Trunk Isokinetic Strength and Dynamic Balance Explain More Than Half of the Variance in Single Leg Hop Performance

Objective: The single-legged hop for distance (SLHD) is a functional test widely used to assess lower limb performance and readiness for return to sport. While lower limb strength and balance are known contributors to SLHD performance, the influence of trunk function has received limited attention. To investigate the relationship between trunk strength, dynamic balance, and SLHD performance in healthy young adults. Materials and Methods: Twenty-nine recreationally active participants (22.5±1.7 years; 16 females) underwent isokinetic trunk flexion and extension strength testing, dynamic balance assessment using the Y-Balance Test, and SLHD testing. Pearson correlations and multiple linear regression were used to identify predictors of SLHD performance. Results: SLHD performance was significantly correlated with trunk extension strength (r=0.60, p=0.001), trunk flexion strength (r= 0.42, p= 0.024), posteromedial balance (r= 0.47, p= 0.002), and posterolateral balance (r= 0.54, p= 0.002). In the final regression model, trunk extension strength (β= 0.504, p= 0.001) and posterolateral balance (β= 0.439, p= 0.003) emerged as significant predictors, together explaining 54% of the variance in SLHD (R²=0 .54, p< 0.001). Conclusion: Trunk extension strength and posterolateral dynamic balance are significant contributors to SLHD performance in healthy individuals. These findings highlight the importance of trunk function and multidirectional balance in dynamic functional tasks and may inform training and rehabilitation strategies targeting performance and injury prevention.