Comparison of volleyball athletes by the kinematic and dynamic analysis of the service balls trajectories

Abstract

The aim of this study was to compare the volleyball athletes by the kinematic and dynamic analysis of the service balls trajectories. The sample comprised 11 players of the volleyball basic categories, and one of the adult category. Each player makes four types of services. 128 services are executed and video taped. The throws are selected, digitalized and 3D reconstructed by the DLT method. The velocity and acceleration of the ball, the initial throw angle and initial height, as well as the height that the balls reaches above the net are calculated, and the Drag Coefficient (C_D) and Reynolds’ Number (Re) for each service are estimated. Considering the kinematic variables, better results of the high level player in relation to the other players were observed. The differences between the other categories of players are less evident and are different from service to service and from variable to variable. The distribution of the services concerning the relation between the Drag Coefficient and Reynolds’ Number shows that the floating with jump services of the basic categories are observed in the region of a wide range of the Drag Coefficient.