Data analysis. To assess the impact of fatigue on the ankle angle during prolonged walking, ankle angle data in the first and last 60 seconds of the walk will be recorded. Two way ANOVA will be employed to analyse both the effects of time (within session) and that of FES use ('Off' and 'On', between sessions) on the degree of foot-drop if data are normally distributed. Equivalent non-parametric statistics will be used for non normally distributed data. Statistical significance will be accepted at p<0.05.