Efeito agudo do alongamento estático dos isquiotibiais no desempenho isocinético dos músculos flexores e extensores de joelho

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Stretching exercises are commonly prescribed before training sessions and competitions aiming at performance improvements and injury prevention. However, recent studies have shown that stretching may cause acute muscular torque production deficits. The physiological and biomechanical mechanisms underlying this behavior are not completely known. Moreover, there are open questions regarding the minimal duration of a stretching protocol able to produce muscular torque deficits and about the effects that the stretching of a muscle group on the strength performance of its antagonist. On this perspective, the aim of this work was to investigate the acute effects of two hamstrings static stretching protocols of different volumes on the isokinetic performance of knee flexors and extensors muscles. Thirty six male volunteers were randomly and evenly distributed in three groups: E1, E2 and C. After warming up, the active range of motion (AROM) of hip flexion was assessed and the subjects went through isokinetic evaluations of the knee flexors and extensors. Subjects from groups E1 and E2 performed static stretching protocols 180 of 360 seconds, respectively. Then a new isokinetic evaluation and a new assessment of AROM were performed. The subjects of the control group (C) also went through a second evaluation, as well, after remaining at rest during a period of 270 seconds. The variables studied were the AROM of hip flexion, the isokinetic peak torque, the maximum work and the total work. The AROM increased after the application of both stretching protocols, and no changes were observed on this variable for the control group. Considering the hamstrings isokinetic performance it was observed that the peak torque and the maximum work decreased on the poststretching evaluation of E2 group, but not in the E1 and C groups. The total work variable, nevertheless, behaved similarly for E1, E2 and C groups without changes on post-stretching evaluation. Regarding the knee extensor muscle group, it was observed that only E2 group have shown post-stretching deficits on all the studied isokinetic variables. From these results one can conclude that for the hamstrings both stretching protocols were efficient on producing acute gain on the hip flexion AROM. On the other hand only the longest protocol was able to produce maximal torque deficits for both knee flexors and extensors, while, the total work was not affected by any of the stretching protocols.

ASSUNTO(S)

muscle strength alongamento (fisiologia) engenharia biomédica - dissertações torque força muscular - testes stretch (physiology) engenharia medica biomedical engineering torque

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