サッカーのゴールキーパーにおけるダイビング動作の到達可能範囲

抄録

The present study investigated the area covered by soccer goalkeepers during diving motions (reaching area). Goalkeepers were asked to dive towards the ball in accordance with a directional indicator that presented random electronic displays. To examine the characteristics of goalkeepers' diving motion toward each position of the ball, the time needed to reach the ball (reaching time) was measured, as well as the velocity and trajectory of the diving motion. Comparison of the reaching time for each ball height (upper, medium, and low) when each goalkeeper dived for only a short distance revealed statistically significant differences in attempts to stop the ball, the times increasing in the order medium, upper, low height. When a goalkeeper dived longer distances, there was a significant difference in the reaching time, which increased in the order medium, low, and upper height. No significant differences in reaching time were observed between the left and right sides for the same distances and heights. These results suggest that for short distances, more time is needed for relatively lower heights, whereas for longer distances, more time is needed to reach balls at relatively high levels. In terms of the velocity of the diving motion, when the center point between the shoulders was measured with the ball at longer distances, there was a trend for an acceleration phase to start 0.3 s after the directional indicator had been shown. It slowed temporarily at 0.5 s and then resumed. Meanwhile, when attempting to stop the ball at shorter distances, there was a trend for only one phase of acceleration without any stepping action (i.e., taking a running start). Moreover, temporal changes in the center position of the hand (the third metacarpophalangeal joint) that touched the ball were used to create a diagram depicting the estimated range of time needed to reach the ball. This diagram was able to clarify differences in reaching area with respect to ball height and distance.