1. Department of Sport Science and Sport, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
2. Department of Health Services Research, Universiteit Maastricht, Maastricht, The Netherlands
3. Department of Medicine, Stanford Prevention Research Center, Stanford University School of Medicine, Stanford, CA, USA
4. Division of Epidemiology, Department of Health Research and Policy, Stanford University School of Medicine, Stanford, CA, USA