Pilot randomized controlled trial of functional electrical stimulation cycling exercise in people with multiple sclerosis with mobility disability

Background: Exercise training has been shown to be beneficial for persons with multiple sclerosis (MS). Adapted exercise modalities are needed to accommodate those with severe mobility impairment (Expanded Disability Status Scale [EDSS] scores 5.5–6.5). Functional electrical stimulation (FES) cycling is one such exercise modality; however, few studies have examined the feasibility and potential benefits of FES cycling for people with MS with severe mobility impairment. Objective: Determine the feasibility of FES cycling exercise for people with MS with severe mobility impairment, and the efficacy of FES cycling exercise for improving mobility and physiological fitness. Methods: 11 participants with MS with mobility impairment (EDSS = 5.5–6.5) were randomly allocated to FES cycling exercise (n = 6) or passive leg cycling (PLC; n = 5). Feasibility metrics included participant recruitment, retention, adherence, safety, and satisfaction. The primary mobility outcome was walking speed assessed by the Timed 25-Foot Walk (T25FW) test. The primary physiological fitness outcome was peak oxygen consumption (VO_2peak), assessed using a cardiopulmonary exercise test. Results: Eight participants completed the intervention (FES n = 4; PLC n = 4) with an adherence rate ≥80%. Three participants (FES n = 2, PLC n = 1) withdrew due to a lack of time. Six Grade 1 (i.e., mild) adverse events were experienced by participants in the FES group. Participants in the FES cycling condition demonstrated small-to-moderate improvements on T25FW performance (Cohen's d = 0.40; 22.9%) and VO_2peak (Cohen's d = 0.34; 13.8%) compared to participants in the PLC condition. Conclusions: We provide evidence that FES cycling exercise is feasible for individuals with MS with severe mobility impairment, and might have positive effects on mobility and physiological decondition. These results will inform the design of future efficacy trials of FES cycling exercise for persons with MS with mobility disability.