The effect of FES of the tibial nerve on physiological activation of leg muscles during gait

The effects of surface functional electrical stimulation (FES) of the tibial nerve of healthy subjects were evaluated. The FES was applied at three different times during gait: early, mid and late stances. The purpose of this work is to understand the effect of unilateral stimulation on the bilateral activation patterns of leg muscles, because FES is used in practice to improve gait, while associated neuromuscular change is not often measured. The experimental protocol presented here will be transferred to stroke subjects, who could benefit from improved push-off during gait. Results show that FES of the tibial nerve changes the offset timing of the tibialis anterior muscle on the stimulated side and the on- and offset timings of the tibialis anterior muscle of the leg contralateral to stimulation. Additionally, activity levels of the semitendinosus ipsilateral and tibialis anterior contralateral to the stimulated leg significantly decreased, with respect to the non-stimulated condition. For the semitendinosus, this was a difference of 6–7 μV, with p < 0.05. For the tibialis anterior, this was a difference of 7–15 μV, with a significance of p = 0.00, respectively. This information is important for future applications of stimulation as it means that stimulation not only affects the stimulated muscle but also the physiological motor control by the CNS.