Effects of the Different Patterns of a Preliminary Jump before Jumping in the Vertical Jump

The purpose of this study was to investigate the effects of three different preliminary jumps before a main jump during jump performances. Seven infrared cameras and a force platform were used to analyze the jump tasks for 10 male college students. The participants were subjected to jump randomly on the force platform with countermovement jump, drop jump and double jump. With regards of vertical component of the center of mass(CoM), there were no significant differences in the peak height, the range of motion and the positive peak velocity except the negative peak velocity among jump patterns. In the vertical reaction force, the peak value of countermovement jump was greater than corresponding value for drop and double jump. Both of the peak value of angle and angular velocity for drop jump significantly increased, but this was not followed by changing the magnitude of knee joint angle at take off. The results indicated that jumping height on the vertical jump was not increased, although the vertical preliminary jump which may increase stretch velocity and preactivation level during the eccentric phase in the process of stretch-shortening cycle was performed before jumping.