Funding for this research was provided by:
Bundesamt f?r Sport (13_06)
Bundesamt für Gesundheit (13.005223)
Health Promotion Switzerland (13.099)
Text and Data Mining valid from 2019-01-30
Received: 21 November 2018
Revised: 11 January 2019
Accepted: 17 January 2019
First Online: 30 January 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all parents of participants included in the study. In addition also adolescents filled in a consent form.