Orientation of body segments in ski jumps using wearable sensors: Analysis of relevant parameters during stable flight phase

3D kinematic and dynamic analysis is highly required in ski jumping. Current recording techniques (e.g. camera systems) suffered from limitations, such as volume capture or complexity of use and processing. This study proposed a new 3D approach based on inertial sensors to calculate automatically the whole body segments orientation of the entire jump during in-field measurements. Combination of accelerometers and gyroscopes allowed devising a functional calibration procedure adapted to ski jumping activity. Then, segments orientation was obtained based on strapdown integration of gyroscopes. Finally, accelerometers were used to define in-run initial orientations and to improve segments orientations during stable flight. In order to show the efficacy of the proposed system, relevant 3D parameters of stable flight phase (V-and attack ski angles, joint angles, drag and lift forces) were extracted from 86 jumps of 34 jumpers. Combination of these parameters expressed 55% of whole variance of distance score.