Inter-limb Asymmetry in Y Balance and Single Leg Hop as a Predictor of Sports Injuries in Volleyball Players

Abstract

Background: Sports injuries, particularly those affecting the lower extremities, are prevalent in volleyball. Neuromuscular asymmetry in the lower limbs may play a significant role in predicting injury risk. This study investigates the impact of limb asymmetry as a predictor of sports injuries in volleyball players. Objectives: The primary objective of this study was to examine the role of lower limb neuromuscular asymmetry as a predictor of injury risk in volleyball players. Additionally, the study aimed to assess the impact of limb asymmetry in functional tests, including the single-leg hop, 90-degree direction change, and dynamic Y-balance tests. Methods: This prospective cohort study began in June 2024 and will continue for nine months in Kermanshah. A sample of 101 male and female volleyball players was purposefully selected based on inclusion and exclusion criteria. Lower limb symmetry indices were assessed using functional tests (single-leg hop, 90-degree direction change, dynamic Y-balance) before the study. Injury registration and follow-up were conducted for nine months. Data were analyzed using SPSS version 27, employing independent t-tests to compare injured and non-injured groups and univariate logistic regression to explore the relationship between predictive variables and sports injuries. Results: Logistic regression analysis identified limb asymmetry in the single-leg hop for distance and Y-dynamic balance (anterior position) tests as significant predictors of sports injuries. The models explained 2.5% to 9.1% of injury variance for the single-leg hop and 1.4% to 7.4% for the Y-dynamic balance test, both of which were statistically significant (P = 0.02 and P = 0.04, respectively). Each 1% increase in limb asymmetry in the Y-dynamic balance (anterior position) test and each centimeter of limb difference in the single-leg hop for distance test increased the risk of injury by 18%. Conclusions: Limb asymmetry, as measured by the single-leg hop for distance and Y-dynamic balance (anterior position) tests, significantly predicts sports injuries in volleyball players. Even small increases in asymmetry raise the risk of injury by 18%. These findings emphasize the importance of incorporating these functional tests into injury risk assessments and prioritizing the reduction of asymmetries in injury prevention programs.