After a short period of warm-up, they were instructed to perform side-foot and instep kicks, using their preferred leg (right) with maximum effort, to the center of goal, which was located at a distance of 11 m in front of them. A regulation soccer ball (FIFA standard) was used. All subjects performed at least three attempts for each type of kick
so that one shot could be selected with both a good foot–ball impact and adequate center of goal targeting. The quality of the impact was judged in each trial by both the participant and the present investigator. When the participants could not produce a successful shot within three attempts, kicks were repeated until an additional shot satisfied the above two criteria. Two electrically synchronized high-speed video cameras (NAC Inc., Tokyo, Japan) were used to sample the kicking motion at 200 fps (shutter speed was 1/2000 s), positioned at the rear and kicking leg (right) side. For calibrating the performance area, a calibration frame (1.5 1.5 1.8 m) with 16 control points was videotaped before the trails.