RT Journal Article SR Electronic T1 Keeping your top players on the pitch: the key to football medicine at a professional level JF British Journal of Sports Medicine JO Br J Sports Med FD BMJ Publishing Group Ltd and British Association of Sport and Exercise Medicine SP 723 OP 724 DO 10.1136/bjsports-2013-092771 VO 47 IS 12 A1 Jan Ekstrand YR 2013 UL http://bjsm.bmj.com/content/47/12/723.abstract AB