1. Department of Preventive and Rehabilitative Sport and Exercise Medicine, Institute for Cardiology and Sports Medicine, German Sport University Cologne , D-50933 Köln , Germany
2. Cuschmann Klinik, Saunaring 6, D-23669 Timmendorfer strand; Universität zu Lübeck, Medical Department , Ratzeburger-Allee 160, D-23562 Lübeck , Germany