Splitting the Difference: Split-Belt Treadmill Training Improves Spatial and Temporal Gait Symmetry in People with Multiple Sclerosis

Multiple sclerosis (MS) is a neurodegenerative disease affecting two million people worldwide. This disease is characterized by degradation of the myelin sheath resulting in impaired neural communication throughout the body. As a result, most people with MS (PwMS) experience significant mobility impairments. Gait asymmetries between the two legs are prevalent leading to an increased risk of falls, musculoskeletal injury, and decreased quality of life. Recent work indicates that split-belt treadmill training, where the speed of each leg is controlled independently, can decrease gait asymmetries for other neurodegenerative impairments. In this study, 26 PwMS have undergone split-belt treadmill training, with the faster paced belt moving under the more affected limb. Phase coordination index (PCI), which measures temporal coordination to assess stepping accuracy and consistency, and limb excursion asymmetry (LEA), which measures spatial coordination by quantifying sagittal displacement from toe off to heel strike of the ipsilateral leg, are the primary outcome measures used to assess gait symmetry in the current study. Previous work has identified an average PCI for PwMS population to be 5.19%, thus we grouped participants based on their baseline PCI value as either 1) above (poor baseline symmetry) or 2) below (good baseline symmetry) the previously recorded MS mean PCI of 5.19%, predicting that participants with a baseline PCI greater than 5.19% would show a greater response to split-belt treadmill training. Preliminary results show a mean PCI change of -1.31% (SE=0.65) for the poor baseline symmetry group and a mean PCI change of 0.92% (SE: 0.32) (p=0.0062). Among participants with poor baseline symmetry, the mean LEA change is -13.02mm (SE: 5.25) compared to a mean LEA change of 0.83mm (SE=3.35) for participants with good baseline symmetry (p=0.037). These findings suggest that PwMS retain the ability for gait adaptation, and provide the template for a novel, targeted mobility intervention.