Review on January 28, 2008
Young and middle aged female athletes are often at a greater risk for osteoporosis, despite the beneficial effects of exercise on bone health. For most women, however, regular and moderate exercise is essential for preserving healthy bones and preventing osteoporosis
According to RL Wolman's article in The British Medical Journal, women have an inactive lifestyle are at a notably greater risk for developing osteoporosis and experiencing potentially disabling fractures later in life. Even a few days of bed rest during a sickness or after surgery can result in calcium deficiency and accelerated reduction in bone density.
Regular weight-bearing exercise can augment bone density, although the force of gravity appears to be vital in creating this effect (swimming, for instance, is less effectual at boosting bone density than walking or running). Astronauts, for example, rapidly lose bone density while in zero-gravity.
Bone density will be most marked in the area most employed in any given exercise. Wolman gives the example of a professional tennis player, whose playing arm can have bones as much as 30 % more dense than elsewhere in the body, while runners will show enhanced bone strength in the femur (thigh bone) and spine.
Both aerobic exercise and strength training can help to boost bone density. A routine exercise regimen of either type regularly preformed over an extended period can effectively be prescribed to increase bone strength. Habitual, moderate exercise can even lessen osteoporosis risk in the very elderly. In addition to augmenting bone density, regular exercise also helps to tone muscle and improve balance in older people, and thus cuts the risk of falls and fractures.
For the majority of the population, regular exercise is essential for bone health. However, female athletes who exercise intensively are actually at a risk for weaker bones. Young or middle-aged women who are competitive athletes (or follow an unusually severe weight-loss program involving excessive exercise) may cease menstruating, a condition known as "amenorrhoea."
Amenorrhoea is usually linked to low body fat, a low-calorie diet, and rigorous training. During amenorrhea, estrogen levels are inadequate, meaning that bone density will decrease. This decline can be reversed if amenorrhoea lasts for less than six months, but reversal becomes increasingly unlikely the longer amenorrhoea continues, thus proportionately augmenting the risk for osteoporosis. Athletes have been diagnosed with osteoporosis and experienced related fractures as early as in their teens and twenties.
Female athletes should seek advice from their doctor about how to best prevent potentially serious bone loss during intensive training. Most women, however, do not expect to reach this level of athleticism and should be encouraged to begin a regular exercise regimen.
- Wolman, RL. "ABC of sports Medicine: Osteoporosis and Exercise." The British Medical Journal 1994;309:400 (6 August).