Trunk Muscle Strength and Endurance in Chronic Ankle Instability

Inclusion Criteria: * The initial sprain must have occurred at least 12 months prior to study enrollment. * The most recent injury must have occurred more than three months prior to study enrollment (unassisted walking without limping for at least three months after injury). * A history of the previously injured ankle joint giving way, recurrent sprain and/or feelings of instability. * The injured/unstable ankle functionally weaker, more painful, looser, and less functional than the uninvolved ankle. * The Oswesty Disability Index (ODI) score for both groups is from 0 to 20% (minimal disability) (Fairbank and Pynsent, 2000). 6- The Identification of Functional Ankle Instability questionnaire (IdFAI) score is less than 10 for the experimental group and 11 or more for the control group (Simon et al., 2012). Exclusion Criteria: * 1-A history of previous surgeries or fractures in either limb of lower extremity. 2-Acute injury to musculoskeletal structures of other joints of the lower extremity in the previous three months, which impacted joint integrity and function (ie, sprains, fractures) resulting in at least one interrupted day of desired physical activity. 3-Any positive findings of the anterior drawer or talar tilt test (Hubbard and Kaminski, 2002). 4-Any shoulder (Kibler et al., 2006) or elbow injuries (Ben Kibler and Sciascia, 2004).