Beyond immediate effects: aperiodic EEG markers of delayed cortical reorganization after physical exercise

Acute exercise induces immediate and delayed neurophysiological changes, which may influence subsequent cognitive and behavioral performance, an aspect often overlooked. The aperiodic component of the EEG spectrum, reflecting excitatory/inhibitory balance, offers a complementary window beyond classical oscillatory activity. This study analyzed resting-state, eyes-closed EEG (30 channels) from two healthy participants who performed a HIIT protocol (10x40"/20" at 90% maximal load). We extracted aperiodic components (offset and exponent) at three time points: pre-exercise (PRE), immediately post (POS1), and 5-min post (POS2). Kruskal-Wallis tests assessed changes across moments. Both participants exhibited consistent temporal trends yet with opposing directions: Participant 1 showed a decrease of the magnitude in both components at POS1 and POS2 relative to PRE, whereas Participant 2 displayed an increase. Notably, despite divergent baselines, both showed a significant increase in dispersion of both components at POS2 compared to PRE and POS1. This increased variability suggests the delayed post-exercise period may represent a phase of differential cortical reorganization. These preliminary trends highlight the potential of aperiodic markers to capture individual neurophysiological responses to acute exercise, and underscore the need to consider delayed effects when timing post-exercise cognitive ad behavioral assessments, warranting further investigation with larger cohorts.