Neuromuscular fatigue differs following unilateral vs bilateral sustained submaximal contractions.

International audienceThe purpose of the present study was to compare the mechanisms of fatigue induced by a unilateral vs a bilateral submaximal isometric knee extension. Ten physically active men completed two experimental sessions, randomly presented. They were asked to maintain an isometric knee extension force corresponding to 20% of the maximal voluntary contraction (MVC) until task failure with one leg (unilateral) vs two legs (bilateral). MVCs were performed before and after the sustained contraction. Transcutaneous electrical stimuli were used to examine central (voluntary activation) and peripheral (peak doublet force at rest) fatigue on the exercised leg. Time to task failure was significantly shorter (P<0.05) for the bilateral (245 ± 76 s) compared with the unilateral task (295 ± 85 s). Unilateral MVC force and maximal voluntary activation losses were significantly greater (P<0.05) after the unilateral task than after the bilateral task. Peak doublet force was significantly reduced (P