Gains in aerobic capacity with whole-body functional electrical stimulation row training and generalization to arms-only exercise after spinal cord injury

Study design: Longitudinal study in adults (n = 27; 19–40 years old) with tetraplegic or paraplegic spinal cord injury (SCI). Objectives: Determine physiological adaptations and generalizable fitness effects of 6 months of whole-body exercise training using volitional arm and functional electrical stimulation (FES) leg rowing. Setting: Outpatient hospital-based exercise facility and laboratory. Methods: Participants enrolled in hybrid FES-row training (FESRT) and performed peak exercise tests with arms-only (AO; baseline and 6 months) and FES rowing (baseline, 3, 6 months). Results: Participants demonstrated increased aerobic capacity (VO_2peak) after FESRT (p < 0.001, n_p² = 0.56) that tended to be higher when assessed with FES than AO rowing tests (0.15 ± 0.20 vs. 0.04 ± 0.22 L/min; p = 0.10). Changes in FES and AO VO_2peak were significantly correlated (r = 0.55; p < 0.01), and 11 individuals demonstrated improvements (>6%) on both test formats. Younger age was the only difference between those who showed generalization of training effects and those who did not (mean age 26.6 ± 5.6 vs. 32.0 ± 5.7 years; p < 0.05) but changes in FES VO_2peak correlated to time since injury in individuals <2 years post-SCI (r = −0.51, p < 0.01, n = 24). Lastly, VO_2peak improvements were greater during the first 3 months vs. months 4–6 (+7.0% vs. +3.9%; p < 0.01) which suggests early training adaptations during FESRT. Conclusions: Gains in aerobic capacity after whole-body FESRT are better reflected during FES-row testing format. They relate to high-intensity exercise and appear early during training, but they may not generalize to equivalent increases in AO exercise in all individuals with SCI.