The effects of FES cycling combined with virtual reality racing biofeedback on voluntary function after incomplete SCI: a pilot study.

Only eleven participants were analysed after two were ineligible and two withdrew, so the sample is small and results were variable. The study had no control group, and participants continued usual care, so improvement cannot be separated from usual care, placebo effect or natural recovery. The intervention combined motor-driven cycling, electrical stimulation, VR feedback and usual care, so the contribution of any single component cannot be separated. Sub-acute participants were 2 to 5 months post-injury, and most natural recovery occurs in the first 6 months, so their gains may not be due to iCycle training. Training dose was not equal, because cycling time and pedal revolutions varied between participants. Only two participants were ambulatory, so walking outcomes were available for very few people. Some participants produced negative torque, likely from spasticity or co-contraction, which the VR feedback system may penalise. Stimulation current was limited by sensory impairments, and weak participants may have had torque too small compared with background interference. Power output alone may be confounded by muscle-training effects.

The supplied text names the Inspire Foundation as funder and gives no author conflict-of-interest declaration.

Do not conclude that iCycle training causes motor recovery. The intervention combined motor-driven cycling, electrical stimulation, VR feedback and usual care, and the study had no control group, so natural recovery may explain some gains.