Physical Activity Is Associated With Neuromuscular And Physical Function In Patients With Multiple Sclerosis Independent Of Disease Severity

Purpose: Examine the association between physical activity and neuromuscular and physical function in patients with multiple sclerosis when also considering disease severity. Methods: 91 patients with multiple sclerosis were enrolled. Assessments included physical activity by 7-day thigh-worn accelerometry, knee extensor neuromuscular function by dynamometry (maximal isometric muscle strength, rate of force development (0-50 ms)), and physical function by 5x sit-to-stand, 2-min walk test, and timed 25 ft walk test. Physical activity tertile comparisons along with simple and multiple regressions (adjusting for age, gender, EDSS, time since diagnosis) were performed. Results: Physical activity tertiles revealed differences (p < 0.05) in maximal muscle strength (1.77 approximate to 1.97 < 2.28 Nm/kg), rate of force development (4.66 < 8.03 approximate to 10.55 Nm/kg/s), 5x sit-to-stand (11.4 approximate to 9.7 > 8.5 s), 2-min walk test (153 < 183 < 207 m), and timed 25 ft walk test (6.3 > 4.4 > 4.3 s). Moreover, physical activity was associated (p < 0.05) with maximal muscle strength and rate of force development (r(2) = 0.13-0.15) along with 5x sit-to-stand, 2-min walk test, and timed 25 ft walk test (r(2) = 0.18-0.24), also after adjusting for age + gender + EDSS + time since diagnosis (r(2) = 0.25-0.37 and 0.24-0.52), with physical activity consistently being a strong predictor. Conclusions: Higher levels of physical activity are associated with greater neuromuscular and physical function in ambulatory patients with multiple sclerosis independent of disease severity. These findings emphasize the importance of performing regular physical activity at all stages of multiple sclerosis.