title: Determination of the centre of mass kinematics in alpine skiing using differential global navigation satellite systems.
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.
authors.affiliation: a Department of Physical Performance , Norwegian School of Sport Sciences , Oslo , Norway.
authors.forename: Matthias
authors.initials: M
authors.lastname: Gilgien
authors.forename: Jörg
authors.initials: J
authors.lastname: Spörri
authors.forename: Julien
authors.initials: J
authors.lastname: Chardonnens
authors.forename: Josef
authors.initials: J
authors.lastname: Kröll
authors.forename: Philippe
authors.initials: P
authors.lastname: Limpach
authors.forename: Erich
authors.initials: E
authors.lastname: Müller
mesh_terms: D000054:Acceleration; D054874:Athletic Performance / Q000502:physiology*; D001696:Biomechanical Phenomena; D040362:Geographic Information Systems; D006801:Humans; D008297:Male; D012015:Reference Standards; D015203:Reproducibility of Results; D012865:Skiing / Q000502:physiology*; D014741:Video Recording
keywords: GPS and GNSS; alpine skiing; position–velocity–acceleration; technical validation; video-based 3D kinematics