Cardiorespiratory and power adaptations to stimulated cycle training in paraplegia

Purpose: The extent to which cardiorespiratory fitness and cycling power can be improved in individuals with paraplegia by progressive, high-volume, home-based, electrically stimulated (ES) cycle training was investigated using a novel, sensitive method and protocol that allowed high-resolution power Output analyses to be performed for the first time in ES cycling. Methods: Nine male and two female individuals with paraplegia trained progressively at home for up to five 60-min sessions.wk(-1) for 12 months. Peak power and cardiorespiratory parameters were estimated during quarterly feedback-controlled incremental work rate tests in the laboratory. Results: Cycle training endurance increased from 10 to 60 min of continuous pedaling for all subjects. Peak power Output (POpeak) increased by 132% (P = 0.001), peak oxygen uptake (VO2peak) increased by 56% (P < 0.001), and oxygen pulse increased by 34% (P = 0.002). All significant adaptations occurred during the first 6 months of training when training load was progressive and duration compliance (90%) and frequency compliance (88%) were at their highest. A strong positive relationship between the total training duration and the magnitude of improvements in both POpeak (r(2) = 0.84, P < 0.001) and VO2peak (r(2) = 0.52, P = 0.012) was found during the first 6 months only. Conclusions: High-volume, home-based ES cycle training using the current training and the ES strategies can significantly improve cardiorespiratory fitness and cycling power output in paraplegia but only while training is progressive. The training plateau reached by 6 months may be physiological in nature or due to the ES strategy used.