Priming Robotic Plantarflexor Resistance With Assistance to Improve Ankle Power During Exoskeleton Gait Training

Robotic exoskeletons are increasingly being used for gait rehabilitation in individuals with neuromuscular disorders, such as cerebral palsy (CP). A primary rehabilitation goal for those with CP is to improve ankle push-off power, which is crucial for enhancing gait function. Previous research suggests that interleaving assistance and resistance within the same training session may improve certain aspects of gait, such as joint trajectories and torque profiles. This feasibility study sought to investigate the efficacy of priming the plantar flexor muscles with ankle exoskeleton plantar flexor assistance to facilitate increased ankle push-off power during subsequent resisted gait training bouts in individuals with CP. Specifically, we hypothesized that providing plantar-flexor assistance immediately prior to walking with resistance would increase peak biological ankle power and muscle activity compared to walking with resistance alone. We found that peak biological ankle power increased by 25% (p = 0.021) during assistance-primed resisted walking compared to the baseline resisted walking trail. While ankle angular velocity also increased alongside power, there was no significant difference in plantar flexor muscle activity, suggesting more efficient recruitment. These results contribute to our overarching goal of optimizing robotic exoskeleton interventions, potentially leading to the future design of more effective gait rehabilitation strategies.