Interpersonal gait synchronization reduces gait asymmetry and induces a carry-over effect during overground side-by-side walking.

INTRODUCTION: Interpersonal gait synchronization is widely observed during side-by-side walking and has been hypothesized to contribute to gait rehabilitation. Nonetheless, the specific effects of gait synchronization on gait asymmetry, as distinguished from mere side-by-side walking, have not been experimentally investigated under overground walking conditions. This study aimed to examine the effects of interpersonal gait synchronization on gait asymmetry during overground side-by-side walking. METHODS: Ten pairs of participants performed overground side-by-side walking tasks under synchronization and asynchronization (control) conditions. Gait asymmetry was simulated in one member of each pair by applying unilateral ankle loading and was quantified across five spatiotemporal gait parameters using inertial measurement unit sensors. The degree of interpersonal synchronization was verified using the Gait Synchronization Index (GSI). Statistical analyses were conducted using Friedman's test, followed by Wilcoxon signed-rank test with Bonferroni correction. RESULTS: All participants achieved synchronized walking under the synchronization condition and asynchronized walking under the asynchronization condition, as verified by the GSI values. Compared with baseline, stride height asymmetry was significantly reduced during synchronized walking (W = 0, p = 0.002, r = 0.979), and this reduction was maintained immediately after synchronization ceased (p = 0.002), indicating a short-term carry-over effect. No significant changes in gait asymmetry or other gait parameters were observed under the asynchronization condition. CONCLUSION: Interpersonal gait synchronization specifically reduces stride height asymmetry and produces a short-term carry-over effect in overground walking, suggesting its potential as a basis for gait rehabilitation interventions.