Is There a Sex Difference in the Minimum Number of Static Stretch Repetitions That Should Be Recommended to Improve Flexibility?

Abstract

The purpose of the present study was to determine whether the minimum number of static stretch repetitions required to induce an increase in range of motion of the ankle joint and a decrease in passive torque of the muscle-tendon unit is different between men and women. Twelve men and 15 women participated in this study. Ankle range of motion and passive torque were measured during the passive dorsiflexion phase of ten 10-s static stretching repetitions. The stiffness of the muscle-tendon unit and stress relaxation were also determined. There was no significant sex difference in any parameter. Ankle range of motion was significantly higher after the first stretch, but thereafter further increases were not observed. Passive torque at submaximal ankle angles was significantly lower after the first stretch, and passive torque at maximal dorsiflexion angle was significantly higher after the first stretch, although further increases were not observed. There were no significant stretching-induced effects on stiffness and stress relaxation. These results indicate that there are no sex differences in the effects of ten 10-s repetitions on flexibility, but show that this protocol is sufficient to induce changes in ankle range of motion and passive torque. Therefore, coaches should prescribe the same short-duration static stretching protocol for both sexes of athlete.