Hatem Jaber


Ankle sprains are common and potentially disabling musculoskeletal injuries occur among physically active individuals. A subsequent problem that is commonly encountered by clinicians due to ankle sprains is the development of ongoing instability. The presence of ankle instability has been linked to impairments in postural and neuromuscular control; however, inconsistent findings have been reported. These discrepancies deem the need to further investigate and provide additional knowledge regarding postural and neuromuscular control strategies utilized by this population. This may enhance the current understanding of chronic ankle instability (CAI) and help to understand how rehabilitation can be customized to specifically target and improve patient outcomes. Therefore, the purpose of this study was to compare postural stability, as well as electromyographic (EMG) activity of hip and ankle muscles during the performance of the Star Excursion Balance Test (SEBT) in subjects with and without CAI. Methods: Forty-eight physically active participants were assigned into three groups (16 control, 16 copers, 16 CAI) based on ankle sprain history and Cumberland Ankle Instability Tool score. Outcome measures included normalized reach distance, center of

pressure (COP), and integrated EMG activation of the gluteus medius (Gmed), gluteus maximus (Gmax), tibialis anterior (TA), and peroneus longus (PL) during each reach direction of the SEBT. Results: There was a significant difference in mean outcome measures between the three study groups. When compared to copers and controls, the CAI group demonstrated significantly diminished dynamic stability as quantified by reach distance and COP measures (p<0.05) and less EMG activity of the muscles acting on the ankle and hip (p<0.05). Conclusion: Our findings indicate that individuals with CAI exhibited diminished dynamic stability and decreased EMG activity of ankle and hip musculature during functional testing. Alteration in both, the proximal and distal muscles activity appears to negatively affect measures of postural control and the quality of movement, which may lead to the prolonged functional impairments and the increased recurrence of the undesired lower extremity injuries in this population. Hence, implementing functional exercises that target hip and ankle muscles in the rehabilitation of ankle instability might benefit these patients.

LLU Discipline

Physical Therapy


Physical Therapy


School of Allied Health Professions

First Advisor

Lohman, Everett B., III

Second Advisor

Bains, Gurinder

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

Ankle -- Abnormalities; Sprains and Strains;

Subject - Local

Ankle Sprains; Musculoskeletal Injuries; Postural Stability



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