Lower limb muscle activity underlying temporal gait asymmetry post-stroke

ObjectiveAsymmetric walking after stroke is common, detrimental, and difficult to treat, but current knowledge of underlying physiological mechanisms is limited. This study investigated electromyographic (EMG) features of temporal gait asymmetry (TGA). MethodsParticipants post-stroke with or without TGA and control adults (n=27, 8, and 9, respectively) performed self-paced overground gait trials. EMG, force plate, and motion capture data were collected. Lower limb muscle activity was compared across groups and sides (more/less affected). Correlation between burst timing variables and asymmetry ratios was examined. ResultsSignificant group by side interaction effects were found: fewer TGA group dorsiflexor bursts during swing (p=.0009), more affected plantarflexor stance activity ended early (p=.0006) and less affected dorsiflexor on/off time was delayed (p<.01) in persons with asymmetry compared to symmetric and normative controls. Less affected side EMG timing correlated most with swing time ratio (r=0.68-0.90, p<.001). ConclusionsTemporal patterns of muscular activation, particularly about the ankle around the stance-to-swing transition period, are associated with TGA. The results may reflect specific impairments or compensations that affect locomotor coordination. SignificanceNeuromuscular underpinnings of spatiotemporal asymmetry have not been previously characterized. These novel findings may inform targeted therapeutic strategies to improve gait quality after stroke.