Inter-limb functional asymmetries and their association with swimming performance in elite male water polo players

Introduction: Given the unilateral nature of throwing sports, functional asymmetries between the dominant and non-dominant sides are expected in water polo players. Although, research on this topic remains limited, inter-limb asymmetry has been suggested to reduce sport performance. This study aimed to examine the magnitude of inter-limb functional asymmetry as well as its association with swimming performance in elite male water polo players.
Methods: Twenty-one male players (23.5 ± 6.2 years) competing in the Belgian Super League completed a series of functional asymmetry assessments. Isokinetic internal and external rotation shoulder strength (peak torque and average power) was measured using an isokinetic dynamometry (Biodex), while throwing performance was measured using an overhead throwing test. Change-of-direction performance was evaluated using a newly developed 505 change-of-direction swimming test, which included change-of-direction trials in both the right and left turning direction as well as a 10-meter sprint test. The change-of-direction deficit was calculated by subtracting the 10-meter sprint time from the 505-test time. The magnitude of asymmetry was calculated using the percentage difference method (PDM): [(dominant value - non-dominant value) / dominant value] × 100. Side-to-side differences were analyzed with paired sample t-tests, and associations between asymmetry and 10-m sprint swimming performance were examined using Pearson correlations.
Results: Significant side-to-side differences (p-values ranging between < 0.001 - 0.007) were observed for all metrics of interest, with PDM scores ranging from 9.5–55.7%. No significant associations (r-values ranging between -0.315 - -0.051; p-values ranging between 0.164 - 0.853) were detected between functional asymmetry and swimming performance .
Conclusion: These findings demonstrate clear functional adaptations in elite water polo players aligning with those reported in other unilateral sports such as tennis . Although this study found no significant association between the magnitude of inter-limb asymmetry and swimming performance, future research is warranted to explore its potential implications for injury risk.