Physical Function, Muscle Strength, and Fatigue in Patients with Multiple Sclerosis: An Exploratory Cross-Sectional Study.

Background: Physical function, muscle strength, and fatigue are often impaired in patients with multiple sclerosis (MS). This study aimed to assess these parameters and their associations. Methods: This cross-sectional study included patients with relapsing-remitting MS. Physical function was assessed using the dynamic gait index (DGI), two-minute walk test (2MWT), and Expanded Disability Status Scale (EDSS). Muscle strength and fatigue were assessed using a load cell (measured in kgf). Generalized linear models (GLMs) with log link and gamma distribution examined the associations between MS and physical function, muscle strength, and fatigue. In the MS group, GLMs explored links between fatigue, muscle strength, and physical function. Results: Forty-seven individuals participated (18 MS; 27 controls). Patients with MS showed reduced physical function and muscle strength, and higher fatigue. Knee extension fatigue was associated with DGI (Exp β = 0.23; p = 0.03), 2MWT (Exp β = 0.11; p = 0.02), and EDSS (Exp β = 17.17; p < 0.0001); knee flexion fatigue was associated with EDSS (Exp β = 2.45; p = 0.006). Knee flexion and extension strength were also associated with EDSS. Conclusions: Patients with MS show reduced physical function and strength, increased fatigue, and knee muscle performance. The associations between strength, fatigue, and functional outcomes varied in magnitude, with knee-related measures, especially knee extension fatigue, showing the most consistent relationships.