Determination of the centre of mass kinematics in alpine skiing using differential global navigation satellite systems |
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| Authors: | Matthias Gilgien Jörg Spörri Julien Chardonnens Josef Kröll Philippe Limpach Erich Müller |
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| Institution: | 1. Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway;2. Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Rif, Austria;3. Laboratory of Movement Analysis and Measurement, école Polytechnique Fédérale de Lausanne, Lausanne, Switzerland;4. Swiss Federal Institute of Technology, Institute of Geodesy and Photogrammetry, Zürich, Switzerland |
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| Abstract: | In the sport of alpine skiing, knowledge about the centre of mass (CoM) kinematics (i.e. position, velocity and acceleration) is essential to better understand both performance and injury. This study proposes a global navigation satellite system (GNSS)-based method to measure CoM kinematics without restriction of capture volume and with reasonable set-up and processing requirements. It combines the GNSS antenna position, terrain data and the accelerations acting on the skier in order to approximate the CoM location, velocity and acceleration. The validity of the method was assessed against a reference system (video-based 3D kinematics) over 12 turn cycles on a giant slalom skiing course. The mean (± s) position, velocity and acceleration differences between the CoM obtained from the GNSS and the reference system were 9 ± 12 cm, 0.08 ± 0.19 m · s-1 and 0.22 ± 1.28 m · s-2, respectively. The velocity and acceleration differences obtained were smaller than typical differences between the measures of several skiers on the same course observed in the literature, while the position differences were slightly larger than its discriminative meaningful change. The proposed method can therefore be interpreted to be technically valid and adequate for a variety of biomechanical research questions in the field of alpine skiing with certain limitations regarding position. |
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| Keywords: | position–velocity–acceleration GPS and GNSS technical validation video-based 3D kinematics alpine skiing |
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