Effects of stepping practice and functional electrical stmulation on neuromotor excitability in able bodied young adults.

The neural processes underlying gait retraining interventions that combine stepping practice with electrical stimulation are poorly understood. The purpose of this study was to compare acute changes in corticomotor excitability measured by motor evoked potential (MEP) amplitude, monosynaptic stretch reflex excitability measured by H/M ratio, and propulsive force generation during gait measured by anterior ground reaction forces (AGRF), induced by 30-minutes of fast walking (Fast) and 30-minutes of fast walking with functional electrical stimulation of the ankle plantarflexors and dorsiflexors (FastFES) in 14 able-bodied young adults. Our results showed that FastFES, but not Fast elicited a significant acute decrease in tibialis anterior MEP amplitude (p = .01). Furthermore, the practice-induced acute decrease in tibialis anterior MEP amplitudes was significantly larger for FastFES than Fast (p = .04). FastFES also elicited a statistically significant increase in the AGRF in the tested limb (p = .01), which was significantly larger than the change induced by Fast (p = .04). Additionally, baseline soleus MEP amplitude was positively correlated with within-session change in AGRF (p = .04, r = 0.16). Acute decrease in tibialis anterior MEP amplitude for the FastFES condition relative to the Fast condition may be caused by fatigue, while the greater increase in AGRF for the FastFES condition signify that stepping practice facilitated alterations of gait patterns. More research is needed to confirm neural mechanisms and investigate the acute as well as long-term effects of Fast and FastFES on clinical populations.