ABSTRACT
Functionally the sequence of motions during ski-jumping can be divided into the phases approach, take-off, flight, landing preparation, and landing, all of which have, to a greater or lesser extent, an influence on the length and evaluation of the ski-jump. The take-off is regarded as the most important phase, since it determines the take-off velocity, the take-off angle, the moment of forward rotation of the system ‘jumper-skis’, and, therefore, the initial conditions for the flight [13]. This is also the reason why an analysis of the take-off motion has been the topic of numerous field investigations using biodynamic methodology. Sobotka/Kastner [10], Sägesser et al. [8], Vaverka [12], and Virmavirta/Komi [13] [14] use force plates built into ski-jumping ramps in order to measure ground-reaction forces during take-off motion. Tveit/Pedersen [11] have developed force recorders, which being mounted in the area of the toes and heels can measure the ground-reaction forces between boot and ski at different points. An extensive investigation of measurements of differentiated ground-reaction forces between the sole of the foot and the boot over the entire course of motion, from approach to landing, has been shown by Schwameder/Müller [9], the examination of ground-reaction forces as a whole, as well as in selected sections, is of special interest in that study.
