Received: 27 May 2020
Accepted: 4 November 2020
First Online: 23 November 2020
Ethics approval and consent to participate
: Ethical permission was given by the Human Ethics Committee at the University of Duisburg-Essen, Faculty of Educational Sciences. Participants’ assent and parents’ written informed consent were obtained prior to the start of the study.
: Not applicable.
: The authors declare that they have no competing interests. TM is an Associate Editor of the BMC Sports Science, Medicine, and Rehabilitation journal.