1 Institute for Sport, Physical Activity and Leisure, Centre for Sport Performance, School of Sport, Leeds Beckett University, Leeds, UK.
2 Division of Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.
3 Yorkshire Carnegie Rugby Union Football Club, Headingley Carnegie Stadium, Leeds, UK.
4 Department of Public & Occupational Health and the EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.