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

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).

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).

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.

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.

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.