Background: Motion sensitivity, or motion sickness, is common among individuals in modern vehicular and visually stimulating environments; notably, people with normal vestibular function are susceptible to this condition. Motion-provoked dizziness often causes postural instability. Purposes: This study aimed to compare the effects of head motion on postural stability in healthy adults with and without chronic motion sensitivity (CMS) and to determine the effects of head motion direction (horizontal versus vertical) on postural stability. Methods: Sixty healthy adult males and females aged 20 to 40 years old were assigned to two groups, 30 participants with CMS and 30 participants without CMS. Pre-data collection, all participants were trained on specific parameters of cervical rotation, flexion, and extension. Then, postural stability measurements were taken during three conditions (static, horizontal, and vertical head movements) using the Bertec Balance Advantage Dynamic Computerized Dynamic Posturography (CDP). Results: There was a significant difference between the CMS and non-CMS groups in mean postural stability during head movement in both horizontal and vertical head motions (p = 0.005 and p = 0.024, respectively); however, no significant difference was shown in mean postural stability between horizontal and vertical head motions within each group (p = 0.297 in CMS group and p = 0.179 in non-CMS group). Conclusions: The results indicate that healthy young adults without CMS have better postural stability during head motion than those with CMS, and that head motion direction (horizontal versus vertical) does not influence postural stability within each study group.

LLU Discipline

Physical Therapy


Physical Therapy


School of Allied Health Professions

First Advisor

Johnson, Eric

Second Advisor

Cordett, Tim

Third Advisor

Daher, Noha S.

Degree Name

Doctor of Science (DSc)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Postural Balance; Sensitivity and Specificity; Range of Motion; Vestibular Function Tests.

Subject - Local

Motion Sensitivity; Head Motion; Cervical Rotation; Motion-provoked Dizziness



Page Count


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 and Dissertations

Collection Website



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