Cross-country ski technology

Skiing has a centuries-old history (Astrom and Norberg 1984;Yijanheikki 2004) . Initially, it was a way to move in the winter time, when the ground is covered with loose snow. At the same time, skiing has always been a kind of sport and recreation (Allen 2007). Cross-country skiing, in contrast to ski jumping and alpine skiing, is human-powered; it is a race on skis on a specially prepared track over a certain distance. There are two skiing styles used in contemporary cross-country skiing: the classic style and the free style (skating; Figure 11.1). The most common kind of the classic style is the diagonal stride, a running action with parallel skis (usually in a prepared track), pushing and gliding with each stride. The poles are positioned alternately on the opposite side to the pushing action. The leg motion in freestyle skiing is comparable to ice skating. The principal difference between the two styles is that the classic style characterised by a stop-and-go glide, whereas the free style shows a non-stop glide.