The effect of amenorrhea on calcaneal bone density and total bone turnover in runners.

To examine in athletes the effect of long-term amenorrhea on the skeleton, measurements of calcaneal density and whole body retention of 99mTc-imidodiphosphate were made in 42 women who could be allocated to one of 3 groups defined by their level of physical activity and by menstrual status. There was no difference in bone density between eumenorrheic normoactive females and either eumenorrheic or amenorrheic athletes. However, calcaneal density was significantly greater for each group than for previously measured sedentary controls. Total body bone turnover was greater in both eumenorrheic and amenorrheic athletes than in eumenorrheic normoactive women. Sustained, intense physical activity does not significantly increase calcaneal bone density over and above the increase associated with normal levels of activity. This is despite a significant increase in the rate of total body bone mineral turnover.