Hip Strength and Balance in Adolescent High School Aged Females in Relation to Lower Extremity Injury During One Competitive Season

Abstract

PURPOSE: The purpose of the study was to examine specific potential risk factors for lower extremity injury in adolescent high-school aged females participating in an organized sport. It has been suggested that core stability may be related to risk of injury. METHODS: High school females involved in a varsity or school recognized club sport participated in this study. Sports included lacrosse, track and field, tennis and softball. Individuals were excluded from the study if they sustained any lower extremity injury within the 4 months prior to the study. Prior to testing, subjects completed a health questionnaire which included medical and injury, training and competition, as well as menstrual history. Subjects completed a 3-station circuit before their season to assess hip abduction (ABD) and external rotation (ER) strength, and static and dynamic balance. Isometric strength was measured bilaterally, using a hand-held dynamometer and recorded in kgs to the nearest tenth. Static balance was measured using a modified Single Limb Eyes-Closed Balance Test. Dynamic balance was measured using the Star Excursion Balance Test (SEBT), using the 3 directions of posterior medial, anterior medial and medial. The SEBT was normalized for height for data analysis. Data was collected throughout the season for the type of injuries sustained by the athletes. RESULTS:62 athletes participated in this study. 11 sustained an injury and while 51 remained injury free during the season, with an incidence rate of 18%. Average hip abduction strength for those that were injured was 45 kg, while it was 50.5 kg for those in the uninjured group. This difference was statistically significant between groups (p≤.015). There were no other significant differences between the groups. Normalized SEBT and hip strength were significant contributors to a bivariate logistic regression (p=.005), though only 16 to 26% the variance was explained by these 2 variables. Previous injury did not help distinguish between those that incurred an injury and those that did not. CONCLUSIONS: The results suggest that hip abduction strength deficits could be a risk factor for sustaining a lower extremity injury during an athletic season for some sports. Thus, we would recommend assessing hip strength for female athletes prior to their competitive season.