Aerodynamic drag plays an important role in performance for athletes practicing sports that involve high-velocity motions. In giant slalom, the skier is continuously changing his/her body posture, and this affects the energy dissipated in aerodynamic drag. It is therefore important to quantify this energy to understand the dynamic behavior of the skier. The aims of this study were to model the aerodynamic drag of alpine skiers in giant slalom simulated conditions and to apply these models in a field experiment to estimate energy dissipated through aerodynamic drag.
The aerodynamic characteristics of 15 recreational male and female skiers were measured in a wind tunnel while holding nine different skiing-specific postures. The drag and the frontal area were recorded simultaneously for each posture. Four generalized and two individualized models of the drag coefficient were built, using different sets of parameters. These models were subsequently applied in a field study designed to compare the aerodynamic energy losses between a dynamic and a compact skiing technique.
The generalized models estimated aerodynamic drag with an accuracy of between 11.00% and 14.28%, and the individualized models estimated aerodynamic drag with an accuracy between 4.52% and 5.30%. The individualized model used for the field study showed that using a dynamic technique led to 10% more aerodynamic drag energy loss than using a compact technique.
The individualized models were capable of discriminating different techniques performed by advanced skiers and seemed more accurate than the generalized models. The models presented here offer a simple yet accurate method to estimate the aerodynamic drag acting upon alpine skiers while rapidly moving through the range of positions typical to turning technique.
1Sport Science Institute, University of Lausanne, Lausanne, SWITZERLAND; 2Department of Mechanical Engineering, Faculty of Engineering, The University of Auckland, Auckland, NEW ZEALAND; and 3Department of Sport and Exercise Science, Faculty of Science, The University of Auckland, Auckland, NEW ZEALAND
Address for correspondence: Frédéric Meyer, Institut des Sciences du Sport de l’Université de Lausanne, Université de Lausanne, Batiment Vidy, 1015 Lausanne, Switzerland; E-mail: firstname.lastname@example.org.
Submitted for publication June 2011.
Accepted for publication November 2011.