Ankle Power Biofeedback Augments Wearable Resistance for Improved Push-Off Power and Muscle Recruitment.

Ankle push-off power generated by the plantar flexor muscles is essential for efficient walking but is often impaired in individuals with cerebral palsy (CP), leading to inefficient walking. Both powered and passive (i.e., motor- and spring-based) wearable resistance devices are being developed for targeted training. This study explored the use of ankle power biofeedback across powered and passive wearable resistive devices to improve muscle recruitment and push-off power in individuals with CP. Seven individuals with CP completed walking sessions under the following conditions: (1) baseline (no device), (2) spring resistance with and without biofeedback, and (3) motor resistance with and without biofeedback. Push-off power and muscle recruitment were compared between biofeedback vs no-biofeedback conditions for both devices, and to baseline. Combined spring resistance and biofeedback increased soleus activity by 40 % compared to the spring resistance only ($p=0.004$) and by 48 % compared to baseline ($p =0.002$). Similarly, spring resistance and biofeedback increased peak ankle power by 32% relative to the spring resistance only ($\mathbf{p}=0.009$) and by 33% compared to baseline ($\mathbf{p}=0.010$). In contrast, motorized resistance and biofeedback did not significantly increase peak soleus activity or peak ankle power relative to motor resistance only ($\mathrm{p}=0.544; \mathrm{p}=0.544$). These findings show that ankle power biofeedback can augment spring resistance to elicit increased muscle recruitment and power during push-off in CP.