ANALYSIS OF VIBRATIONS AND SHOCKS DURING THE PARALLEL TURN IN ALPINE SKIING

Abstract

INTRODUCTION: In downhill skiing a skier is exposed to shocks and vibrations caused by the interaction of skis and snow (Muller and Hautz, 1991; Hull and Mote, 1978; Wunderley et al., 1988). This interaction is directed by the controlled and reflex action of a skier’s muscles. In this paper we present results on measurements of forces normal to the ski during downhill skiing and evaluate their effect on skiing safety. The main goal of the research is to the develop a tool for the evaluation of vibration isolators inserted between skis and ski bindings. METHODS: Forces during downhill skiing on well packed snow using parallel technique were measured. Forces were measured at the contact point between the ski boot sole and the ski, using four force transducers per each leg (Nemec, 1997). Forces on both skis were measured simultaneously at the rate of 50 measurements per second. Force measurement was synchronized with the video image. Filtered data, using a low-pass filter with the cut-off frequency at 20 Hz, were then analyzed using power spectrum density in the frequency domain.