Motion and EMG Analysis of Soccer-ball Heading for the Lateral Direction

抄録

This study investigated head-trunk motion and muscle activity during soccer-ball heading for the frontal and lateral directions. Subjects were six soccer players who each had a soccer playing career of more than 10 years. Kinematic data were collected by three high-speed-video cameras. Head-rotation and trunk-twisting angles in the back-swing, forward-swing and follow-through phases were calculated. The electromyographic (EMG) activities of four muscles (the sternocleidomastoid, trapezius, external oblique abdominal and erector spinae muscle) were recorded bilaterally. The peak-time-lag, the lag between the greatest activation point of the right side and left side muscles, was calculated to evaluate the qualitative features of muscle activation. The volume of variation of head rotation angle in the backswing showed a significant difference between the two conditions (P<0.01). In the trapezius and external oblique abdominal muscles, the peak-time lag revealed a significant difference between the two conditions (P<0.01). From the results of this study, when skilled players headed the ball for the lateral direction, in the backswing, the head was rotated and the trunk was bent laterally to the opposite direction of the target. In the forward swing, the head was kept in position to see the target and ball in the same field of vision and the trunk was bent laterally toward the direction of target to impact the ball. The muscles surrounding the neck were activated to prepare for ball impact. Finally, in the follow through, back muscles were used to prevent the body from falling forward. We concluded that in the heading motion for the lateral direction, subjects move their trunk laterally while rotating their heads, and that in the heading motion for the frontal direction, subjects move their heads and trunks backward and forward. These results from this study are useful in coaching activities.