Interval-based cycling for wheelchair users with spinal muscular atrophy: feasibility, tolerability, and exercise effects

PURPOSE: Spinal muscular atrophy (SMA) often leads to wheelchair use and sedentary lifestyle. Previous exercise studies suggest that prolonged exercise may cause fatigue and limit feasibility. We assessed feasibility and tolerability of interval-based assisted cycling in wheelchair users with SMA and explored potential effects on symptoms, motor performance, and metabolic outcomes. MATERIALS AND METHODS: In this exploratory self-controlled crossover study, 15 wheelchair users with SMA completed three test days separated by a control period and an 8-week home-based exercise intervention. Assessments included questionnaires on pain, constipation, fatigue, sleep quality, and quality of life, along with lung function, blood sampling, and cycle testing. Training consisted of 10 min of assisted interval cycling five times weekly. RESULTS: No clinically meaningful changes were observed in primary or secondary outcomes. Nevertheless, attendance was high (95%), no exercise-related dropouts occurred, and no systematic increase in fatigue was observed. During exercise testing, participants increased their heart rate by an average of 42 bpm, indicating cardiovascular engagement. CONCLUSION: Interval-based assisted cycling was feasible and well tolerated in wheelchair users with SMA without inducing excessive fatigue. Although no clinically meaningful group-level effects were observed, interval training enabled cardiovascular engagement despite severe motor impairments.