FUNCTIONAL ELECTRICAL STIMULATION COMBINED WITH VOLUNTARY CYCLING ACCENTUATES VO2 RESPONSE IN PEOPLE WITH ADVANCED MULTIPLE SCLEROSIS: A PILOT STUDY

Lower limb muscle weakness and reduced balance due to disease progression in multiple sclerosis (MS) may make robust aerobic exercise difficult. Functional electrical stimulation (FES) cycling combined with voluntary cycling may allow people with advanced MS to enhance the intensity of aerobic exercise. The aim of this study was to investigate the cardiorespiratory, power, and participant perceptions during acute bouts of FES cycling, voluntary cycling, and FES cycling combined with voluntary cycling (FES assist cycling). Participants with advanced MS (Expanded Disability Status Scale [EDSS] ≥ 6.0) undertook three exercise trials on a leg cycle ergometer. Trial 1: 30 minutes of FES cycling; Trial 2: two 10-minute bouts of voluntary cycling separated by 10 minutes rest; and Trial 3: a combination of trials 1 and 2 (FES assist cycling). Outcome measures included VO2, cycle power output, heart rate, exertion, and post-exercise perceptions of fatigue. Ten people with advanced MS participated (9 female; age 52.4±9.98 y; EDSS 7.1±0.6). Average VO2 during the 30-minute trials was significantly higher for FES assist cycling compared to voluntary cycling (429.7 ± 111.0 vs 388.5 ± 101.0 mL/min, 95% CI 23.4 to 113.0 mL/min, p=0.01), with a large effect size (Hedges’ g=1.04). Participants reported similar perceptions of exertion at the end of each trial (p=0.14). There was no difference in self-reported fatigue at the end of each trial (p=0.21). This study found FES assist cycling produced significantly higher VO2 values than voluntary cycling, although the clinical significance of these differences is unknown. Participants performed FES assist cycling at a self-reported levels of exertion consistent with moderate to vigorous intensity, however it was considered light-intensity exercise when expressed by METS. FES assist cycling was no more fatiguing post-exercise than the other modes.