Associations Between the Horizontal Force-Velocity Profile and Change of Direction Asymmetries and Phase-Specific Performance in Elite U21 Football Players.

The horizontal force-velocity profile (H-FVP) provides insights into sprint mechanical capacities, but its relationship with change of direction (COD) performance, inter-limb asymmetry, and phase-specific outcomes in elite football remains unclear. This study examined associations between H-FVP variables and COD performance in 15 elite male players from the Czech Republic U21 national team. Athletes performed a 40 m sprint and a 15-0-5 COD test with a motorized resistance device. H-FVP variables (F0, V0, Pmax, RF, DRF) were derived from sprint trials, while COD outcomes included overall times, asymmetry indices, and specific phases. Correlations were calculated between sprint mechanics and COD outcomes. Significant relationships were observed between H-FVP and COD performance on the dominant leg. Faster COD times were correlated with higher F0 (r = -0.73, p < 0.01), Pmax and RF (r = -0.72, p < 0.01), and with lower DRF. Sprint performance also correlated negatively with F0 and Pmax. In contrast, relationships between H-FVP and COD asymmetry were limited, although V0 showed positive correlations with overall and Phase 1b asymmetry. Phase-specific analysis revealed stronger links with Phase 1a and initial acceleration, particularly on the dominant side, whereas deceleration and re-acceleration phases showed weaker or inconsistent correlations. These findings indicate that H-FVP, especially F0 and Pmax, is strongly related to sprint and early COD performance but provides limited information on inter-limb asymmetry and later COD phases. Integrating horizontal sprint profiling with phase-specific COD assessments may therefore enhance athlete monitoring and training design in elite football players.