Relationship between Symmetry of Gait Parameters and Intermuscular Coherence with Walking Speed in Stroke Survivors

Abstract

Stroke often causes asymmetry in gait parameters, such as step length and double support time, which negatively affects walking ability and quality of life. While slower walking speeds are associated with greater asymmetry, spatiotemporal symmetry in stroke survivors cannot be fully explained by walking speed alone. Neurological factors, including the lesion site and corticospinal function, must also be considered. This study aimed to elucidate the relationship between walking speed, spatiotemporal symmetry, and corticospinal drive in stroke survivors. A total of 22 chronic stroke survivors and 10 healthy older adults participated in the study. Gait analysis was performed using a double-belt treadmill and synchronized three-dimensional motion capture. Electromyography signals were collected from the bilateral tibialis anterior (TA), soleus, and gastrocnemius muscles. Coherence in the β-band was quantified as the area under the curve (AUC) to assess corticospinal connectivity. In healthy participants, AUC significantly increased during fast walking compared to normal walking (p＝0.001-0.02). Stroke survivors were divided into subgroups based on four symmetry indices, including step length and double support time. Only the subgroup with consistent double support time symmetry showed a significant increase in AUC of TA from normal to fast walking (p＝0.04). No significant differences in AUC were found in the other subgroups or in step length symmetry (p＝0.58). The findings suggest that maintaining double support time symmetry, regardless of walking speed, may reflect more efficient corticospinal control. Stroke survivors who achieved this symmetry exhibited gait dynamics similar to those of healthy individuals, with coordinated muscle activation across both lower limbs. These results underscore the importance of assessing spatiotemporal symmetry during gait interventions and highlight the need to consider neurological control alongside functional outcomes.