Exercise-induced changes in high-γ cortical functional connectivity and short-interval intracortical inhibition

Objective: To analyze exercise-induced changes in functional connectivity (FC) using high-density EEG (HD-EEG) and primary motor cortex excitability via paired-pulse TMS (pp-TMS). Methods: Ten healthy volunteers performed a 3 km high-intensity run. Neurophysiological assessments were conducted at baseline (T0), 24 h (T1), and 72 h (T2) post-exercise. FC was measured using HD-EEG, and primary motor cortex excitability was assessed with pp-TMS to measure short-interval intracortical inhibition (SICI) and facilitation (ICF). Results: At T1, a significant hyperconnected network in the high-γ band was observed in several brain regions, including sensorimotor, limbic, temporal, and occipital lobes, which normalized by T2. Additionally, pp-TMS revealed disinhibition (reduced SICI) in M1 at ISI 2–3 ms at T1. Conclusions: The study highlighted specific features of exercise-induced central fatigue. Post-exercise, the primary motor cortex became hyperexcitable, possibly as a compensatory response to peripheral fatigue. A complex network of cortical areas involved in cognition and behavior was hyperactivated, likely reflecting awareness of fatigue and self-protection decision-making processes. These changes were reversible, allowing subjects to return to baseline conditions. Significance: This research provides insight into the neurophysiological mechanisms of central fatigue, emphasizing the brain's adaptive responses to intense physical activity and their temporal dynamics