Abstract des Autors

The aim of the study was to determine the profile of isokinetic strength of elite young soccer players (n = 12, mean age 17.5±1.5 years, body height 174±8.5 cm and body weight 75.6±13.1 kg) and to determine the ratio of muscle strength between knee flexors and extensors and their bilateral strength imbalances. Diagnostics was performed on the isokinetic dynamometer. We evaluated: maximum peak muscle torque of knee extensors (PTE) and flexors (PTF) in both legs, ipsilateral ratio of muscle torque for both preferred and non-preferred limbs (HP : QP , respectively
HN : QN), bilateral ratio between the developed strength of knee extensors (Q : Q) and flexors (H : H). Strength parameters were obtained in the concentric contraction at angular velocities of 60, 120, 180, 240 and 300°.s–1. PTE and PTF were significantly reduced with increasing angular velocity in both preferred and non-preferred limbs (p<0.05). At all velocities, PTE was higher in the preferred limb. A significant difference was at 60°.s–1 (p<0.05). We did not found any significant difference in the level of strength between the preferred and non-preferred limb in PTF (p>0.05). Increasing angular velocity had a significant effect size of ipsilateral H : Q ratio in both limbs (p<0.05). An insignificant difference was found between the results of the preferred and non-preferred limbs (p>0.05). The bilateral ratio of the developed strength in knee extensors, or flexors respectively, was not significantly different in the movement velocity (p>0.05). At the highest velocity, a significant difference was between the bilateral Q : Q and H : H ratios (p<0.05). Strength bilateral asymmetry was demonstrated in at least one of the measurements in 50% of players at velocity 60°.s–1 and 75% of players at velocity 300°.s–1. Precise determination and quantification of muscle strength imbalances is essential for determination of the fundamental level of organized and intentionally controlled training process and for early compensation of the found imbalances as prevention against potential injury of athletes. Verf.-Referat