Beneficial effects of eight weeks of FES-assisted cycling on aerobic capacity and paretic quadriceps thickness in post-stroke hemiparesis

Stroke is a leading cause of long-term disability worldwide, frequently impairing walking ability, postural control, and muscle strength. Hemiparesis, affecting nearly 90% of stroke survivors, results in unilateral motor deficits and presents substantial rehabilitation challenges. Functional electrical stimulation-assisted cycling (FES-assisted cycling) has shown potential to activate paretic muscles, improve aerobic capacity, and enhance motor coordination. This study aimed to compare the effects of an 8-week FES-assisted cycling program (Kurage, Lyon, France) versus traditional cycling (without stimulation) on aerobic fitness, muscle thickness, and walking performance in post-stroke participants. This randomized study included 31 post-stroke participants (21 men, 10 women; age: 57 ± 12 years), who were randomly assigned to either an FES-assisted cycling group or a conventional cycling group. Both groups completed 24 cycling sessions (30 min each) over 8 weeks, in addition to standard rehabilitation. Outcomes included peak oxygen uptake (V̇O₂peak), maximal power output, muscle thickness (rectus femoris and vastus intermedius), and walking ability (6-Minute and 10-Meter Walk Tests). Both groups showed significant improvements in V̇O₂peak, power output, muscle thickness, and walking test performance. The FES group showed greater gains in V̇O₂peak (+ 27% vs. +12% in the control group; P = 0.038) and in paretic muscle thickness (rectus femoris: +17% vs. +3%, P = 0.036; vastus intermedius: +24.6% vs. +7%, P = 0.029). A trend toward greater improvement in the 6-Minute Walk Test was also observed in the FES group (+ 43% vs. +25%; P = 0.082). FES-assisted and traditional cycling improved exercise capacity, muscle thickness, and walking ability in post-stroke participants. FES-assisted cycling led to additional benefits specifically for V̇O₂peak and localized hypertrophy in the paretic muscles targeted by FES, suggesting specific neuromuscular adaptations that are not commonly described in previous studies. These peripheral changes indicate that FES-assisted cycling may offer unique muscular benefits, particularly for individuals with limited voluntary control. These findings refine our understanding of FES as a complementary tool in stroke rehabilitation. Further research with larger cohorts and longer follow-up is needed to confirm these effects and assess long-term outcomes.