1 Department of Pediatrics and Adolescent Medicine, Turku University Hospital and University of Turku, Turku 20521, Finland. Electronic address: olli.ruuskanen@tyks.fi.
2 Finnish Institute of High Performance Sport KIHU, Jyväskylä 40700, Finland.
3 Institute of Biomedicine, University of Turku and Department of Clinical Virology, Turku University Hospital, Turku 20520, Finland.
4 Department of Pediatrics and Adolescent Medicine, Turku University Hospital and University of Turku, Turku 20521, Finland.
5 Paavo Nurmi Centre and Unit for Health and Physical Activity, University of Turku, Turku 20520, Finland.