It is generally accepted that exercise promotes bone health. However, research which has been undertaken on the relationship between intensive exercise, bone health, and estrogen (estrogen is a hormone responsible for growth and development of reproductive organs and maintenance of bone health), and irregular menstruation cycles show detrimental results on bone health in female athletes. Alarmingly, there appears also to be evidence from a study showing that highly trained females who appear to be menstruating normally may still be at risk for low bone strength (or osteopenia).
Women who train intensively may produce abnormally low levels of estrogen, which in turn, leads to weakened bones. Low bone strength is also a risk factor for stress fractures and young female adults with low bone strength are also more likely to develop osteoporosis later in life.
The direct relationship between a low estrogen state and bone loss would suggest that if normal estrogen levels are reestablished that this should prevent and perhaps reverse bone loss. To this end, doctors often prescribe oral contraceptives to provide estrogen and regulate the menstrual cycle and strengthen the bones of women athletes, especially those who suffer from recurrent stress fractures. It should be noted however, that studies which suggest that oral contraceptive use reduces stress fracture incidence, are unable to establish a cause/effect relationship (because it is conceivable that the women who chose to take oral contraceptives may have had greater bone mass before they started taking oral contraceptives).
