The impact of walking speed on the effects of functional electrical stimulation for foot drop in people with multiple sclerosis

Purpose: Functional electrical stimulation (FES) is effective in assisting people with multiple sclerosis (pwMS) with gait. Previous studies have investigated the effects of FES in pwMS with slow self-selected walking speeds (SSWS). This study reports on the effect of the Odstock Dropped Foot Stimulator (ODFS) on the speed and oxygen (O2) cost of gait in pwMS walking at a range of SSWS. Methods: Twenty pwMS (mean age 50.4 ± 7.3 years) currently using FES walked at their SSWS for 5 min with and without FES. O2 cost of gait was measured using a gas analysis system, and gait speed was calculated. Data were analysed for all participants, and comparisons were made between those with a SSWS < and >0.8 m/s (walking speed required for community ambulation). Results: Significant improvements in the speed and O2 cost of gait were seen using FES in the group with SSWS 0.8 m/s, no difference in gait speed was noted, and a significant increase in O2 cost of gait using FES (n = 9, p = 0.004) was noted. Conclusion: FES has a different effect on the speed and O2 cost of gait dependent on the SSWS of pwMS. This requires further investigation.Implications for Rehabilitation Functional electrical stimulation (FES) used for foot drop is effective in improving the speed and oxygen cost of walking in pwMS walking at SSWS 0.8 m/s. Further research is needed to understand the possible mechanisms involved so that FES for foot drop can be efficiently prescribed.