INTRODUCTION: The quality of the take-off phase in ski jumping is influenced by many different parameters. Both dynamometric and kinemetric measurements have been done for many years. In the present study both methods were combined to obtain an integrated assessment of Jumpers with different performance levels. METHOD: The force measurement system (AMTI® force plates) is located under the porcelain inrun track of the take-off table for the last 10.5m. Kinemetric measurements were made synchronously via video recording with two cameras. Dynamometric parameters were presented in a report. Forces were separately measured for the left and right leg. Parameters of interest were the ground reaction forces, torques and direction of forces in x-, y- and z-direction. Angle progressions, angle velocities and accelerations were assessed as kinemetric parameters. A modified model of DeLeva1 was used to generate center of gravity progressions, velocities and accelerations. These parameters were compared within the German ski jumping World cup team (WT), the Continental cup team (CT) and the junior national team (JT). Concerning the shifting of the centre of gravity, comparisons with recent results of Summer Grand Prix were made. RESULTS: Dynamometric parameters are shown in Figure 1. There are little differences in take-off velocity (2.43, 2.37 and 2.24 m/s) and acceleration distance (34.22, 33.21 and 31.62cm) between the three teams. The differences in take-off timing are 9.20 and 8.76 cm for WT and CT, whereas JT achieves 6.89 cm. Centre of gravity (CoG) shifted in WT 5.8 cm forward, in CT 2.6 and the JT 1.2 cm. The average of the best five jumpers in the Summer Grand Prix 2007 reaches values of 6.7cm. DISCUSSION: The differences in dynamometric parameters between the junior national team and the two others may occur because of their not yet fully developed strength and their instable jumping technique. The differences between WT and CT may most likely occur due to technical reasons. Differences in CoG between CT, JT and the WT are likely to be based on (technical) deficits in the inrun Position and reduced flexibility of the ankle joint. CONCLUSION: Technical deficits are likely to be the most important differences between WT and CT in dynamometric parameters. The differences between JT and WT may occur because of technical deficits in the inrun position and the lack of power. Technical deficits were fostered by results data of CoG data.
© Copyright 2007 4th International Congress on Science and Skiing. Julkaistu Tekijä University of Salzburg. Kaikki oikeudet pidätetään. / Kääntänyt https://www.DeepL.com/Translator