Different Body Partialization Procedures Considering Maximum Strength and Explosiveness: Factorial Analysis Approach / Diferentes Procedimientos de Parcialización Corporal Considerando Fuerza Máxima y Explosividad: Enfoque de Análisis Factorial

SUMMARY: The aim of this study was to determine the sensitivity of different methods of partialization, in terms of different body component indices in relation to indicators of strength and explosiveness. The research involved 187 subjects who were divided into two groups based on sex. This research consisted of measuring body composition characteristics by multichannel bioimpedance analysis (BIA) InBody 720, as well as contractile characteristics of different muscle groups with tenziometric Dinamometry method. Based on the results of the factor analysis we found that regardless of the sex the most sensitive variable for partialization of absolute body isometric strength variable (ABiS) is partialization by allometric scaling (0.964 for females and 0.947 for males explained factor variance). However, in the case of absolute body isometric explosiveness (ABiE), the results of this study have demonstrated that partialization relative to skeletal muscle mass according to the body longitudinality - skeletal muscle mass index (SMMI) is the methodological choice disregarding the sex (0.982 for females and 0.980 for males explained factor variance). The results of the study have shown that for the purpose of scaling the maximal strength relative to body composition, the allometric method can be considered as a choice, while for the partialization of maximal isometric explosiveness skeletal muscle mass index is the best choice insensitive of the sex.

El objetivo de este estudio fue determinar la sensibilidad de distintos métodos de parcialización, en términos de diferentes índices de componentes corporales en relación a los indicadores de fuerza y explosividad. En la investigación participaron 187 sujetos que se dividieron según el sexo en dos grupos. Esta investigación consistió en medir las características de composición corporal mediante análisis de bioimpedancia multicanal (BIA) InBody 720, así como las características contráctiles de diferentes grupos musculares con el método de Dinamometría tenciométrica. Con base en los resultados del análisis factorial, encontramos que, independientemente del sexo, la variable más sensible para la parcialización de la variable de fuerza isométrica corporal absoluta (ABiS) fue la parcialización mediante escala alométrica (0,964 para las mujeres y 0,947 para los hombres). Sin embargo, en el caso de la explosividad isométrica corporal absoluta (ABiE), los resultados de este estudio han demostrado que la parcialización relativa a la masa del músculo esquelético según la longitudinalidad del cuerpo - índice de masa del músculo esquelético (SMMI) es la opción metodológica sin tener en cuenta el sexo (0,982 para las mujeres y 0,980 para los hombres). Los resultados del estudio han demostrado que para escalar la fuerza máxima en relación con la composición corporal, el método alométrico puede considerarse como una opción, mientras que para la parcialización de la explosividad isométrica máxima, el índice de masa del músculo esquelético es la mejor opción independiente del sexo.

Characteristic changes in morphology and function of skeletal muscles in a rat model of"tendon off-position" / 中国组织工程研究

BACKGROUND:"Tendon off-position"is a disease name included in the International Classification of Diseases 11th Revision,and also a clinical indication of manipulation,acupuncture and other treatments.However,its specific mechanism is still unclear.It is urgent to establish an animal model that can reflect the clinical and pathological characteristics of"tendon off-position,"so as to further study the mechanism of effective clinical treatments. OBJECTIVE:To establish an animal model of"tendon off-position"in rats based on isometric contraction of skeletal muscles,and to explore the changes of skeletal muscle function and morphological phenotype after"tendon off-position." METHODS:Sixty rats were randomly divided into control group,static-loading group and extra loading group,with twenty rats in each group.Rats in the control group were kept normally without treatment.In the latter two groups,the rats were fixed by the self-made static-loading modeling device and a static-loading(the body mass of each rats was applied as the static-loading)was applied to cause sustained isometric contraction of the upper limb muscles.Then,animal models of"tendon off-position"were successfully established.In the extra loading group,50%of the body mass was added to the ankle joint after modeling.The skeletal muscle samples were harvested at 2 and 4 weeks after modeling.The changes of limb grip strength,wet mass of skeletal muscle,and serum levels of creatine kinase-muscle and lactate dehydrogenase A were measured,and the changes of skeletal muscle histomorphology and ultrastructure were observed. RESULTS AND CONCLUSION:At 2 weeks after modeling,the rats in the static-loading group and extra loading group showed significantly decreased grip strength and wet muscle mass,significantly increased serum levels of creatine kinase-muscle and lactate dehydrogenase A,and abnormal muscle fiber morphology and structure accompanied by a large number of deposited collagen fibers.Electron microscopy results showed that the structure of myofibrils was disordered,the Z-line was distorted,and the light and dark boundaries were blurred.At 4 weeks after modeling,the grip strength of the model rats was increased compared with that at 2 weeks,the serum creatine kinase-muscle and lactate dehydrogenase A levels were decreased,and the changes of muscle fiber morphology and ultrastructure were recovered to varying degrees.It is suggested that the rat skeletal muscle injury model based on continuous isometric contraction of skeletal muscle can well reflect the pathological characteristics of"tendon off-position"at 2 weeks,and can be used to study the mechanism of acupuncture and manipulation in the treatment of"tendon off-position."

Rate of force development and its relationship with functional performance in patients after anterior cruciate ligament reconstruction / 中国组织工程研究

BACKGROUND:The maximum muscle strength is typically used for evaluating the recovery of muscle function after anterior cruciate ligament reconstruction.Recent studies have suggested that neuromuscular function should also be considered,such as rate of force development,which measures the slope of the force time curve at different time intervals under conditions of isometric muscle contraction. OBJECTIVE:To elaborate on the current research status and shortcomings of muscle isometric rate of force development in patients undergoing anterior cruciate ligament reconstruction surgery,and analyze the degree of defects in quadriceps femoris and hamstring isometric rate of force development at different times after surgery;to analyze the effect of isometric rate of force development on postoperative functional performance,thereby providing important information for optimizing postoperative rehabilitation following anterior cruciate ligament reconstruction,reducing secondary injury to patients,and reducing the incidence of knee osteoarthritis. METHODS:Literature retrieval of CNKI,VIP,WanFang and PubMed was performed using"anterior cruciate ligament,rate of force development"as Chinese search terms and"anterior cruciate ligament,rate of force development,rate of torque development"as English search terms.Finally,69 articles were included according to inclusion and exclusion criteria. RESULTS AND CONCLUSION:Most studies have found defects in bilateral muscle isometric rate of force development in patients undergoing anterior cruciate ligament reconstruction within 6 months.Early isometric rate of force development of the bilateral hamstring muscles(i.e.the slope of the force time curve at any time interval during muscle contraction of 100 ms)showed significant improvement after 6 months.However,long-term defects in early isometric rate of force development of the bilateral quadriceps indicate long-term damage to the neuromuscular function of the quadriceps after surgery.There is limited research on late isometric rate of force development(the slope of the force time curve at any time interval after 100 ms of muscle contraction),and conclusions cannot be drawn.Regarding landing exercises(jumping to the ground,lateral cutting,etc.)and daily activities(walking,running),early isometric rate of force development of the quadriceps is more correlated with isometric peak torque.Abnormal biomechanical changes during exercise are considered an important risk factor for secondary injury and traumatic knee osteoarthritis in patients.Actively improving early isometric rate of force development of the quadriceps may reduce the incidence of secondary injury and traumatic knee osteoarthritis.Currently,there is limited evidence to suggest that whole-body vibration training can improve early isometric rate of force development of the quadriceps femoris in patients undergoing anterior cruciate ligament reconstruction.It is recommended to use neuromuscular electrical stimulation to intervene in the quadriceps and hamstring in the early postoperative stage and implement explosive force and high resistance training in the late postoperative stage,which may improve the isometric rate of force development in patients.Generating sufficient muscle strength in a short period of time is necessary to effectively protect the anterior cruciate ligament,while the relationship between isometric rate of force development in the hamstring muscle and functional performance is still unclear,which may provide information on preventing secondary injury in patients.It is recommended to use the isometric rate of force development as one of the evaluation indicators for guiding rehabilitation and restoring movement.In addition to focusing on improving symmetry and differences from normal individuals,the hamstring to quadriceps strength ratio should also be considered.An appropriate range of ratios can ensure the balance of muscles during rapid muscle exertion,which may reduce the occurrence of secondary injuries.However,the normal range of ratios is not yet clear.Future research should consider the effects of graft type and knee flexion angle on isometric rate of force development,in order to identify neuromuscular dysfunction in patients as much as possible and help them recover better.

Preparation of static training animal models and research status analysis / 针灸推拿医学（英文版）

As a form of Tuina(Chinese therapeutic massage)Qigong exercises and an essential part of exercise therapy,static training has proven clinical efficacy.However,further evidence is required to reveal its mechanism of action provided by animal experiments.There are four major ways to establish static training animal models:pole climbing,hind-limb suspension,isometric-contraction weight bearing,and electrical stimulation.These models have been used to study diseases of the motor,circulatory,and endocrine systems,etc.,and the mechanism has got extensive exploration.It reviewed static training animal models and the research progress to provide theoretical evidence for static training's experimental research and mechanism exploration.

Strength of scapular elevation in women with TMD and asymptomatic women - a cross-sectional study

Temporomandibular disorder (TMD) is recognized for its high prevalence, presenting characteristic signs and symptoms. Cervical spine pain is present in 70% of diagnosed TMD cases. Aim To verify if women with TMD present changes in isometric muscle strength in the scapula elevation. Methods This is an observational, cross-sectional study. Thirty-five women, aged 22.89±2.04 years, were divided into the TMD group (TMDG), diagnosed with TMD according to the DC/TMD, and control group (CG), with asymptomatic individuals. The volunteers accessed a online link by the smartphone in order to answer questions on personal data, the Fonseca Anamnestic Index (FAI), Neck Disability Index (NDI), and Masticatory preference. In all participants, evaluation of the force of the scapula elevation muscles was performed, using a load cell model MM-100 (Kratos® SP, Brazil). Data were analyzed descriptively using the maximum, mean, and standard deviation and a two-way ANCOVA test was applied for all variables. A significance level of 5% was considered. Results There were no statistically significant differences between the TMDG and CG for the maximal and mean muscle strength of scapular elevation. There were statistically significant differences in FAI (p <0.001*) between the CG and the TMDG. Conclusion Based on the results, it was not possible to confirm the hypothesis that women diagnosed with TMD present lower isometric strength during scapular elevation (right/left).

Gender-based Variations in Trunk Motion and Isometric Strength in Young Adults with Low Back Pain: A Prospective Case-control Study / Variações baseadas em gênero no movimento e na força isométrica do tronco em jovens adultos com dor lombar: Um estudo de caso-controle prospectivo

Abstract Objective To determine gender-based variations in trunk range of motion (RoM) and isometric strength (IS) in symptomatic and asymptomatic young adults. Methods In this prospective case-control study, 73 subjects with low back pain (LBP) and 80 asymptomatic subjects were analyzed. Dynamometer-based device trunk RoM and IS measurements in extension, flexion, and rotation were compared in both groups and gender-based subgroups. Multivariate analysis was used to determine factors influencing trunk RoM and IS. Results Symptomatic males had significantly less extension RoM and extension, flexion, and rotation isometric trunk strength (ITS) (p < 0.0001) compared with asymptomatic males, whereas no significant difference was found between asymptomatic and symptomatic females. However, the mean extension-flexion RoM and mean extension-flexion ITS ratios were significantly lower (p = 0.04) in asymptomatic females compared with symptomatic females. Female gender was significantly associated with less extension and flexion ITS in both asymptomatic and symptomatic subjects. Conclusion Males with LBP had significant global ITS weakness when compared with asymptomatic males. Despite no significant ITS difference in symptomatic versus asymptomatic females, LBP caused significant extension-flexion RoM and ITS imbalance in females. These gender-based variations in trunk RoM and IS, especially the extensor-flexor IS imbalance in females, must be considered while designing rehabilitation treatment protocols for LBP.

Resumo Objetivo Determinar as variações na amplitude de movimento (ADM) do tronco e na força isométrica do tronco (FIT) em jovens adultos sintomáticos e assintomáticos baseadas no gênero dos indivíduos. Métodos Neste estudo caso-controle prospectivo, 73 indivíduos com dor lombar (DL) e 80 indivíduos assintomáticos foram analisados. As medidas de ADM do tronco e FIT de extensão, flexão e rotação foram comparadas em ambos os grupos e em subgrupos organizados por gênero. A análise multivariada foi usada para determinar os fatores que influenciam a ADM do tronco e a FIT. Results Symptomatic males had significantly less extension RoM and extension, flexion, and rotation isometric trunk strength (ITS) (p < 0.0001) compared with asymptomatic males, whereas no significant difference was found between asymptomatic and symptomatic females. However, the mean extension-flexion RoM and mean extension-flexion ITS ratios were significantly lower (p = 0.04) in asymptomatic females compared with symptomatic females. Female gender was significantly associated with less extension and flexion ITS in both asymptomatic and symptomatic subjects. Conclusão Indivíduos do sexo masculino com DL apresentaram significativa fraqueza global relacionada à FIT quando comparados com indivíduos do sexo masculino assintomáticos. Apesar de não haver diferença significativa de FIT em indivíduos do sexo feminino sintomáticos versus assintomáticos, a DL impactou a ADM e a FIT de extensão-flexão em indivíduos do sexo feminino. Essas variações de ADM do tronco e FIT baseadas no sexo, especialmente o desequilíbrio extensor-flexor de força isométrica em indivíduos do sexo feminino, devem ser consideradas ao projetar-se protocolos de tratamento de reabilitação para lombalgia.

The effects of neuromuscular electrical stimulation on strength, pain, and function in individuals with knee osteoarthritis: a systematic review with meta-analysis / Efeitos da estimulação elétrica neuromuscular na força, dor e função em indivíduos com osteoartrite de joelho: uma revisão sistemática com meta-análise / Efectos de la electroestimulación neuromuscular sobre la fuerza, el dolor y la función en personas con osteoartritis de la rodilla: una revisión sistemática con metaanálisis

ABSTRACT We aimed to investigate the effects of neuromuscular electrical stimulation on muscle strength, pain relief, and improvement in function in patients with knee osteoarthritis. Databases were searched from December 2017 to July 2020 and included PubMed, Embase, LILACS, and the Cochrane Central Register of Controlled Trials. A manual search was also performed by checking the reference lists of eligible articles. The PRISMA guidelines were followed. The studies selected compared NMES with an exercise program on isometric muscle strength as a primary outcome. The secondary outcomes were pain and function. The quality of the studies was assessed using the Risk of Bias assessment and PEDro scale, and the overall quality of the evidence was assessed using the GRADE approach. Eight studies were included in this systematic review. A total of 571 patients were analyzed. Neuromuscular electrical stimulation associated with exercise promoted an increase in isometric strength of the quadriceps muscle compared to the active control group, demonstrating heterogeneity and statistical difference (95% CI=1.16 to 5.10, I2=97%, p=0.002; very low-certainty evidence). NMES associated with exercise did not improve physical function (95% CI=−0.37 to 0.59, I2=0%, p=0.67; low-certainty evidence) and showed controversial results for pain compared to an active control group (qualitative assessment). In conclusion, NMES induces an increase in muscle strength in patients with osteoarthritis compared to an active control group. No differences were found for physical function and pain outcomes. Further research is needed due to the uncertain level of evidence.

RESUMO O objetivo deste estudo foi investigar os efeitos da estimulação elétrica neuromuscular (EENM) na força muscular, alívio da dor e melhora da função em pacientes com osteoartrite de joelho. Realizou-se uma pesquisa em diferentes bases de dados, como PubMed, Embase, LILACS e o Cochrane Central Register of Controlled Trials, no período de dezembro de 2017 até julho de 2020. Procedeu-se a uma busca manual com o intuito de verificar as listas de referências dos artigos elegíveis. As diretrizes PRISMA foram seguidas. Os estudos selecionados comparavam a estimulação elétrica neuromuscular com um programa de exercícios de força muscular isométrica como desfecho primário. Os resultados secundários foram dor e função. A qualidade dos estudos foi avaliada usando avaliação de risco de viés e a escala PEDro e a qualidade geral das evidências foi avaliada usando a abordagem GRADE. Oito estudos foram incluídos nesta revisão sistemática com um total de 571 pacientes analisados. A EENM associada ao exercício promoveu o aumento da força isométrica do músculo quadríceps em relação ao grupo controle ativo, demonstrando heterogeneidade e diferença estatística (IC 95%=1,16 a 5,10, I2=97%, p=0,002; evidência de muito baixa certeza), mas não melhorou a função física (IC 95%=−0,37 a 0,59, I2=0%, p=0,67; evidência de baixa certeza) e mostrou resultados controversos para dor em comparação ao grupo de controle ativo (avaliação qualitativa). Conclui-se que a EENM induz o aumento da força muscular em pacientes com osteoartrite, porém não foram encontradas diferenças nos resultados de funcionalidade e dor em comparação com o grupo de controle ativo. Devido à incerteza das evidências, são necessárias mais pesquisas sobre o assunto.

RESUMEN El objetivo de este estudio fue analizar los efectos de la electroestimulación neuromuscular (NMES) sobre la fuerza muscular, el alivio del dolor y la mejora de la función en pacientes con osteoartritis de la rodilla. Se realizó una búsqueda en las bases de datos PubMed, Embase, LILACS y Cochrane Central Register of Controlled Trials, en el periodo de diciembre de 2017 y julio de 2020. Se llevó a cabo una búsqueda manual para verificar las listas de referencias de los artículos elegibles. Se aplicó las pautas PRISMA. Los estudios seleccionados compararon la electroestimulación neuromuscular con un programa de ejercicio de fuerza muscular isométrica como resultado primario. Los resultados secundarios fueron el dolor y la función. La calidad de los estudios se evaluó mediante la evaluación del riesgo de sesgo y la escala PEDro, y la calidad general de la evidencia se estimó con el uso del sistema GRADE. Ocho estudios con un total de 571 pacientes compusieron esta revisión sistemática. La EENM asociada con el ejercicio aumentó la fuerza isométrica del músculo cuádriceps en comparación con el grupo control activo, demostrando una heterogeneidad y diferencia estadística (IC 95%=1,16 a 5,10, I2=97%, p=0,002; evidencia con muy baja seguridad), pero no mejoró la función física (IC 95%=−0,37 a 0,59, I2=0%, p=0,67; evidencia con baja seguridad) y mostró resultados controvertidos para el dolor en comparación con el grupo control activo (evaluación cualitativa). Se concluyó que la EENM indujo un aumento de la fuerza muscular en pacientes con osteoartritis, pero no se encontraron diferencias en los resultados de función y dolor en comparación con el grupo control activo. Debido a la incertidumbre de la evidencia, se necesitan más estudios sobre el tema.

Delayed onset muscle soreness intensity affects muscular performance / El Dolor muscular de aparición tardía afecta el desempeño muscular

Abstract Background: The study of functional impact of delayed onset muscle soreness has been limited to describe the decline on maximal isometric contraction, but muscular work and time to peak torque has not been examined yet. Purpose: To describe the changes induced by a session of lengthening contractions on muscle performance and delayed onset muscle soreness (DOMS). Methods: A quasi-experimental study was conducted in the Institutional laboratory; Twenty healthy men; mean age 21 SD 0.34 were recruited, all subjects performed 200 lengthening contractions of the quadriceps at 120°/s. Isometric and isokinetic peak torque, muscular work, time to peak torque, DOMS and creatine kinase activity were assessed at baseline, 48 h and 96 h post-exercise. The muscle performance was assessed with an isokinetic dynamometer and DOMS with a visual analog scale (VAS). Results: Relative to baseline, isometric and isokinetic peak torque and muscular work decreased in ~30% at 48 h post-exercise; delayed onset muscle soreness increased ~300%, which remained at 96 h post-exercise. Conclusions: These reflect that the decline in muscular performance is due to the changes in peak torque and muscular work, which has greater implications on muscle function. No changes were detected in time to peak torque. The alterations in muscular performance variables are accompanied by delayed onset muscle soreness which has also a negative impact on force production (29% of the drop on peak torque is explain by soreness intensity).

Resumen Introducción: Los estudios de impacto funcional del dolor muscular de aparición tardía (DMAT) se han limitado a describir la disminución de la contracción isométrica máxima, pero aún no se ha examinado el trabajo muscular y el tiempo del torque máximo. Objetivo: Describir los cambios inducidos por una sesión de ejercicio excéntrico sobre el rendimiento muscular y DMAT. Método: se realizó un estudio cuasi-experimental, los participantes fueron veinte hombres sanos; edad media 21 DE 0,34, todos los sujetos realizaron 200 contracciones excéntricas del cuádriceps a 120°/s. Se evaluó el torque pico isométrico e isocinético, el trabajo muscular, el tiempo hasta el torque máximo, DMAT y la actividad de la creatina quinasa al inicio, 48 h y 96 h después del ejercicio, el rendimiento muscular se evaluó con un dinamómetro isocinético y DOMS con una escala análoga visual (EAV). Resultados: en relación con la línea de base, el torque pico isométrico e isocinético y el trabajo muscular disminuyeron en ~ 30 % a las 48 h post-ejercicio; El dolor muscular de aparición tardía aumentó ~300 %, que permaneció 96 h después del ejercicio. Conclusiones: los resultados reflejan que la disminución del rendimiento muscular se debe a los cambios en el torque pico y trabajo muscular, lo que tiene mayores implicaciones en la función muscular. No se detectaron cambios en el tiempo hasta el torque máximo. Las alteraciones en las variables de rendimiento muscular se acompañan de DMAT que también tiene un impacto negativo en la producción de fuerza (el 29 % de la caída en el torque máximo se explica por la intensidad del dolor).

Influence of maximal isometric strength on 20-meter sprint time / Influência da força isométrica máxima sobre o tempo em sprints de 20 metros / Influencia de la fuerza isométrica máxima sobre el tiempo en sprints de 20 metros

ABSTRACT Introduction The squat is an exercise that is widely used for the development of strength in sports. However, considering that not all sports gestures are vertical, it is important to investigate the effectiveness of propulsive force stimuli applied in different planes. Objective The main purpose of this study was to determine the influence of maximum isometric force (MIF) exerted on starting blocks over performance in 5, 10 and 20-meter sprints. Methods Seven high-level male sprinters (mean age ± SD = 28 ± 5.77 years) participated in this study. The variables were: a) MIF in squats and on starting blocks (measured using a functional electromechanical dynamometer [FEMD]), b) time in 5, 10 and 20-m sprints and c) jump height (measured by the squat jump test). For data analysis, a Pearson correlation was performed between the different variables. The criteria for interpreting the strength of the r coefficients were as follows: trivial (<0.1), small (0.1−0.3), moderate (0.3−0.5), high (0.5−0.7), very high (0.7−0.9), or practically perfect (>0.9). The level of significance was p < 0.05. Results There was very high correlation between MIF exerted on starting blocks and performance in the first meters of the sprint (5-m: r = -0.84, p = 0.01). However, there was small correlation between MIF in squats and performance in the first meters of the sprint (5-m: r = -0.22, p < 0.62). Conclusion The MIF applied on starting blocks correlates very high with time in the first meters of the sprint in high-level athletes. In addition, the use of the FEMD provides a wide range of possibilities for evaluation and development of strength with a controlled natural movement. Level of evidence IV; Prognostic Studies - Case series.

RESUMO Introdução O agachamento é um exercício amplamente utilizado para o desenvolvimento de força nos esportes. No entanto, considerando que nem todos os gestos esportivos são verticais, é importante investigar a eficácia dos estímulos de força propulsiva em diferentes planos. Objetivo O principal objetivo deste estudo foi determinar a influência da força isométrica máxima (FIM) exercida em os blocos de largada sobre o desempenho em sprints de 5, 10 e 20 metros. Métodos Sete velocistas de alto nível do sexo masculino (média ± DP = 28,0 ± 5,77 anos) fizeram parte deste estudo. As variáveis foram: a) FIM no agachamento e nos blocos de largada (avaliados com um dinamômetro eletromecânico funcional (DEF)), b) tempo de sprints de 5, 10 e 20 metros e c) altura do salto (medida pelo teste de squat jump). Para análise dos dados, foi usada a correlação de Pearson entre as diferentes variáveis. Os critérios para interpretar o coeficiente r foi: nulo (< 0,1), pequeno (0,1 a 0,3), moderado (0,3 a 0,5), alto (0,5 a 0,7), muito alto (0,7 a 0,9) ou praticamente perfeito (> 0,9). O nível de significância foi p < 0,05. Resultados Houve correlação muito alta entre a FIM exercida nos blocos de largada e o desempenho nos primeiros metros do sprint (5-m: r = -0,84, p = 0,01). No entanto, a correlação entre o agachamento da FIM e os primeiros metros de sprint foi pequena (5-m: r = -0,22, p < 0,62). Conclusão A FIM aplicada aos blocos de largada teve uma correlação muito alto com o tempo nos primeiros metros de sprint em atletas de alto nível. Além disso, o uso de um DEF oferece uma ampla gama de possibilidades para avaliar e desenvolver força com um movimento natural controlado. Nível de evidência IV; Estudos Prognósticos - Série de casos.

RESUMEN Introducción La sentadilla es un ejercicio ampliamente usado para el desarrollo de fuerza en los deportes. Sin embargo, considerando que no todos los gestos deportivos son verticales, es importante investigar la eficacia de los estímulos de fuerza propulsiva en diferentes planos. Objetivo El principal objetivo de este estudio fue determinar la influencia de la fuerza isométrica máxima (FIM) ejercida en los bloques de salida sobre el rendimiento en sprints de 5, 10 y 20 metros. Métodos Siete velocistas de alto nivel del sexo masculino (promedio ± SD = 28,0 ± 5,7 años) formaron parte de este estudio. Las variables fueron: a) FIM en la sentadilla y en los bloques de salida (evaluados con un dinamómetro electromecánico funcional [DEF]) b) tiempo de sprints de 5, 10 y 20-metros y c) altura del salto (medida a través del test de squat jump). Para el análisis de los datos se usó la correlación de Pearson entre las diferentes variables. Los criterios para interpretar el coeficiente r fueron: nulo (<0,1), pequeño (0,1 a 0,3), moderado (0,3 a 0,5), alto (0,5 a 0,7), muy alto (0,7 a 0,9) o prácticamente perfecto (>0,9). El nivel de significancia fue p < 0,05. Resultados Hubo correlación muy alta entre la FIM ejercida en los bloques de salida y el rendimiento en los primeros metros del sprint (5-m: r = -0,84, p = 0,01). Sin embargo, la correlación entre la FIM en sentadilla y los primeros metros de sprint fue pequeña (5-m: r = -0,22, p < 0,62). Conclusión La FIM aplicada a los bloques de salida tuvo una correlación muy alta con el tiempo en los primeros metros de sprint en atletas de alto nivel. Además, el uso de un DEF ofrece una amplia gama de posibilidades para evaluar y desarrollar fuerza con un movimiento natural controlado. Nivel de evidencia IV; Estudios pronósticos: Serie de casos.

Effects of Different Interventions on Activation Mode of Trapezius Muscle during Exercise / 中国康复理论与实践

Objective:To analyze the activation characteristics of trapezius muscle in normal people, and explore whether different interventions could restore the activation pattern of people with abnormal trapezius muscles to normal during subsequent exercises. Methods:From September to October, 2017, 20 persons with normal shoulder joints (control group) and 20 persons with mild discomfort in shoulder joints (observation group) participated in the study. All of them were treated randomly with four steps, including no intervention, static traction of upper trapezius muscle (UT), isometric contraction of lower trapezius muscle (LT) and combined intervention. Then, they were asked to complete three actions, including straight arm side lifting, sitting in rowing and flying birds. Myoelectric signal was recorded before and after test. Results:Compared with the control group, the UT activation degree increased (P < 0.05), and the activation time shortened (P < 0.05); the activation degrees of middle trapezius muscle (MT) and LT decreased (P < 0.05), and the activation time delayed (P < 0.05); the ratios of UT/LT and UT/MT increased (P < 0.05) in the observation group with no intervention. After static traction of UT, isometric contraction of LT, and both interventions, the MVE%, activation time and the ratios of activation varied in different muscles under different actions in both groups (P < 0.05). Conclusion:In different actions, the activation degree and activation time of three trapezius muscles are different. Static traction of UT and isometric contraction of LT before exercise could improve the activation pattern of trapezius muscles of people with shoulder joint discomfort during exercise, which is conducive to the normal function of the shoulder joint.

Análise de diferentes tarefas para normalização do sinal elétrico do músculo orbicular da boca pela contração voluntária máxima: estudo piloto / Analysis of different tasks to normalize the electrical signal of the orbicularis oris muscle by maximum voluntary contraction: pilot study

RESUMO Objetivo pesquisar a atividade elétrica do músculo orbicular da boca em quatro diferentes tarefas isométricas e indicar a mais apropriada para utilização como referência na normalização do sinal elétrico do músculo orbicular da boca pela contração voluntária máxima. Métodos participaram do estudo 22 indivíduos, sendo dez do sexo masculino e 12 do feminino, com idades entre 20 e 33 anos. A atividade elétrica das porções superior e inferior do músculo orbicular da boca foi registrada durante a realização das seguintes tarefas isométricas: protrusão labial com fechamento, protrusão labial sem fechamento, contrarresistência com a placa de resistência labial e preensão de lábios. A ordem de realização das tarefas foi randomizada entre os participantes. Os dados foram comparados entre as tarefas, para cada seguimento labial. Resultados no segmento marginal superior, a tarefa com maior média e mediana de amplitude foi preensão labial, embora sem diferença significativa entre tarefas. O menor coeficiente de variação foi obtido na tarefa de contrarresistência com a placa de resistência labial. No segmento marginal inferior, a tarefa com maior média e mediana de amplitude foi protrusão labial com fechamento, que também teve o menor coeficiente de variação e diferença significativa entre as tarefas protrusão labial com fechamento e preensão, sendo os maiores valores obtidos na primeira. Conclusão indica-se como referência para a normalização do sinal elétrico do músculo orbicular da boca, pela contração voluntária máxima, a tarefa de protrusão labial com fechamento.

ABSTRACT Purpose To verify the electrical activity of the orbicularis oris in four different isometric tasks and to indicate the most appropriate task for use as a reference in the normalization of the electrical signal of the orbicularis oris muscle by maximum voluntary contraction. Methods Twenty-two individuals participated in the study, of which 10 were male and 12 were female, with ages ranging from 20 to 33 years. The electrical activity of the upper and lower parts of orbicularis oris muscle was recorded during the following isometric tasks: lip protrusion with bilabial closure; lip protrusion without bilabial closure; the counter resistance using the plate of labial resistance and lips prehension. The order of the tasks was randomized among participants. Data were compared between tasks for each lip part. Results in the upper marginal segment, the task with the highest mean and median amplitude was lip prehension, although there was no significant difference between tasks. The lowest coefficient of variation was obtained in the counter resistance task with the plate of labial resistance. In the lower marginal segment, the task with the highest mean and median amplitude was labial protrusion with lips closure, which also had the lowest coefficient of variation. In this segment, there was a significant difference between labial protrusion with lips closure and prehension, with the highest values obtained in the first task. Conclusion lip protrusion with bilabial closure is suggested as reference for the normalization of the electrical signal of the orbicularis oris muscle, by maximum voluntary contraction.

Entrenamiento de handgrip isométrico de alta intensidad en adultos mayores pre-hipertensos y con diagnóstico de hipertensión arterial sistémica etapa I / Effects high intensity isometric handgrip training on blood pressure of hypertensive older people

Background: Moderate isometric handgrip exercise is an effective tool in the management of systemic hypertension. Aim: To evaluate the effectiveness of a high intensity isometric handgrip exercise protocol for the reduction of blood pressure in older people with pre or stage-1 hypertension. Material and Methods: Twenty-three participants aged 73.8 ± 6.6 years (range 61-90) completed eight weeks of high intensity isometric handgrip training 2 times per week, performing 32 contractions maintained for 5 seconds, with breaks of 5 seconds. Blood pressure (BP) was measured at baseline and at the end of the intervention. Results: Systolic blood pressure decreased from 141 ± 11 to 127 ± 10 mmHg (p < 0.01). The decrease in diastolic blood pressure was from 79 ± 7 to 74 ± 6 mmHg (p < 0.01). Conclusions: A blood pressure reduction was recorded in these participants after a period of high intensity isometric handgrip exercise.

Pilates training induces changes in the trunk musculature of adolescents / Treinamento com pilates induz alterações na musculatura do tronco de adolescentes / Entrenamiento de pilates induce cambios en la musculatura del tronco de adolescentes

ABSTRACT Introduction The Pilates Method may be an appropriate form of exercise for improving trunk muscle strength, which can be a predictor of pain and musculoskeletal problems. Objective The objective of this study was to assess the effects of the Pilates Method on muscle strength and endurance of the extensor and flexor muscles of the trunk in a group of adolescents. Methods The sample consisted of 101 high-school students divided into two groups: an experimental group (EG=81) and a control group (CG=20). The intervention was carried out twice a week for six weeks. Each session lasted 55 minutes, and was divided into three parts: warm-up, main part, and cool down. Muscle strength was assessed by the Sörensen Test and the Bench Trunk-curl Test. The paired sample T-test, the T- test for independent samples, and Pearson's correlation coefficient were applied. The size of the effect (d) was determined. Results The EG showed significant improvements in both tests (+34.77 points; +18.55 points, respectively). No changes were observed in the CG. The effect size was high (d>1.15) for both tests, which means that the results were improved in a large proportion of the participants. The control group showed a decline in strength of the trunk musculature. In the experimental group, both boys and girls showed significant improvements in both tests. This strength increase was enhanced for a large proportion of boys and girls (d>1.15). The effect size was high (d>1.15) for both tests and for both sexes. Conclusion Six-weeks after implementing the Pilates Method in Physical Education lessons, the muscle strength of the flexor and extensor muscles of the trunk in adolescents was improved. Level of Evidence II; Therapeutic studies-Investigation of treatment results.

RESUMO Introdução O método Pilates pode ser uma forma adequada de exercício para melhorar a força dos músculos do tronco, que podem ser um preditor de dor e problemas musculoesqueléticos. Objetivo O objetivo deste estudo foi avaliar os efeitos do método Pilates sobre a força muscular e resistência dos músculos extensores e flexores do tronco em um grupo de adolescentes. Métodos A amostra foi composta de 101 estudantes do ensino médio divididos em dois grupos: um grupo experimental (GE = 81) e um grupo controle (GC = 20). A intervenção foi realizada duas vezes por semana durante seis semanas. Cada sessão durou 55 minutos e foi dividida em três partes: aquecimento, parte principal e relaxamento. A força muscular foi avaliada com o teste de Sörensen e o teste de flexão abdominal com apoio de pernas. Para a análise de dados, foram empregados o teste t de amostras pareadas, o teste t para amostras independentes e o coeficiente de correlação de Pearson. O tamanho do efeito (d) foi determinado. Resultados O GE apresentou melhoras significativas em ambos os testes (+34,77 pontos; +18,55 pontos, respectivamente). Não foram observadas alterações no GC. O tamanho do efeito foi alto (d > 1,15) para ambos os testes, o que significa que os resultados foram melhores em uma grande proporção de participantes. O grupo controle apresentou declínio da força muscular do tronco. No grupo experimental, meninos e meninas apresentaram melhoras significativas em ambos os testes. Esse aumento de força foi atingido por uma alta proporção de meninos e meninas (d > 1,15). O tamanho do efeito foi alto (d > 1,15) nos dois testes e sexos. Conclusão Seis semanas depois da implantação do método Pilates nas aulas de educação física, a força muscular dos flexores e extensores do tronco aumentou nos adolescentes. Nível de Evidência II; Estudos Terapêuticos - Investigação dos resultados do tratamento.

RESUMEN Introducción El método Pilates puede ser una forma apropiada de ejercicio para la mejora de la fuerza de la musculatura del tronco, la cual puede ser un predictor de dolor y problemas musculoesquéticos. Objetivo El objetivo de este estudio fue evaluar los efectos del método Pilates sobre la fuerza muscular y la resistencia de los músculos extensores y flexores del tronco en un grupo de adolescentes. Métodos La muestra consistió en 101 estudiantes de secundaria divididos en dos grupos: un grupo experimental (GE = 81) y un grupo control (GC = 20). La intervención se realizó dos veces a la semana durante seis semanas. Cada sesión duró 55 minutos y se dividió en tres partes: calentamiento, parte principal y relajación. La fuerza muscular se evaluó mediante la prueba de Sörensen y la prueba de flexión abdominal con apoyo de piernas. Se aplicaron pruebas t de muestras pareadas t de muestras independientes y el coeficiente de correlación de Pearson. Se determinó el tamaño del efecto (d). Resultados El GE mostró mejoras significativas en ambas pruebas (+34,77 puntos; +18,55 puntos, respectivamente). No se observaron cambios en el GC. El tamaño del efecto fue alto (d > 1,15) para ambas pruebas, lo que significa que los resultados mejoraron en una gran proporción de participantes. El grupo control mostró una disminución en la fuerza de la musculatura del tronco. En el grupo experimental, tanto los niños como las niñas mostraron mejoras significativas en ambas pruebas. Este aumento de la fuerza fue mayor para una alta proporción de niños y niñas (d > 1,15). El tamaño del efecto fue alto (d > 1,15) para ambas pruebas y para ambos sexos. Conclusión Después de seis semanas de implementar el método Pilates en las clases de educación física, se mejoró la fuerza muscular de los flexores y extensores del tronco en adolescentes. Nivel de evidencia II; Tipo de estudio: Estudios terapéuticos - Investigación de resultados de tratamiento.

Balance autonómico basal y durante el ejercicio isométrico en jóvenes con diferente reactividad cardiovascular / Basal autonomic balance and during the isometric exercise in young people with different cardiovascular reactivity

RESUMEN Introducción: El sistema nervioso autónomo desempeña un papel importante en los reajustes cardiovasculares al ejercicio. En la hiperreactividad cardiovascular existe una mayor sensibilidad del sistema simpático ante diferentes estímulos estresantes. Objetivo: Determinar las características del control autonómico cardíaco en adultos jóvenes con diferentes grados de reactividad cardiovascular en condiciones basales y durante el ejercicio isométrico. Método: La muestra estuvo constituida por 97 individuos de ambos sexos, y se dividió en tres grupos: normorreactivos, hiperreactivos y con respuesta hipertensiva, de acuerdo a la respuesta presora a la prueba del peso sostenido. A todos los individuos se les realizó un estudio de variabilidad de la frecuencia cardíaca en reposo y durante la prueba isométrica. Se estudiaron las variables en el dominio de la frecuencia: baja, alta, relación baja/alta en reposo, y los parámetros del diagrama de Poincaré en reposo y durante el ejercicio (valores de desviación estándar 1 [SD1], 2 [SD2], y la razón entre ambos). Resultados: En estado basal los individuos hiperreactivos y con respuesta hipertensiva presentaron un predominio simpático sobre la función cardíaca y una menor variabilidad de la frecuencia cardíaca. Durante el ejercicio isométrico disminuyeron los valores de los ejes SD1 y SD2 en todos los grupos y la razón SD1/SD2 decreció en individuos normorreactivos y con respuesta hipertensiva; pero apenas se modificó en los hiperreactivos. Conclusiones: En los individuos con hiperreactividad cardiovascular ya está presente un desbalance autonómico en estado basal y existe una reducción de la modulación autonómica vagal durante el ejercicio, que puede favorecer el desarrollo de la hipertensión arterial.

ABSTRACT Introduction: The autonomic nervous system plays an important role in cardiovascular readjustments to exercise. In cardiovascular hyperreactivity there is a greater sensitivity of the sympathetic system to different stressors. Objective: To determine the characteristics of cardiac autonomic control in young adults with different degrees of cardiovascular reactivity under basal conditions and during isometric exercise. Method: The sample consisted of 97 individuals of both sexes, and was divided into three groups: normoreactive, hyperreactive and with hypertensive response, according to the pressor response to weight-bearing tests. The individuals underwent a complete study of heart rate variability at rest and during isometric test. The frequency domain for the variables was: low, high, low/high resting ratio, and the parameters of Poincaré plots at rest and during exercise (values of standard deviation 1 [SD1], 2 [SD2], and the reason between them). Results: Under basal conditions, hyperreactive individuals with a hypertensive response had a sympathetic predominance over cardiac function and lower heart rate variability. During the isometric exercise SD1 and SD2 axes values decreased in all groups and SD1/SD2 ratio decreased in normoreactive individuals with hypertensive response; but it was hardly modified in those hyper-reactive. Conclusions: Individuals with cardiovascular hyperreactivity have a prior autonomic imbalance under basal conditions and a reduction of autonomic vagal modulation during exercise that may favor the development of arterial hypertension.

Analysis of Recruitment Pattern of Related Muscles in Two Types of Active Straight Leg Raise / 中国康复理论与实践

Objective:To compare the rate of recruitment in two types of active straight leg raise (ASLR) and to investigate the activation patterns of the related muscles. Methods:From June to October, 2018, eleven healthy subjects were recruited. Surface electromyography (sEMG) signals of unilateral rectus femoris, bilateral rectus abdominis, internal oblique abdominis, external oblique abdominis and multifidus were recorded in normal ASLR (Action A) and raising leg for ten seconds (Action B). %maximal voluntary isometric contraction (MVIC) of these muscles was processed and analyzed. Results:%MVIC of ipsilateral internal oblique muscle and external oblique muscle were greater than the opposite side (t > 2.549, P < 0.05) in Action A; %MVIC of ipsilateral internal oblique muscle, external oblique muscle and rectus abdominis muscle were greater than the opposite side (t > 2.240, P < 0.05) in Action B; compared with action B, Action A had higher %MVIC of bilateral internal oblique and rectus femoris (t > 3.549, P < 0.05). Conclusion:The activation mode of ipsilateral dominance was shown in both actions, and the different motion control strategies may be adopted by the neuromuscular system in different ASLR.

Effects of Isometric Handgrip Exercise versus Aerobic Exercise on Arterial Stiffness and Brachial Artery Flow-Mediated Dilation in Older Hypertensive Patients / 대한스포츠의학회지

PURPOSE: Isometric handgrip exercise (IHE) is an easy and accessible form of exercise that has beneficial effects on blood pressure (BP). However, it remains unclear whether IHE is similar benefits on arterial stiffness and endothelial function compared with aerobic exercise (AE) in elderly hypertensive patients. The aim of this study was to compare the effects of IHE versus AE on arterial stiffness and endothelial function in elderly hypertensive patients.METHODS: We conducted a randomized controlled trial with a three-arm design. Fifty-four elderly hypertensive patients (15 men; mean age, 69±6 years; systolic blood pressure, 131.2±14.7; diastolic blood pressure, 80.2±7.9 mm Hg) were randomized to IHE training (n=18), AE training (n=21), or non-exercise control group (n=21) for 12 weeks. Bilateral IHE training was performed four times of 2 minutes at 30% of maximal voluntary contraction with three times per week. AE training was performed brisk walking for 30 minutes at moderate intensity with three times per week. Carotid-femoral pulse wave velocity (PWV), augmentation index heart rate corrected (AIx@75 bpm) and brachial artery flow-mediated vasodilation (FMD) as indices of arterial stiffness and endothelial function were measured at baseline and after the intervention.RESULTS: Following 12-week intervention, resting BP was significantly decreased in both IHE (p=0.001) and AE groups (p=0.002). AIx@75 bpm and FMD were unchanged in the all groups. However, PWV was significantly decreased in both IHE and AE groups (IHE, 10.9±2.3 to 9.9±2.1 m/s [p<0.001]; AE, 10.5±2.0 to 9.4±1.6 m/s [p=0.001]), without any change in the control group.CONCLUSION: These findings suggest that both IHE and AE trainings were comparable effect in improving arterial stiffness in elderly hypertensive patients.

Efeito agudo da aplicação de vibração de corpo inteiro na força muscular de membros superiores / Acute effect of whole body vibration in the upper limbs strength

RESUMO O objetivo desse estudo foi verificar o efeito agudo da aplicação de vibração de corpo inteiro (VCI) sobre o impulso e sobre a força máxima de membros superiores. Vinte voluntários do sexo masculino, treinados, com idade: 23,8 ± 3,3 anos, foram submetidos a 3 sessões (uma sessão de familiarização e duas sessões de intervenção). Em cada uma das sessões de intervenção os voluntários realizaram uma contração voluntária máxima (CVM) de flexores do cotovelo sem aplicação de vibração e duas CVM com adição de vibração. Foram utilizadas 4 frequências de VCI (10, 20, 30 e 40Hz) distribuídas de maneira aleatória nas 4 CVM realizadas com vibração nas duas sessões de coleta. Os resultados encontrados mostraram que a força máxima e o impulso gerados na contração sem vibração foram significativamente maiores do que a força máxima e o impulso gerados durante a contração realizada com aplicação de VCI. Para o treinamento de força, a aplicação de VCI, nas frequências testadas na presente investigação, representou um menor estímulo de treinamento para os membros superiores, uma vez que gerou uma redução na força máxima e no impulso dos músculos flexores do cotovelo.

ABSTRACT The aim of this study was to investigate, from a protocol of maximal isometric contractions of the elbow flexors, the effect of WBV in the maximal force and of impulse in strength-trained individuals. Twenty male volunteers, age: 23.8 ± 3.3 years, performed 3 sessions (one familiarization session and two intervention session). The sessions were composed by 3 MVC of the elbows flexor muscles with 5 minute of rest between them. The first CVM was performed without vibration and the others, applying aleatory WBV with 10, 20, 30, 40Hz, and amplitude of 6mm. The results showed that the maximal force and of impulse obtained during the MVC without vibration was significantly higher than the maximal force and of impulse recorded during the application of WBV. For strength training, the application of WBV, in the adopted frequencies, was not able to generate sufficient stimulus to induce acute adaptations in muscle strength of upper limbs.

Neuromuscular electrical stimulation of medium and low frequency on the quadriceps femoris / Estimulação elétrica neuromuscular de média e baixa frequência no músculo quadríceps femoral

ABSTRACT Objective: The purpose of this study was to investigate the effects of neuromuscular electrical stimulation (NMES) in different frequencies on the quadriceps femoris. A randomized, controlled, blind cross-sectional study. Methods: Thirty subjects (12 men and 18 women), with an average age of 24.67 years, weight of 65.62 kg and height of 1.69 m were evaluated. Three random test conditions were applied: maximum voluntary isometric contraction (MVIC), maximum voluntary isometric contraction with medium frequency current (MVIC-MF) and maximum voluntary isometric contraction with low frequency current (MVIC-LF). Four MVICs were applied in each situation. The time between different isometric contraction types was 90 seconds while the time between the same conditions of contraction was 10 seconds. Results: Two-way ANOVA test showed that MVIC-MF had higher values for peak torque than MVIC-LF (p=0.02). Significant statistical results were found when comparing MVIC-MF and MVIC (p=0.03), but not for MVIC and MVIC-LF (p=0.52). Conclusion: Maximum voluntary isometric contraction associated with medium-frequency electrical stimulation was more effective than other NMES conditions. Level of Evidence II, Therapeutic Studies - Investigation of treatment results.

RESUMO Objetivo: A finalidade deste estudo foi investigar os efeitos da estimulação elétrica neuromuscular (EENM) em diferentes frequências sobre o músculo quadríceps femoral. Estudo randomizado, transversal, controlado e cego. Métodos: Foram avaliados trinta indivíduos de ambos os sexos (12 homens e 18 mulheres) com média de idade de 24,67 anos, peso 65,62 kg e altura 1,69 m. Os indivíduos foram submetidos a três condições de testes randomizados: contração voluntária isométrica máxima (CVIM), contração voluntária isométrica máxima associada à corrente de média frequência (CVIMMF) e contração voluntária isométrica máxima associada à baixa frequência (CVIMBF), sendo realizadas quatro repetições de CVIM em cada situação. O tempo entre as diferentes condições de contrações isométricas foi de 90 segundos e o tempo entre as contrações isométricas das mesmas condições foi de 10 segundos. Resultados: O teste ANOVA mostrou que a CVIMMF obteve valores de pico de torque maiores do que a CVIMBF (p = 0,02), com diferença significativa. Foram encontrados resultados com significância estatística ao comparar CVIMMF e CVIM (p = 0,03), mas não entre CVIM e CVIMBF (p = 0,52). Conclusões: A contração voluntária isométrica máxima associada a EENM de média frequência foi mais efetiva do que as outras situações de EENM. Nível de evidência II, Estudos Terapêuticos - Investigação dos resultados do tratamento.

Relação entre força isométrica de extensão de joelhos e quadris e o desempenho na virada olímpica do nado livre / Relationship between isometric strength of knee and hip extension and the performance at the flip turn of freestyle

O estudo objetivou verificar a correlação da força isométrica de extensão de joelho e quadris com o desempenho na virada do nado livre. Participaram do estudo 9 nadadores com experiência em competições de natação (idades: 23,11 ± 4,20 anos; estatura: 178 ± 0,05 cm; massa: 77,73 ± 8,56 kg; IMC: 24,46 ± 2,40 kg/m²). Um transdutor de força acoplado ao aparelho leg press horizontal foi usado para determinar a contração voluntária máxima e a taxa de desenvolvimento de força pico em três diferentes ângulos de joelho (78,4 ± 5,9o ; 100,4 ± 5,3o ; 116,2 ± 8,8o ) durante extensão máxima de joelhos e quadris. O desempenho da virada do nado livre foi registrado por videogametria subaquática e analisado por meio do software Kinovea 08.15. Cada nadador realizou três viradas máximas sendo registrado o melhor tempo entre as tentativas. Foram utilizadas média e desvio padrão, ANOVA one-way, correlação de Pearson e α= 0,05. Os resultados indicaram que os maiores ângulos registraram maiores picos de contração voluntária máxima: 2279,14 ± 441,89 N; 4690,98 ± 1148,06 N; 5052,57 ± 1349,92 N e taxa de desenvolvimento de força pico: 18068,33 ± 3238,18 N/s; 24790,11 ± 7214,60 N/s; 25684,88 ± 9366,64 N/s. A correlação foi significativa (r = - 0,74) entre o desempenho da virada do nado livre (1,80 ± 0,14s) e a contração voluntária máxima no maior ângulo. Logo, a capacidade de membros inferiores em produzir força máxima, em ângulos de extensão de joelhos e quadris próximos a 116°, pode ter importante papel no desempenho da virada. Além do mais, essa avaliação pode ser uma ferramenta na avaliação e prescrição de treinamento de viradas...(AU)

The study aimed to assess the correlation between isometric strength of knee and hip extension and the performance at freestyle flip turn. Participated in the study 9 swimmers with experience in swim championships (age: 23.11 ± 4.20 years, height: 178 ± 0.05 cm, weight: 77.73 ± 8.56 kg, BMI: 24.46 ± 2.40 kg/m²) comprised the sample. A transducer unit coupled to the horizontal leg press was used to determine the maximum voluntary contraction and rate of strength development peak at three different angles of knee (78.4 ± 5,9o ; 100.4 ± 5.3o ; 116.2 ± 8.8o ) during maximal knee extension and hip. The freestyle flip turn performance was recorded by an underwater camera and subsequently analyzed by Kinovea 08.15 software. Each swimmer performed three maximal attempts and recorded the best time. Mean, standard deviation, one-way ANOVA, Pearson's correlation and α = 0.05 were used. The results indicated a larger angles recorded highest peaks of maximum voluntary contraction: 2279.14 ± 441.89 N; 4690.98 ± 1148.06 N; 5052.57 ± 1349.92 N and peak rate force development:18068.33 ± 3238.18 N/s, 24790.11 ± 7214.60 N/s, 25684.88 ± 9366.64 N/s. The correlation was significant (r = - 0.74) between the performance at freestyle flip turn (1.80 ± 0,14s) and the maximum voluntary contraction in wider angle. Thus, the ability of the lower limbs to produce maximum force in angles of knee extension and hip near 116°, may play a role in performance at freestyle flip turn. Furthermore, this assessment can be a tool in the evaluation and training of the turning....(AU)