Physical activity shapes corticospinal capacity and neural efficiency during progressive motor demands

Background: Habitual physical activity may influence neural strategies used to control posture during increasing motor demands. This study examined whether self-reported physical activity moderates task-dependent changes in corticomuscular coherence (CMC) and electroencephalographic (EEG) spectral power during graded postural challenges in healthy young adults. Methods: Sixty-four participants were recruited; four were excluded due to signal quality, resulting in a final sample of 60 (21.3 ± 2.1 years; 48.3% male). Participants performed four levels of increasing postural difficulty while simultaneous EEG and electromyography (EMG) were recorded. Peak beta-band CMC (13–30 Hz; Cz–tibialis anterior) and log-transformed EEG spectral power (theta 4–7 Hz, alpha 8–12 Hz, beta 13–30 Hz, low-gamma 30–50 Hz) were analysed using linear mixed-effects models including task difficulty, physical activity level, and their interaction, adjusted for age, sex, body mass index, and smoking status. False discovery rate correction was applied. Results: Task difficulty significantly influenced all neural outcomes (p<0.001). Significant Difficulty×Physical Activity interactions were observed for peak CMC and EEG spectral power in theta, alpha, beta, and low-gamma bands (q<0.01). Individuals with higher physical activity showed stronger CMC scaling and greater low-gamma modulation with increasing task difficulty, whereas individuals with lower activity levels demonstrated greater alpha and beta desynchronization and larger theta increases. Conclusions: Habitual physical activity is associated with differences in frequency-specific neural responses during progressively challenging postural tasks. These findings suggest that physical activity level may influence neural control strategies during motor challenge. However, the cross-sectional design and reliance on self-reported activity limit causal inference.