Biomechanics of Alpine Skiing

Abstract

Understanding the biomechanics of Alpine skiing is fundamental to the design of training protocols, to identify the metabolic burden of athletes and to help preventing traumas. Despite the apparent simplicity of the overall mechanics related to a descent with skiis, the scientific community is still uncertain about the role of muscle contraction in controlling the trajectory on the snow and about the partitioning between force and skill in determining the performance outcome. Generally speaking, skiers increase their body energy (in terms of potential energy) by taking the cable car up to the mountain top; then, to reach the bottom of the track, all that energy needs to be dissipated (as heat). There are just three dissipators involved: snow, air and muscles. If muscles play a major role in transforming potential energy into heat, they need to contract eccentrically, and athletes should be mostly trained in that respect. Conversely, if snow (and its displacement) is responsible for most of the slowdown of the skier, it would be advisable for racers to be trained to generate force both concentrically and eccentrically, with a deeper focus on controlling the fast and intense alternation of the two muscle conditions (a sort of ‘intensively perturbed isometric contraction’). This chapter starts from constraints from physics and, through experimental data, tries to shed light on this, still debated topic.