MALES FATIGUE SOONER THAN FEMALES IN LOW-INTENSITY ISOMETRIC CONTRACTIONS
Griffith, E. E., Yoon, T., Schlinder-Delap, B., & Hunter, S. K. (2006). Sex differences in muscle fatigability are task dependent and not explained by a difference in central fatigue. Medicine and Science in Sports and Exercise, 38(5), Supplement abstract 1351.
The purpose of this study was to compare the time to failure and voluntary activation of young males (N = 9) and females (N = 9) for a sustained isometric contraction performed at a high- and low-intensity with the elbow flexor muscles. Ss performed an isometric contraction at 20% and 80% of maximal voluntary contraction (MVC) force during two separate and randomized sessions until the target force could no longer be achieved. Voluntary activation was quantified before and after the fatiguing contraction using the interpolated twitch technique.
Males were stronger than females on both days of testing. Males had a briefer time to failure than females for the 20% MVC task but not for the 80% MVC task. Voluntary activation was reduced at the end of the 20% MVC task but did not change after the 80% MVC task for both genders. There was no gender difference in voluntary activation at the end of the 20% MVC fatiguing contraction or 80% MVC task.
Implication. The gender difference in time to failure of a sustained contraction is not explained by a difference in fatigue central to the motor nerve in males and females. Furthermore, in young adults the contribution of central fatigue to task failure is dependent on the intensity of the task with greater impairment after a long-duration low-intensity isometric contraction.
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