Sex differences of intermittent elbow flexion power using various loads.

This study was designed to clarify a sex difference in muscle power output properties by intermittent elbow flexion using various loads. 10 young males and 10 young females performed intermittent elbow flexion power outputs at 30 times x min.(-1) for 1 min. using 30%, 40%, and 50% MVC loads. For both sexes, the decreasing peak power showed a similar trend between trials at all loads, and the reliability of each power parameter was good. The power outputs decreased largely with increasing load mass, and the power output in 50% MVC for males markedly decreased to the same level as that during the final phase in 30% MVC. Although the absolute value of regression coefficients for males became significantly larger with increasing load mass, that for females showed a significant difference only between 30% and 50% MVC. In 50% MVC, a large decrease for males was observed. Maximal peak power outputs were significantly larger with increasing load mass for both sexes, but for males more than for females. In both sexes, there were no significant differences among final powers of each load mass, and between total powers of 40% and 50% MVC. For the sum of every 5 consecutive power outputs, males showed significant differences between 30% and 40% MVC in all periods after the 6th contraction, but females did not and also between 30% and 50% MVC in periods after the 16th contraction. In conclusion, it is considered that power outputs in the latter phases in 50% MVC are affected largely by muscle fatigue, and an intermittent power output test with 50% MVC can measure sustained power (fatigue resistance) in the latter phases, but there is a sex difference in the tendency to decrease.