RT Journal Article SR Electronic T1 Exercise is effective for patellofemoral pain, but what type, who benefits most and by how much remain unknown 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 625 OP 626 DO 10.1136/bjsports-2017-098296 VO 52 IS 10 A1 Callaghan, Michael J YR 2018 UL http://bjsm.bmj.com/content/52/10/625.abstract AB