Profiling Single-Leg Balance by Leg Preference and Position in Rugby Union Athletes.

Our aims were to assess single-leg balance in rugby union athletes and compare the stability indices between legs and between positions. Thirty athletes, forwards and backs (n = 15/15), performed single-leg balance measured at two difficulty levels (Level 8: more stable and Level 2: less stable) using the Biodex Balance SD System. The backs' nonpreferred leg had worse scores in medial-lateral and overall indices (effect size = 1.05 and 0.63) compared with the preferred leg on Level 8 stability. Backs had better scores in all indices in the preferred (effect size = -1.20 to -1.82) and nonpreferred (effect size = -0.66 to -1.36) legs compared with the forwards at both stability difficulties. Asymmetry between the two legs is also present between forwards and backs when examined on an individual basis. This study illuminates the importance of single-leg balance screening among rugby athletes to detect individuals with asymmetries in balance that may increase the risk of lower-extremity injury.