Effects of auditory perturbations on recovery dynamics as a component of locomotor resilience in healthy young and older adults

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INTRODUCTION: Overground walking involves various challenges (i.e., surface changes, elevation) in maintaining balance and preventing falls. One of the most important properties of locomotor behavior in this context is resilience: the capacity to resist and recover after a disturbance. Despite its importance, locomotor resilience through recovery dynamics remains poorly documented in older adults. RESEARCH QUESTION: This study aims to investigate differences in recovery time between young and older adults during step synchronization with a periodic metronome displaying auditory tempo perturbations. METHODS: Twenty healthy young and older adults were instructed to synchronize their steps with a periodic metronome presenting two unexpected tempo alterations (± 25%). Post-perturbation recovery time was quantified from the vertical displacement of a virtual S2 position, used as an estimate of center of mass motion (zCoM). In addition, the time required to regain step synchronization, computed from the temporal delay between foot contact events and auditory cue, was measured to compare relative timing between recovery processes. RESULTS: Step resynchronization occurred earlier relative to zCoM stabilization following both slow (+5.79 s, 95% CI [2.04, 10.15], Cohen's d = 1.17 and fast (+4.66 s, 95% CI [0.65, 9.76], Cohen's d = 0.7) perturbations in young adults. No significant temporal difference between recovery processes were observed in older adults. SIGNIFICANCE: These findings provide insights into recovery dynamics following perturbation, emphasizing differences in temporal classification of recovery processes between individuals. In addition, this protocol could serve as a complementary assessment tool for postural adaptation strategies in older adults.

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