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

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. Sixty-four participants were recruited; four were excluded due to signal quality, resulting in a final sample of 60 (21.3 ± 2.1 yr; 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 analyzed 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. 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. 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.NEW & NOTEWORTHY This study is the first to demonstrate that habitual physical activity moderates the scaling of corticomuscular coherence and EEG spectral power across progressively challenging postural tasks. Physically active individuals exhibited enhanced corticospinal coupling and gamma synchronization alongside reduced theta and alpha/beta desynchronization, suggesting that physical activity optimizes neural resource allocation during motor challenge. These findings provide novel neurophysiological evidence supporting the coexistence of corticospinal capacity enhancement and neural efficiency in physically active individuals.