Exercising women who take contraceptives should be especially careful to get enough calcium in their diets.
A new study suggests that if you're under 30, take birth control pills and exercise regularly, you may be a greater risk of bone fractures later on than someone who doesn't exercise.
The pill, it seems, keeps estrogen levels steady, offsetting the exercise induced estrogen surge that helps prevent bone loss.
Rather than avoid exercise, which has countless other health benefits, researchers suggest women aim to eat at least two to three servings of calcium-rich foods per day.
Source: Medicine & Science in Sports & Exercise, 2001; 33, 873-880