Synergy-based functional electrical stimulation for gait rehabilitation in chronic stroke: a pilot study

Chronic stroke gait disorders involve impaired motor coordination. While high-intensity gait training (HIGT) is supported by current clinical practice guidelines, and Functional Electrical Stimulation (FES) to tibialis anterior addresses foot drop, extending FES to multiple muscles may improve functional outcomes. Leveraging a fast-to-don FES sleeve, we tested feasibility and preliminary efficacy of a personalized multichannel FES (MFES) intervention based on the individual’s motor coordination impairment paired with HIGT. Fourteen chronic stroke survivors were randomly assigned to either HIGT or MFES+HIGT for six weeks. Feasibility was evaluated by measuring setup time and collecting feedback from participants and four therapists. Gait speed, endurance, gait biomechanics, and muscle synergies were assessed at baseline, midpoint, post-training, and one-month follow-up. System setup time plateaued at 4.53 minutes by the ninth session. Both participants and therapists rated the intervention highly feasible, acceptable, and usable. Adherence was high, with no dropouts in the MFES+HIGT group. While most participants reached target heart rate zones, those with severe impairments (N=3, <0.4 m/s gait speed) struggled to maintain these levels. Despite the small sample, only the MFES+HIGT group demonstrated significant endurance gains from baseline to post-training and follow-up, while both groups improved walking speed, impaired limb step length, and muscle synergy similarity to normative data. When excluding household ambulators, only the MFES+HIGT group showed post-training and follow-up gains in endurance and self-selected walking speed. This study demonstrates that synergy-based MFES is feasible for integration into chronic stroke gait rehabilitation supports larger-scale trials to validate clinical efficacy and identify responders.