1. Swiss Paraplegic Research; Nottwil Switzerland
2. Department of Sports Medicine and Sports Nutrition; Ruhr University Bochum; Bochum Germany
3. Department of Health Sciences and Health Policy; University of Lucerne; Lucerne Switzerland
4. Institute of General Practice and Family Medicine; Witten/Herdecke University; Witten Germany
5. Institute of General Practice; Heinrich Heine University Düsseldorf; Düsseldorf Germany
6. Department of Medical Informatics, Biometry and Epidemiology; Ruhr University Bochum; Bochum Germany
7. Institute of Sport and Exercise Sciences; University of Münster; Münster Germany