EFFECTS OF MENTAL FATIGUE ON MUSCLE ACTIVITY AND EXHAUSTION DURING SUSTAINED SUBMAXIMAL HANDGRIP CONTRACTION AT DIFFERENT ARM POSTURES

Abstract

This study aimed to determine the effects of mental fatigue on muscle activity and exhaustion during sustained submaximal handgrip contraction at different arm postures. Healthy volunteers performed sustained handgrip contractions at 30% maximum voluntary contraction until exhaustion in the 90° of shoulder flexion position (PROX condition) or neutral position (DIST condition) after a 30-min Stroop task (MF condition) or watching documentary task (control [CON] condition). The time to task failure did not differ significantly among the four conditions. The electromyography values recorded from the anterior deltoid were significantly higher in the MF than CON condition, but only in the PROX condition. This study indicates that mental fatigue does not influence sustained handgrip contraction performance but does increase muscle activity of anterior deltoid with shoulder flexion angles.