Error-driven intralimb and interlimb adaptations under asymmetric treadmill and cueing conditions

Rhythmic auditory cueing is commonly used in gait rehabilitation for post-stroke and Parkinson's disease populations, typically improving functional metrics such as walking speed and cadence. In addition, the timing of the cues may be adjusted to deliver asymmetric cues that mimic the effects observed with split-belt treadmill training, where the left and right belt speeds move at different speeds. This study investigates spatiotemporal modifications to asymmetric rhythmic auditory cues by analyzing changes within (intralimb) and between (interlimb) legs under asymmetric mechanical (split-belt treadmill) and instructional (asymmetric rhythmic cues) perturbations. We also examine how timing errors (differences between assigned and actual step durations) affect step velocity under combined treadmill and cueing conditions. We evaluated the effects of limb laterality, rhythmic cue adaptability, and experimental stage on these measures, and correlated timing error with gait harmony (a measure associated with step velocity). Findings revealed that individuals exhibit distinct cue-specific error correction strategies based on adaptability level-from predictive central timing mechanisms to feedback-driven or subcortically mediated responses, reinforcing the need to tailor rhythmic interventions to motor-cognitive profiles. These insights support the development of personalized gait rehabilitation approaches that account for an individual's rhythm processing capacity, cueing responsiveness, and underlying motor learning mechanisms.