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No association of leg strength asymmetry with walking performance, fatigability or fatigue in multiple sclerosis




Proessl, Felix, author
Rudroff, Thorsten, advisor
Fling, Brett, committee member
Burzynska, Agnieszka, committee member

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Background: One of the first signs of Multiple Sclerosis (MS) is weakness on one side of the body, which is associated with an increased reliance on the stronger leg during walking as indicated by asymmetric muscle activity. The role of leg strength asymmetry on walking performance, fatigue and fatigability is unknown in people with MS (PwMS). Objective: The purpose of this cross-sectional study was to determine whether leg strength asymmetry is associated with walking performance, objective measures of fatigability, or subjective perceptions of fatigue during a 6-minute walk test (6MWT). Methods: Maximal knee extensor strength was assessed in 19 PwMS, and a symmetry index was calculated based on the objectively defined more- and less-affected leg. Walking ability was determined by measuring the total distance covered during a 6MWT and fatigability by calculating the change in distance covered between minutes six and one. Perceptions of fatigue were assessed by obtaining ratings of perceived exertion (RPE) using the modified Borg 10-point scale during the first and the final minute of the 6MWT. Results: PwMS covered less distance (P=0.01) and perceived greater exertion (P<0.01) during minute six compared to minute one. Maximal knee extensor strength was different between the more- and less-affected side (P<0.01). The magnitude of asymmetry did not correlate with walking performance, fatigability, or perceptions of fatigue. Conclusions: Maximal knee extensor strength asymmetry may not play an important role in walking performance, fatigability or fatigue in PwMS. Future asymmetry studies should include the flexor muscles and measures of sensory function.


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