- Correspondence to Professor Martin Schwellnus, Faculty of Health Sciences, Sport, Exercise Medicine and Lifestyle Institute (SEMLI), University of Pretoria, Pretoria 0002, South Africa;
- Received September 17, 2018
- Revised February 4, 2019
- Accepted February 8, 2019
- First published February 22, 2019.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.