Effect of altered reproductive function and lowered testosterone levels on bone density in male endurance athletes

The effect of intense physical activity on female reproductive hormones is well recognised(1-3) 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.