Effects of Muscle Fatigue on FES Assisted Walking of SCI Patients: A review

Sequel to spinal cord injury (SCI), functional impairment is sustained and the SCI individuals are often confined to wheelchair usage. Current trends of walking rehabilitation adopted is functional electrical stimulation (FES) assisted gait with partial body weight support. However, lack of lower limb proprioception, inability to control complex joint trajectory, rapid energy consumption, unstable and insufficient muscle force due to motor unit recruitment strategy often lead to fatigue thus constituting major limitation. Substantial literatures document significant effect of FES assisted rehabilitation of SCI individuals with highlights on functional gait and characteristics. Advances in neuroscience have also improved FES assisted gait but limiting effect of muscle fatigue consistently remains a considerable challenge. It is also evident from reviewed articles that rate of fatigue during FES elicited contraction is generally higher than voluntary contractions. By implication, optimized functional recovery of people with SCI by FES could significantly improve once muscle fatigue is addressed. This review constitutes a unique attempt to assess available evidence of effects and extents of muscle fatigue in FES assisted walking of SCI patients. It highlights state of the art procedures to minimize fatigue and looking forward to approaches that could further reduce the effect of fatigue on FES evoked contraction for patient enhanced beneficial gait to avoid secondary illness due to physical inability. The outcome of this study is relevant in clinical optimization of effects of FES rehabilitation on individuals with SCI. Keywords— SCI, functional electrical stimulation, muscle fatigue, rehabilitation.