1. Department of Pediatrics, Medisch Spectrum Twente, Enschede, the Netherlands;
2. Roessingh Research and Development, Enschede, the Netherlands;
3. Medical School Twente, Medisch Spectrum Twente, Enschede, the Netherlands;
4. Department of Research Methodology, Measurement and Data Analysis, University of Twente, Enschede, the Netherlands;
5. OCON Sport, Ziekenhuisgroep Twente, Hengelo, the Netherlands;
6. Department of Sportsmedicine, Tjongerschans Hospital, Heerenveen, the Netherlands