Is there any weakness in sports performance in volleyball athletes regarding the correlation between foot posture index and lower limb functional hopping performance?

Objective: The aim of the study was to investigate the relationship between 1RM calf raise, countermovement jump (CMJ), and functional hop performance with foot posture index (FPI). Methods: Twenty-six volleyball athletes were evaluated in this study. Foot posture index was evaluated with six-item criteria; talar head palpation, curves above and below the malleoli, calcaneus inversion/eversion, talonavicular congruence, medial longitudinal arch high, and forefoot abduction/adduction. Single hop, triple hop, crossover hop for distances, medial side triple hop, 90° medial rotation hop, single-leg vertical jump, 6m. timed hop, 1RM calf raise, and CMJ were measured in this study.Results: All measurements were tested on both right and left side. Significant differences were found in single hop (p = 0.016), triple hop (p = 0.005), medial side triple hop (p = 0.001), medial rotation hop (p = 0.020) in single leg vertical jump, and FPI for right and left sides (p < 0.001, p < 0.005). There were significant differences when comparing the limb symmetry indexes (LSI%) calculated from hop tests. When the correlations between FPI and hop tests were found significant, correlation and no significant correlations were found between left side and FPI. Conclusion: This study has shown that young female volleyball players may produce low hop performances due to the asymmetric structure relationship FPI scores. Level of Evidence IV; Therapeutics Studies; Cases Series.