Biomechanical pathways linking push-off enhancement to toe clearance: Insights from a wearable auditory feedback system

Background Reduced push-off during walking, particularly among older adults, compromises dynamic stability and increases tripping risk. Although push-off enhancement has been proposed as a target for fall prevention, the mechanisms linking increased push-off to minimum toe clearance (MinTC)—a key determinant of tripping risk—remain unclear, and practical interventions are limited. The objectives of this study were (1) elucidate the biomechanical pathways through which push-off enhancement is associated with changes in MinTC and (2) evaluate an inertial measurement unit (IMU)-based auditory feedback (AFB) approach for modulating push-off during walking. Methods An AFB system targeting push-off intensity by peak foot pitch angular velocity (PitchV) was developed using a single shoe-mounted IMU. Twenty-four young adults walked on a treadmill under normal walking, maximal push-off, and PitchV-based AFB conditions. Lower limb kinematics, electromyography, and MinTC were measured. Structural equation modeling (SEM) was used to examine phase-coupled causal pathways linking push-off–related kinematic changes to MinTC, including the influence of stride length. Results PitchV-based AFB increased push-off intensity relative to normal walking. SEM revealed two opposing effects of push-off on toe trajectory: a dominant positive indirect effect mediated by facilitated ankle dorsiflexion during early swing outweighing a smaller negative direct effect of late-stance ankle plantarflexion. This indirect pathway, consistent with a toe-lift mechanism, dominated the net association with MinTC. Importantly, the path coefficient linking PitchV to MinTC remained stable when stride length was included in the model. Conclusion Push-off enhancement is associated with improved toe clearance through coordinated cross-phase ankle plantarflexion–dorsiflexion dynamics, providing mechanistic support for the push-off hypothesis . The proposed IMU-based AFB offers a biomechanically targeted approach to gait modulation with potential relevance to reduce the risk of falls.