Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Health and Nutritional Sciences

First Advisor

Bradley Bowser


Multiple Sclerosis is a neurological disease which affects an estimated 2.5million people worldwide. People with Multiple Sclerosis often experience high rates of falls, which have been associated with age, disability, and increased postural sway. Additionally, people with Multiple Sclerosis often exhibit muscular weakness and poor responses to perturbations. PURPOSE: To determine if trunk stability and postural control are altered among PwMS and if trunk muscle activity is correlated with postural stability. METHODS: Ten participants with a physician's diagnosis of Multiple Sclerosis (9 female, 1 male) were included in this study. Ten healthy controls were matched for age, height, weight, and gender. To analyze postural sway, participants stood quietly on a force platform for 30s with eyes closed and 30s with eyes open. Participants were then administered anticipated and unanticipated perturbations to the trunk while in a semiseated position. Finally, participants underwent three maximum isometric contractions. Surface electromyography was collected at the erector spinae muscle group 3cm lateral to the L3 spinous process. High speed motion capture was used to determine peak accelerations of a reflective marker placed approximately at the C7 vertebrae. RESULTS: No statistical differences were observed in trunk accelerations following perturbations. However, people with multiple sclerosis exhibit significantly greater trunk muscle activity following anticipated perturbations (p = 0.04, d = 0.98). Additionally, numerous large significant correlations were found between trunk muscle activity and postural sway. People with Multiple Sclerosis who experience falls appear to have greater trunk muscle activity following unanticipated perturbations than non-fallers (p = 0.07, d = 1.47). However, non-fallers may be better able to anticipate perturbations than fallers (p = 0.10, d = 1.29). CONCLUSION: People with Multiple Sclerosis demonstrate greater trunk muscle activity in response to perturbations than healthy controls. Trunk muscle activity is significantly correlated to postural sway in people with multiple sclerosis. People with Multiple Sclerosis who experience falls show greater trunk muscle activity following perturbations than non-fallers. However, non-fallers may be better able to anticipate perturbations than fallers.

Library of Congress Subject Headings

Multiple sclerosis.
Equilibrium (Physiology)
Abdomen -- Physiological aspects.
Posture -- Physiological aspects.


Includes bibliographical references (pages 42-53)



Number of Pages



South Dakota State University


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