Introduction:
Inter-limb asymmetry stands out as a useful sign of injury risk, explored in numerous studies. Scientists have measured and studied this index through various functional tests and through different mathematical equations. Limb dominance and frequent use of one side of the body has been pointed out as one of the reasons for the emergence of asymmetry. Volleyball, a widely loved sport, involves a dominant side in its performance.
The Landing Error Scoring System (LESS) and Y-Balance tests are widely used to assess the risk of injury in the lower extremities.
The aim of this study was to investigate if Inter-limb asymmetry in forward and lateral jumps are associated with Landing Error Scoring System (LESS) and Y-Balance asymmetry test in young professional female volleyball players.
Method:
The study sample comprised of 22 young professional female volleyball players (age: 17.4± 1.4 years, height: 175.13 ±6.84) playing in Division 1 and 2 National League. Athletes performed four tests including Single-Leg Forward Jump, Single-Leg Lateral Jump, LESS and Y-Balance test. Each test’s protocol was extracted from similar researches.
After calculating Inter-limb asymmetries in forward and lateral jumps and LESS and Y-Balance tests, normality tests and correlation analysis were performed at the significance level of p<0.05.
Results:
Results of variables analysis showed strong significant correlation between single-leg forward jumping Asymmetry and LESS (r=0.69 , pvalue=0.000). Furthermore a moderated correlation was observed between single-leg lateral jumping Asymmetry and LESS (r=0.52 , pvalue=0.013). Nevertheless, there was no significant correlation between forward and lateral jumping asymmetries and Y-Balance asymmetry test (pvalue=0.092, pvalue=0.21).
Discussion and conclusion:
Due to the results, LESS test as a common test of evaluating risk of injury is related to single-leg jumping. Athletes with higher asymmetry exhibited higher risk of lower extremity injury. According to the results of the present and previous studies, it is recommended that future researchers investigate the inter-limb asymmetry factor in long term and in other functional tasks so that if there is a relationship, coaches use proper assessment and exercises to reduce functional asymmetry, enhance performance, and lower the risk of injury in volleyball athletes.