This study measured the takeoff forces exerted by jumpers during the 70-m ski jumping competition of the 1988 Winter Olympics in Calgary. Instrumentation consisted of four force plates installed under the snow of the takeoff platform. The results indicated that the greatest force was already exerted 149±9 ms before the release. The second force peak appeared closer to the edge of the takeoff platform. The correlations between the variables measured in this study were generally weak but some were considered important. The official approach velocity of the first round and relative maximum force as well as the mean relative force during the whole takeoff sequence of the second round correlated to length of jump. The mean relative forces at the end of takeoff and for the whole takeoff sequence were significantly higher among the best jumpers. It is concluded that although the force analyses among the jumpers do not reveal conclusive interrelationships, the fast development of the takeoff forces may be an important prerequisite for successful ski jump performance.
Mikko Virmavirta and Paavo V. Komi are with the Department of Biology of Physical Activity at the University of Jyväskylä, SF-40100 Jyväskylä, Finland.