Beat Knechtle1,2, Eckhard Wengler3, Pantelis T Nikolaidis4. 1. St. Gallen Medical Center, St. Gallen, Switzerland - beat.knechtle@hispeed.ch. 2. Institute of Primary Care, University of Zurich, Zurich, Switzerland - beat.knechtle@hispeed.ch. 3. Orthopädie am Park, St. Gallen, Switzerland. 4. Exercise Physiology Laboratory, Nikaia, Greece.