Statistics from Altmetric.com
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.
Competing interests For full author disclosures and competing interests see the online supplementary folder on the BJSM website (http://dx.doi.org/10.1136/bjsports-2017-097699).
Provenance and peer review Commissioned; internally peer reviewed.