The purpose of this study was to examine postural sway, cortical response and muscle activation of the hip and ankle muscles during eight balance tasks routinely used in sensorimotor training. This was a single group repeated measure study. The postural sway; the power of alpha, beta and sigma wave bands; and the EMG activity of gluteal maximus, gluteal medius, tibialis anterior and medial gastrocnemius were measured in 17 subjects during eight balance tasks with eyes open or closed, feet in tandem or apart and on foam or a firm surface. The results of this study showed that postural sway, EEG power of the beta and sigma wave bands, and EMG activity of the hip and ankle muscles were significantly higher due to the alteration of sensory information in the eight common balance tasks when compared to the control task. The postural sway was affected by the extent of sensory information available for postural control. The recruitment of specific muscles was affected by the context of the tasks rather than the number of sensory factors altered. EEG power of beta and sigma wave bands showed significant increases at the central and parietal area of the brain relative to the control tasks when eyes were open in the tasks. The cortical involvement decreased as the task became more difficult with vision and somatosensory information altered. When the balance task became more challenging with vision, base of support and surface compliance altered, the cortical activity increased significantly again. The postural sway and cortical activity were affected by the amount of sensory information available for postural control. The recruitment of specific muscles was affected by the context of the tasks rather than the numbers of sensory factor altered. Our results suggest that balance training should start with alteration of one sensory factor by first altering the somatosensory input (base of support then the surface compliance), and followed by excluding the visual input. The balance training should then be progressed by altering two then three sensory factors. A balance program should include exercises to strengthen hip and ankle muscles in order to facilitate the postural control in static balance tasks.

LLU Discipline

Physical Therapy


Physical Therapy


School of Allied Health Professions

First Advisor

Petrofsky, Jerrold S.

Second Advisor

Berk, Lee S.

Third Advisor

Daher, Noha S.

Fourth Advisor

Laymon, Michael S.

Fifth Advisor

Lohman, Everett

Degree Name

Doctor of Science (DSc)

Degree Level


Year Degree Awarded

January 2012

Date (Title Page)




Library of Congress/MESH Subject Headings


Subject - Local

Postural sway; Balance training; Balance control; Muscle activation; Cortical response



Page Count

87 p.

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses & Dissertations

Collection Website



Loma Linda University. Del E. Webb Memorial Library. University Archives