Delayed neuromuscular fatigue recovery unveils reduced fatigue tolerance in elderly following maximal intermittent exercise

The aim of the study was to assess the impact of aging on neuromuscular fatigue and recovery. Ten young (23.08 ± 1.43 years) and older (61.19 ± 1.80 years) males performed an intermittent maximal isometric exercise with the knee extensors followed by 27 min of recovery. Maximal voluntary contraction (MVC), total work ( W ′), voluntary activation (VA), potentiated resting twitch (Ptw), and electromyography (EMG) were recorded and then analyzed. Peripheral and central fatigue following exercise were lower in old compared to young (− 29.99% vs. − 42.68% and − 14.55 vs. − 20.02%; P 0.05, respectively). During the recovery period, our results showed that recovery of the MVC was impaired for old (14.93% for old vs. 30.66% for young) and still incomplete until 27 min.VA increased significantly compared to post exercise after 1 min only for young ( P = 0.001), potentially affecting the recovery pattern of MVC during the early phase due to their significant correlation ( r 2 = 0.58, P = 0.01). Peripheral fatigue recovery was also lower for old (11.18% vs. 18.72%; P