Differential effects of local and general fatigue on brain network efficiency, corticospinal and neuromuscular excitability.

Objectives: This study aimed to investigate the effect of fatigue induced by local- and general-muscular exercise on brain network efficiency, corticospinal and neuromuscular excitability. Methods: Twenty-four participants randomly performed two different fatigue protocols (i.e., locally induced vs generally induced) separated by 5-7 days. Local fatigue was provided with maximum isokinetic plantar dorsiflexion, and general fatigue was provided with a running exercise on a treadmill at a personalized constant velocity. M-wave, H-reflex, and the resting-state electroencephalography signal, were recorded before and after local and general fatigue. Results: Compared with local fatigue, fatigue induced by general muscular exercise can significantly increase clustering coefficient (p = 0.003), global efficiency (p = 0.001) and local efficiency (p = 0.005) in the beta band relative to the baseline values. The two fatigue protocols can significantly decrease maximal M-wave (Mmax, p < 0.001), maximal H-reflex (Hmax, p < 0.001), Hmax/Mmax (p = 0.001) and level of activation (p < 0.001). Conclusion: The two different fatigue protocols can decrease peripheral neuromuscular excitability and affect spinal fatigue. General fatigue can promote the integration of local and global efficiency by strengthening the functional connectivity of the brain network to optimize resource allocation and resist the negative effects of fatigue.