RT Journal Article SR Electronic T1 Heart rates during female physical education lessons. 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 22 OP 26 DO 10.1136/bjsm.12.1.22 VO 12 IS 1 A1 T. Hale A1 F. Bradshaw YR 1978 UL http://bjsm.bmj.com/content/12/1/22.abstract AB