Foot impact behaviour in soccer instep kicking across varying ball directions.

This study aims to elucidate the distinct characteristics of foot motion at ball impact, which affect the lateral ball launch direction in soccer instep kicking. Seven experienced male university soccer players each performed instep kicks towards a standard goal 11 m away, divided vertically into left, centre and right target areas (six kicks per area). Three high-speed cameras captured the foot and ball behaviours during ball impact at 2000 Hz. Multiple regression analysis was conducted with the lateral ball launch direction (dependent variable) to identify the key foot behaviours (independent variables) that contribute to the lateral launch angle of the ball. Consequently, the regression model (R2 = .91, p < .001) indicated that the foot contact point on the ball (β = -.649, p < .001) and the instep facing direction at ball impact (β = .324, p < .001) significantly predicted the ball direction, whereas the foot swing direction did not (β = .078, p = .312). These findings indicated that manipulating the foot-ball contact point and foot posture at ball impact is necessary to control the ball direction. Players strike the ball on the side opposite the target and orient the dorsal surface of the foot towards the intended direction.