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Aerodynamic drag is not the major determinant of performance during giant slalom skiing at the elite level

Authors

  • M. Supej,

    1. Department of Biomechanics, Faculty of Sport, University of Ljubljana, Ljubljana, Slovenia
    2. Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Koper, Slovenia
    3. Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
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  • L. Sætran,

    1. Department of Energy and Process Engineering, Norwegian University of Science and Technology, Trondheim, Norway
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  • L. Oggiano,

    1. Department of Energy and Process Engineering, Norwegian University of Science and Technology, Trondheim, Norway
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  • G. Ettema,

    1. Department of Human Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
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  • N. Šarabon,

    1. Faculty of Mathematics, Natural Sciences and Information Technologies, University of Primorska, Koper, Slovenia
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  • B. Nemec,

    1. Department of Biocybernetics, Automatics and Robotics, Josef Stefan Institute, Ljubljana, Slovenia
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  • H.-C. Holmberg

    Corresponding author
    1. Swedish Olympic Committee, Stockholm, Sweden
    • Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
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Corresponding author: Hans-Christer Holmberg, Swedish Winter Sports Research Centre, Mid Sweden University, 83125 Östersund, Sweden. Tel: +46 70 4058960, Fax: +46 63 165740, E-mail: hc.holmberg@miun.se

Abstract

This investigation was designed to (a) develop an individualized mechanical model for measuring aerodynamic drag (Fd) while ski racing through multiple gates, (b) estimate energy dissipation (Ed) caused by Fd and compare this to the total energy loss (Et), and (c) investigate the relative contribution of Ed/Et to performance during giant slalom skiing (GS). Nine elite skiers were monitored in different positions and with different wind velocities in a wind tunnel, as well as during GS and straight downhill skiing employing a Global Navigation Satellite System. On the basis of the wind tunnel measurements, a linear regression model of drag coefficient multiplied by cross-sectional area as a function of shoulder height was established for each skier (r > 0.94, all P < 0.001). Skiing velocity, Fd, Et, and Ed per GS turn were 15–21 m/s, 20–60 N, −11 to −5 kJ, and −2.3 to −0.5 kJ, respectively. Ed/Et ranged from ∼5% to 28% and the relationship between Et/vin and Ed was r = −0.12 (all NS). In conclusion, (a) Fd during alpine skiing was calculated by mechanical modeling, (b) Ed made a relatively small contribution to Et, and (c) higher relative Ed was correlated to better performance in elite GS skiers, suggesting that reducing ski–snow friction can improve this performance.

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