| Popis |
INTRODUCTION: This study investigates the relationships between countermovement jump (CMJ) metrics, linear 40 m sprint (Lin40), the horizontal force-velocity profile (FVP) and change of direction (COD) ability in soccer players. The aim is to explore how CMJ parameters are associated with Lin40, FVP and COD parameters to optimize training strategies. Special attention is given to the interplay between horizontal and vertical force production and its impact on acceleration and deceleration phases, which are crucial for sprinting and rapid direction changes. METHODS: Fifteen male U21 Czech national team soccer players participated in a training camp assessment, completing two trials of the CMJ, linear 40 m sprint (Lin40), and COD performance, with only the best individual results—jump height for CMJ, and time for Lin40 and COD—analyzed. Additional CMJ parameters, including braking-phase rate of force development (DecRFD) and maximal relative power (PP), were measured using K-deltas (Kinvent, France). Sprint (Lin40) and COD performances were assessed with the 1080 Sprint device (1080 Motion, Sweden) under a constant 3 kg isotonic resistance. In the COD test, athletes sprinted 15 m with 3 kg assistance, performed a 180° turn, and continued for 5 m with 3 kg resistance. COD metrics included maximal acceleration (MaxAcc) and maximal deceleration (MaxDec). Lin40 performance included maximal acceleration (MaxAcc) and horizontal force-velocity profile (FVP) metrics: maximal power output (Pmax), theoretical maximum force (F0) and maximum velocity (V0). RESULTS: COD: 4.35 ± 0.08 s (time), 7.22 ± 0.72 m/s^2 (MaxAcc), and 8.71 ± 0.99 m/s^2 (MaxDec). CMJ: 43.4 ± 3.94 cm (jump height), 60.1 ± 5.5 W/kg (PP), and 10740.7 ± 4531.67 N/s (DecRFD). Lin40 and FVP: 5.9 ± 0.21 s (time), 7.8 ± 0.58 N (F0), 9.3 ± 0.47 m/s (V0), 17.86 ± 1.19 W/kg (Pmax), and 7.3 ± 0.62 m/s^2 (MaxAcc). CMJ height demonstrated a moderately strong positive correlation with Pmax (r = 0.55, p < 0.05) and F0 (r = 0.51, n.s.), as well as with CMJ PP (both r = 0.66, p < 0.05). No significant correlations were found between CMJ and COD parameters, although CMJ DecRFD was positively correlated with COD MaxAcc (r = 0.21), and COD MaxDec was negatively correlated with CMJ height (r = -0.37) but not with CMJ DecRFD (r = 0.09). CONCLUSION: CMJ, Lin40 and COD performances share common neuromuscular determinants, while COD ability appears to rely more on acceleration and deceleration capacities. These findings highlight the necessity for targeted training strategies in elite U21 soccer players. Specific exercises designed to improve both explosive strength for CMJ and agility for COD are essential for optimizing performance across all facets of the game. Future research should further investigate how tailored training programs can enhance both vertical and horizontal power, thus improving overall athletic performance.
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