A KINEMATIC ANALYSIS OF THE FLIGHT PHASE OF SKI JUMPING

Abstract

The purpose of this study was to identify and quantify selected kinematic variables of the flight phase of ski jumping. Secondly, this study attempted to determine the statistical contribution of specific kinematic variables during the flight to the distance jumped. The subjects for the investigation were 51 highly skilled competitors participating in the 1995 Springer tournee K-110 World Cup event. Forty six jumps were used from the first competitive round for the subsequent analyses. Data were collected using a Panasonic video camera equipped with a high speed shutter. Data for the distance jumped were collected from the competition records published following the completion of the event. The 2D Peak Performance Analysis System was used to extract the horizontal and vertical coordinates for a 3 link segmental model. The data was smoothed using a second order Butterworth digital filter and processed to compute the path of the centre of mass, linear displacements and velocities, and angular displacement values. Further measurements and calculations were performed to calculate a variety of angles involving the ski, leg, direction of flight, truck, and flight curve as well as the vertical distance of the centre of mass to the jump hill. A correlation analysis was conducted to determine the existence and strength of any relationships between the selected variables and distance jumped. The results suggest that for jumpers who want to increase their distance jumped they should increase their ski and leg angle, decrease the trunk and ski angle throughout the flight phase, and maintain an angle between the ski and the direction of flight of approximately 40 degrees. The angle between the trunk and direction of flight should also be approximately 40 degrees with a small leg and direction of flight angle during the second part of the flight phase. Additional studies should focus on the effect of the previous ski jumping phases upon the variables associated with a good flight position.