A comparison of the effects of mediolateral surface and foot placement perturbations on balance control and response strategies during walking.

Background: Balance perturbation studies during walking have improved our understanding of balance control in various destabilizing conditions. However, it is unknown to what extent balance recovery strategies can be generalized across different types of mediolateral balance perturbations.

Research Question: Do similar mediolateral perturbations (foot placement versus surface translation) have similar effects on balance control and corresponding balance response strategies?

Methods: Kinetic and kinematic data were previously collected during two separate studies, each with 15 young, healthy participants walking on an instrumented treadmill. In both studies, medial and lateral balance perturbations were applied at 80% of the gait cycle either by a treadmill surface translation or a pneumatic force applied to the swing foot. Differences in balance control (frontal plane whole body angular momentum) and balance response strategies (hip abduction moment, ankle inversion moment, center of pressure excursion and frontal plane trunk moment) between perturbed and unperturbed gait cycles were evaluated using statistical parametric mapping.

Results: Balance disruptions after foot placement perturbations were larger and sustained longer compared to surface translations. Changes in joint moment responses were also larger for the foot placement perturbations compared to the surface translation perturbations. Lateral hip, ankle, and trunk strategies were used to maintain balance after medial foot placement perturbations, while a trunk strategy was primarily used after surface translations.

Significance: Surface and foot placement perturbations influence balance control and corresponding response strategies differently. These results can help inform the development of perturbation-based balance training interventions aimed at reducing fall risk in clinical populations.