A New Method of Measuring 3-D Ground Reaction Forces under the Ski during Skiing on Snow

in Journal of Applied Biomechanics
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A new method was developed for measuring the distribution of real time ground reaction forces under the snow ski. A platform composed of 20 separate beams was buried in snow under the ski track. Vertical, cross horizontal, and longitudinal horizontal force components were measured with strain gauge bridges separately on each beam, and the results were recorded with a data logger at 90 Hz. The test results for two types of skating skis are described. Anomalous behavior was observed in horizontal force components, where negative force values were recorded on some sections of the ski at the end of the initial kick phase. This suggests that some parts of the ski edge pushed in the opposite direction from the kicking force. This is interpreted to be due to a sharp bending along the bottom edge of the ski. It is concluded that the method could be used to measure 3-D dynamic forces under snow.

Antti P. Leppävuori is with the Finnish Ski Association and the Research Institute for Olympic Sports, Rautpohjankatu 6, 40700 Jyväskylä, Finland. Matti Karras is with the Department of Electrical Engineering, University of Oulu, Linnanmaaa 90570 Oulu, Finland. Heikki Rusko and Jukka T. Viitasalo are with the Research Institute for Olympic Sports, 40700 Jyväskylä, Finland.