Gait adaptation to asymmetric foot-ground compliance applied by robotic footwear

Perturbing foot-ground interaction dynamics has shown promise for eliciting adaptations to inter-limb weight-bearing symmetry, a critical target for rehabilitation of asymmetrical neuromotor deficits affecting gait. To date, this perturbation paradigm has been delivered via adjustable stiffness treadmills, in which the treadmill deck displaces under the walker's foot during the stance phase of gait. Recently, we developed robotic footwear capable of delivering asymmetrical ground stiffness perturbations during walking, offering a portable experimental platform for asymmetrical ground stiffness perturbations, allowing it to be executed overground and on conventional treadmills. In this study, we quantified kinetic and spatio-temporal gait adaptation to a foot-ground compliance perturbation delivered by the novel robotic footwear. We found that participants shifted their vertical ground reaction force impulse, vertical pushoff peak, and peak braking force toward the unperturbed limb after the perturbation was removed, indicating a shift in neuromotor control elicited by the perturbation. We conclude that the robotic footwear can elicit weight bearing adaptations similar to adjustable stiffness treadmills, and that the dissipative mechanical properties of the shoes likely play a key role in the direction of the adaptation.