Symmetry of corticomotor input to plantarflexors influences the propulsive strategy used to increase walking speed post-stroke

Abstract

ObjectiveA deficit in paretic limb propulsion has been identified as a major biomechanical factor limiting walking speed after stroke. The purpose of this study was to determine the influence of corticomotor symmetry between paretic and nonparetic plantarflexors on the propulsive strategy used to increase walking speed. MethodsTwenty-three participants with post-stroke hemiparesis underwent transcranial magnetic stimulation and biomechanical testing at their self-selected and fastest walking speeds. Plantarflexor corticomotor symmetry (CSPF) was calculated as a ratio of the average paretic versus nonparetic soleus motor evoked potential amplitude. The ratio of the paretic and nonparetic peak ankle plantarflexion moments (PFsym) was calculated at each speed. ResultsCSPF predicted the ΔPFsym from self-selected and fastest speeds (R2=.629, F(1,21)=35.56, p<.001). An interaction between CSPF and ΔPFsym (β=.596, p=.04) was observed when predicting Δspeed (adjR2=.772, F(3,19)=20.48, p<.001). Specifically, the ΔPFsym with speed modulation was positively related to the Δspeed (p=.03) in those with greater CSPF, but was not related in those with poor CSPF (p=.30). ConclusionsSymmetry of the corticomotor input to the plantarflexors influences the propulsive strategy used to increase post-stroke walking speed. SignificanceRehabilitation strategies that promote corticomotor symmetry may positively influence gait mechanics and enhance post-stroke walking function.