[1] Karl Franzens Univ Graz, Inst Sport Sci, Graz, Austria
[2] Univ Witwatersrand, Ctr Exercise Sci & Sports Med, Fac Hlth Sci, Sch Therapeut Sci, Private Bag 3, ZA-2050 Johannesburg, South Africa
[3] Univ Witwatersrand, MRC Wits Dev Pathways Hlth Res Unit, Dept Paediat, Fac Hlth Sci,Sch Clin Med, Private Bag 3, ZA-2050 Johannesburg, South Africa
[4] Vrije Univ Amsterdam Med Ctr, Dept Publ & Occupat Hlth, Amsterdam Publ Hlth Res Inst, Amsterdam, Netherlands
[5] Vrije Univ Amsterdam Med Ctr, Dept Epidemiol & Biostat, Amsterdam, Netherlands
[6] Johannes Gutenberg Univ Mainz, Inst Occupat Social & Environm Med, Univ Med Ctr, Mainz, Germany