2014 Volume 59 Issue 2 Pages 397-411
The aim of this study was to clarify the point of attention and determine an effective method for the vertical single-leg rebound jump (VSJ) and horizontal single-leg bounding jump (HSJ) in plyometrics by investigating the differences and relationship between the two jumps with respect to take-off movement and joint kinetics. 11 male track and field athletes performed the VSJ, 50%HSJ, 75%HSJ, and HSJ. The kinematics and kinetics during the take-off phase were recorded using a high-speed video camera (300 Hz) for movements in the sagittal plane and force platforms (1000 Hz), and then analyzed. The results are summarized below:
1. According to a spring-mass model, the vertical velocity of the center of gravity in the VSJ was attained by using shortening-lengthening movements. However, in the HSJ, most of the horizontal velocity of the center of gravity was due to rotational movement. This velocity increased with increasing jump distance.
2. The extension torque of the knee and hip joints during the former phase, the negative torque power of the knee, and the positive torque power of the ankle and hip joints in the HSJ were greater than those in the VSJ. However, the ankle joint torque during the former phase and the negative torque power in the HSJ were smaller than those in the VSJ.
3. The jump distance for the HSJ was correlated with the RJ-index for the VSJ. Moreover, there was a correlation between the HSJ and VSJ with respect to negative joint work and joint contribution.
These results suggest that there are differences in take-off movement and joint kinetics between the VSJ and HSJ; however, both jumps show similarities in the recruitment characteristics of the take-off leg muscle during the former phase.