Animals change gait patterns to minimize metabolic cost. Horses walk at slow speeds, trot at intermediate speeds, and gallop at high speeds. Likewise, cross-country skiers use the 2-skate technique at slow speeds, the 1-skate technique at intermediate speeds, but then, in contrast to everything known about animal locomotion, they revert to the previously rejected 2-skate technique at high speeds.

I determined the oxygen cost for the 1- and 2-skate technique while measuring forces in the skis and poles for eight athletes skiing at speeds ranging from 6-35km/h.

I found that the oxygen cost curves for the two techniques intersected twice, and that propulsion comes primarily from the poles for the 1-skate and the skis for the 2-skate technique.

Furthermore, the arm action becomes metabolically much more costly with increasing speeds of skiing than the leg action, thereby partly explaining the non-intuitive gait transitions in skiers.