Multivariate association with disease progression and walking kinematics in relapsing-remitting multiple sclerosis

Declines in walking function commonly occur in people with multiple sclerosis (MS). Walking is a continuous movement and a complex motor task that requires precise timing and scaling of activation across many muscles. The objectives of this study were to identify kinematic gait characteristics during a 2-minute walk test that are associated with disease duration in individuals with relapsing-remitting MS (n=45). Participants were instrumented with inertial measurement units from APDM (APDM Inc, Portland, OR, USA) and performed the 2-minute walk test twice: once at their self-selected speed and another at their fastest, safe speed. Gait speed was not associated with MS disease duration (Self-selected: p= 0.180; Fast: p=0.167). Canonical correlation analysis showed that disease progression was strongly associated with lateral step width variability and ankle pitch at toe-off, which was also reflected in the multiple linear regression models. Both self-selected and fast-speed kinematics were associated with disease duration (Self-selected: p=0.007; Fast: p=0.004). Thus, we identified a multivariate model that is associated with disease duration in highly ambulatory MS individuals. Our study highlights the importance of considering individual differences in specific gait kinematics (such as lateral step width variability and ankle pitch at toe-off) when assessing disease progression in MS. This approach may provide more personalized insights into the impact of MS on mobility and help tailor interventions to improve gait and overall function in affected individuals. Future research should continue exploring these kinematic parameters to better understand their role in MS progression and develop targeted therapeutic strategies.