Abstract
The purpose of this study was to quantify the changes in movement and performance of general students during their practice of mastering the float serve, and to obtain basic information on effective coaching methods. The subjects were 14 college students with no experience in volleyball competition. The coaching and practice of serves and the filming of the trials were conducted a total of 14 times once a week. The serves were recorded from behind and to the right, and each subject performed a total of 4 attempts. The subjects were verbally instructed to "toss the ball high", "touch the back of the head with the right hand just before hitting the ball", and "hit the ball with the left foot forward". The items analyzed were evaluation, initial ball velocity, ball hitting angle, impact point height, front and back position of the ball, and wrist height. As a result, the front and back position of the ball changed significantly backward to 4.9±7.6cm in the fourth experiment, and the most backward change was in the ninth experiment, where the impact point changed to -4.4±6.4cm behind the top of the head. A very high correlation (r=0.93) was observed between the forward distance and the elevation angle. The reason for the forward distance changing backward is thought to be the strong influence of the verbal instruction to pull the hitting arm largely upward and backward. Furthermore, since a high correlation was observed between the ball hitting angle and the front and back position of the ball, it seems necessary to move the point of catching the ball slightly behind the top of the head.in order to increase the ball hitting angle of the ball. From the above, it is inferred that verbal instruction to hit the ball behind the head are one of the effective methods for improving serving technique when teaching float serves in volleyball instructions for general students.
