EFEITOS DE UM PROTOCOLO DE BAIXO VOLUME DO EXERCÍCIO NÓRDICO DE ISQUIOTIBIAIS EM FATORES DE RISCO PARA LESÕES MUSCULOESQUELÉTICAS E DESEMPENHO DE ATLETAS: UM ENSAIO CLÍNICO RANDOMIZADO CONTROLADO

Abstract

Background: The practice of Nordic Hamstring Exercise (NHE) has been shown to protect athletes against hamstring injuries (HI). However, the effect of low-volume NHE on factors associated with HI, as well as physical performance in athletes, is not fully understood. Objective: To compare the effects of applying NHE once a week to twice a week for 10 weeks on the strength/endurance of the hamstring muscles (primary outcome), flexibility of the muscles of the posterior chain of the body, physical performance, workload and late onset muscle pain in the hamstring muscles (secondary outcomes) in male intermittent sports athletes. Study design: Randomized clinical trial with parallel arms and balanced distribution. Methods: Thirty-five male amateur intermittent sports athletes (futsal and basketball) were randomized and allocated to two experimental conditions: NHE practice once a week (G1, n = 18) and NHE practice twice a week (G2, n = 17), totaling 115 and 230 programmed repetitions for each group, respectively, for 10 weeks. The participants were assessed before and after the interventions, measuring indices of strength/resistance of the hamstring muscles, flexibility of the muscles of the posterior chain of the body, jumping ability, speed and change of direction. Workload, late onset muscle soreness and adherence to the protocols were recorded at each session. Results: Adherence to the protocol for G1 and G2 was 85.40% and 78.70%, respectively. NHE was able to induce significant changes in the strength/resistance of the hamstring muscles in the right leg (p = 0.046; η2p = 0.090). In the strength/resistance of the hamstring muscles in the left leg, G1 (+27.11%) showed significant improvements compared to G2 (+8.33%) (p = 0.014; η2p = 0.338). There were no significant differences in the other variables analyzed. The workload was lower in the period be-tween weeks six and 10 between the groups (p = 0.009; η2p = 0.419), but there was no significant difference between the periods analyzed and late onset muscle pain. Conclusion: NHE induces increases in the strength/endurance of the hamstring muscles of the right leg, as well as improving jumping ability after ten weeks of intervention. The workload decreases after continuous exercise prescription. In this study, prescribing NHE once or twice a week led to similar results in factors associated with HI and physical performance in amateur athletes.