Development of a measurement system to capture the athlete movement during the ski jump.

Ski jumping is a complex sequence of movement which should be realized in a very short period of time at 90km/h. Video camera based system is currently used to evaluate jumper performance, but it is limited in capture volume and provides a qualitative assessment. It is crucial to evaluate quantitatively and objectively the athlete performance without restriction of capture volume and to give a direct feedback to coaches and athletes. 

The first aim of this study was to propose a system to capture the athlete movement during the entire jump that is compatible with daily training. The second aim was to assess the reliability and the relevance of angular, coordination and dynamic parameters automatically calculated by the proposed system.

The proposed system was composed of eight inertial modules (Physilog) fixed on torso, sacrum, thighs, shanks and skis. Each module, sampled at 500 Hz, included a 3D gyroscope, a 3D accelerometer and an embedded datalogger. 33 athletes of Swiss ski team (from junior to world-class) performed up to three jumps with the proposed system. A total of 86 jumps were collected. 

No additional movement was required to calibrate the system and the system did not hinder the athlete. Automatic and validated algorithms provided timing, angular movements, forces and coordination metrics. Several key metrics were extracted for the entire jump sequence during training conditions and  84% of the performance variation was explained based on the most relevant metrics.