Heavy mental task has no effect on sex differences in muscle fatigability during moderate-intensity isometric contraction.

In some physical activities with simultaneous mental task, we can observe greater muscle fatigability in women than in men. These differences are evident in various muscle groups, especially during low-intensity isometric or intermittent isometric contractions with the simultaneous heavy mental task. The aim of this study was to monitor the effect of heavy mental task on sex differences in muscle fatigability during isometric contraction of moderate intensity in the biceps brachii muscle. Seventeen men (27.1 ± 2.5 years) and seventeen women (26.2 ± 3.5 years) attended two sessions (control and stressor) where they performed isometric contraction of the biceps brachii muscle to failure at an intensity of 40% maximum voluntary contraction (MVC). In control session, the participants performed the isometric contraction to failure alone. In stressor session, a simultaneous heavy mental task was included (subtracting the number 13 from any four-digit number). The time to task failure (TTF) and percentage decrease in the median frequency (MDF) were monitored. We did not observe a sex: session interaction effect for the TTF nor the MDF percentage decrease and therefore we can assume that simultaneous heavy mental task did not affect women more than men. We also did not observe a session effect, so we also can state that the simultaneous heavy mental task did not affect the TTF or the MDF percentage decrease. A sex effect was not observed for the percentage decrease in MDF, but it was statistically significant for TTF, where women lasted 47.9% longer in the control session and 56.4% longer in the stressor session. The simultaneous heavy mental task during isometric contraction to failure of the biceps brachii muscle of moderate intensity does not have a greater effect on women than on men.