Motor control performance-related modulation of beta-band EEG-sEMG coherence differs between general and local muscular exercise-induced fatigue.

Purpose: Exercise-induced fatigue can reduce motor control performance and increase the risk of sporting injuries, which are related to functional coupling within the corticomotoneuronal pathway. However, the differences in functional coupling caused by general and local muscular exercise-induced fatigue are unknown. This study aimed to investigate the effects of exercise-induced fatigue on the beta-band (16-30 Hz) functional coupling between the sensorimotor cortex (SM1) and muscles of the dominant lower limb under different fatigue protocols.

Methods: Twenty-four healthy male participants were recruited to participate in randomized sessions of personalized constant speed running as general muscular exercise (GME) and maximum isokinetic ankle plantar-dorsiflexion as local muscular exercise (LME) to induce fatigue. These sessions were separated by 7 days. The electroencephalogram (EEG) signals of SM1 (e.g., FC1, FCz, and Cz) and surface electromyography signals (sEMG) of four muscles (soleus, SOL; medial gastrocnemius, MG; later gastrocnemius, and LG; tibialis anterior, TA) were simultaneously recorded before and after fatigue during the ankle plantar-dorsiflexion task, which were used for beta-band coherence analyses.

Results: Following fatigue induced by GME, the EEG-sEMG coherence was significantly greater than that induced by LME (P < 0.04). Compared to pre-fatigue state, the coherence of FC1-SOL, FCz-SOL, and Cz-SOL increased significantly after general fatigue, while these coherences decreased significantly after local fatigue.

Conclusion: Fatigue induced by GME indicates an enhancement in beta-band functional coupling between the SM1 and muscles of the dominant lower limb, which is related to higher motor control performance. In contrast, fatigue induced by LME diminishes the functional coupling.