Cecília Ferreira de Aquino

Stretching versus strength training in lengthened position in subjects with tight hamstring muscles: A randomized controlled trial

Stretching is used to modify muscle length. However, its effects seem to be temporary. There is evidence in animal models that strengthening in a lengthened position may induce long lasting changes in muscle length. The objective of this study was to compare changes in hamstrings flexibility, peak torque angle and stretch tolerance after two training programs: stretching and strengthening in a lengthened position. Forty-five subjects with tight hamstrings were randomly assigned into three groups: control, stretching and strength training in lengthened position. The interventions were performed three times a week for eight weeks. The subjects were assessed before and after the end of the programs. Data provided by an isokinetic dynamometer were used to assess hamstrings flexibility, peak torque angle, and stretch tolerance. The data analysis demonstrated that strengthening in lengthened position changed peak torque angle in the direction of knee extension (p=0.001). No change in flexibility was observed (p=0.449). Both experimental groups showed an increase in stretch tolerance (p=0.001). The results demonstrated that strengthening in a lengthened position produced a shift of the torque-angle curve, which suggests an increase in muscle length. Conversely, stretching did not produce modification of torque-angle curve and flexibility; its effects appear restricted to increases in stretch tolerance.

Análise da relação entre flexibilidade e rigidez passiva dos isquiotibiais

INTRODUCAO: Rigidez e flexibilidade sao propriedades musculares frequentemente consideradas como sinonimas na literatura, apesar de apresentarem diferencas com relacao as suas definicoes. OBJETIVO: Investigar a contribuicao da medida de flexibilidade dos isquiotibiais para a rigidez passiva deste grupo muscular. METODOS: A rigidez e a flexibilidade foram avaliadas em 33 individuos saudaveis. Um dinamometro isocinetico registrava o torque passivo oferecido pelos isquiotibiais durante a extensao passiva do joelho, a velocidade de 5o/s. Durante os testes, foi feita a monitoracao da atividade muscular para garantir silencio eletromiografico. A inclinacao da reta torque x ângulo foi utilizada para determinar a rigidez total dos isquiotibiais. A amplitude de teste foi dividida em tres porcoes para calcular a rigidez do 1o, 2o e 3o tercos do movimento angular. A flexibilidade foi avaliada atraves do ângulo articular do joelho em que o movimento da alavanca foi interrompido pelo examinador ao perceber resistencia a movimentacao adicional e o participante relatar sensacao de desconforto pelo alongamento dos isquiotibiais. Como tratamento estatistico, foram utilizadas analises de regressao simples. RESULTADOS: Analises de regressao demonstraram valores de correlacao r = -0,48 (R2 = 0,23; p = 0,005), r = -0,54 (R2 = 0,29; p = 0,001), r = -0,46 (R2 = 0,21; p = 0,007) e r = -0,45 (R2 = 0,20; p = 0,008) entre flexibilidade e rigidez passiva total, 1o, 2o e 3o tercos, respectivamente. CONCLUSAO: Apesar de as associacoes entre as variaveis terem sido significativas, uma percentagem pequena da variabilidade da medida de rigidez passiva pode ser explicada pela flexibilidade. Conclui-se que essas propriedades nao sao sinonimas e devem ser analisadas de forma independente.Introduction: The terms stiffness and flexibility, which refer to muscle properties, are frequently used as synonymous in the literature. However, these two muscle properties have distinct definitions. Objective: To investigate the contribution of the measure of flexibility to the passive stiffness of the hamstrings. Methods: Stiffness and flexibility were measured in 33 healthy individuals. An isokinetic dynamometer registered the resistance torque offered by the hamstrings during knee passive extension at 5o/Muscle activity was monitored during the tests to guarantee electromyographic silence. The slope of the torque-angle curve was used to determine the hamstrings passive stiffness. The range of the test was divided into three portions to calculate the stiffness of the 1st, 2nd and 3rd thirds of knee movement. Flexibility was assessed by having the examiner move the lever of the dynamometer in the direction of knee extension. The final measure was determined as the angle at which movement was interrupted because the examiner perceived a resistance to further movement and the volunteer reported a sensation of discomfort. Simple regressions were used for statistical analysis. Results: The regression analysis demonstrated correlation values of r = –0.48 (R2 = 0.23; p = 0.005), r = – 0.54 (R2 = 0.29; p = 0.001), r = –0.46 (R2 = 0.21; p = 0.007) and r = –0.45 (R2 = 0.20; p = 0.008) between flexibility and total, 1st, 2nd and 3rd third stiffness, respectively. Conclusion: Despite significant associations between the analyzed variables, flexibility explains only a low percentage of the variability of the stiffness measure. Stiffness and flexibility are not equivalent and should be analyzed independently.

Análise da relação entre dor lombar e desequilíbrio de força muscular em bailarinas

OBJECTIVE: To investigate the relationship between low back pain and muscle strength imbalance in the lumbopelvic region of classical ballet dancers. METHODS: This cross-sectional exploratory study was developed in the ballet academies of Divinopolis and Oliveira, Minas Gerais State. Forty-two ballet dancers were selected and then divided into two groups (Pain and Painless Groups), according to the presence or absence of pain complaints in the low back. Firstly, the ballet dancers were submitted, by one examiner, to four tests of muscle strength imbalance in the lumbopelvic region: gluteus maximus × hamstrings muscles and gluteus maximus × paraspinal muscles in the hip extension movement; gluteus maximus and medius × tensor fascia latae muscles in the hip abduction movement; abdominal × hip flexors in the hip flexion movement. After that, a second examiner applied the muscular strength tests for the abdominal and paraspinal muscles. Chi-square tests were used to verify the association between low back pain and muscle imbalances. The level of significance was set at α = 0.05. RESULTS: Most of the ballet dancers, independently of the group, showed muscle strength imbalances in the lumbopelvic region. The abdominal × hip flexors test demonstrated a significant association with low back pain (p = 0.043). CONCLUSION: Muscle imbalances in the lumbopelvic region are common in classical ballet dancers. However, it is not possible to assure that these muscle imbalances are specific adaptations to the classical ballet or dysfunctions associated to algic symptoms resulted from training faults.

Analysis of the relation between flexibility and passive stiffness of the hamstrings

INTRODUCAO: Rigidez e flexibilidade sao propriedades musculares frequentemente consideradas como sinonimas na literatura, apesar de apresentarem diferencas com relacao as suas definicoes. OBJETIVO: Investigar a contribuicao da medida de flexibilidade dos isquiotibiais para a rigidez passiva deste grupo muscular. METODOS: A rigidez e a flexibilidade foram avaliadas em 33 individuos saudaveis. Um dinamometro isocinetico registrava o torque passivo oferecido pelos isquiotibiais durante a extensao passiva do joelho, a velocidade de 5o/s. Durante os testes, foi feita a monitoracao da atividade muscular para garantir silencio eletromiografico. A inclinacao da reta torque x ângulo foi utilizada para determinar a rigidez total dos isquiotibiais. A amplitude de teste foi dividida em tres porcoes para calcular a rigidez do 1o, 2o e 3o tercos do movimento angular. A flexibilidade foi avaliada atraves do ângulo articular do joelho em que o movimento da alavanca foi interrompido pelo examinador ao perceber resistencia a movimentacao adicional e o participante relatar sensacao de desconforto pelo alongamento dos isquiotibiais. Como tratamento estatistico, foram utilizadas analises de regressao simples. RESULTADOS: Analises de regressao demonstraram valores de correlacao r = -0,48 (R2 = 0,23; p = 0,005), r = -0,54 (R2 = 0,29; p = 0,001), r = -0,46 (R2 = 0,21; p = 0,007) e r = -0,45 (R2 = 0,20; p = 0,008) entre flexibilidade e rigidez passiva total, 1o, 2o e 3o tercos, respectivamente. CONCLUSAO: Apesar de as associacoes entre as variaveis terem sido significativas, uma percentagem pequena da variabilidade da medida de rigidez passiva pode ser explicada pela flexibilidade. Conclui-se que essas propriedades nao sao sinonimas e devem ser analisadas de forma independente.Introduction: The terms stiffness and flexibility, which refer to muscle properties, are frequently used as synonymous in the literature. However, these two muscle properties have distinct definitions. Objective: To investigate the contribution of the measure of flexibility to the passive stiffness of the hamstrings. Methods: Stiffness and flexibility were measured in 33 healthy individuals. An isokinetic dynamometer registered the resistance torque offered by the hamstrings during knee passive extension at 5o/Muscle activity was monitored during the tests to guarantee electromyographic silence. The slope of the torque-angle curve was used to determine the hamstrings passive stiffness. The range of the test was divided into three portions to calculate the stiffness of the 1st, 2nd and 3rd thirds of knee movement. Flexibility was assessed by having the examiner move the lever of the dynamometer in the direction of knee extension. The final measure was determined as the angle at which movement was interrupted because the examiner perceived a resistance to further movement and the volunteer reported a sensation of discomfort. Simple regressions were used for statistical analysis. Results: The regression analysis demonstrated correlation values of r = –0.48 (R2 = 0.23; p = 0.005), r = – 0.54 (R2 = 0.29; p = 0.001), r = –0.46 (R2 = 0.21; p = 0.007) and r = –0.45 (R2 = 0.20; p = 0.008) between flexibility and total, 1st, 2nd and 3rd third stiffness, respectively. Conclusion: Despite significant associations between the analyzed variables, flexibility explains only a low percentage of the variability of the stiffness measure. Stiffness and flexibility are not equivalent and should be analyzed independently.

Análisis de la relación entre flexibilidad y rigidez pasiva de los isquiotibiales

INTRODUCAO: Rigidez e flexibilidade sao propriedades musculares frequentemente consideradas como sinonimas na literatura, apesar de apresentarem diferencas com relacao as suas definicoes. OBJETIVO: Investigar a contribuicao da medida de flexibilidade dos isquiotibiais para a rigidez passiva deste grupo muscular. METODOS: A rigidez e a flexibilidade foram avaliadas em 33 individuos saudaveis. Um dinamometro isocinetico registrava o torque passivo oferecido pelos isquiotibiais durante a extensao passiva do joelho, a velocidade de 5o/s. Durante os testes, foi feita a monitoracao da atividade muscular para garantir silencio eletromiografico. A inclinacao da reta torque x ângulo foi utilizada para determinar a rigidez total dos isquiotibiais. A amplitude de teste foi dividida em tres porcoes para calcular a rigidez do 1o, 2o e 3o tercos do movimento angular. A flexibilidade foi avaliada atraves do ângulo articular do joelho em que o movimento da alavanca foi interrompido pelo examinador ao perceber resistencia a movimentacao adicional e o participante relatar sensacao de desconforto pelo alongamento dos isquiotibiais. Como tratamento estatistico, foram utilizadas analises de regressao simples. RESULTADOS: Analises de regressao demonstraram valores de correlacao r = -0,48 (R2 = 0,23; p = 0,005), r = -0,54 (R2 = 0,29; p = 0,001), r = -0,46 (R2 = 0,21; p = 0,007) e r = -0,45 (R2 = 0,20; p = 0,008) entre flexibilidade e rigidez passiva total, 1o, 2o e 3o tercos, respectivamente. CONCLUSAO: Apesar de as associacoes entre as variaveis terem sido significativas, uma percentagem pequena da variabilidade da medida de rigidez passiva pode ser explicada pela flexibilidade. Conclui-se que essas propriedades nao sao sinonimas e devem ser analisadas de forma independente.Introduction: The terms stiffness and flexibility, which refer to muscle properties, are frequently used as synonymous in the literature. However, these two muscle properties have distinct definitions. Objective: To investigate the contribution of the measure of flexibility to the passive stiffness of the hamstrings. Methods: Stiffness and flexibility were measured in 33 healthy individuals. An isokinetic dynamometer registered the resistance torque offered by the hamstrings during knee passive extension at 5o/Muscle activity was monitored during the tests to guarantee electromyographic silence. The slope of the torque-angle curve was used to determine the hamstrings passive stiffness. The range of the test was divided into three portions to calculate the stiffness of the 1st, 2nd and 3rd thirds of knee movement. Flexibility was assessed by having the examiner move the lever of the dynamometer in the direction of knee extension. The final measure was determined as the angle at which movement was interrupted because the examiner perceived a resistance to further movement and the volunteer reported a sensation of discomfort. Simple regressions were used for statistical analysis. Results: The regression analysis demonstrated correlation values of r = –0.48 (R2 = 0.23; p = 0.005), r = – 0.54 (R2 = 0.29; p = 0.001), r = –0.46 (R2 = 0.21; p = 0.007) and r = –0.45 (R2 = 0.20; p = 0.008) between flexibility and total, 1st, 2nd and 3rd third stiffness, respectively. Conclusion: Despite significant associations between the analyzed variables, flexibility explains only a low percentage of the variability of the stiffness measure. Stiffness and flexibility are not equivalent and should be analyzed independently.