抄録
Recently, accuracy of the infront kick (the ankle is in an "L" shape and turned out at a 45o angle and contact is with the side of the instep), which has greatly influenced the success or failure of set play, has garnered increased importance in soccer. The aim of the present study was to examine the accuracy of the infront kick by analyzing the conditions, such as angle and velocity of kick, preceding the kick and the ball's resulting trajectory. Subjects were 7 male players who belonged to a university soccer club. Using the infront kick, they were required to hit each of 4 targets set up at different distances behind a screen positioned 9.15 m in front of the kicker. The behavior of the ball was recorded from the rear by two normal-speed video cameras and analyzed using the three-dimensional direct linear transformation method. Another video camera was placed facing the kicker to capture variables related to ball rotation. Results revealed that displacement of the ball from the center point of each target occurred in an oval distribution on a diagonal axis from top-right to bottom-left, though the axis inclination was different for each player. Moreover, the ball trajectory was affected by the initial direction and velocity of the ball just after being kicked and by the rotation of the ball and the inclination of its rotation axis. It was thought that by mapping each player according to their own kicking strategy, values for hitting the target could be determined.
