Effects of repeated blocks of split-belt walking on locomotor adaptation, physiological arousal response and cortical activation.

Adaptability of motor control of gait is fundamental to navigating obstacles and variable environments. While the central nervous system (CNS) is recognized as the primary driver of gait adaptation, the extent to which the autonomic nervous system (ANS) co-modulates with cortical activity and motor output during gait adaptation remains unclear. Thus, this study examined how cortical activation, physiological arousal, and motor adaptation co-modulate during repeated exposure to split-belt treadmill walking. Twenty unimpaired young adults (10 F, 10 M; 26.8 ± 3.3 years) completed a single-session, repeated-block split-belt treadmill protocol (three, 3.5-min, 2:1 speed adaptation blocks, interspersed with tied-belt walking). Physiological arousal response [electrodermal activity (EDA)], step length symmetry (SLS), rating of perceived stability (RPS) and cortical activation [via functional near-infrared spectroscopy oxyhemoglobin (HbO)] of the prefrontal, premotor, sensorimotor and posterior parietal cortices were assessed. Linear-mixed-effects models assessed block- and phase-dependent changes in SLS, EDA, HbO response for each region, and RPS. Split-block 1 was perceived as the most destabilizing by RPS scores (p ≤ 0.05) and elicited the largest within-block changes in SLS, EDA, and HbO activation in all regions (p ≤ 0.05), suggesting that split-block 1 encompassed the largest adaptation response across the CNS and ANS. CNS and ANS savings were noted in blocks 2 and 3. Pearson’s correlations revealed that greater gait asymmetry was associated with heightened arousal during early adaptation (r = − 0.569, p < 0.001), suggesting an association between error detection and ANS response. Together, these findings suggest cross-system adaptation, with reduced cortical demand, physiological arousal, and perceived challenge and more efficient locomotor adaptation with practice.