Feasibility of dynamic entrainment with ankle mechanical perturbation to treat locomotor deficit

Dynamically entraining human gait with periodic torque from a robot may provide an approach to walking therapy that is uniquely supportive of normal biological function. To test the feasibility of this approach we perturbed the gait of unimpaired human subjects by applying a periodic impulsive ankle torque at various frequencies. Eighteen subjects out of 19 exhibited entrained gaits: for a small range of frequencies their gait periods adapted to synchronize with the mechanical perturbation. In addition, the phase when synchronized was such that the robot perturbation assisted propulsion. These results support a new strategy for walking therapy that exploits an embedded neural oscillator interacting with peripheral mechanics and the resulting natural dynamics of walking, which are essential but hitherto neglected elements of walking therapy.