Relationship between Ball Kick Velocity and Leg Strength: A Comparison between Soccer Players and Other Athletes

This study compared soccer players with non-soccer players, with respect to the relationship between ball velocity due to an instep kick and various leg strengths. Ten young university soccer players and ten other athletes (non-soccer players) had their instep kick ball velocity (BV) measured with respect to isokinetic leg strength. The BVs from the soccer players were significantly greater than those from the non-soccer group. However, this group also had significantly inferior dorsiflexion strength of the ankle joint (low: low angular velocity), extension of the knee joint (low, middle, and the total value of the evaluation parameters of all angular velocities), and flexion of the hip joint (middle). Positive and significant correlations between BV and flexion and dorsiflexion strengths of the ankle joint (low), extension (low, middle, high, and total), and flexion of knee joint (low and total), extension (low, high, and total), and flexion (high) of the hip joint were found in the soccer group, but a significant negative correlation was found only between BV and hip joint flexion strength (middle) in the non-soccer group. In conclusion, soccer players have similar or inferior isokinetic leg strength in comparison to other athletes, but their BV is faster.