Abstract

The objective of this work is to examine the conditions for dynamic equilibrium in three dimensions during a turn in alpine skiing based on translations, rotations, and Euler’s equations for rigid body dynamics for torques and angular accelerations about the side to side axis, i.e., fore-aft torques and movement. This work is important for ski coaches because it advances the understanding of the positions and movements that skiers use to maintain line and balance in turns. The fore-aft torques are among the most interesting in skiing. While the merits of foreword torque entering a turn are well accepted, those of aft torques exiting a turn have been debated (Reid 2010). Three cases are discussed here regarding fore-aft equilibrium conditions in three dimensions. Two of the cases are obvious to coaches because they are clearly observable, upper-body movements. One is more subtle because it involves loading the front of the ski in the first part of the turn and the rear in the last part. The analyses in this work improve the understanding of the causes of the upper-body movements based in classical physics of motion. The upper-body movements are understood as compensations for not the sufficiently loading the front or rear of the ski during the appropriate parts of the turn. These analyses can also provide a basis for interpreting experimental observations of loads on the skis (Reid et al. 2008). Aus demt Text