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Experience in Resistance Training Does Not Prevent Reduction in Muscle Strength Evoked by Passive Static Stretching
Abstract
This study examined whether passive static stretching reduces the maximum muscle strength achieved by different body segments in untrained and resistance-trained subjects. Twenty adult men were assigned to one of two groups: untrained (UT, N = 9) and resistance-trained (RT, N = 11). The subjects performed six one-repetition maximum load (1RM) tests of the following exercises: horizontal bench press, lat pull-downs, barbell curls, and 45o leg press. The results achieved in the last two 1RM tests were used for statistical analysis. A passive static stretching program was incorporated prior to the sixth 1RM test. The body fat content was significantly higher in the UT group compared to the RT group (P < 0.0001). Moreover, the RT group showed significantly higher proportion of lean body mass compared to the UT group (P < 0.0001). Maximum muscle strength on all four exercises was significantly reduced in both groups after stretching (P < 0.01). Furthermore, the magnitude of muscle strength reduction was similar for the UT and RT groups. The exception was for barbell curls, in which the muscle strength depression was significantly higher in the UT group compared to RT group (P < 0.0001). In conclusion, the passive static stretching program was detrimental to upper and lower body maximal muscle strength performance in several body segments. The negative effects of stretching were similar for subjects participating in resistance training regimens.
... Some scientific evidence has shown that stretching before of the competition, before of the strength training, or before of another type of activity is not adequate [42,43] and certain researches have shown that it is indicated the stretching before of the competition, before of the strength training and others activities [44,45]. Throughout the text the reader will have access to some studies and then will be informed the best way to organize the flexibility training and other training task or how to perform this exercise before the competition. ...
... These results are with a short static stretch. But some investigations of the static stretching with a short time of 15 [42] and 30 seconds [43] causes on the strength a decline and the prescription of this work before of the competition no improvement the motor capacities. ...
Flexibility is defined as the movement practiced in great amplitude and according to the sports modality it manifests itself with a degree of exigency. The objective of the review was to explain how to prescribe the stretching according to the objective of the next task. Some studies have evidenced that static and PNF stretching interfere with the strength, the speed and the agility, but other studies have reported that this does not happen. Then, it is indicated to practice in the session the static stretching in different days of the strength, of the speed and of the agility. But dynamic stretching optimizes the performance of these conditioning motor capacities (strength, speed, and agility). Therefore, dynamic stretching deserves to be practiced before of the training of the conditioning motor capacities (strength, speed and agility) and before of the competition. In conclusion, an adequate elaboration of the work of flexibility provides an adequate athletic performance of the sportsman.
... Apesar de muito investigado, ainda persistem debates sobre o efeito agudo de diferentes métodos de alongamento sobre o desempenho da força e potência, sobremaneira em exercícios com séries sucessivas. A maioria dos estudos apontam para uma queda no desempenho da força após rotinas de alongamento estático 15,16 e da facilitação neuromuscular proprioceptiva (FNP) 17,18 . No entanto, outros autores apontam para ausência de efeito desses métodos de alongamento sobre os níveis de força 4,19,20 . ...
... Alguns autores têm sugerido que indivíduos treinados ou atletas são menos suscetíveis à queda no desempenho da força após exercícios de alongamento e que sujeitos destreinados seriam mais afetados 33,39 . No entanto, Serra et al. 16 , verificaram o efeito de três séries de 30 s de alongamento estático sobre a força máxima (1-RM) em diferentes exercícios em sujeitos treinados e destreinados e encontraram quedas similares no desempenho após o alongamento para ambos os grupos. No presente estudo, os participantes eram treinados em exercício contra-resistência há mais de um ano e todos eram bem familiarizados com o exercício supino reto. ...
There is still no consensus about the use of stretching before strength exercises in successive series. Thus, the aim was to verify the acute effect of two stretching methods on the strength performance in the bench press exercise. Trained subjects performed 3 sets of 8 to10-RM in the bench press immediately after the static stretching (SS), Proprioceptive Neuromuscular Facilitation (PNF) or control condition. There was a significant decrease in repetitions in the second and third series compared to the first for all conditions. There was no significant difference in the number of repetitions or total volume between the conditions with and without stretching. The SS and PNF induced no negative effect on strength performance and can be used prior to this exercise
... A principal razão para aplicação de AE em rotinas pré-exercício é a suposta capacidade de aumentar temperatura, reduzir a viscosidade e os riscos de lesões musculares, contribuindo para melhorar o desempenho em atividades físicas (21). Entretanto, a literatura exibe estudos que indicam que o AE parece não reduzir os riscos de lesões musculares, além de provocar efeitos deletérios em curto e longo prazos sobre a força, modulação autonômica, pressão arterial e controle motor, afetando desempenho em exercício (22)(23)(24)(25)(26). ...
Introdução: O alongamento muscular é uma prática popularmente realizada com o propósito de melhorar a qualidade de vida e o desempenho em atividades físicas. Alguns estudos científicos relatam efeitos deletérios desta prática relacionadas às respostas mecânicas e neurais para a realização do movimento, os quais poderiam ser diretamente interferentes em variáveis como o tempo de reação manual (TRM), visto que, rapidez e precisão nesta variável são fundamentais em diversas atividades da vida diária, em algumas profissões e, especialmente, para o desempenho em exercício.
Objetivo: O presente comentário teve por objetivo examinar e discutir o efeito das diferentes técnicas e volumes de alongamento muscular sobre o TRM e suas consequências.
Conclusão: O baixo volume de alongamento (≤ 30s), independentemente da técnica ou intensidade, não interfere sobre o TRM. Face ao que se apresenta na literatura sobre o tema, não é possível realizar julgamento conclusivo da associação de alto volume de alongamento (duração > 30s) com a resposta motora manual. Adicionalmente, é imperativo estudos que objetivem avaliar o efeito do alongamento sobre o TRM, em mulheres ou associado ao dimorfismo sexual.
Influence of Muscle Stretching on Hand Reaction TimeIntroduction: Muscle stretching is a popular practice with the purpose of improving quality of life and performance in physical activities, although some scientific studies report negative effects related to mechanical and neural responses to the movement, which could directly interfere in variables such as hand reaction time (HRT). Since, speed and precision in this variable are fundamental in several activities of daily living, in some professions, and especially for performance in exercise.
Objective: This commentary aims to examine the state of the art on the effect of different techniques and volumes of muscle stretching on HRT and its consequences.
Conclusion: Literature suggests that stretching volume (≤ 30s), regardless of technique or intensity, is not able to interfere on HRT. On the other hand, it´s not possible to make a conclusive judgment on whether high stretching volume (> 30s) is able to compromise hand motor response. Additionally, other studies are imperative to evaluate the stretching effect on HRT for women, or its association to sexual dimorphism.
... Na literatura, existem relatos que mostram uma relação inversamente proporcional entre a força máxima e o alongamento prévio da musculatura solicitada, tanto quando realizado de maneira estática quanto dinâmica, em uma sessão de treinamento de força. Ou seja, o alongamento pode influenciar negativamente na capacidade de produção de força (ARRUDA et al., 2006;ENDLICH et al., 2009;FOWLES;SALE;MACDOUGALL, 2000;SERRA et al., 2013). ...
RESUMO O alongamento muscular é fundamental para manutenção ou melhora dos níveis de flexibilidade. Ao longo dos anos, com o efeito do envelhecimento, essa capacidade tende a ser prejudicada. A prática regular de exercícios físicos pode proporcionar uma redução desses prejuízos, assim como também beneficiar outras capacidades físicas, como a força muscular. Contudo, a união dessas duas capacidades, principalmente em uma mesma sessão de treino, é questionada na literatura, tendo em vista que o alongamento precedendo o treinamento de força pode oferecer prejuízos no rendimento. O objetivo desse estudo foi analisar a influência aguda dos alongamentos estáticos e dinâmicos sobre a produção de força muscular máxima de homens treinados. Participaram da pesquisa 12 indivíduos do sexo masculino, maiores de 18 anos e com experiência mínima de 6 meses em treinamento resistido. Todos os indivíduos foram submetidos a três condições: sem alongamento (AS), alongamento estático (AE) e alongamento dinâmico (AD). Posteriormente ao protocolo de alongamento, os indivíduos foram submetidos aos exercícios supino reto e leg press 45º para avaliar a força muscular máxima a partir do teste de 1 RM. O intervalo entre cada um dos protocolos de teste foi de 48 horas. Utilizou-se o teste ANOVA de medidas repetidas para comparar os protocolos. Não foi encontrada diferença estatística na carga média nas três situações, assim como na comparação de pares, baseada em médias estimadas de 1RM. Conclui-se que a prática prévia de alongamento estático, dinâmico, ou sem alongamento, não influem na produção de força máxima em adultos praticantes recreacionais de treinamento resistido. Palavras-chave: Alongamento estático. Alongamento dinâmico. Força máxima. ABSTRACT The muscle stretching is essential to maintaining or improving levels of flexibility. Over the years, with the effect of aging, that capacity, tends to be impaired. The regular practice of physical exercises can provide a reduction of these losses, as well as benefit from other physical capacities, as muscular strength. However, the Union of these two capacities, mostly in the same workout, is questioned in the literature, since the stretching preceding strength training can offer income losses. The aim of this study was to analyze the acute influence of dynamic and static stretching on the production of maximum muscle strength in trained men. Participated in the research, 12 male individuals, older than 18 years old, and with 6 months of minimum experience in resistance training. All individuals were exposed to three conditions: no stretching (NO), static stretching (SS) and dynamic stretching (DS). After the stretching protocol, individuals were subjected to exercises bench press and leg press 45° to evaluate maximum muscle strength from a 1 MR. The interval between each protocol test was 48 hours. We used the repeated measures ANOVA test to compare the protocols. No statistical difference was found in load average in three situations, as well as in the comparison of pairs, based on estimated average 1MR. It appears that the prior practice of dynamics, static, or the lack of stretching, do not influence the maximum force production in adult recreational practitioners of resistance training.
... A principal razão para aplicação de AE em rotinas pré-exercício é a suposta capacidade de aumentar temperatura, reduzir a viscosidade e os riscos de lesões musculares, contribuindo para melhorar o desempenho em atividades físicas (21). Entretanto, a literatura exibe estudos que indicam que o AE parece não reduzir os riscos de lesões musculares, além de provocar efeitos deletérios em curto e longo prazos sobre a força, modulação autonômica, pressão arterial e controle motor, afetando desempenho em exercício (22)(23)(24)(25)(26). ...
Introduction: Muscle stretching is a popular practice with the purpose of improving quality of life and performance in physical activities, although some scientific studies report negative effects related to mechanical and neural responses to the movement, which could directly interfere in variables such as hand reaction time (HRT). Since, speed and precision in this variable are fundamental in several activities of daily living, in some professions, and especially for performance in exercise. Objective: This commentary aims to examine the state of the art on the effect of different techniques and volumes of muscle stretching on HRT and its consequences. Conclusion: Literature suggests that stretching volume (≤ 30s), regardless of technique or intensity, is not able to interfere on HRT. On the other hand, it's not possible to make a conclusive judgment on whether high stretching volume (> 30s) is able to compromise hand motor response. Additionally, other studies are imperative to evaluate the stretching effect on HRT for women, or its association to sexual dimorphism.
... In the fi eld of exercise training, static stretching is the broadly applied stretching in warm-up. Although static stretching could relax muscles and enhance tendons and joint motion (Small, K et al., 2008), a lot of research found out the acute negative eff ects of static stretching on exercise performance and up to 24hr negative eff ects on power and speed (Haddad et al., 2014) , the decrease in 1mile endurance run performance and the extension of time for ground contact during running (Lowery et al., 2014), the reduction of noncontractile resistance of muscles and tendons (Nakamura et al., 2013), as well as the signifi cant reduction of muscle strength performance (Serra et al., 2013). Beckett et al. (2009) discovered that static stretching showed less eff ects on directional motion, but would remarkably aff ect straight dash. ...
... Active static stretching was carried out to induce mild discomfort in the following muscle groups: biceps, trapezius, latissimus dorsi, pectoralis, paraspinal, hamstrings, and quadriceps. Each stretching exercise was performed for three times of 30 s with a 30-s rest between each stretching, which shows to be a common rest interval for stretching exercises [10]. The TMJ exercises were performed as previously reported in details [6]. ...
This study evaluated the role of the phototherapy and exercise training (EXT) as well as the combined treatment in general symptoms, pain, and quality of life in women suffering from fibromyalgia (FM). A total of 160 women were enrolled and measures were carried out in two sets: it was sought to identify the acute effect for a single phototherapy and EXT session (Set 1); long-term effect (10 weeks) of the interventions (Set 2). Phototherapy irradiation was performed at 11 locations in their bodies, employing a cluster with nine diodes (one super-pulsed infrared 905 nm, four light-emitting diodes [LEDs] of 640 nm, and four LEDs of 875 nm, 39.3 J per location). Algometry and VAS instrument were applied to evaluate pain. The FM symptoms were evaluated with Fibromyalgia Impact Questionnaire (FIQ) and Research Diagnostic Criteria (RDC) instruments. Quality of life was assessed through SF-36 survey. Set 1: pain threshold was improved with the phototherapy, and EXT improved the pain threshold for temporomandibular joint (right and left body side) and occipital site (right body side). Set 2: there was improved pain threshold in several tender points with the phototherapy and EXT. There was an overlap of therapies to reduce the tender point numbers, anxiety, depression, fatigue, sleep, and difficulty sleeping on FIQ/RDC scores. Moreover, quality of life was improved with both therapies. The phototherapy and EXT improved the pain threshold in FM women. A more substantial effect was noticed for the combined therapy, in which pain relief was accomplished by improving VAS and FIQ scores as well as quality of life.
... Scharmann et al., 5 investigaram os efeitos do aquecimento no teste de 1RM no leg press e supino e não verificaram aumento na produção de força, entretanto estudo de Barroso et al., 6 observou que o aquecimento geral de longa duração e baixa intensidade resultou em melhora no desempenho durante o teste de 1RM. Em outro estudo, Serra et al., 7 avaliou o efeito de alongamento estático na força máxima em diferente exercícios em indivíduos treinados e destreinados demonstrando que o alongamento promoveu efeito negativo de 17% na força máxima membros superiores e 8% em membros inferiores. Ainda demonstraram que indivíduos destreinados apresentaram os menores valores de força máxima em relação aos treinados. ...
Introduction: Although the warm-up is considered essential for sports, little is known about its effect on strength training. Objective: To evaluate the effect of different warm-up strategies in neuromuscular performance in young adults undergoing maximum repetitions of upper and lower limb exercises. Methods: Two experiments were conducted separately. For the first experiment, 16 healthy young adults performed a test of maximal repetitions at 70% 1RM in the bench press (previously determined). Four warm-up conditions were tested: control (CON) without prior warm-up, 5 min on the treadmill at 60% VO2max(EST), strength endurance (REF) with 1 set x 15 repetitions with 40% 1RM and maximal strength (MS) with two sets of two reps with 90% 1RM. For the second experiment, 14 healthy young adults performed a maximal number of repetitions at 70% 1RM in the unilateral leg press (previously determined). Five warm-up conditions were tested: control (CON) without prior warm-up, 5 min of cycling at 60% VO2max(BIC), 5 min on the treadmill to 60% VO2max(EST), strength endurance (REF) with 1 set vs. 15 repetitions with 40% 1RM and maximal strength (MS) with two sets of two reps with 90% 1RM. For both experiments the number of repetitions performed and perceived exertion were evaluated. Results: For the first experiment, the MS condition was superior when compared to other protocols. No differences between the other conditions were observed. For the second experiment differences between all protocols were observed, except CON and EST, being MS> BIC> REF> = CON. Conclusion: The results of this study suggest that a warming-up of maximum strength may produce higher force production for the upper and lower limbs. Additionally, aerobic and strength resistance warm-up showed an improvement in strength performance for the lower limbs in a smaller magnitude.
... Scharmann et al., 5 investigaram os efeitos do aquecimento no teste de 1RM no leg press e supino e não verificaram aumento na produção de força, entretanto estudo de Barroso et al., 6 observou que o aquecimento geral de longa duração e baixa intensidade resultou em melhora no desempenho durante o teste de 1RM. Em outro estudo, Serra et al., 7 avaliou o efeito de alongamento estático na força máxima em diferente exercícios em indivíduos treinados e destreinados demonstrando que o alongamento promoveu efeito negativo de 17% na força máxima membros superiores e 8% em membros inferiores. Ainda demonstraram que indivíduos destreinados apresentaram os menores valores de força máxima em relação aos treinados. ...
Introdução:
Apesar do aquecimento ser considerado essencial na prática dos esportes, pouco se conhece sobre seu efeito no treinamento de força.
Objetivo:
Avaliar o efeito de diferentes estratégias de aquecimento no desempenho neuromuscular em adultos jovens submetidos a testes de repetições máximas de membro superior e inferior.
Métodos:
Dois experimentos foram realizados separadamente. Para o primeiro experimento, 16 adultos jovens hígidos realizaram um teste de repetições máximas a 70% de 1RM no supino reto (previamente determinado). Quatro condições de aquecimento foram testadas: Controle (CON) sem aquecimento prévio, esteira (EST) 5' a 60% VO2max, resistência de força (REF) 15 repetições com 40% de 1RM e força máxima (FM) duas séries de duas repetições com 90% de 1RM. Para o segundo experimento, 14 adultos jovens hígidos, realizaram um teste de repetições máximas a 70% de 1RM no leg press unilateral (previamente determinado). Cinco condições de aquecimento foram testadas: controle (CON) sem aquecimento prévio, esteira (EST) 5' a 60% VO2max, bicicleta (BIC) 5' a 60% VO2max, resistência de força (REF) 15 repetições com 40% de 1RM e força máxima (FM) duas séries de duas repetições com 90% de 1RM. Para ambos os experimentos o número de repetições realizadas e a percepção subjetiva de esforço foram avaliadas.
Resultados:
Para o primeiro experimento o protocolo FM foi superior a todos os outros protocolos. Não foram observadas diferenças entre as outras condições. Para o segundo experimento, foi observado diferenças entre todos os protocolos, exceto CON e EST. Sendo FM>BIC>REF>EST=CON.
Conclusão:
Os resultados do presente estudo sugerem que um aquecimento de força máxima levou a uma maior produção de força para os membros superiores e inferiores. Adicionalmente, aquecimentos aeróbios e de resistência de força apresentaram melhora no desempenho de força para os membros inferiores em uma menor magnitude.
It was our objective to verify the time course of muscle thickness and cytokine concentration after a resistance training session. In one of the experimental conditions, the training session was performed with low load (20% 1RM) and restriction of blood flow. In the other experimental condition, the same training was performed with high load (80% 1RM) and without blood flow restriction. Femoral rectus muscle, vastus lateralis, brachial biceps and triceps brachii muscle thickness and the serum cytokine dosage were analyzed pré, 0h, 24h and 48h after the training sessions. For the upper and lower limbs, the main results showed significant (p< 0.05) effect on time for the thickness in all muscle but not (p> 0.05) to experimental condition. To cytokines concentrations, a significant (p= 0.004) interaction between the time and conduction for IL10. Conversely, there was no difference between the weeks (p= 0.698) or time (p= 0.142) in the means of TNF. In conclusion both experimental conductions promoted similar changes on muscular swelling without alterations on TNFα, however, the RST protocol induced increase on IL-10 concentration after 24 hours of exercise session.
It was our objective to verify the time course of muscle thickness and cytokine concentration after a resistance training session. In one of the experimental conditions, the training session was performed with low load (20% 1RM) and restriction of blood flow. In the other experimental condition, the same training was performed with high load (80% 1RM) and without blood flow restriction. Femoral rectus muscle, vastus lateralis, brachial biceps and triceps brachii muscle thickness and the serum cytokine dosage were analyzed pré, 0h, 24h and 48h after the training sessions. For the upper and lower limbs, the main results showed significant (p< 0.05) effect on time for the thickness in all muscle but not (p> 0.05) to experimental condition. To cytokines concentrations, a significant (p= 0.004) interaction between the time and conduction for IL10. Conversely, there was no difference between the weeks (p= 0.698) or time (p= 0.142) in the means of TNF. In conclusion both experimental conductions promoted similar changes on muscular swelling without alterations on TNFα, however, the RST protocol induced increase on IL-10 concentration after 24 hours of exercise session.
Historial do artigo: O presente artigo expressa uma opinião fundamentada em evidência e lógica. Foi elaborado e registado em 2013 e lançado a público no âmbito de ações de formação em várias certificações em exercício organizadas pelo autor, fazendo parte da documentação de apoio entregue aos alunos. As duas seguintes revisões (2016 e 2017) tiveram como revisor o Professor José Vilaça-Alves, onde se acrescentaram algumas secções de texto e a pesquisa científica atualizada. A versão de 2017 foi apresentada a público no 1o Congresso Internacional Exercise Summit (Oeiras, Portugal, Maio de 2017). A presente versão (2018), já tendo como revisor o Professor José Afonso Neves, é a última versão revista pelo autor, com a expansão das últimas secções, que se referem às verdadeiras causas da falta de flexibilidade e aos métodos mais vantajosos para a sua melhoria.
Problema: A capacidade motora designada de flexibilidade é uma componente importante do movimento humano e, consequentemente, do fitness físico. Contudo, a forma de desenvolvimento desta capacidade não tem sido consensual, principalmente no que respeita às causas da sua pouca expressividade. Habitualmente, esta tem sido atribuída à falta de extensibilidade muscular antagonista e não às possíveis debilidades na capacidade de coordenação entre a musculatura agonista, antagonista e sinergista do movimento, que confere o arco articular analisado. Desta forma, a utilidade do alongamento do tipo passivo estático, aplicado à musculatura antagonista, com o propósito do aumento da amplitude do movimento articular (entre outros objetivos), embora seja a intervenção mais utilizada, tem sido colocada em causa. Assim, o objetivo do presente artigo foi efetuar uma reflexão crítica sobre esta problemática, tendo como base o raciocínio lógico e a revisão da literatura científica. Será dado enfâse aos efeitos do treino da flexibilidade em diversos domínios: nos níveis de força, na prevenção de lesões, no desempenho desportivo e na estrutura e função muscular. Será, igualmente, efetuada uma reflexão sobre o efeito das diferentes técnicas de treino da flexibilidade, tais como a facilitação neuromuscular propriocetiva (PNF) e o alongamento dinâmico. Serão abordados os efeitos do treino com resistências na flexibilidade e na capacidade de produzir força.
Recursos bibliográficos: Para o efeito, foram utilizados manuais de referência em fisiologia humana (p.e. Joint Structure and Function; Principles of Neural Science), bem como da área da prescrição de exercício, e revistos cerca de 100 artigos científicos (dos quais 34 são revisões), que relacionam alongamento e/ou treino com resistências com as capacidades motoras flexibilidade e força, no desempenho desportivo, na prevenção ou incidência de lesão, na estrutura e na função neural muscular. Os estudos usados apresentam probabilidade de erro inferior a 5%, mas nem todos reportam as magnitudes dos efeitos observados (i.e., effect sizes).
Conclusões: Tendo como base a revisão da literatura científica consultada e a reflexão lógica efetuada sobre a mesma, concluímos que, à luz dos conhecimentos presentes, o alongamento do tipo passivo estático pode não ser útil na obtenção de flexibilidade ativa (funcional) e, mesmo que o seja, comportará uma diminuição dos níveis de força muscular – à custa de alterações estruturais e neurais negativas. O aumento da extensibilidade muscular – e o consequente incremento de amplitude articular –, que é verificado com o treino de alongamento, é maioritariamente causado por inibição neural aferente e eferente. São verificadas alterações nas propriedades estruturais musculares, tais como a viscoelasticidade ou o comprimento, que, apesar de contribuírem também para o acréscimo de amplitude articular, são de menor relevância que os efeitos neurais. Efeitos estes que detêm um potencial negativo nos níveis de força. O alongamento pode ter um efeito negativo no desempenho desportivo, não previne lesões e os aumentos de flexibilidade que gera, passivos apenas, não se transferem necessariamente para a amplitude funcional. O treino com resistências pode melhorar a flexibilidade ativa, mesmo com o uso de contrações musculares isométricas, além de gerar ganhos superiores nos níveis de força quando comparado com o treino de alongamento. A combinação de ambos os tipos de treino – com resistências e alongamento na mesma sessão – não é relevante o suficiente para que se considere um método superior a sessões apenas com treino com resistências. As diretrizes do ACSM, no que concerne ao treino da flexibilidade, são incoerentes e não deverão ser seguidas. Além de não cumprirem com os pressupostos que propõem, representam um investimento temporal que melhor poderia ser aplicado com outras atividades.
Aplicações práticas: Por definição e bom uso da língua portuguesa, o termo flexibilidade deverá ser substituído por melhor termo, um que expresse realmente a qualidade física que se manifesta em amplitude de movimento articular. O termo mais correto será mobilidade. É sugerida uma origem alternativa para a sua diminuída expressão, nomeadamente a falta de controlo da musculatura agonista. O autor defende o treino com resistências como método superior ao alongamento, no treino da mobilidade ativa, ganhos de força e prevenção de lesões. O cumprimento das diretrizes tradicionais de prescrição do treino com resistências, tal como apresentadas pelo ACSM, apresenta-se como suficiente para tal efeito. Contudo, recomendações mais concisas e menos generalistas são aqui descritas, ainda que sejam necessárias mais pesquisas para clarificar os parâmetros ideais (se é que existem) de construção dos exercícios para o objetivo pretendido.
O presente artigo expressa uma opinião fundamentada, com recurso a dados científicos e à lógica. Foi elaborado e registado em 2013 e lançado a público no âmbito da Formação Contínua da EXS – Exercise School, fazendo parte da documentação de apoio entregue aos alunos. Entretanto foi revisto em 2016, conjuntamente com o Professor José Vilaça-Alves, e novamente em 2017, onde se acrescentou algumas secções de texto e a pesquisa científica atualizada. Problema: A capacidade motora designada de flexibilidade é uma componente importante do movimento humano e consequentemente do fitness físico. Contudo, a forma de desenvolvimento desta capacidade não tem sido consensual, principalmente no que respeita às causas da sua pouca expressividade. Habitualmente, esta tem sido atribuída à falta de extensibilidade muscular antagonista e não às possíveis debilidades na capacidade de coordenação entre a musculatura agonista, antagonista e sinergista do movimento que confere o arco articular analisado. Desta forma, a utilidade do alongamento do tipo passivo estático, aplicado à musculatura antagonista, com o objetivo do aumento da amplitude do movimento articular (entre outros objetivos), embora seja a intervenção mais utilizada, tem sido colocada em causa. Assim, o objetivo do presente artigo foi efetuar uma reflexão crítica sobre esta problemática tendo como base o raciocínio lógico e a revisão da literatura científica. Será dado enfâse aos efeitos do treino da flexibilidade: nos níveis de força, na prevenção de lesões, no desempenho desportivo e na estrutura e função muscular. Será, igualmente, efetuado uma reflexão sobre o efeito das diferentes técnicas de treino da flexibilidade, tais como a facilitação neuromuscular proprioceptiva (PNF) e a dinâmica. Serão abordados os efeitos do treino com resistências na flexibilidade e na capacidade de produzir força. Recursos bibliográficos: Para o efeito foram utilizados manuais de referência na área da prescrição de exercício e revistos cerca de 60 artigos científicos, entre eles 9 revisões sistemáticas, que relacionam alongamento e/ou treino com resistências com as capacidades motoras flexibilidade e força, no desempenho desportivo, na prevenção ou incidência de lesão, na estrutura e na função neural muscular. Os estudos usados apresentam probabilidade de erro inferior a 5%. Conclusões: Tendo como base a revisão da literatura científica consultada e a reflexão lógica efetuada sobre a mesma, concluímos que o alongamento do tipo passivo estático pode não ser útil na obtenção de flexibilidade ativa (funcional), e mesmo que seja, comportará sempre uma diminuição dos níveis de força muscular – à custa de alterações estruturais e neurais negativas. O aumento da extensibilidade muscular, e o consequente incremento de amplitude articular, que é verificado com o treino de alongamento, é maioritariamente causado por inibição neural aferente e eferente. São verificadas alterações nas propriedades estruturais musculares, tais como a viscoelasticidade ou o comprimento, que apesar de contribuírem também para o acréscimo de amplitude articular (em menor relevância que os efeitos neurais), também detêm potencial negativo nos níveis de força. O alongamento pode ter um efeito negativo no desempenho desportivo, não previne lesões e os aumento de flexibilidade que gera, passivos apenas, não transferem para a amplitude funcional. O treino com resistências pode melhorar a flexibilidade ativa, mesmo com o uso de contrações musculares isométricas, e permite ganhos superiores nos níveis de força quando comparado com o treino de alongamento. A combinação de ambos os tipos de treino – com resistências e alongamento na mesma sessão – não é relevante o suficiente para que se considere um método superior a sessões apenas com treino com resistências. As diretrizes do ACSM, no que concerne ao treino da flexibilidade, são incoerentes e não deverão ser seguidas. Aplicações práticas: Por definição e bom uso da língua portuguesa, o termo flexibilidade deverá ser substituído por melhor termo, um que expresse realmente a qualidade física que se manifesta em amplitude de movimento articular. O termo correto deverá ser mobilidade. É sugerida uma origem alternativa para a sua diminuída expressão, nomeadamente a falta de controlo da musculatura agonista. O autor defende o treino com resistências como método superior ao alongamento, no treino da mobilidade ativa, ganhos de força e prevenção de lesões. O cumprimento das diretrizes tradicionais de prescrição do treino com resistências, tal como apresentadas pelo ACSM, apresenta-se como suficientes para tal efeito. Contudo, recomendações mais concisas e menos generalistas são aqui descritas, ainda que seja necessário mais pesquisas para clarificar os parâmetros ideais de construção dos exercícios para o objetivo pretendido.
The incidence of low back pain in construction workers is consistently reported as being higher than in all other industries. This summary of an extensive review explores the following: mechanisms, epidemiology, prevention and management, suggested workplace interventions, and possible future directions.
BACKGROUND: Muscular stretching is frequently used in sports practice with the aim to increase muscular flexibility and joint range of motion as well as to reduce injury risks and to improve athletic performance. AIM: To analyze the acute effect of stretching with different times in the dynamic strength performance of lower and upper extremities in young men. METHODS: The sample was composed by 14 healthy male volunteers aged 23 ± 2 years, weight of 84 ± 10 Kg , height of 178 ± 7 cm, BMI of 26 ± 2 Kg/m2 and body fat of 11 ± 3 %. They were evaluated in a 10-maximum repetition test (10-RM) in three situations: no stretching (NS); after an 8-minute session of static stretching followed by specific warm-up (SS-8); and after 16-minute and specific warm-up before 10 RM test (SS-16). Tests were performed in bench press and 45º leg press exercises, and stretching was selected as to reach the musculature required in these exercises. RESULTS: There was significant reduction (p<0.001) of dynamic muscular strength of upper extremities in comparison to NS with SS-16 (9.2%) and between SS-8 (4.2%) and SS-16 (14.3%) to lower extremities. This difference was found in all tested conditions. CONCLUSION: Static stretching sessions before activities involving dynamic strength are able to negatively change performance in longer stretching periods.
Stretching exercises are commonly prescribed before training sessions and competitions aiming at performance improvement and reduction of injury risk. However, many studies have shown that muscular torque production capacity may be reduced just after stretching. Therefore, the stretching duration necessary to produce these acute force deficits, as well as the physiological mechanisms responsible for them are relevant issues. The aim of this work was to investigate the acute effects of static stretching protocols with different durations on the isokinetic hamstrings performance. Thirty-six young male volunteers took part in this study and were evenly distributed in three groups: E1, E2 and C. All of them performed a systemic warm-up for five minutes and went through active range of motion (AROM) of hip flexion and isokinetic assessment. The participants of groups E1 and E2 performed static stretching protocols of 180s (4 x 45s) and 360s (8 x 45s) respectively, and were evaluated again. The participants of group C (control) remained at rest for a period of 270s and were evaluated again. The variables considered were AROM, peak torque, maximum work and total work. Both stretching protocols were able to produce increase in AROM; however, only the longest protocol produced deficits on peak torque and maximum work. Total work was not affected by any of the stretching protocols, though. Therefore, these results suggest that changes in muscular stiffness, that caused AROM gain, would not be responsible alone for the force deficits. Moreover, one can conclude that the maximum muscular strength depends on the stretching duration, but the muscular work along some repetitions of an exercise does not.
INTRODUÇÃO: O alongamento muscular é frequentemente utilizado nas práticas desportivas, com o objetivo de aumentar a flexibilidade muscular e amplitude articular, assim como diminuir o risco de lesões e melhorar o desempenho atlético. OBJETIVO: Analisar o efeito agudo do alongamento com diferentes tempos no desempenho da força dinâmica de membros superiores e inferiores em homens jovens. MÉTODOS: Participaram da amostra 14 voluntários do sexo masculino com idade de 23 ± 2 anos, peso corporal de 84 ± 10kg, estatura de178 ± 7cm, IMC de 26 ± 2kg/m2 e percentual de gordura de 11 ± 3%. Eles foram avaliados com o teste de 10RM em três situações distintas: condição sem alongamento (SA), aquecimento especifico seguido do teste de 10-RM; condição com oito minutos de alongamento (AL-8), uma sessão de alongamento estático com oito minutos de duração, seguido do aquecimento e teste de 10RM; e a condição alongamento 16 minutos (AL-16), 16 minutos de alongamento seguidos dos procedimentos descritos anteriormente. Os testes foram feitos no supino reto e leg-press 45º; os alongamentos foram selecionados de forma a atingir as musculaturas solicitadas nos respectivos exercícios. RESULTADOS: Houve redução de 9,2% da força muscular dinâmica de membros superiores em comparação dos grupos SA e AL16, e entre os grupos AL8 e AL16 (p < 0,001). Em membros inferiores essa redução de força (p < 0,001) foi de 4,8% para AL-8 e de 14,3% para AL-16 em comparação com o grupo SA. CONCLUSÃO: Sessões de alongamentos estáticos efetuados antes de atividades que envolvam força dinâmica possuem a capacidade de alterar negativamente o desempenho dessa qualidade física, acarretando pior rendimento em longos períodos de alongamento.
Stretching exercises have been traditionally incorporated into warm-up routines before training sessions and sport events. However, the effects of stretching on maximal strength and strength endurance performance seem to depend on the type of stretching employed. The objective of this study was to compare the effects of static stretching (SS), ballistic stretching (BS), and proprioceptive neuromuscular facilitation (PNF) stretching on maximal strength, number of repetitions at a submaximal load, and total volume (i.e., number of repetitions × external load) in a multiple-set resistance training bout. Twelve strength-trained men (20.4 ± 4.5 years, 67.9 ± 6.3 kg, 173.3 ± 8.5 cm) volunteered to participate in this study. All of the subjects completed 8 experimental sessions. Four experimental sessions were designed to test maximal strength in the leg press (i.e., 1 repetition maximum [1RM]) after each stretching condition (SS, BS, PNF, or no-stretching [NS]). During the other 4 sessions, the number of repetitions performed at 80% 1RM was assessed after each stretching condition. All of the stretching protocols significantly improved the range of motion in the sit-and-reach test when compared with NS. Further, PNF induced greater changes in the sit-and-reach test than BS did (4.7 ± 1.6, 2.9 ± 1.5, and 1.9 ± 1.4 cm for PNF, SS, and BS, respectively). Leg press 1RM values were decreased only after the PNF condition (5.5%, p < 0.001). All the stretching protocols significantly reduced the number of repetitions (SS: 20.8%, p < 0.001; BS: 17.8%, p = 0.01; PNF: 22.7%, p < 0.001) and total volume (SS: 20.4%, p < 0.001; BS: 17.9%, p = 0.01; PNF: 22.4%, p < 0.001) when compared with NS. The results from this study suggest that, to avoid a decrease in both the number of repetitions and total volume, stretching exercises should not be performed before a resistance training session. Additionally, strength-trained individuals may experience reduced maximal dynamic strength after PNF stretching.
The purpose of the study was to investigate the acute effects of stretching exercises on maximal strength performance. Eleven subjects were submitted to a one repetition maximum test (1 RM) under two experimental conditions: 1) preceded by stretching exercises (WS) and 2) without stretching exercises (NS). In condition WS, subjects performed a static stretching exercises session for the lower limbs for approximately 20 minutes. A total of six exercises were done with three repetitions of 30 seconds in each exercise. At the end of the stretching session all subjects were tested. In condition NS the subjects were tested right after the warm up session. The test consisted in the complete execution of a knee extension/flexion movement on the leg-press machine. The testing loads were incremented by 4%, 3%, and 3% from a lifted amount of weighi during a familiarization session. A 3-minute interval was given between each maximum effort. In condition WS the average result on the 1 RM test (391.7 kg ± 86.5) was significantly lower (p < 0.05) than the average obtained in the condition NS (405.5 kg ± 89.1). We conclude that, independently of the mechanism involved, a single session of stretching exercises performed immediately before a physical activity may impair maximal strength performance.
Static stretching (SS) is widely used in warm-ups before training and competition. A growing amount of research, however, has demonstrated that SS can impair muscle performance, leading to a reevaluation of optimal warm-up protocols. This commentary discusses many of the methodological issues that can influence conclusions about the acute effects of SS on performance. One difficulty in interpreting the literature is the lack of control or communication about the volume and intensity of the various stretching treatments used. Another major issue is the failure of many researchers to evaluate SS as it is used in practice, particularly the interaction with the other general and sport-specific components of the warm-up. Acute warm-up effects on performance should be considered in conjunction with potential effects on injury prevention. Future directions in research include optimizing general and sport-specific warm-ups, time course of physiological and performance effects, and individualization of warm-ups according to fitness and skill level.
Sixteen experienced male powerlifters served as subjects in a training study designed to examine the effect of flexibility training on: (i) the stiffness of the series elastic components (SEC) of the upper body musculature and (ii) rebound and purely concentric bench press performance. Nine of the subjects participated in two sessions of flexibility training twice per week for 8 wk. Prior to and after the training period the subjects' static flexibility, SEC stiffness, rebound bench press (RBP), and purely concentric bench press (PCBP) performance were recorded. The flexibility training induced a significant reduction in the maximal stiffness of the SEC. Furthermore, the experimental subjects produced significantly more work during the initial concentric portion of the RBP lift, enabling a significantly greater load to be lifted in the post-training testing occasion. The benefits to performance achieved by the experimental group consequent to flexibility training were greater during the RBP lift as compared with the PCBP lift. The control subjects exhibited no change in any variable over the training period. These results implied that the RBP performance enhancement observed consequent to flexibility training was directly caused by a reduction in SEC stiffness, increasing the utilization of elastic strain energy during the RBP lift.
The purpose of this study was to assess strength performance after an acute bout of maximally tolerable passive stretch (PS(max)) in human subjects. Ten young adults (6 men and 4 women) underwent 30 min of cyclical PS(max) (13 stretches of 135 s each over 33 min) and a similar control period (Con) of no stretch of the ankle plantarflexors. Measures of isometric strength (maximal voluntary contraction), with twitch interpolation and electromyography, and twitch characteristics were assessed before (Pre), immediately after (Post), and at 5, 15, 30, 45, and 60 min after PS(max) or Con. Compared with Pre, maximal voluntary contraction was decreased at Post (28%) and at 5 (21%), 15 (13%), 30 (12%), 45 (10%), and 60 (9%) min after PS(max) (P < 0.05). Motor unit activation and electromyogram were significantly depressed after PS(max) but had recovered by 15 min. An additional testing trial confirmed that the torque-joint angle relation may have been temporarily altered, but at Post only. These data indicate that prolonged stretching of a single muscle decreases voluntary strength for up to 1 h after the stretch as a result of impaired activation and contractile force in the early phase of deficit and by impaired contractile force throughout the entire period of deficit.
The purpose of this study was to examine the effects of static stretching on concentric, isokinetic leg extension peak torque (PT) at 60 and 240 degrees.s(-1) in the stretched and unstretched limbs. The PT of the dominant (stretched) and nondominant (unstretched) leg extensors were measured on a calibrated Cybex 6000 dynamometer. Following the prestretching PT assessments, the dominant leg extensors were stretched using 1 active and 3 passive stretching exercises. After the stretching, PT was reassessed. The results of the statistical analyses indicated that PT decreased following the static stretching in both limbs and at both velocities (60 and 240 degrees.s(-1)). The present findings suggested that the stretching-induced decreases in PT may be related to changes in the mechanical properties of the muscle, such as an altered length-tension relationship, or a central nervous system inhibitory mechanism. Overall, these findings, in conjunction with previous studies, indicated that static stretching impairs maximal force production. Strength and conditioning professionals should consider this before incorporating static stretching in preperformance activities. Future studies are needed to identify the underlying mechanisms that influence the time course of stretching-induced decreases in maximal force production for athletes and nonathletes across the age span.
It is generally accepted that increasing the flexibility of a muscle-tendon unit promotes better performances and decreases the number of injuries. Stretching exercises are regularly included in warm-up and cooling-down exercises; however, contradictory findings have been reported in the literature. Several authors have suggested that stretching has a beneficial effect on injury prevention. In contrast, clinical evidence suggesting that stretching before exercise does not prevent injuries has also been reported. Apparently, no scientifically based prescription for stretching exercises exists and no conclusive statements can be made about the relationship of stretching and athletic injuries. Stretching recommendations are clouded by misconceptions and conflicting research reports. We believe that part of these contradictions can be explained by considering the type of sports activity in which an individual is participating. Sports involving bouncing and jumping activities with a high intensity of stretch-shortening cycles (SSCs) [e.g. soccer and football] require a muscle-tendon unit that is compliant enough to store and release the high amount of elastic energy that benefits performance in such sports. If the participants of these sports have an insufficient compliant muscle-tendon unit, the demands in energy absorption and release may rapidly exceed the capacity of the muscle-tendon unit. This may lead to an increased risk for injury of this structure. Consequently, the rationale for injury prevention in these sports is to increase the compliance of the muscle-tendon unit. Recent studies have shown that stretching programmes can significantly influence the viscosity of the tendon and make it significantly more compliant, and when a sport demands SSCs of high intensity, stretching may be important for injury prevention. This conjecture is in agreement with the available scientific clinical evidence from these types of sports activities. In contrast, when the type of sports activity contains low-intensity, or limited SSCs (e.g. jogging, cycling and swimming) there is no need for a very compliant muscle-tendon unit since most of its power generation is a consequence of active (contractile) muscle work that needs to be directly transferred (by the tendon) to the articular system to generate motion. Therefore, stretching (and thus making the tendon more compliant) may not be advantageous. This conjecture is supported by the literature, where strong evidence exists that stretching has no beneficial effect on injury prevention in these sports. If this point of view is used when examining research findings concerning stretching and injuries, the reasons for the contrasting findings in the literature are in many instances resolved.
The purpose of the study was to investigate the effect of an acute bout of lower limb static stretching on balance, proprioception, reaction, and movement time.
Sixteen subjects were tested before and after both a static stretching of the quadriceps, hamstrings, and plantar flexors or a similar duration control condition. The stretching protocol involved a 5-min cycle warm-up followed by three stretches to the point of discomfort of 45 s each with 15-s rest periods for each muscle group. Measurements included maximal voluntary isometric contraction (MVC) force of the leg extensors, static balance using a computerized wobble board, reaction and movement time of the dominant lower limb, and the ability to match 30% and 50% MVC forces with and without visual feedback.
There were no significant differences in the decrease in MVC between the stretch and control conditions or in the ability to match submaximal forces. However, there was a significant (P < 0.009) decrease in balance scores with the stretch (decreasing 9.2%) compared with the control (increasing 17.3%) condition. Similarly, decreases in reaction (5.8%) and movement (5.7%) time with the control condition differed significantly (P < 0.01) from the stretch-induced increases of 4.0% and 1.9%, respectively.
In conclusion, it appears that an acute bout of stretching impaired the warm-up effect achieved under control conditions with balance and reaction/movement time.
Strength and flexibility are common components of exercise programmes; however, it is not clear how best to include both of these elements in a single training programme. It is common practice among athletes, coaches and recreational exercisers to perform a stretching routine before a strength training session. Stretching exercises are regularly recommended, even in many textbooks, with the claimed purpose of preventing injury and muscle soreness, or even enhancing performance. However, as highlighted in recent review articles, this recommendation lacks scientific evidence. Thus, the purpose of the present review is to determine the acute and chronic effects of stretching on strength performance, together with the underlying mechanisms. Although most studies have found acute decreases in strength following stretching, and that such decreases seem to be more prominent the longer the stretching protocol, the number of exercises and sets, and the duration of each set have, in general, exceeded the ranges normally recommended in the literature. Consequently, the duration of the stimuli were excessively long compared with common practice, thus making evident the need for further studies. In addition, when recommending flexibility exercises, one should consider other underlying issues, such as the safety of the participants, possible increases in injury risks and the unnecessary time expenditure. Many mechanisms underlying stretching exercises still demand investigation so that links between the observed effects, their causes and the consequences may be constructed.
Objective: To evaluate the clinical and basic science evidence surrounding the hypothesis that stretching immediately before exercise prevents injury. Data Sources and Selection: MEDLINE was searched using MEDLINE subject headings (MeSH) and textwords for English- and French-language articles related to stretching and muscle injury. Additional references were reviewed from the bibliographies, and from citation searches on key articles. All articles related to stretching and injury or pathophysiology of muscle injury were reviewed. Clinical articles without a control group were excluded. Results: Three (all prospective) of the four clinical articles that suggested stretching was beneficial included a cointervention of warm-up. The fourth study (cross-sectional) found stretching was associated with less groin/buttock problems in cyclists, but only in women. There were five studies suggesting no difference in injury rates between stretchers and nonstretchers (3 prospective, 2 cross-sectional) and three suggesting stretching was detrimental (all cross-sectional). The review of the basic science literature suggested five reasons why stretching before exercise would not prevent injuries. First, in animals, immobilization or heating-induced increases in muscle compliance cause tissues to rupture more easily. Second, stretching before exercise should have no effect for activities in which excessive muscle length is not an issue (e.g., jogging). Third, stretching won't affect muscle compliance during eccentric activity, when most strains are believed to occur. Fourth, stretching can produce damage at the cytoskeleton level. Fifth, stretching appears to mask muscle pain in humans. Conclusion: The basic science literature supports the epidemiologic evidence that stretching before exercise does not reduce the risk of injury.
It is generally accepted that increasing the flexibility of a muscle-tendon unit promotes better performances and decreases the number of injuries. Stretching exercises are regularly included in warm-up and cooling-down exercises; however, contradictory findings have been reported in the literature. Several authors have suggested that stretching has a beneficial effect on injury prevention. In contrast, clinical evidence suggesting that stretching before exercise does not prevent injuries has also been reported. Apparently, no scientifically based prescription for stretching exercises exists and no conclusive statements can be made about the relationship of stretching and athletic injuries. Stretching recommendations are clouded by misconceptions and conflicting research reports. We believe that part of these contradictions can be explained by considering the type of sports activity in which an individual is participating. Sports involving bouncing and jumping activities with a high intensity of stretch-shortening cycles (SSCs) [e.g. soccer and football] require a muscle-tendon unit that is compliant enough to store and release the high amount of elastic energy that benefits performance in such sports. If the participants of these sports have an insufficient compliant muscle-tendon unit, the demands in energy absorption and release may rapidly exceed the capacity of the muscle-tendon unit. This may lead to an increased risk for injury of this structure. Consequently, the rationale for injury prevention in these sports is to increase the compliance of the muscle-tendon unit.
Recent studies have shown that stretching programmes can significantly influence the viscosity of the tendon and make it significantly more compliant, and when a sport demands SSCs of high intensity, stretching may be important for injury prevention. This conjecture is in agreement with the available scientific clinical evidence from these types of sports activities. In contrast, when the type of sports activity contains low-intensity, or limited SSCs (e.g. jogging, cycling and swimming) there is no need for a very compliant muscle-tendon unit since most of its power generation is a consequence of active (contractile) muscle work that needs to be directly transferred (by the tendon) to the articular system to generate motion. Therefore, stretching (and thus making the tendon more compliant) may not be advantageous. This conjecture is supported by the literature, where strong evidence exists that stretching has no beneficial effect on injury prevention in these sports. If this point of view is used when examining research findings concerning stretching and injuries, the reasons for the contrasting findings in the literature are in many instances resolved.
This study was undertaken to investigate and compare the effects of proprioceptive neuromuscular facilitation (PNF) stretching and static stretching on maximal voluntary contraction (MVC). Thirteen male university students (age, 20 ± 1 years; height, 172.2 ± 4.6 cm; weight, 68.4 ± 6.7 kg; mean ± SD) completed three different conditions on three non-consecutive days in randomized order: static stretching (SS), PNF stretching (PNF), and no stretching (control, CON). Each condition consisted of a 5-minute rest accompanied by one of the following activities: (a) control, (b) static stretching, or (c) PNF stretching. The hip flexion range of motion (ROM) was evaluated immediately before and after the activity. The MVC of knee flexion was then measured. Surface electromyography was recorded from the biceps femoris and vastus lateralis muscles during MVC tests and stretching. Although increases in ROM were significantly greater after PNF than after SS (P < 0.01), the decreases in MVC were similar between the two treatments. These results suggest that, although PNF stretching increases ROM more than static stretching, PNF stretching as well as static stretching is detrimental to isometric maximal strength.
Experiments were carried out to test the effect of prolonged and repeated passive stretching (RPS) of the triceps surae muscle on reflex sensitivity. The results demonstrated a clear deterioration of muscle function immediately after RPS. Maximal voluntary contraction, average electromyographic activity of the gastrocnemius and soleus muscles, and zero crossing rate of the soleus muscle (recorded from 50% maximal voluntary contraction) decreased on average by 23.2, 19.9, 16.5, and 12.2%, respectively. These changes were associated with a clear immediate reduction in the reflex sensitivity; stretch reflex peak-to-peak amplitude decreased by 84. 8%, and the ratio of the electrically induced maximal Hoffmann reflex to the maximal mass compound action potential decreased by 43. 8%. Interestingly, a significant (P < 0.01) reduction in the stretch-resisting force of the measured muscles was observed. Serum creatine kinase activity stayed unaltered. This study presents evidence that the mechanism that decreases the sensitivity of short-latency reflexes can be activated because of RPS. The origin of this system seems to be a reduction in the activity of the large-diameter afferents, resulting from the reduced sensitivity of the muscle spindles to repeated stretch.
To evaluate the clinical and basic science evidence surrounding the hypothesis that stretching immediately before exercise prevents injury.
MEDLINE was searched using MEDLINE subject headings (MeSH) and textwords for English- and French-language articles related to stretching and muscle injury. Additional references were reviewed from the bibliographies, and from citation searches on key articles. All articles related to stretching and injury or pathophysiology of muscle injury were reviewed. Clinical articles without a control group were excluded.
Three (all prospective) of the four clinical articles that suggested stretching was beneficial included a cointervention of warm-up. The fourth study (cross-sectional) found stretching was associated with less groin/buttock problems in cyclists, but only in women. There were five studies suggesting no difference in injury rates between stretchers and nonstretchers (3 prospective, 2 cross-sectional) and three suggesting stretching was detrimental (all cross-sectional). The review of the basic science literature suggested five reasons why stretching before exercise would not prevent injuries. First, in animals, immobilization or heating-induced increases in muscle compliance cause tissues to rupture more easily. Second, stretching before exercise should have no effect for activities in which excessive muscle length is not an issue (e.g., jogging). Third, stretching won't affect muscle compliance during eccentric activity, when most strains are believed to occur. Fourth, stretching can produce damage at the cytoskeleton level. Fifth, stretching appears to mask muscle pain in humans.
The basic science literature supports the epidemiologic evidence that stretching before exercise does not reduce the risk of injury.
Recent research has shown that a regimen of stretching provides an acute inhibition of maximal force production by the stretched muscle group. To further characterize this phenomenon, the effect of an acute stretching regimen on maximal isokinetic knee-extension torque at 5 specific movement velocities (1.05, 1.57, 2.62, 3.67, and 4.71 rad x s(-1)) was examined in 10 men and 5 women (22-28 years). Each person's 5 baseline maximal isokinetic knee-extension torques (dominant leg) were measured on a Cybex NORM dynamometer. Following the baseline torque measurements, the participants stretched the dominant quadriceps for 15 minutes using 1 active and 3 passive stretching exercises. Once the stretching exercises were completed, the maximal torque measurements were repeated. Poststretch maximal torque at 1.05 rad x s(-1) was significantly reduced (p < 0.05) from 218 +/- 47 Nm (mean +/- SD) to 199 +/- 49 Nm (7.2% decrease). At 1.57 rad x s(-1), a similar decrease (p < 0.05) was also seen (204 +/- 48 Nm vs. 195 +/- 47 Nm; 4.5% decrease), but at the other velocities (2.62, 3.67, and 4.71 rad x s(-1)), poststretch maximal torque was unaltered (p > 0.05). It appears, therefore, that the deleterious impact of stretching activities on maximal torque production might be limited to movements performed at relatively slow velocities.
To determine the effects of stretching before and after exercising on muscle soreness after exercise, risk of injury, and athletic performance.
Systematic review.
Randomised or quasi-randomised studies identified by searching Medline, Embase, CINAHL, SPORTDiscus, and PEDro, and by recursive checking of bibliographies.
Muscle soreness, incidence of injury, athletic performance.
Five studies, all of moderate quality, reported sufficient data on the effects of stretching on muscle soreness to be included in the analysis. Outcomes seemed homogeneous. Stretching produced small and statistically non-significant reductions in muscle soreness. The pooled estimate of reduction in muscle soreness 24 hours after exercising was only 0.9 mm on a 100 mm scale (95% confidence interval -2.6 mm to 4.4 mm). Data from two studies on army recruits in military training show that muscle stretching before exercising does not produce useful reductions in injury risk (pooled hazard ratio 0.95, 0.78 to 1.16).
Stretching before or after exercising does not confer protection from muscle soreness. Stretching before exercising does not seem to confer a practically useful reduction in the risk of injury, but the generality of this finding needs testing. Insufficient research has been done with which to determine the effects of stretching on sporting performance.
This prospective study was designed to evaluate whether static stretching can prevent training-related injuries in Japan Ground Self-Defense Force military recruits. A total of 901 recruits between 1996 and 1998 were divided into two groups. Of which, 518 recruits were assigned to the stretching group and practiced static stretching before and after each physical training session. The control subjects (383 recruits in the nonstretching group) did not stretch statically prior to exercise. The static stretching consisted of 18 exercises. We collected injury data from medical records and assessed the incidence and the location of injury. The total injury rate was almost the same between two groups; however, the incidences of muscle/tendon injury and low back pain were significantly lower in the stretching group (p < 0.05). Static stretching decreased the incidence of muscle-related injuries but did not prevent bone or joint injuries.
The purpose of this study was to determine the effect of an acute static stretching bout of the biceps brachii on torque, electromyography (EMG), and mechanomyography (MMG) during concentric isokinetic muscle actions. Eighteen (men, n = 10; women, n = 8) adult subjects (M +/- SD age = 22.7 +/- 2.8 years; weight = 78.0 +/- 17.0 kg; height = 177.9 +/- 11.0 cm) performed maximal isokinetic (30 and 270 degrees.s(-1)) forearm flexion strength testing on 2 occasions while EMG and MMG were recorded. Subjects were randomly assigned to stretching (STR) or nonstretching (NSTR) protocols before strength testing. Two-way ANOVAs with repeated measures revealed significantly (p < or = 0.05) greater torque for NSTR (M +/- SEM = 36.9 +/- 3.3 N.m) vs. STR (35.2 +/- 3.3 N.m), significantly greater MMG amplitude for STR vs. NSTR for 30 degrees.s(-1) (STR = 93.5 +/- 14.4 mV; NSTR = 63.1 +/- 10.6 mV) and 270 degrees.s(-1) (STR = 207.6 +/- 35.6 mV; NSTR = 136.4 +/- 31.7 mV), and no difference in EMG amplitude. These results indicate that a greater ability to produce torque without prior stretching is related to the musculotendinous stiffness of the muscle rather than the number of motor units activated. This suggests that performing activities that reduce muscle stiffness (such as stretching), may be detrimental to performance.
We conducted a systematic review to assess the evidence for the effectiveness of stretching as a tool to prevent injuries in sports and to make recommendations for research and prevention.
Without language limitations, we searched electronic data bases, including MEDLINE (1966-2002), Current Contents (1997-2002), Biomedical Collection (1993-1999), the Cochrane Library, and SPORTDiscus, and then identified citations from papers retrieved and contacted experts in the field. Meta-analysis was limited to randomized trials or cohort studies for interventions that included stretching. Studies were excluded that lacked controls, in which stretching could not be assessed independently, or where studies did not include subjects in sporting or fitness activities. All articles were screened initially by one author. Six of 361 identified articles compared stretching with other methods to prevent injury. Data were abstracted by one author and then reviewed independently by three others. Data quality was assessed independently by three authors using a previously standardized instrument, and reviewers met to reconcile substantive differences in interpretation. We calculated weighted pooled odds ratios based on an intention-to-treat analysis as well as subgroup analyses by quality score and study design.
Stretching was not significantly associated with a reduction in total injuries (OR = 0.93, CI 0.78-1.11) and similar findings were seen in the subgroup analyses.
There is not sufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury among competitive or recreational athletes. Further research, especially well-conducted randomized controlled trials, is urgently needed to determine the proper role of stretching in sports.
The purpose of this article was to evaluate the clinical and basic science evidence surrounding the hypothesis that stretching improves performance.
MEDLINE and Sport Discus were searched using MeSH and textwords for English-language and French-language articles related to stretching and performance (or performance tests). Additional references were reviewed from the bibliographies and from citation searches on key articles. All articles related to stretching and performance (or performance tests) were reviewed.
Of the 23 articles examining the effects of an acute bout of stretching, 22 articles suggested that there was no benefit for the outcomes isometric force, isokinetic torque, or jumping height. There was 1 article that suggested improved running economy. Of 4 articles examining running speed, 1 suggested that stretching was beneficial, 1 suggested that it was detrimental, and 2 had equivocal results. Of the 9 studies examining the effects of regular stretching, 7 suggested that it was beneficial, and the 2 showing no effect examined only the performance test of running economy. There were none that suggested that it was detrimental.
An acute bout of stretching does not improve force or jump height, and the results for running speed are contradictory. Regular stretching improves force, jump height, and speed, although there is no evidence that it improves running economy.
The purpose of this study was to examine the acute effects of static stretching on peak torque (PT), the joint angle at PT, mean power output (MP), electromyographic (EMG) amplitude, and mechanomyographic (MMG) amplitude of the vastus lateralis (VL) and rectus femoris (RF) muscles during maximal, voluntary concentric isokinetic leg extensions at 60 and 240 degrees x s(-1) of the stretched and unstretched limbs. Twenty-one volunteers [mean age (SD) 21.5 (1.3) years] performed maximal, voluntary concentric isokinetic leg extensions for the dominant and non-dominant limbs at 60 and 240 degrees x s(-1). Surface EMG (muVrms) and MMG (mVrms) signals were recorded from the VL and RF muscles during the isokinetic tests. PT (Nm), the joint angle at PT, and MP (W) were calculated by a dynamometer. Following the initial isokinetic tests, the dominant leg extensors were stretched using four static stretching exercises. After the stretching, the isokinetic tests were repeated. PT decreased (P< or =0.05) from pre- to post-stretching for the stretched limb at 60 and 240 degrees x s(-1) and for the unstretched limb at 60 degrees x s(-1). EMG amplitude of the VL and RF also decreased (P< or =0.05) from pre- to post-stretching for the stretched and unstretched limbs. There were no stretching-induced changes (P>0.05) for the joint angle at PT, MP, or MMG amplitude. These findings indicated stretching-induced decreases in force production and muscle activation. The decreases in PT and EMG amplitude for the unstretched limb suggested that the stretching-induced decreases may be due to a central nervous system inhibitory mechanism.
This study compares the effects of 3 common stretching techniques on the length of the hamstring muscle group during a 4-week training program. Subjects were 19 young adults between the ages of 21 and 35. The criterion for subject inclusion was tight hamstrings as defined by a knee extension angle greater than 20 degrees while supine with the hip flexed 90 degrees . The participants were randomly assigned to 1 of 4 groups. Group 1 (n = 5) was self-stretching, group 2 (n = 5) was static stretching, group 3 (n = 5) was proprioceptive neuromuscular facilitation incorporating the theory of reciprocal inhibition (PNF-R), and group 4 (n = 4) was control. Each group received the same stretching dose of a single 30-second stretch 3 days per week for 4 weeks. Knee extension angle was measured before the start of the stretching program, at 2 weeks, and at 4 weeks. Statistical analysis (p < or = 0.05) revealed a significant interaction of stretching technique and duration of stretch. Post hoc analysis showed that all 3 stretching techniques increase hamstring length from the baseline value during a 4-week training program; however, only group 2 (static stretching) was found to be significantly greater than the control at 4 weeks. These data indicate that static stretching 1 repetition for 30 seconds 3 days per week increased hamstring length in young healthy subjects. These data also suggest that active self-stretching and PNF-R stretching 1 repetition for 30 seconds 3 days per week is not sufficient to significantly increase hamstring length in this population.
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