Resumen de Chronic Effects of a Static Stretching Program on Hamstring Strength

Sayaka Nakao, Tome Ikezoe, Masatoshi Nakamura, Hiroki Umegaki, Kosuke Fujita, Jun Umehara, Takuya Kobayashi, Satoko Ibuki, Noriaki Ichihashi

• This study investigated the effects of a 4-week static stretching (SS) program on isokinetic and isometric knee flexor peak torque and angle of peak torque. Thirty healthy men (age, 22.7 +/- 2.2 years) were randomized to receive either of the following: (a) a 4-week stretch intervention for the hamstrings (SS intervention group; n = 15) or (b) no intervention (control group; n = 15). The maximum pain-free knee angle, passive stiffness, which was determined by a slope of torque-angle curve, isometric and isokinetic (at 60[degrees][middle dot]s-1 and 180[degrees][middle dot]s-1) peak torque, and angle of peak torque for knee flexors were measured before and after 4 weeks. After 4 weeks, passive stiffness decreased significantly in the intervention group. There were no significant changes in isometric and isokinetic (neither at 60[degrees][middle dot]s-1 nor at 180[degrees][middle dot]s-1) peak torque, or angle of peak torque at 180[degrees][middle dot]s-1. A significantly increased peak extension angle at 60[degrees][middle dot]s-1 was observed in the intervention group. These results suggest that SS intervention is effective for decreasing musculotendinous unit stiffness of the hamstrings and that an SS program influences the angle of peak torque, whereas no significant changes occur in peak torque. Because a previous study suggests that angle of peak torque is associated with hamstring strain injuries, the results of this study would be helpful when considering the training program for preventing or treating hamstring strain injuries.