Do Single-Leg Balance Control and Lower Extremity Muscle Strength Correlate with Ankle Instability and Leg Injuries in Young Ballet Dancers?

Abstract

Ankle injuries are common among young ballet dancers. These injuries may be attributed to ankle instability, insufficient lower extremity strength, and poor balance control. The purpose of this study was to explore whether these dancers exhibit functional ankle instability and if their single-leg balance control and lower extremity muscle strength correlate with functional ankle instability and leg injuries. Twenty-one ballet dancers (aged 10 to 17 years) participated in the study. The Cumberland Ankle Instability Tool (CAIT) questionnaire was used to examine functional ankle stability. Isometric muscle strength of the major lower extremity muscles was measured with a digital hand-held dynamometer. Single-leg balance was evaluated with the Y-Balance Test (YBT) and three Athletic Single-leg Stability Test (ASLST) protocols. Lower extremity injuries (self-reported) within 6 months after testing were recorded for correlation analyses. Both dominant and non-dominant ankles of the subjects exhibited functional ankle instability (26.71 and 25.71, respectively). Raising the center of mass (passé and first arm position) during the ASLST did not significantly affect balance performance (p = 0.104). However, removing extrinsic visual feedback significantly decreased single-leg balance (p < 0.001). In general, there was low correlation (r ≤ 0.49) between muscle strength, CAIT, YBT, and ASLST scores with lower extremity injuries. It is concluded that for young ballet dancers lower extremity muscle strength and single-leg balance control may not be strong contributing factors to leg injuries. This study also suggests that functional ankle stability may not have a direct impact on single-leg balance, and ballet dancers rely heavily on extrinsic visual feedback for single-leg balance control. Teachers might consider minimizing extrinsic feedback to challenge ballet dancers when implementing training protocols for single-leg balance control.