1. Department of Diagnostic and Interventional Radiology, Goethe-University Hospital Frankfurt, Frankfurt am Main, Germany;
2. Faculty of Medicine and University Hospital Cologne, Cologne Germany;
3. Institute of Sports Science, Eberhard Karls University of Tübingen, Germany;
4. Methods Center, Eberhard Karls University of Tübingen, Germany;
5. DFB (Deutscher-Fußball-Bund)-Akademie, Germany;
6. Faculty of Sports Sciences and Personality, Business and Law School, BSP, Berlin, Germany; and
7. Swiss Federal Institute of Sport Magglingen (SFISM), Magglingen, Switzerland.