Multi-joint isokinetic strength profiling as a predictor of vertical jump performance in elite freestyle wrestlers: A cross-sectional principal component analysis

Wrestling requires coordinated lower-limb strength for explosive techniques. While isokinetic testing isolates joint-specific strength and countermovement jumps assess functional power, comprehensive multi-joint assessments with advanced factor analysis remain unexplored in elite wrestlers. Twenty-one national-level male freestyle wrestlers (22.3 ± 2.8 years; 76.2 ± 14.7 kg) completed cross-sectional neuromuscular assessments. Isokinetic concentric strength testing at 60°/s evaluated hip, knee, and ankle joint functions bilaterally using an Isomed 2000 dynamometer. Vertical jump power was assessed through countermovement jumps under bilateral and unilateral conditions using the Optojump system. All strength and power variables were normalized to fat-free mass determined via air displacement plethysmography. Statistical analyses included Pearson correlations with Benjamini-Hochberg correction, stepwise multiple regression, and principal component analysis. Bilateral jump performance correlated strongly with knee extension (R = 0.798, P < .001) and hip extension strength (R = 0.664, P = .001), with combined predictors explaining 68.8% of variance (F₂,₁₈ = 19.8, P < .001). Principal component analysis identified a primary extensor factor (hip and knee extension, 52.6% variance) and an auxiliary factor (ankle plantar flexion and hip adduction, 19.0% variance). Unilateral jump models demonstrated lower explanatory power (dominant: 39.8%, non-dominant: 25.7%). Multi-joint isokinetic strength assessment, particularly hip and knee extension capacity, provides a robust prediction of vertical jump performance in elite wrestlers. The identified primary extensor strength factor represents a fundamental neuromuscular capacity underlying explosive lower-limb function, supporting targeted strength development strategies for wrestling-specific performance enhancement.