The Influence of Isokinetic Muscle Torque Exerted in Various Speeds on Soccer Ball Velocity

Numerous variables influence soccer kick performance and among those initial soccer ball velocity is considered to be important. The purpose of this study was to investigate the correlation between initial ball velocity and two physical characteristics: relative isokinetic torque of the lower extremity and muscle contraction velocity. Eleven elite Greek soccer players age 25.5 +/- 3 years, weight 73.6 +/- 5.6 kg, height 176.5 +/- 5.5 cm, were tested on an isokinetic apparatus at different angular velocities to determine isokinetic muscle torque of the dominant lower extremity. To determine muscle contraction velocity and initial soccer ball velocity a cycling ergometer and a photocell apparatus were used, respectively. Relative isokinetic muscle torque values of the lower extremity were at 30 degrees /sec 3.29 +/- 0.32 Nm/kg, at 90 degrees /sec 2.49 +/- 0.28 Nm/kg, and at 180 degrees /sec 1.75 +/- 0.24 Nm/kg. Muscle contraction velocity was 3.69 +/- 0.27 c/s and initial ball velocity was 27.08 +/- 1.32 m/s. Initial ball velocity correlated significantly with relative isokinetic muscle torque at different angular velocities as follows: at 30 degrees /sec, r = 0.82, p < 0.01; at 90 degrees /sec, r = 0.73, p < 0.02; at 180 degrees /sec, r = 0.64, p < 0.05. Initial ball velocity was also significantly correlated with muscle contraction velocity (r = 0.77, p < 0.01). These results indicate that both physical qualities, i.e., relative isokinetic torque and muscle contraction velocity are significant variables related to soccer ball velocity which is considered to be an important factor of soccer kick performance.J Orthop Sports Phys Ther 1988;10(3):93-96.