Adaptation of motor control strategies and physiological arousal during repeated blocks of split-belt walking.

Physiological arousal, mediated by the autonomic nervous system (ANS), has been shown to adapt alongside motor control strategies, governed by the central nervous system (CNS), in response to repeated standing perturbations. However, adaptation of the ANS physiological arousal response during repeated exposure to walking challenges remains unknown. This study examines the physiological arousal response (electrodermal activation, EDA) and motor adaptation of gait during a single session of repeated exposure to blocks of split-belt walking. Twenty young adults completed three repeated blocks (3.5 min each) of split-belt walking (2:1 speed ratio) alternating with three blocks of tied-belt walking. Step length symmetry, EDA, bilateral tibialis anterior, and gastrocnemius medialis muscle activation, and ground reaction forces were measured. For each block, the first (early) and last (late) 15 strides were analyzed. A linear mixed-effects model tested the effect of repeated blocks and phases (early/late) on step length symmetry. Statistical parametric mapping examined patterns of within-block changes in EDA, muscle activation, and ground reaction forces. The greatest within-block adaptation of step length symmetry occurred during the first split-belt walking exposure (split 1; P < 0.001). The largest magnitude of within-block adaptation in muscle activation, ground reaction forces, and EDA occurred during split 1 (P < 0.05). Attenuated EDA responses together with lower magnitude of motor adaptation in subsequent split blocks 2 and 3 were observed, indicating savings across the ANS and CNS (P < 0.05). Taken together, these findings demonstrate that the ANS-mediated physiological arousal response modulates alongside the CNS-driven locomotor adaptation to repeated exposure to blocks of split-belt walking.NEW & NOTEWORTHY Our study examines how the autonomic nervous system (ANS) and central nervous system (CNS) responses adapt during repeated exposure to split-belt walking. Findings show that ANS-mediated physiological arousal modulates alongside with CNS-driven motor control strategy, with the most pronounced adaptation occurring during the first exposure to the split-belt walking challenge. These results provide new insights into the neurophysiological mechanisms of motor adaptation in dynamic environments and have important implications for advancing gait rehabilitation.