A Kinematic Analysis Of Spike Jumps And Plyometric Depth Jumps As Performed By Elite Female Volleyball Players

Abstract

Much research has been completed on identifying contributing factors in the vertical jump but little information exists on the process variables related to vertical jumping as executed in a performance skill such as spiking and a training jump. This study focuses on the jumping techniques used by elite volleyball players during training and spiking performance. The purpose of this study was to identify and measure selected components of the vertical jump as utilized in the specific skill of spiking and a plyometric depth jump as utilized in jump training performed by volleyball players. Two dimensional high-speed photography was used to compare the performance and training jumps of six elite female volleyball players at the University of IllinoisUC. A high-speed 16-mm camera operating at a nominal rate of 100 Hz and two video cameras were used to film the subjects performing three successful spikes (SI) of a high, outside set in left front position and three plyometric jumps (PJ). The plyometric depth jump consisted of the subject dropping off a 60 cm box onto the floor and immediately rebound jumping onto a 76 cm box. Kinematic data were obtained by digitizing 10 anatomical landmarks. Significant jumping phases analyzed included loading (setup), propulsion (extension), flight and landing. ANOVA was used to test the significance of the differences between biomechanical variables common to both styles of jumping. After processing, the average of the three spike and three pIyometric trials was used for detailed analysis. Several kinematic differences were noted between 51's and PI's including a longer propulsive . phase, faster vertical velocity at takeoff, longer flight time and greater jump height in the 51's than the PI's. There was less flexion during loading in the spike jumps than in the plyometric jumps. A certain amount of flexion of the hips and knees is important in the loading phase to facilitate the active lengthening of the quadriceps muscles group prior to extension, while too much bending results in the dissipation of forces leading to a lower vertical velocity at takeoff. During the SJ, the players landed with straighter legs and had a significantly smaller range of motion at the knee and ankle during landing than during the depth jumps. The trunk in both 51's and PI's extended during setup, positioning the cg over the base of support prior to the start of propulsion. Training jumps and performance jumps share certain common technique characteristics, but there are a number of critical differences. In designing an effective jump training program for successful performance, emphasis should be placed on simulating performance requirements and rule restrictions imposed on the vertical jump under performance conditions.