Usually, we connect exercise with bone health. Exercise gets the remodeling cells in the bone up and going. This normally leads to stronger, more dense bones. But what about women who use oral contraceptives and who intend to exercise? Will their efforts to exercise pay off in better bone health?
The pill alters how bone is built, leading the authors to question whether the pill keeps women who exercise from building better bones.
The authors compared the bone density of 179 women 18 to 31 years old. These women hadn’t taken part in athletics, and just over half were using birth control pills. Four groups were formed in order to compare the effects of exercise and birth control on bone health. Both those who used the pill and those who didn’t were fairly divided into exercise and nonexercise groups. Exercisers were to train with weights three days per week and to jump rope for a total of 60 minutes each week.
Bone density was checked before and after the two-year study period. As expected, exercisers developed better bone content than nonexercisers. And women exercisers who weren’t on the pill had even better bone content than those who were on the pill.
Females in their teens and twenties lay down nearly all the bone density they will have for the rest of their lives. What they don’t get then, they can’t recapture. If they happen to be on the pill during this “bone-crucial” time, they could end up with bone problems in the future.
For example, past research has shown that women who used birth control pills before menopause had more problems later on with broken bones. These small differences in bone content earlier in life may make big differences as women become elderly, the time in life when fractures can be devastating.
Why wouldn’t exercisers who used birth control pills have improved bone content? After all, the hormones found in birth control pills are the same ones doctors prescribe to prevent and treat osteoporosis. Calcium, the authors suggest, might be the missing puzzle piece.
Numerous studies have shown that after menopause, women who exercise increased their bone density only when they took more than 1,000 mg of calcium a day. In this study, three of the exercisers using the pill avoided bone building problems (compared to other exercisers on the pill), presumably because they were also taking 1,200 mg of calcium per day. Once again, motherly advice is proven right: “Drink your milk so your bones will be strong.”