This study aimed to clarify techniques for kicking along various trajectories toward variously positioned targets in direct free kicks in soccer. Four experienced soccer players (career：12±0.8 years) belonging to a university soccer club participated in this study. Participants were asked to kick a soccer ball to 4 targets at various combinations of vertical and lateral positions in the goal (3.5 m left of center and 3.5 m right of center; 1.2 m from the ground and 2.2 m from the ground) from behind a screen (height 1.8 m×width 2.5 m) positioned 9.15 m in front of kicking points. Participants kicked from 3 positions located 20m from the goal (center of goal, 3.5 m left of center, 3.5 m right of center). The behavior of the kicked ball was recorded by 4 normal-speed video cameras and analyzed using three-dimensional direct linear transformation. Two high-speed video cameras were used to capture parameters related to ball rotation; one was placed facing the kicker and another was placed beside the kicker to capture the moment the ball was kicked. Results indicated that the lateral component of the Z-coordinates tended to approach the center of the goal and varied more widely than the vertical component. Additionally, lateral kicking direction was the most important parameter to kicking along various trajectories for all participants and combinations of target positions. The kicking direction for greatest reduction of error appeared to differ by strategies for kicking along various trajectories. Lastly, vertical kicking direction was an important parameter to kicking along various trajectories for some participants, but for other participants, initial velocities as well as kicking direction were important parameters.
