RT Journal Article SR Electronic T1 Effect of altered reproductive function and lowered testosterone levels on bone density in male endurance athletes 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 205 OP 208 DO 10.1136/bjsm.30.3.205 VO 30 IS 3 A1 Kim L Bennell A1 Peter D Brukner A1 Susan A Malcolm YR 1996 UL http://bjsm.bmj.com/content/30/3/205.abstract AB The effect of intense physical activity on female reproductive hormones is well recognised1–3 and there is evidence that menstrual disturbances associated with hypo-oestrogenism adversely affect bone density especially at the lumbar spine.4 5 Physical activity can also have a range of effects on male reproductive function depending upon the intensity and duration of the activity and the fitness of the individual.6 In particular, endurance training may be associated with reductions in circulating testosterone levels. Since testosterone has important anabolic roles, alterations in reproductive hormone profiles may have detrimental skeletal consequences similar to those seen in females with menstrual disturbances. The aim of this brief review is to present the limited literature on the relation between bone density and testosterone levels in male endurance athletes.