Comparing the Balance, Strength, and Range of Motion of Hip and Ankle Joints in Volleyball Players With and Without Dynamic Knee Valgus

Background and Aims Dynamic knee valgus (DKV) is an abnormal pattern of movement or abnormal alignment of the lower limb that causes changes in lower limb function in the frontal plane and absorption of excessive reaction force by the knee ligaments during sports activities, which can increase the risk of anterior cruciate ligament injury. This study aims to compare the balance, strength, and range of motion (ROM) of hip and ankle joints in volleyball players with and without DKV.Methods This is a quasi-experimental and causal-comparative study. Participants were 60 volleyball players (30 with DKV and 30 without DKV). The tuck jump test was used to evaluate their DKV. The ROM of knee and ankle joints was measured using a goniometer, while the isometric strength of the hip and ankle muscles was determined using a hand dynamometer. Then static and dynamic balances were evaluated by the Stork test and the Y balance test, respectively. Independent t-test was used to compare the means of variables between the two groups in SPSS  software, version 24.Results The results showed a significant difference in static balance (P=0.005), dynamic balance (P≤0.05), hip abduction strength (P=0.03), hip external rotation strength (P=0.01), and ROM of ankle dorsiflexion (P=0.03) between the two groups, where those without DKV performed better. The difference in other variables was not significant between the two groups.Conclusion The results indicate the importance of improving hip abduction and hip external rotation strength as well as the ROM of ankle dorsiflexion for reducing the DKV, which should be considered in designing training protocols.