Relationship between lower extremity isokinetic strength ratio and dynamic balance ability in elite combat sports athletes

Dynamic balance is essential for performance and injury prevention in combat sports, but its relationship with isokinetic strength ratios of the lower extremity and trunk is not well understood. This study investigated the associations between knee, hip, and trunk strength ratios and dynamic balance in elite combat sport athletes. Fifty-one elite judo and wushu athletes (31 males, 20 females) underwent isokinetic testing of the knee, hip, and trunk, with peak torque normalized to body mass (%body weight). Dynamic balance was assessed using the Biodex Balance System SD. Interaction effects between strength ratios and balance variables were analyzed using three-way analysis of variance. Male athletes showed greater muscle strength, whereas female athletes demonstrated better dynamic balance. Higher knee flexor-to-extensor strength ratios (≥61%) and moderate hip (35%–40%) and trunk strength ratios were associated with better dynamic balance. Significant interaction effects were found between knee and hip strength ratios. Our findings suggest that dynamic balance in elite combat sport athletes may depend on the coordinated strength balance of the knee, hip, and trunk rather than on absolute muscle strength alone.