Three-dimensional Kinematic Analysis of Elite Javelin Throwers at World Championship in Athletics, “sevilla’99”

A Biomechanical analysis of Javelin Throw in the Sevilla’99 World Athletics Championships , was carried out by the University of Valencia (Department of Physical Education and Sports). This paper presents the results of a study of the male finalists. The methodology used is based on 3D Video Photogrammetry at 50 Hz. The results show the characteristics of the throwers’ individual model at the event, which for practical purposes can be compared with the performance of the same throwers in other competitions. Detailed information on the kinematic parameters is provided. The most significant differences between the patterns used by the throwers are located in the kinematic chain in the preparatory and final phases, and in the instant of javelin release and the vertical and horizontal velocity combinations of the javelin at delivery. 1.INTRODUCTION A description of the technique used by elite throwers gives insight into individual forms of organization used to obtain high performance. These models eventually become references that help coaches and athletes to organize their own strategies to achieve maximum mechanical efficiency. The pattern of motion used in javelin throw is similar to that used in other movements when striking or throwing an object. These movements are characterized by the fact that the body segments act sequentially to attain the maximum speed in the most distal segment of the system in the instant when the object is struck or thrown (Atwater, 1979; Menzel, 1987). Many studies have described the javelin throwing technique, including those by Hay (1993), Whiting et al (1991), Best et al (1993), Mero et al (1994) and Bartlett et al (1996). The present paper also describes the technical models used by a group of athletes who were finalists in the “Sevilla 99” World Athletics Championship. The aim of the study is to compare the throwers’ individual models in the light of the documented data available on the biomechanical analysis of javelin throw. 2.METHODS: 3D photogrammetric analysis was used. During the finals all throws were filmed and the best attempts of each athlete were subsequently analyzed . The cameras were phaselocked and aligned with their optical axis at approximately 90o. (side and back views): • Two synchronized SVHS Panasonic video cameras, operating at 50 fps. • Modulated reference system (Two integrated cubes of 2x2 m. each) for spatial calibration. • Kinescan 8.3 (IBV)software for the digitizing process. All coordinates were smoothed using quintic spline. The DLT (Direct linear transformation) algorithm was used to calculate the 3D marker coordinates (Abdel-Azir