A kinematic study on the volleyball spiking motions in international players : The preparatory motion for effective takeoff on the jumping height

This study was designed to analyze the spiking motions of international players,and to pro vide these information with clarifying the preparatory motion for effective takeoff on the jumping height.Soviet.Cuban.Polish and Japanease male players who participated in the1981 World Cup Volleyball Games held in Tokyo were filmed at lOO f.p.s.with two 16mm cinecameras during the games.23 spikings performed successfully were selected for the analysis and were digitized from the start of the approach run to the end of the swing in the air.23 three dimensional coordinates for the segment endpoints were computed by the Direct Linear Transformation Method.The kinematic data were obtained from the 3D coordinates.The results and findings were summarized as follows;In order to increase the jumping height,the approach velocity just before takeoff should be increased up to nearly 4m/s.The approach velocity at the end of each step phases was significantly related with the horizontal CG displacement in each step phases,while there was no significant correlation with the vertical CG displacement.The stride length of each steps increased nearly twice as much in order of 3,2,1 step phases before the takeoff.With theincrease in the stride length,the horizontal CG displacement increased.These results suggested that increasing the stride length should be one of the important motions for increasing the jumping height.In particular.the phase just before takeoff might be important phase for increasing the jumping height,because the longest stride length seemed to result from the motions of swinging the arms backward and flexing the trunk forward during the flight period in the phase