groups and the p values for Student's t-test. 

	Scoliosis Group	Control Group	Difference	p
Age (years)	18.2 (±3.9)	21.1 (±2.2)	2.9	<0.01
Weight (kg)	54.9 (±8.7)	55.3 (±7.6)	0.4	0.44
Height (m)	1.61 (±0.78)	1.60 (±0.72)	0.1	0.69

The inclusion criteria for the study were the following: volunteers between 10 and 25 years of age, no history of surgery on the back or lower limbs, and a lower limb length discrepancy smaller than 2.5 cm. Only patients with a diagnosis of idiopathic scoliosis were included in the SG.

The female volunteers had their hair tied up and wore a customized backless t-shirt to provide a full view of their back. The male volunteers performed the tests bare-chested. Through palpation, the spinous processes T1 to L5 and the posterior iliac superior spine were located and marked using a marker pen. The same rater performed the process of locating and marking the areas. The rater had four years of experience in manual therapy, which involves the palpation of anatomic structures of the spine.

On top of each anatomic reference mark, 5-mm metal markers were attached using double-sided tape. These markers did not interfere with the scoliosis measurement because they were 3 mm high and did not touch the scoliometer during the measurement process. These markers remained taped over the spinous processes until the experiment was completed to ensure that every measurement was made with the same markings.

During the scoliometer measurement, the patients bent their trunk forward until it was parallel to the ground, keeping the palms of their hands together with their arms hanging down and perpendicular to their trunk. In this position, rater 1 (R1) measured the ATR value of the 17 previously marked levels of the 64 volunteers. The ATR values were obtained by positioning the center of the scoliometer over the spinous process and perpendicular to the spine.

Two months before beginning the data collection, the raters were trained to use the scoliometer (Orthopaedic Systems Inc, Hayward, CA) on volunteers with and without scoliosis to become familiar with handling the device and taking measurements.

Forty-two of the sixty-four volunteers submitted to this measurement three times to obtain the data for calculating the interrater reliability values. This group consisted of 25 volunteers from the SG and 17 from the CG. The first and third measurements were performed by a second rater (R2), and the second measurement was performed by R1. Each rater made their measurements, which took approximately three minutes, with no breaks. Between the measurements, the volunteers were instructed to return to the upright position. The measurement made by R1 was performed shortly after a rest interval, the duration of which was determined by the volunteer, after the first measurement was performed by R2. Between the first and last measurements by R2, there was a 15-20 minutes interval for procedures that were not analyzed in this study. At the end of each measurement, 17 ATR values were obtained, one for each vertebral level.

After completing the scoliometer measurements, an anteroposterior (AP) radiograph was obtained of each volunteer, comprising the entire spine in an orthostatic position. The same radiology technician performed all of the radiographic examinations. The Cobb angle was determined by R1 after the completion of the measurements, always using the same negatoscope and goniometer.

The reliability data analysis for the 714 ATR values was performed using SPSS11 software. The intrarater reliability analysis assessed the values from the first measurement by R2 with the values from the second measurement by R2. The test used for this analysis was the Intraclass Correlation Coefficient (ICC) one-way random model with measures of absolute agreement. The interrater reliability was determined by comparing the values of the first measurement by R2 with the values of the measurement by R1. The test used for this analysis was the Intraclass Correlation Coefficient two-way random model with measures of absolute agreement. ICC values smaller than 0.7 were considered unacceptable; the ICC values were considered acceptable between 0.71 and 0.79, very good between 0.8 and 0.89, and excellent above 0.9²⁰.

The data from the scoliometric and radiographic analyses were correlated using Pearson correlation coefficients with a level of significance of 5%, using Statistica 6.0 software. The Cobb angles were compared with the highest ATR value obtained in the R1 scoliometer measurements of all 64 volunteers. Correlation values smaller than 0.25 were considered poor, between 0.25 and 0.49 were low, between 0.50 and 0.69 were moderate, between 0.70 and 0.89 were good, and between 0.90 and 1.0 were excellent²¹.

The 64 volunteers were analyzed for sensitivity, specificity, positive predictive value, and negative predictive value using a Cobb angle of 10º as the radiographic criteria for referral. Referral criteria of 5, 6, 7, 8, 9, and 10 ATR degrees were also investigated.

The same analysis was performed for 17 SG volunteers and 17 CG patients paired according to height and weight for a Cobb angle of 20º as the criteria for radiographic referral.

RESULTS

Forty-two subjects were assessed to obtain the intra- and interrater reliability values. They showed a mean angle of 3.9º (±4.0º) for the 714 ATR values obtained in the measurements by R1. In the second measurement by R2, the mean value for the 714 ATR values was 3.7º (±4.0º), and 3.8º (±4.0º) was the mean for the 714 values obtained in the third measurement by R2. The intrarater reliability was 0.92, and the interrater reliability was 0.89.

The highest mean ATR values obtained in the scoliometer measurements of the 64 volunteers was 7.3º (±4.3º), and the mean Cobb angle was 13.2º (±18º). The correlation between the scoliometer measurement and the radiographic analysis was r=0.7 with p<0.05. The linear regression equation determining the Cobb angle from the ATR value was Cobb=-6.3 + 2.7 * ATR.

Table 2 presents the sensitivity, specificity, positive predictive value and negative predictive value for the referral criteria of 5, 6, 7, 8, 9, and 10 ATR degrees of the scoliometer measurement for a scoliotic curvature greater than 10º Cobb. The greatest sensitivity and negative predictive value were found at 5º trunk rotation, which were 87% and 73%, respectively.

Table 2 Sensitivity, specificity, and positive and negative predictive values of the scoliometer measurements at different values of axial trunk rotation (ATR) used for referral and of scoliotic curvatures greater than 10º Cobb. 

ATR	5°	6°	7°	8°	9°	10°
Sensitivity	0.87	0.68	0.62	0.56	0.46	0.37
Specificity	0.34	0.68	0.75	0.81	0.87	0.90
Positive Predictive Value	0.57	0.68	0.71	0.75	0.78	0.80
Negative Predictive Value	0.73	0.68	0.66	0.65	0.62	0.59

Table 3 presents the sensitivity, specificity, positive predictive value and negative predictive value for the referral criteria of 5, 6, 7, 8, 9, and 10 ATR degrees of the scoliometer measurement of scoliotic curvature greater than 20º Cobb. The sensitivity and negative predictive value were both 100% at the 5º trunk rotation.

Table 3 Sensitivity, specificity, positive and negative predictive values of the scoliometer measurements at different values of axial trunk rotation (ATR) used for referral and of scoliotic curvatures greater than 20º Cobb (n=34). 

ATR	5°	6°	7°	8°	9°	10°
Sensitivity	1	0.76	0.66	0.70	0.64	0.53
Specificity	0.35	0.70	0.66	0.76	0.76	0.82
Positive Predictive Value	0.60	0.72	0.66	0.75	0.73	0.75
Negative Predictive Value	1	0.75	0.66	0.72	0.68	0.63

DISCUSSION

The present study found excellent intrarater reliability values and very good interrater reliability values for ATR. The results previously reported in the literature are contradictory in terms of the intra- and interrater reliability values of the scoliometer measurements^9,10,15,17. In the studies cited, only the vertebral level presenting the greatest asymmetry between the trunk sides was considered. The method proposed in the present study measured the reliability of all vertebral levels of the thoracic and lumbar spine, which makes it possible to state that regardless of the vertebral level and magnitude of the patient's ATR, the scoliometer measurement is reliable.

Predicting the radiographic Cobb angle using noninvasive methods has great potential as it would permit professionals to clinically follow up the scoliotic curvature without recourse to measurements using ionizing radiation. The present study found good correlation between the scoliometer measurements and the Cobb angles. Reports in the literature are contradictory, with some authors proposing a strong correlation between the methods^11,12,15 and others stating there is a poor correlation^9,13,14. These studies correlated the ATR of the level with the greatest asymmetry with the Cobb angle value. However, the level of greatest asymmetry was determined in a subjective manner by the examiner. The low reliability in determining the level with the greatest asymmetry used to measure the trunk rotation can lead to measurement errors¹⁴. In the present study, the level of greatest asymmetry was determined after evaluating every vertebral level, and the one with the greatest ATR value was used for the correlation with the Cobb angle. The correlation function presented in the present study permitted the estimation of the Cobb angle using the scoliometer measurement. Hence, a clinician can screen idiopathic scoliosis patients with a scoliometer and calculate the Cobb angle, which is the gold standard for diagnosing and following curvatures, without the need for excessive radiography.

The results of the present study showed that it is possible to identify 87% of the patients with idiopathic scoliosis with lateral curvatures greater than 10º Cobb and 100% of the patients with curves greater than 20º Cobb using 5ºas the criteria for referral. The literature reported that increased ATR values do not lead to increased sensitivity of the scoliometer measurements. According to Bunnell¹², the 5º criteria for referral would permit the detection of 23% of patients measured by the scoliometer with Cobb angle greater than 20º, whereas Burwell et al.¹⁸ proposed an 87% sensitivity for the referral criteria of 7.5º ATR. The use of ATR criteria for referral with greater sensitivity and smaller specificity examinations for idiopathic scoliosis is justified by the importance of detecting every individual with lateral curvature given the important consequences for the health of patients with skeletal immaturity¹⁷. Using a 5º ATR criterion for referral, two studies used the scoliometer to screen students and investigate the prevalence of idiopathic scoliosis^19,22.

A scoliosis diagnosis is confirmed when a curvature greater than 10º Cobb is determined by radiographic examination²³. Curves smaller than 20º Cobb are rarely treated^12,19 and have not been included in previous studies^9,12,18. However, patients with curves between 10º and 20º Cobb should be evaluated to eliminate factors that could lead to an increase in the curvature, such as the Risser index and the date of menarche in female patients²⁴. We propose that patients with ATR values of at least 5º by scoliometer measurement should be referred for a more thorough clinical evaluation to identify those with a greater probability of the progression of the curvature of the lateral vertebral spine.

The scoliometric method for measuring the ATR is quick and easy to learn but requires a well-trained physical therapist to palpate the spinal levels, or the measurements can be made at the wrong anatomical marks, resulting in an unreliable angle value.

Further studies are needed to evaluate the capability of the scoliometer measurements in following the progression of the curvature of patients with idiopathic scoliosis of different magnitudes to confirm the use of the scoliometer as an instrument not only for screening but also for clinically following the scoliotic curvature and effectiveness of the treatments.

Scoliometer measurements, following the methodology proposed in this study, showed good correlation with the Cobb angle, the gold standard measurement. It had good intra- and interrater reliability and was sensitive in detecting curvatures greater than 10º Cobb using a referral criterion of 5º ART, indicating its potential for screening individuals with idiopathic scoliosis. Further studies should be performed to measure the test-retest reliability and the measurement responsiveness with the purpose of incorporating it into clinical practice as an alternative to radiographic exposure.

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Eccentric training for shoulder abductors improves pain

Eccentric training for shoulder abductors improves pain, function and isokinetic performance in subjects with shoulder impingement syndrome - a case series

Treino excêntrico para abdutores do ombro melhora dor, função e desempenho isocinético em sujeitos com síndrome do impacto - série de casos

Paula R. Camargo^{I, II}; Mariana A. Avila^II; Francisco Alburquerque-Sendín^III; Naoe A. Asso^II; Larissa H. Hashimoto^II; Tania F. Salvini^II

^IPhysical Therapy Graduation Program, Universidade Metodista de Piracicaba (UNIMEP), Piracicaba, SP, Brazil
^IIPhysical Therapy Department, Universidade Federal de São Carlos (UFSCar), São Carlos, SP, Brazil
^IIIPhysical Therapy Department, University of Salamanca, Salamanca, Spain

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ABSTRACT

BACKGROUND: Conservative treatments have been proposed for people with shoulder impingement syndrome (SIS), such as strengthening of the rotator cuff and scapular muscles and stretching of the soft tissues of the shoulder. However, there is a lack of studies analyzing the effectiveness of eccentric training in the treatment of SIS.
OBJECTIVES: To evaluate the effects of eccentric training for shoulder abductors on pain, function, and isokinetic performance during concentric and eccentric abduction of the shoulder in subjects with SIS.
METHODS: Twenty subjects (7 females, 34.2 SD 10.2 years, 1.7 SD 0.1 m, 78.0 SD 16.3 kg) with unilateral SIS completed the study protocol. Bilateral isokinetic eccentric training at 60º/s for shoulder abductors was performed for six consecutive weeks, twice a week, on alternate days. For each training day, three sets of 10 repetitions were performed with a 3-minute rest period between the sets for each side. The range of motion trained was 60° (ranging from 80° to 20°). The Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire was used to evaluate functional status and symptoms of the upper limbs. Peak torque, total work and acceleration time were measured during concentric and eccentric abduction of the arm at 60º/s and 180º/s using an isokinetic dynamometer.
RESULTS: DASH scores, peak torque, total work and acceleration time improved (p<0.05) after the period of intervention.
CONCLUSIONS: This study suggests that isokinetic eccentric training for shoulder abductors improves physical function of the upper limbs in subjects with SIS.

Keywords: physical therapy; supraspinatus; subacromial; DASH.

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RESUMO

CONTEXTUALIZAÇÃO: Tratamentos conservadores têm sido propostos para pessoas com síndrome do impacto (SI) do ombro, como fortalecimento do manguito rotador e dos músculos escapulares e alongamento dos tecidos moles do ombro. No entanto, são escassos os estudos que analisaram a eficácia do treinamento excêntrico no tratamento da SI.
OBJETIVOS: Avaliar os efeitos do treinamento excêntrico para abdutores do ombro na dor, função e desempenho isocinético durante a abdução concêntrica e excêntrica do ombro em indivíduos com SI.
MÉTODOS: Vinte indivíduos (sete mulheres, 34,2 DP 10,2 anos, 1,7 DP 0,1 m, 78,0 DP 16,3 kg) com SI unilateral completaram o protocolo do estudo. Realizou-se treinamento isocinético excêntrico bilateral a 60º/s para abdutores do ombro durante seis semanas consecutivas, duas vezes por semana, em dias alternados. Para cada dia de treinamento, foram realizadas três séries de dez repetições, com um período de descanso de 3 minutos entre as séries para cada lado. A amplitude de movimento treinada foi de 60° (de 80° a 20°). O questionário Disabilities of the Arm, Shoulder and Hand (DASH) foi utilizado para avaliar a função e os sintomas dos membros superiores. O pico de torque, o trabalho total e o tempo de aceleração foram avaliados durante a abdução concêntrica e excêntrica do braço a 60º/s e 180º/s por meio de um dinamômetro isocinético.
RESULTADOS: As pontuações do DASH, o pico de torque, o trabalho total e o tempo de aceleração melhoraram (p<0,05) após o período de intervenção.
CONCLUSÕES: Este estudo sugere que o treinamento isocinético excêntrico para abdutores do ombro melhora a função física dos membros superiores em indivíduos com SI.

Palavras-chave: fisioterapia; supraespinal; subacromial; DASH.

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Introduction

Shoulder impingement syndrome (SIS) is one of the most common causes of shoulder pain¹. The pain occurs because of compression and mechanical abrasion of the subacromial structures against the anterior undersurface of the acromion and coracoacromial ligament, especially during elevation of the arm². The supraspinatus tendon is usually the most affected structure due to its location just under the coracoacromial ligament³. Apoptosis in this tendon has already been described in subjects who were treated with subacromial decompression⁴.

Conservative treatments have been proposed for people with SIS^5-9. The literature supports the strengthening of the rotator cuff and scapular muscles and the stretching of the soft tissue of the shoulder^6,9,10. Good clinical results of eccentric training for the supraspinatus and deltoid muscles¹¹ and for the rotator cuff¹² were demonstrated in subjects with painful SIS. Other studies have also shown successful results with eccentric training in different types of tendinopathies^13-16.

Eccentric training is very efficient for muscular and tendon strengthening^17,18. Also, this type of training may induce remodeling of the tendon¹⁸ and changes in neovessels¹⁹. Although the studies related to eccentric training in subjects with SIS have shown interesting results, more investigations are warranted to evaluate the effectiveness of eccentric training in the treatment of SIS.

The aim of this study was to evaluate the effects of eccentric training for shoulder abductors on pain, physical functional status and isokinetic performance during concentric and eccentric abduction of the shoulder in subjects with SIS. It was hypothesized that eccentric training for shoulder abductors would improve pain, function and isokinetic parameters in these subjects.

Methods

Participants

The participants of this study were recruited from a physical therapy waiting list at the clinic at the Universidade Federal de São Carlos (UFSCar), São Carlos, SP, Brazil and also from flyer advertisements at the University premises and orthopedic clinics. The participants with shoulder pain were first evaluated and diagnosed with SIS by a physical therapist and then the diagnosis was confirmed by an orthopedic physician. The clinical diagnosis of SIS was made following the clinical criteria of reproduction of pain by at least 3 of the tests: Neer², Hawkins²⁰, Jobe²¹, Speed²² and Gerber²³. They also had to present painful range of motion during active shoulder elevation. Ultrasonography for both shoulders was performed by an experienced radiologist and used to check tendinopathy of supraspinatus and rule out progression of impingement to rotator cuff or long head biceps tears. Ultrasonography improves the differential diagnosis for shoulder pain as it has high sensitivity (98.1%) for identifying rotator cuff tears²⁴. Other studies also used ultrasonography in the evaluation of patients with SIS^6,11,25.

Exclusion criteria included pregnancy, torn rotator cuff or long head biceps tendons, ligamentous laxity based on positive Sulcus test²⁶ or a positive Apprehension test^27,28, previous shoulder or neck surgery, hooked acromion, systemic illnesses, corticosteroid injection 3 months prior to evaluation, and physical therapy treatment 6 months prior to evaluation.

Thirty-seven participants (22 males) with shoulder pain were initially recruited and evaluated. Twelve of them did not meet the inclusion criteria. From the remaining 25 participants, five did not complete the period of the study because of work scheduling or personal problems. Therefore, 20 participants (7 women, 34.2 SD 10.2 years (range 20-51 years), 1.7 SD 0.1 m (range 1.60-1.96 m), 78.0 SD 16.3 kg

(range 55-120 kg, body mass index 25.87 SD 3.29 kg/m² (range 20.38-31.24 kg/m²)) with unilateral SIS completed the study. The duration of their shoulder pain was 2.8 SD 2.9 years (range from 5 to 120 months) based on self-report. All participants were still able to work and perform their daily activities despite of pain. None of them was on sick leave. The involved side was the dominant side for 12 participants.

All participants gave their written informed consent to participate in this study, which was approved by the local Ethical Committee of the UFSCar (Approval 214/2007) and conducted according to the Helsinki Statement. This study was registered on Clinicaltrials.gov (NCT01090271).

Evaluations

Two baseline evaluations (evaluation 1 and evaluation 2) were performed before the start of the intervention with a period of 4 weeks between them, and 2 follow-up evaluations were performed immediately after 6 weeks of intervention (evaluation 3) and after 6 weeks after the end of the intervention period (evaluation 4). Two baseline evaluations were used to assess any possible improvement without intervention.

The Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire

The DASH self-report questionnaire was used to evaluate functional status and symptoms of the upper limbs of the subjects. The maximum score of the questionnaire is 100, which indicates the worst possible condition²⁹. This questionnaire was previously used to assess the effectiveness of an intervention program in subjects with SIS^6,30 and has been shown to be a reliable, valid and responsive measure^31,32.

Isokinetic evaluation

Involved and uninvolved sides were randomly chosen to begin the evaluation. As studies have shown bilateral deficits in people with unilateral SIS^33-35, both sides were evaluated and trained. Peak torque, total work and acceleration time were measured during concentric and eccentric abduction of the arm using an isokinetic dynamometer (Biodex Multi-Joint System 3, Biodex Medical System Inc., NY, USA). Peak torque was defined as the mean of the maximum torque produced during the 5 repetitions. Total work was determined by the sum of work for every repetition performed in the set. Acceleration time was described as the total time used to reach the preset dynamometer speed.

Participants performed a warm-up procedure at the beginning of the testing sessions that consisted of shoulder movements in all directions followed by stretching exercises for the upper trapezius (3 repetitions of 30s), as previously proposed³³. Afterwards, the participants were seated and their trunk was stabilized with diagonal and pelvic straps. The arm was positioned in the scapular plane, neutral rotation and 20° abduction with the elbow in full extension. The acromioclavicular joint was aligned over the rotational machine axis. Previous studies have used this positioning to test the subjects during isokinetic abduction^25,33. Although studies recommend abduction with glenohumeral internal rotation (empty can) to better activate the supraspinatus^3,36, we performed a pilot study where the participants were not able to perform abduction with internal rotation without increasing pain; therefore, neutral rotation was used for evaluations and intervention. Gravity correction was performed with the arm relaxed in 80° of abduction. The total range of motion assessed was 60°. This range of motion was chosen to avoid pain and exacerbation of impingement in 90° of elevation³⁷.

The evaluation protocol consisted of concentric and eccentric abduction at 60°/s and 180º/s. After some procedure explanations, the participants were familiarized with the procedure by performing 3 submaximal repetitions at each speed. A 2-minute rest period was provided between familiarization and testing. The isokinetic evaluation at each speed consisted of 5 repetitions of maximal effort during the movements. The isokinetic evaluations started at 60°/s. A 2-minute rest period was given between each speed. A standardized verbal encouragement to develop maximal strength in all contractions was given by the principal investigator in a consistent manner to all participants during the testing procedure. No participants experienced pain during the test.

Eccentric training

The positioning for the eccentric training was the same used for the isokinetic evaluation. The eccentric training for the shoulder abductors was performed with maximal strength in all contractions for 6 consecutive weeks, 2 days/week, on alternate days. Studies have shown positive effects of a twice-week intervention^5,6. The training was performed bilaterally in the isokinetic dynamometer at 60º/s³⁸ and the range of motion trained was 60° (ranging from 80° to 20°). This range of motion was chosen to avoid impingement at 90° elevation³⁷. For each training day, 3 sets of 10 repetitions were performed with a 3-minute rest period between the sets for each side. The same verbal encouragement given in the evaluations was provided during all training sessions. All participants performed only the eccentric training proposed in this study while the duration of the study. No other forms of intervention were provided during this period. Also, no specific warm-up or cool-down exercises were performed in addition to the eccentric training.

Sample size calculation

The sample size calculation was performed with the software ENE2.0^© (GlaxoSmithKline, Universidad Autónoma de Barcelona, Spain). The calculations were based on detecting a maximum effect size of 28.6msec in the acceleration time between two means, at least, during concentric abduction of the shoulder at 60º/s with a standard deviation of 26msec³³, an alpha level of 0.05, and a desired power of 90%. These assumptions generated a sample size of at least 19 subjects. The acceleration time was the variable chosen for the calculation of the sample size as some investigations have demonstrated that SIS does not affect muscle torque of the shoulder^39-41, but affects scapular and rotator cuff muscle activity in subjects with SIS during arm elevation^42-44. Therefore, the acceleration time may provide valuable information regarding neuromuscular readiness to produce maximal contraction.

Statistical analysis

Statistical analysis was conducted with the SPSS16.0 package (SPSS, Chicago, Il). Mean, standard error and 95% confidence intervals of the values are presented. The Kolmogorov-Smirnov test showed a normal distribution of quantitative data (p>0.05). For the DASH questionnaire, a 1-way repeated measures analysis of variance (ANOVA) was used to test the main effect of time (evaluations 1, 2, 3 and 4). For each dependent variable (peak torque, total work and acceleration time), a 4x2 mixed model ANOVA with main effects of time (evaluations 1, 2, 3 and 4) as the repeated factor and side (involved and uninvolved) as the independent factor was used at each mode (concentric and eccentric) and speed, separately. Interactions of time and side were also analyzed. The Huynh-Feldt Epsilon correction and the Bonferroni test for post hoc analysis were used when necessary. A p value of less than 0.05 was considered significant.

Effect sizes for each time were calculated using Cohen's d coefficient⁴⁵. An effect size greater than 0.8 was considered large, around 0.5 moderate, and less than 0.2 small. The time periods evaluated were paired as following: evaluation 1 - evaluation 3; evaluation 2 - evaluation 3; evaluation 3 - evaluation 4.

Results

DASH questionnaire

Statistically significant main effect of time was found for the DASH score (p<0.01). DASH scores were lower after the period of intervention (Table 1), which lower scores indicate better condition. There was no difference (p=0.25) between evaluations 1 and 2. However, evaluation 4 showed lower values compared to evaluations 1 (p<0.01), 2 (p=0.02) and 3 (p=0.02); and evaluation 3 when compared to evaluation 1 (p<0.01).

A large effect size was found when evaluation 1 was compared to evaluation 3, and a moderate effect size was demonstrated when evaluation 3 was compared to evaluations 2 and 4 (Table 2).

Isokinetic parameters

Interaction effect of side x time - There were no significant interactions between side and time. Peak torque (concentric-60°/s, p=0.89; eccentric-60°, p=0.80; concentric-180°/s, p=0.97; eccentric-180°/s, p=0.87), total work (concentric-60°/s, p=0.91; eccentric-60°, p=0.4; concentric-180°/s, p=0.7; eccentric-180°/s, p=0.93) and acceleration time (concentric-60°/s, p=0.77; eccentric-60°, p=0.29; concentric-180°/s, p=0.36; eccentric-180°/s, p=0.55) did not identify differences between means (Table 3).

Main effect of side - The intra-side analysis, separately, showed few differences along the evaluations. However, those differences were found in the same variables for both sides (p<0.05): total work (eccentric-60º/s and 180º/s), and acceleration time (eccentric-180º/s). The post-hoc analyses identified a different pattern for pairwise comparisons of each side. In this way, the uninvolved side demonstrated to be more homogeneous in the baseline evaluations (1 and 2), with statistical differences between these evaluations and the post-intervention measures (evaluations 3 and 4). The differences were between evaluations 1 and 3 (p=0.01), evaluations 1 and 4 (p<0.01), and evaluations 2 and 4 (p=0.01) for total work (eccentric-60º/s); and between evaluations 1 and 3 (p=0.01), evaluations 1 and 4 (p<0.01), evaluations 2 and 4 (p=0.03) for total work (eccentric-180º/s). Finally, the statistical differences for acceleration time (eccentric-180º/s) were observed between evaluations 2 and 4 (p =0.03). Notably, the involved side showed less pairwise differences and always between evaluation 1 and post-intervention measures. In this case, the differences were between evaluations 1 and 3 (p=0.02), evaluations 1 and 4 (p=0.04) for total work (eccentric-60º/s); between evaluations 1 and 3 (p=0.04), and evaluations 1 and 4 (p=0.01) for total work (eccentric-180º/s), and between evaluations 1 and 3 (p=0.01, Table 3) for acceleration time (eccentric-180º/s). The effect size for the isokinetic variables for each side was small and moderate for most of the conditions. Table 4 shows the effect size for the variables that reached statistically significance (p<0.05).

Main effect of time Significant main effect of time was found in some conditions after the period of eccentric training, as occurred with peak torque (concentric-180°/s), total work (concentric-180°/s; eccentric-60° and 180°/s) and acceleration time (concentric-180º/s; eccentric-180º/s) (Table 3). Evaluation 3 improved compared to evaluations 1 and 2 for the following outcomes: peak torque (concentric-180°/s, p=0.03 and p=0.01, respectively), total work (concentric-180°/s, p=0.04 and p=0.02, respectively; eccentric-60°, p<0.01, respectively; eccentric-180°/s, p<0.01 and p=0.02 respectively), which the results after the intervention period were higher than before the exercises; and acceleration time (eccentric-180°/s, p<0.01 and p=0.01, respectively) with lower values at the two last evaluations. This tendency was maintained for peak torque (concentric-180°/s, p=0.03) and acceleration time (eccentric-180°/s, p=0.04) which improved during the follow-up period (evaluation 4) when compared to evaluation 2. Acceleration time (concentric-180°/s) also improved (p=0.02) during the follow-up period (evaluation 4) when compared to evaluation 1.

Table 5 shows the effect size for the variables that reached statistical significance (p<0.05), which was small for most of the conditions. As observed in the main effect of side and in the interaction effect of side by time there were no differences (p>0.05) for the baseline period in all conditions.

Discussion

This study showed that eccentric training for shoulder abductors could be effective to reduce pain and physical impairment of the upper limbs during daily activities, as well as to improve isokinetic parameters in subjects with SIS. It is important to state that large and moderate within-group effect sizes were only demonstrated for DASH score, while small and moderate within-group effects were observed for the isokinetic variables.

The literature supports the strengthening of the rotator cuff and scapular muscles and the stretching of the soft tissues of the shoulder to reduce pain and functional loss in people with SIS^6,9,10. Although previous reports also support the idea that elevation exercises should be avoided in SIS^8,46, a study showed good clinical results of eccentric training for the supraspinatus and deltoid muscles in chronic painful SIS¹¹.

Many studies have suggested the use of eccentric exercise in the preventive care or rehabilitation^{11,13,15,18,47-49}. Eccentric exercises have also been advocated as efficient in the treatment of several tendon disorders because this type of exercise accelerates tenocytes metabolism and may speed repair^18,50. Therefore, tendons become stronger as tenoblast activity increases and an appropriate collagen reaction accelerates¹⁸. Neovascularization also seems to play an important role leading to good clinical results showed by the eccentric training¹⁹. It is known that SIS specifically involves the supraspinatus tendon and it has also been linked to apoptosis in this tendon⁴. Although it is beyond the scope of this study, we can suggest that the high forces produced eccentrically may have induced the beneficial tissue remodeling response on the supraspinatus tendon of the subjects leading to a better physical function status according to the DASH score.

The lack of studies on eccentric training in subjects with SIS is evident. One study performed with only 9 subjects investigated if painful eccentric training for shoulder abductors was effective in subjects with chronic shoulder pain due to SIS¹¹. All subjects were on a waiting list for surgery and had to perform painful eccentric training for the supraspinatus and deltoid muscles for 12 weeks, twice a day, 7 days a week. After 12 weeks of eccentric training, 5 out of 9 subjects were satisfied with the result of the treatment, according to the Constant score, and withdrew from the waiting list for surgical treatment. At 52-week follow-up, these same subjects were still satisfied. Despite the difference in methodology between the eccentric training performed in the current study and Jonsson's et al.¹¹ study, the subjects of our study also presented improved physical function of the upper limbs. However, it is important to state that our participants were younger, had shorter duration of symptoms and no indication for surgery.

Another study¹² has also used eccentric training of the rotator cuff for patients with SIS. In addition, scapular control was also incorporated in the program and it was effective to decrease pain an increase function in these subjects.

In the present study, the eccentric training was performed with an isokinetic equipment. However, clinical relevant eccentric exercises can also be incorporated in a treatment protocol for those without isokinetic treatment. The exercises can be easily done with dumbbells and elastic bands and tubings as performed in the previous studies on eccentric training^11,12.

Although there are no homogeneous isokinetic protocols to evaluate all types of patients, the use of isokinetic evaluation of muscle performance can be a valuable tool to assess the effectiveness of rehabilitation protocols because it provides objective documentation of dynamic movements. Isokinetic testing has been demonstrated to be reliable and valid to assess the shoulder complex¹⁷. However, it should be considered that this kind of testing is not specific to a certain muscle²⁵, it evaluates the performance of a muscle group in a determined movement.

Lombardi et al.³⁰ assessed the effects of progressive resistance training on pain, function, quality of life and muscle strength in subjects with SIS. The training program was held 2 days/week for 8 weeks. The resistance was evaluated individually every 2 weeks. Flexion, extension, medial rotation, and lateral rotation of the shoulder were the exercises done considering the eccentric and concentric phases. Peak torque and total work were evaluated during concentric flexion, extension, abduction, adduction, medial rotation and lateral rotation of the shoulder at 60°/s and 180°/s. The training was effective in reducing pain and improving function and quality of life. However, there was no improvement in muscle torque. This finding was explained due to the lack of specificity between the exercises performed and the isokinetic evaluation, and to the short training period. In our study, although there was no lack of specificity, only few improvements in muscle performance were found and of few clinical significance. As such, we can suggest that the time of training was short for these subjects. Maybe our participants needed a longer time of intervention to improve the isokinetic parameters and reach a better within-group effect. However, this hypothesis needs to be further tested. Another possibility for finding only few changes in muscle performance can be that the participants may not have worked on maximum effort during the training sessions although the investigator asked them to perform maximal strength in all contractions. Despite the muscle soreness referred by all participants until the third session, which may indicate that they have put maximal effort during the training sessions, we cannot be confident that they were indeed working at maximum effort.

Therapeutic exercises have previously been determined to have long-term benefits for subjects with SIS^51,52. In this investigation, benefits were observed even 6 weeks after the intervention period. It should be considered that no change was demonstrated in the baseline period. In comparison to studies that showed that exercise intervention is more effective than no intervention or placebo in subjects with SIS^7,51,53, we can hypothesize that the natural course does not account for the positive effects in the isokinetic muscle performance, pain and physical function presented by the participants of this study. It is worth to consider the chronicity of the participants' condition (average 2.83 years), which suggests unlikely spontaneous recovery for subjects within the 4-month period of this study. However, we should also consider that Hawthorne effects might have taken place where subjects improve or modify an aspect of their behavior being experimentally measured simply in response to the fact that they are being studied⁵⁴.

One may also argue if the improvement observed in the present study is a result of learning effect as training and tests were performed in the isokinetic dynamometer. We do not believe that learning effect took place because only few significant differences occurred in the isokinetic parameters and of small effect size. It should also be stated that improvement was also found in the DASH score, which is not related to the isokinetic, with large and moderate within-group effect sizes.

Further investigations are necessary to evaluate the effects of eccentric training programs on the scapular and humeral kinematics and on muscle activity of the supraspinatus and deltoid. It would also be relevant to perform imaging evaluation before and after the period of intervention to verify if changes in the supraspinatus tendon occur. Eccentric training has high clinical relevance, as it seems to improve the quality of the tendon by making it stronger and inducing remodeling of the collagen. In addition, eccentric training is the type of exercises that allows faster gain in muscular mass and neural adaptation compared to other types of training¹⁸. Future studies should also include a control group and wider range of motion.

Conclusions

This study suggests that isokinetic eccentric training for shoulder abductors is efficient to improve pain and function of the upper limbs in subjects with SIS and should be considered in rehabilitation.

Acknowledgments

The authors are deeply grateful to the volunteers who participated in this study and to the funding agenciesCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).

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