Influence of gait-synchronized functional electrical stimulation during exoskeleton-assisted ambulation on cardiorespiratory outcomes in individuals with incomplete spinal cord injury.

The study analysed 11 participants selected from an ongoing trial, so it is a small convenience sample and the result may not hold for a wider group. Participants were already able to walk 10 m with or without aids, although they were partially wheelchair-dependent, so people who cannot walk at all were not included. Only people with intact lower motoneuron function in the gluteal, hamstring, and quadriceps muscles could receive FES, which limits the findings to that subgroup. The sample varied in lesion level, time since injury, prior exoskeleton experience, prior FES experience, and prior combined exoskeleton-FES experience. Measurements were made during a single visit, so day-to-day reproducibility was not tested. Only the last 2 minutes of each 6-minute test were analysed, so early exertion was not captured. Walking speed was self-selected, not fixed, and speed can affect cardiorespiratory demand. The primary outcome was an immediate physiological measure, not a training or function outcome, and the authors state that the ongoing training study must be awaited before a final conclusion. One participant showed lower oxygen consumption with FES, and the authors suggest possible reasons such as higher body fat, maximal mode, and difficulty adapting to the device. Two device deficiencies occurred, but no adverse events were reported. The study was designed to detect a large immediate physiological difference, so smaller differences may be missed.

The authors declared no conflicts of interest.

Do not read the significant increase in oxygen consumption as evidence that FES improves training outcomes. The study measured one session in 11 people, distance and perceived exertion did not differ, and long-term gait function was not tested.