FES-Induced and Voluntary-Induced Fatigue in a Rehabilitation-Like Task.

In the context of FES-based rehabilitation and assistance tasks, there is a growing interest in managing the induced fatigue, which is an obvious limiting factor in training duration. However, it is unclear whether and how fatigue may develop in tasks commonly used in stroke rehabilitation. This work explored the effect of FES- or volition- induced movements on EMG-based effort and M-wave metrics that characterise fatigue, during a continuous wrist target-tracking task completed by 22 unimpaired participants. We found no significant changes in the mechanical and electrical responses of the muscles during the Volition-only, FES-only, and VolitionFES conditions, suggesting that during this task, FES did not induce muscular fatigue, while both mental and physical demands were reported as low. Our results thus suggest that it may not be necessary to consider FES-induced fatigue during such continuous FES-assisted tasks, that can be used in poststroke motor rehabilitation training.