1. Department of Social and Health Sciences, Institute of Sports and Sports Science, Karlsruhe Institute of Technology , Karlsruhe, Baden-Wuerttemberg , Germany
2. Department of Sport Pedagogy, Institute of Sport Science, University of Bern , Bern, Canton Bern , Switzerland
3. Institute of Social and Preventive Medicine, University of Bern , Bern, Canton Bern , Switzerland
4. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health , Baltimore, MD , USA