Eficacia de la técnica sostener relajar en comparación con el estiramiento dinámico sobre la flexibilidad de los isquiotibiales / Efficacy of the hold-relax technique compared to dynamic stretching on hamstring flexibility / Eficácia da técnica segurar-relaxar comparada ao alongamento dinâmico na flexibilidade dos isquiotibiais

Objetivo: el estiramiento muscular se aplica con el propósito de aumentar el arco de movimiento. Para este propósito se usan diferentes técnicas, entre ellas: la facilitación neuromuscular propioceptiva (FNP) y el estiramiento dinámico, pero aún no se conoce cuál de ellas es más efectiva. El objetivo de esta investigación fue estimar la eficacia de la técnica sostener relajar en comparación con el estiramiento dinámico sobre la flexibilidad de los isquiotibiales en adultos jóvenes sanos. Metodología: ensayo clínico controlado aleatorizado, con enmascaramiento de dos brazos. En el estudio participaron un total de 32 voluntarios adultos jóvenes con edades entre los 18 y 30 años y fueron aleatorizados a dos grupos de intervención FNP (n = 16), dinámico (n = 16). La flexibilidad de la articulación de la rodilla se evaluó mediante el ángulo poplíteo a través de la goniometría. Resultados: los resultados de las medias edad, peso, talla e índice masa corporal son equivalentes, lo que indica grupos comparables entre sí. No se hallaron diferencias entre los grupos de estiramiento en los promedios ajustados -2.09 (IC95% -7.05 a 2.87). Conclusiones: tanto la técnica dinámica como la FNP aumentaron el arco de movimiento de rodilla, ambas técnicas de estiramiento mostraron diferencias con la línea de base. No se encontraron diferencias entre los grupos de estiramiento.

Objective: Muscle stretching is applied with the purpose of increasing range of motion. Different techniques are used for this purpose, including proprioceptive neuromuscular facilitation (PNF) and dynamic stretching, but it is still unclear which one is more effective. The objective of this research was to estimate the efficacy of the hold-relax technique compared to dynamic stretching on hamstring flexibility in healthy young adults. Methodology: Randomized controlled trial with blinding, consisting of two intervention arms. The study included a total of 32 young adult volunteers aged 18 to 30 years, who were randomized into two intervention groups: PNF (n = 16) and dynamic stretching (n = 16). Knee joint flexibility was assessed using the popliteal angle measured with a goniometer. Results: The mean age, weight, height, and body mass index were found to be equivalent, indicating comparable groups. No significant differences were found between the stretching groups in the adjusted means, with a mean difference of -2.09 (95 % CI -7.05 to 2.87). Conclusions: Both dynamic stretching and PNF demonstrated an increase in knee range of motion, with both stretching techniques showing differences from the baseline. No significant differences were found between the stretching groups.

Finalidade: O alongamento muscular é aplicado com a finalidade de aumentar a ampli-tude de movimento. Para tanto, diversas técnicas são utilizadas, dentre elas: facilitação neuromuscular proprioceptiva (FNP) e alongamento dinâmico, mas ainda não se sabe qual delas é mais eficaz. O objetivo desta investigação foi estimar a eficáciada técnica segurar-relaxar em comparação com o alongamento dinâmico na flexibilidade dos isquiotibiais em adultos jovens saudáveis. Metodologia: Ensaio clínico randomizado, cego, controlado por dois braços. Um total de 32 voluntários adultos jovens com idades entre 18 e 30 anos participaram do estudo e foram randomizados para dois grupos de intervenção FNP (n = 16), dinâmico (n = 16). A flexibilidade da articulação do joelho foi avaliada por meio do ângulo poplíteo por goniometria. Resultados: os resultados das médias de idade, peso, altura e índice de massa corporal são equivalentes, o que indica grupos comparáveis entre si. Não foram encontradas dife-renças entre os grupos de alongamento nas médias ajustadas - 2,09 (IC 95 % -7,05 a 2,87). Conclusões: tanto a técnica dinâmica quanto o PNF aumentaram a amplitude de mo-vimento do joelho, ambas as técnicas de alongamento apresentaram diferenças com a linha de base. Não foram encontradas diferenças entre os grupos de alongamento.

Curso Temporal de los Efectos Agudos de una Sesión de Estiramiento Muscular en Sujetos Jóvenes y Sanos / Time Course of the Acute Effects of a Muscle Stretching Session in Young and Healthy Subjects

Introducción. La duración de los efectos agudos del estiramiento muscular y su relación con el volumen total de estiramiento es un tema controversial. Método. Se distribuyeron aleatoriamente 29 varones jóvenes y deportistas en tres grupos: Control, "protocolo corto" (5 estiramientos x 30' segundos) y "protocolo largo" (10 estiramientos x 30 segundos). Para medir el efecto se usó el Active Knee Extension Test en forma previa y posterior a los 0, 3, 7, 12, 18 y 25 minutos. Cada medición se grabó en video, y se identificó el rango máximo de estiramiento con el software Kinovea. Se realizó comparación pre y postintervención entre grupos e inter grupo. Se incorporó análisis post hoc en medidas repetidas. Resultados. No hubo diferencias en la medición preintervención entre los grupos (P=0,266). Ambos protocolos tuvieron cambios significativos (P<0,007) respecto del grupo control (P=0,65). Todas las mediciones postintervención comparadas con la preintervención presentan diferencias en el protocolo corto (P≤0,018) y largo (P≤0,009). Hubo diferencia entre el grupo control con el de protocolo corto (P≤0,014) y control con protocolo largo (P≤0,004) para todas las mediciones, y una diferencia entre ambos protocolos en el post inmediato (P=0,033) pero no para las mediciones posteriores (P≤0,139). Conclusión. Un protocolo de 150 segundos de estiramiento estático en isquiotibiales en varones asintomáticos jóvenes, presenta efectos por al menos 25 minutos. Al duplicar a 300 segundos sólo presenta diferencia en la medición inmediatamente posterior. Por lo tanto, ambos protocolos son igualmente efectivos, pero el protocolo corto es más eficiente.

Background. The duration of the acute effects of muscle stretching and its relationship with the total volume of stretching is a controversial issue. Methods. 29 young male athletes were randomly distributed into three groups: control, "short protocol" (5 stretches x 30'') and "long protocol" (10 stretches x 30''). To measure the effect, the Active Knee Extension Test was used before and after 0, 3', 7', 12', 18' and 25'. Each measurement was videotaped, and the maximum range of stretch was identified using the Kinovea software. A pre-post intervention comparison was made between groups and inter groups. Post hoc analysis was incorporated into repeated measures. Results. There were no differences in the pre-intervention measurement between the groups (P=0.266). Both protocols had significant changes (P<0.007) compared to the control group (P=0.65). All post-intervention measurements compared to pre-intervention present differences in the short (P≤0.018) and long (P≤0.009) protocol. There was a difference between the control group with the short protocol (P≤0.014) and the control group with the long protocol (P≤0.004) for all measurements, and a difference between both protocols in the immediate post (P=0.033) but not for the measurements. subsequent measurements (P≤0.139). Conclusion. A protocol of 150'' of static stretching in hamstrings in asymptomatic young men, presents effects for at least 25'. When doubling at 300'', it only presents a difference in the immediately subsequent measurement. Therefore, both protocols are equally effective, but the short protocol is more efficient.

A biomechanical comparison of matched four-strand and five-strand semitendinosus-gracilis grafts / Estudo biomecânico comparativo entre enxertos quádruplos e quíntuplos pareados de tendões dos músculos semitendíneo e grácil / Estudio biomecânico comparativo entre injertos de tendones semitendinoso e gracilis cuádruple e quíntuple

ABSTRACT Introduction: Recent studies have shown that the likelihood of semitendinosus-gracilis graft rupture is inversely correlated to its diameter. A graft can be prepared in a five-strand or four-strand fashion to increase its diameter. However, the biomechanical superiority of five-strand semitendinosus-gracilis grafts is still under debate. Objective: This study aimed to evaluate the biomechanical characteristics of matched four-strand and five-strand human semitendinosus-gracilis grafts. Methods: We evaluated semitendinosus-gracilis tendons harvested from ten fresh human male and female cadavers, aged 18-60 years. Four-strand or five-strand grafts were prepared with the tendons and fixed to wooden tunnels with interference screws. Each graft was submitted to axial traction at 20 mm/min until rupture; the tests were donor matched. Data were recorded in real time and included the analysis of the area, diameter, force, maximum deformation and stiffness of the grafts. Results: The diameter, area and tunnel size were significantly greater in the five-strand grafts than in the four-strand grafts. There were no significant differences in biomechanical properties. The area and diameter of the graft were positively correlated to stiffness, and inversely correlated to elasticity. There was no significant correlation between graft size and maximum force at failure, maximum deformation or maximum tension. Conclusion: Five-strand hamstring grafts have greater area, diameter and tunnel size than four-strand grafts. There were no significant differences in biomechanical properties. In this model using interference screw fixation, the increases in area and diameter were correlated with an increase in stiffness and a decrease in elasticity. Level of evidence V; biomechanical study.

RESUMEN Introducción: Estudios recientes demostraron que la probabilidad de ruptura de los injertos semitendinoso y gracilis (STG) durante el pos operatorio de reconstrucción de ligamento cruzado anterior (LCA) está inversamente correlacionada a su diámetro. Un injerto puede ser preparado para obtener cuatro o cinco hebras para aumentar su diámetro, pero la superioridad biomecanica de los injertos STG de cinco hebras aún se mantiene en discusión. Objetivo: Evaluar las características biomecánicas de los injertos STG de humanos de cuatro o cinco hebras por pares. Métodos: Fueron evaluados tendones STG de diez cadaveres masculinos y diez cadaveres femeninos frescos, entre los 18 y 60 años. Los injertos de cuatro y cinco hebras fueron fijados en túneles de madera con tornillos de interferencia. Cada injerto fue sometido a una tracción axial de 200mm/min hasta su ruptura; estos tendones fueron separados por pares de acuerdo con sus donadores. Los datos fueron registrados en tiempo real y incluyeron el análisis del área del injerto, diámetro, fuerza, deformación máxima y rigidez. Resultados: Los resultados sobre el diámetro, el área y el tamaño del túnel fueron significativamente mayores en los injertos de cinco hebras que en los de cuatro. No existieron diferencias significativas en las propiedades biomecánicas. El área y el diámetro del injerto fueron correlacionados positivamente con la rigidez e inversamente con la elasticidad. No existió correlación significativa entre el tamaño del injerto y la fuerza máxima al momento de la falla, Máxima deformación o máxima tensión. Conclusión: Los injertos de isquiotibiales de cinco hebras tienen una área, diámetro y tamaño de túnel más grande que los injertos de cuatro hebras. No hubieron diferencias biomecánicas significativas. Los aumentos de área y diámetro en este modelo con la fijación de tornillo de interferencia fueron correlacionados con aumento de en la rigidez y una disminución en la elasticidad. Nivel de evidencia V; estudio biomecánico.

RESUMO Introdução: Estudos recentes demonstraram que a probabilidade de ruptura do enxerto dos tendões do semitendíneo e do grácil (STG) é correlacionada inversamente com seu diâmetro. Um enxerto pode ser preparado de forma quádrupla ou quíntupla para se aumentar o diâmetro. No entanto, a superioridade biomecânica dos enxertos STG quíntuplos ainda está em debate. Objetivo: Este estudo teve como objetivo avaliar as características biomecânicas dos enxertos STG humanos quádruplos ou quíntuplos pareados. Métodos: Foram avaliados tendões STG retirados de dez cadáveres masculinos e femininos frescos, com idades entre 18 e 60 anos. Os enxertos quádruplos ou quíntuplos foram preparados com os tendões e fixados em túneis de madeira com parafusos de interferência. Cada enxerto foi submetido à tração axial a 20 mm/min. até a ruptura; os testes foram pareados de acordo com os doadores. Os dados foram registrados em tempo real e incluíram a análise de área, diâmetro, força, deformação máxima e rigidez dos enxertos. Resultados: O diâmetro, a área e o tamanho do túnel foram significativamente maiores nos enxertos quíntuplos do que nos enxertos quádruplos. Não houve diferenças significativas nas propriedades biomecânicas. A área e o diâmetro do enxerto foram correlacionados positivamente com a rigidez e inversamente com a elasticidade. Não houve correlação significativa entre o tamanho do enxerto e a força máxima na falha, deformação máxima ou tensão máxima. Conclusão: Os enxertos quíntuplos dos músculos isquiotibiais têm maior área, diâmetro e tamanho do túnel do que os enxertos quádruplos. Não houve diferenças significativas nas propriedades biomecânicas. Neste modelo de fixação com parafuso de interferência, aumentos da área e do diâmetro foram correlacionados com o aumento da rigidez e a diminuição na elasticidade. Nível de evidência V; Estudo Biomecânico.

Prospective Study of Muscle Injuries in Three Consecutive Seasons of the Brazilian Football Championship / Estudo prospectivo das lesões musculares em três temporadas consecutivas do Campeonato Brasileiro de Futebol

Abstract Objective To perform a prospective evaluation of muscle injuries that occurred during the matches of series A and B of the Brazilian Men's Football Championship from 2016 to 2018. Prospective A prospective-cohort study with data collection regarding muscle injuries that occurred during the official matches of the first and second divisions of the Brazilian Men's Soccer Championship in the 2016, 2017 and 2018 seasons. Results The total number of muscle injuries was of 577 throughout the 3 seasons, with a gradual and annual reduction in the incidence of injuries (219 injuries in 2016, 195 in 2017, and 163 in 2018), with a statistically significant difference between the 2016 and 2018 seasons. Muscle injuries represented approximately 35% of the total lesions. The incidence of muscle injuries was of 7.66 per 1,000 hours of play. During the 3 seasons (2016 to 2018), the most common injury was of the hamstring muscle (41.1%, 40.5%, and 33.7% respectively). Wingers were the most affected players, and the most common injury severity scale was moderate (8 to 28 days). The moment of the match with the highest incidence of injuries was in the period between 61 and 75 minutes, with an index of 19.9%, with no statistical difference in relation to the other periods of the match. Conclusion There was an incidence of muscle injuries of 7.7 /1,000 h, and they occurred predominantly in home games, in defenders (wingers and centre-backs), with an average age of 28 years, mainly involving the hamstring muscles, with a moderate mean time of absence (8 to 28 days).

Resumo Objetivo Realizar uma avaliação prospectiva das lesões musculares ocorridas durante as partidas das séries A e B do Campeonato Brasileiro de Futebol Masculino dos anos de 2016 a 2018. Métodos Estudo de coorte prospectivo com coleta de dados referentes às lesões musculares ocorridas durante os jogos oficiais da primeira e segunda divisões do Campeonato Brasileiro de Futebol Masculino nas temporadas de 2016, 2017 e 2018. Resultados O número total de lesões musculares foi de 577 ao longo das 3 temporadas, havendo uma redução gradual e anual na incidência delas (219 lesões em 2016, 195 em 2017, e 163 em 2018), com diferença estatística significativa entre os anos de 2016 e 2018. As lesões musculares representaram aproximadamente 35% de todas as lesões. A incidência das lesões musculares foi 7,66 para cada 1.000 horas de jogo. Nas 3 temporadas (2016 a 2018), a mais comum foi a lesão muscular dos isquiotibiais (41,1%, 40,5% e 33,7%, respectivamente). Os laterais foram os mais acometidos, e a escala de severidade de lesão mais comum foi a moderada (8 a 28 dias). O momento da partida com maior incidência de lesões foi no período entre 61 e 75 minutos, com um índice de 19,9%, não havendo diferença estatística em relação aos demais períodos de jogo. Conclusão Houve uma incidência de lesões musculares de 7,7 lesões/1.000 h, e ocorreram predominantemente nos jogos em casa, em defensores (laterais e zagueiros), com idade média de 28 anos, envolvendo principalmente a musculatura isquiotibial, com tempo médio de afastamento moderado (8 a 28 dias).

Avaliação do índice de fadiga muscular de flexores e extensores de joelho em indivíduos ativos e sedentários

RESUMO Objetivo: Avaliar a fadiga muscular de flexores e extensores de joelho em indivíduos ativos e sedentários. Metodologia: Foram aplicados o Questionário Internacional de Atividade Física (IPAQ), Questionário de Prontidão para Atividade Física (PAR-Q) e exame clínico funcional, a fim de garantir a segurança durante a dinamometria isocinética, executada em três séries de cinco repetições dos movimentos de flexão e extensão do joelho, nas velocidades 120º/s, 180º/s e 240º/s. Resultados: Indivíduos sedentários obtiveram maior índice de fadiga, essa diferença foi significativa nos isquiotibiais esquerdos. Conclusão: É importante determinar o índice de fadiga, uma vez que a fatigabilidade da musculatura interfere diretamente no desempenho muscular e no aparecimento de lesões.

ABSTRACT Objective: To evaluate the muscular fatigue of flexors and knee extensors in active and sedentary individuals. Methodology: The International Physical Activity Questionnaire (IPAQ), Physical Activity Alert Questionnaire (PAR-Q) and functional clinical examination were performed in order to guarantee safety during Isokinetic Dynamometry, performed in 3 sets of 5 repetitions of the knee flexion and extension movements, at speeds 120º/s, 180º/s and 240º/s. Results: Sedentary individuals had a higher fatigue index, being this difference significant in the left hamstrings. Conclusion: It is important to determine the fatigue index, since the fatigue of the muscles directly interferes with the muscular performance and the appearance of injuries.

RESUMEN Objetivo: Evaluar la fatiga muscular de flexores y extensores de rodilla en individuos activos y sedentarios. Metodología: Se aplicó el Cuestionario Internacional de la Actividad Física (IPAQ), el Cuestionario de Preparación para la Actividad Física (PAR-Q) y un examen clínico funcional a fin de garantizar la seguridad durante la dinamometría isocinética llevada a cabo en 3 series de 5 repeticiones de los movimientos de flexión y extensión de la rodilla, a velocidades de 120º/s, 180º/s y 240º/s. Resultados: Los individuos sedentarios obtuvieron mayor índice de fatiga y esa diferencia fue importante en los isquiotibiales izquierdos. Conclusión: Es importante establecer el índice de fatiga ya que la fatiga de la musculatura interfiere directamente en el rendimiento muscular y en la aparición de lesiones.

Effect of Pre-training and Post-training Nordic Exercise on Hamstring Injury Prevention, Recurrence, and Severity in Soccer Players

OBJECTIVE: To investigate the effect of adding Nordic exercise as post-training in decreasing hamstring initial, recurrent injuries rates, and their severity. METHODS: In this randomly controlled trial study, 34 professional football players aged 21 to 35 years were randomly assigned into two groups (17 players each) from Sporting clubs at Alexandria, Egypt. For group one, Nordic hamstring exercise (NHE) was performed pre-training and post-training. For group two, NHE was only performed pre-training. The control group was the same team during the previous season. Length of the trial was 12 weeks. The Australian football association injury form was used to collect incidence of injuries for each subject in both groups. RESULTS: Pooled results based on total injuries showed that group one had significantly less hamstring initial injuries (92% less) than the previous season, while group two had 80% less initial injuries and 85% less recurrent injuries than previous season. Regarding the severity of injuries in term of mean number of absent days, it was 1 day for group one and 2.7 days for group two while it was 7.95 days for the previous season during total risk time of 116.3±13.2 and 117.6±5.7 exposure hours for group one and group two, respectively. CONCLUSION: The use of NHE as a prevention protocol was effective in reducing all hamstring injuries with the use of NHE during pre-training and post-training having the greatest effect.

Caracterización morfológica del componente tendo-muscular del compartimiento posterior del muslo / Morphological characterization of the tendo-muscular component of the posterior compartment of the thigh

Los aspectos morfológicos del componente tendomuscular del compartimiento posterior han sido descritos en algunos grupos poblacionales. Se evaluó mediante disección directa las características morfológicas y biométricas del compartimento posterior de 50 muslos de especímenes cadavéricos, en una muestra de población colombiana. El 2 % los músculos isquiotibiales se originaron en un tendón común, 58 % presentó un tendón común para el musculo semitendinoso (MSt) y cabeza larga del músculo bíceps femoral (MBF). El 40 % de la cabeza larga del MBF se originó en el margen lateral de la tuberosidad isquiática (TI) y el MSt en su superficie posterior. En el 98 % de los casos el músculo semimembranoso (MSm) se originó en el margen medial de la TI y se dispuso como una estructura medial del muslo. No se observaron variaciones en el lugar de inserción de los músculos isquiotibiales. El MSt presentó la mayor longitud (419,5 DE 33,2 mm); el tendón distal con mayor espesor fue el del MBF (8,5 DE 5,6 mm), mientras que el músculo semimembranoso (MSm) presentó el componente miotendinoso más ancho (22,4 DE 6,5 mm). No hubo diferencias morfométricas estadísticamente significativas con relación al lado de presentación. Los hallazgos obtenidos enriquecen los conceptos morfológicos de la región posterior del muslo, aportan a la cualificación de procedimientos de cirugía plástica, ortopédica y al diseño de programas de entrenamiento muscular específico en diferentes disciplinas deportivas.

The morphological aspects of tendon and muscle component of the posterior compartment have been described in some population groups. The morphological and biometric characteristics of the posterior compartment of 50 thighs of cadaverous specimens were evaluated by means of a direct design, in a sample of the Colombian population. The 2 % of the hamstring beats originated in a common tendon, 58 % with a common tendon for the Semitendinous muscle (MSt) and long head of the femoral Biceps muscle (MBF). The 40 % of the long head of the MBF were originated on the lateral margin of the Ischial Tuberosity (TI) and the MSt on its posterior surface. In 98 % of the cases the semimembranous muscle (MSm) originated in the middle margin of the IT and dissolved as a medial structure of the thigh. No variation was observed in the place of the hamstring insertion. The longest time (419.5 DE 33.2 mm) the distal tendon with greater thickness was that of the MBF (8.5 OF 5.6 mm), while the semimembranosus muscle (MSm) presented the broadest myotendinous component (22.4 SD 6.5 mm). There weren't statistically significant morphometric differences in relation to the presentation side. The findings obtained enrich the morphological concepts of the posterior thigh region, contribute to the qualification of plastic surgery, orthopedic procedures and the design of muscle training programs in different sports disciplines.

Morphometric study of the semitendinosus muscle and its neurovascular pedicles in South Indian cadavers / 대한해부학회지

The purpose of this study was to determine the length of the semitendinosus muscle belly and its tendon in South Indian population and to study the topography and diameter of its neurovascular pedicles. The study included 46 formalin fixed human cadaveric lower limbs. The length of the semitendinosus muscle belly and its tendon were measured. The neurovascular pedicles of the semitendinosus muscle were identified and counted. The diameter of the neurovascular pedicle was measured just before its entrance into the semitendinosus muscle. The topographical distance of the neurovascular pedicles from the origin of the semitendinosus muscle were determined. The mean length of the semitendinosus muscle belly was 332.3±36.1 mm and its tendon measured 154.8±31.9 mm. The mean diameter of the vascular pedicle was measuring 11.4±9.1 mm, just before its entrance into the semitendinosus muscle. The neurovascular pedicles, of the semitendinosus muscle were ranging between 1 and 7. The distance of the entrance of neurovascular pedicle to the semitendinosus muscle from its origin was ranging between 46 and 272 mm. It was observed that the neurovascular pedicles were highest (31%) at the range of 151–200 mm away from the ischial tuberosity. The morphometric data obtained in the present study is enlightening to the orthopedic and plastic surgeons. The topographical knowledge of the neurovascular pedicles has its implications during the harvesting of the grafts and pedicle flaps. The diameter of vessels in the pedicles is enlightening because of new method of anterior cruciate ligament reconstruction.

Efeito agudo do alongamento por Facilitação Neuromuscular Proprioceptiva associado a TENS e crioterapia na flexibilidade dos músculos isquiossurais de mulheres saudáveis / Acute effect of Proprioceptive Neuromuscular Facilitation stretching associated with TENS and cryotherapy in the flexibility of hamstring muscles of healthy women

Introdução: O alongamento por Facilitação Neuromuscular Proprioceptiva (FNP) é o mais efetivo dentre os tipos de alongamento. O ganho de flexibilidade após o alongamento se deve também ao aumento da tolerância do indivíduo ao estiramento do músculo, portanto, recursos analgésicos associados ao alongamento por FNP podem potencializar o efeito desta técnica. Objetivo: Verificar o efeito agudo do alongamento por FNP associado a Estimulação Elétrica Nervosa Transcutânea (TENS) e a crioterapia na flexibilidade dos músculos isquiossurais de mulheres saudáveis. Material e métodos: Sessenta voluntarias foram distribuídas aleatoriamente em quatro grupos: (G1) Grupo Controle; (G2) Alongamento por FNP isolado; (G3) Alongamento FNP associado a TENS; (G4) Alongamento FNP associado à crioterapia. Resultados: Na análise intragrupo foi observado aumento da flexibilidade na comparação antes e depois da aplicação das técnicas em todos os grupos (p < 0,001), exceto no G1. Na análise intergrupo, foi observada diferença estatística apenas na comparação dos três grupos experimentais (G2, G3 e G4) com o grupo controle (G1) (p ≤ 0,002). Conclusão: O alongamento por FNP aplicado isoladamente e associado a TENS ou crioterapia são igualmente eficazes para aumentar a flexibilidade de forma aguda dos músculos isquiossurais de mulheres saudáveis. (AU)

Introduction: Stretching by Proprioceptive Neuromuscular Facilitation (PNF) is the most effective among the types of stretching. Increased flexibility after stretching is also due to increased tolerance of the subject to the stretching of the muscle, therefore, analgesic resources associated with PNF stretching may potentiate the effect of this technique. Objective: To measure the acute effect of PNF stretching associated with Transcutaneous Electrical Nerve Stimulation (TENS) and cryotherapy in the flexibility of hamstring muscles of healthy women. Methods: Sixty volunteers were randomly assigned to four groups: (G1) Control Group; (G2) PNF Stretching isolated; (G3) PNF with TENS; (G4) PNF associated with cryotherapy. Results: In the intragroup analysis, an increase in flexibility was observed in the comparison before and after the application of the techniques in all groups (p < 0.001), except G1. In the intergroup analysis, a statistical difference was observed only in the comparison of the three experimental groups (G2, G3 and G4) with the control group (G1) (p ≤ 0.002). Conclusion: PNF stretching applied isolated and associated with TENS or cryotherapy are equally effective to increase the acute flexibility of the hamstring muscles of healthy sedentary women. (AU)

Exploratory factor analysis for differentiating sensory and mechanical variables related to muscle-tendon unit elongation

ABSTRACT Background Stretching exercises are able to promote adaptations in the muscle-tendon unit (MTU), which can be tested through physiological and biomechanical variables. Identifying the key variables in MTU adaptations is crucial to improvements in training. Objective To perform an exploratory factor analysis (EFA) involving the variables often used to evaluate the response of the MTU to stretching exercises. Method Maximum joint range of motion (ROMMAX), ROM at first sensation of stretching (FSTROM), peak torque (torqueMAX), passive stiffness, normalized stiffness, passive energy, and normalized energy were investigated in 36 participants during passive knee extension on an isokinetic dynamometer. Stiffness and energy values were normalized by the muscle cross-sectional area and their passive mode assured by monitoring the EMG activity. Results EFA revealed two major factors that explained 89.68% of the total variance: 53.13% was explained by the variables torqueMAX, passive stiffness, normalized stiffness, passive energy, and normalized energy, whereas the remaining 36.55% was explained by the variables ROMMAX and FSTROM. Conclusion This result supports the literature wherein two main hypotheses (mechanical and sensory theories) have been suggested to describe the adaptations of the MTU to stretching exercises. Contrary to some studies, in the present investigation torqueMAX was significantly correlated with the variables of the mechanical theory rather than those of the sensory theory. Therefore, a new approach was proposed to explain the behavior of the torqueMAX during stretching exercises.

Comparison of different hamstrings training effect on hamstrings:quadriceps strength ratios / 体力科学

Hamstring muscles form a multi-articular muscle group that crosses the hip and knee joints. It has been said that the imbalance in the hamstrings:quadriceps strength ratio (H:Q ratio) due to weaker hamstring muscles results in an increased susceptibility to hamstring strains and anterior cruciate ligament injuries. Four different hamstrings trainings, Hip Lift (HL), Single-leg Deadlift (DL), Leg Curl (LC), and Nordic Hamstrings (NH), were conducted and compared in the effect on conventional H:Q ratio. After the training of two months, significant increase of hip extension torque and H:Q ratios in the hip joint were found in the DL group, and significant increase of knee flexion torque and H:Q ratios in the knee joint were found in the LC group (<i>P</i> < 0.05). As a conclusion, DL and LC training could be practical for hamstrings injury prevention.