Left-right asymmetry in two types of soccer kick.
The ability to kick with both feet is regarded as a desirable skill in high level soccer players; however, most players display a dominance of kicking ability on one side. This study investigated the characteristics of asymmetry in two types of soccer kick. A low drive and a chip kick from both the left and right foot of 12 élite junior soccer players were analysed. Kick velocity, kick accuracy, position of the plant foot from the ball centre, and time from foot plant to ball contact were measured for each kick. Knee extension and flexion strength were also determined for each leg at 60 degree s-1, 180 degree s-1 and 240 degrees s-1 on a Cybex II Isokinetic Dynamometer. A single factor repeated measures analysis of variance was applied to velocity, plant foot position and timing parameters to compare between sides and between shots. chi 2 analysis was used to compare accuracy between shots and between sides, and a paired Student's t test was used to compare strength parameters between sides. Pearson's product moment correlation analysis was used to examine the relationship between velocity and both leg strength and the time from foot plant to ball contact. Significance was set at P < or = 0.05. The results showed that this group had strength dominance at all speeds tested on the right side and better drive kick performance with their right leg as determined by mean(s.d.) velocity (79(6) versus 66(8) km h-1) and accuracy (66.6% versus 33.3%). There was no difference in these parameters between sides for chip kicks.(ABSTRACT TRUNCATED AT 250 WORDS)