What You Need To Know About Bone Disease

January 31, 2006

Many young dancers may not realize the importance of bone health and what they can do now to build a strong skeleton. Osteoporosis, which means “porous bones,” is a bone-thinning disease caused by a lack of bone minerals, primarily calcium. The seeds of osteoporosis are planted in childhood, adolescence and young adulthood. During these years, the right combination of exercise and nutrition can build bone to last a lifetime, or poor eating and activity habits can greatly increase your chances of getting the disease. Now is the time to debunk the myths, update your thinking and evaluate your diet and exercise regimen.

MYTH #1: I’m too young to be worried about my bones.
The most rapid formation of bone occurs between the ages of 13 and 24. Peak bone mass—the highest bone content of your life—is reached between 25 and 30. Although bone continues to renew itself, from this age on, you’ll experience a natural decline in bone density, which will accelerate at the time of menopause. Since relatively little bone mineral can be added to the mature skeleton, it follows that the key time to put bone “in the bank” is before age 30. The higher the deposit, the more you’ll have to draw from throughout your life. Note, however, that low bone density can cause problems even for young adults. One study by Dr. David J. Sartoris, the director of bone densitometry at the University of California at San Diego, reported in the San Diego Union-Tribune in 1998, showed that 55 percent of 18–25-year-old females had dangerously low bone density; 15 percent met the clinical definition of osteoporosis.

MYTH #2: Osteoporosis only affects older women.
Unfortunately, young women and men are also at risk. Men can develop osteoporosis at any age, especially if they have a chronic condition that requires treatment with medications such as steroids. However, since they tend to have bigger bones, gain more bone mass than women during adolescence and adulthood, and lose less bone later in life, they are generally at lower risk than women. For some dancers, disordered eating (that is, inconsistent or restrictive eating habits) and the excessive physical activity demanded by a rigorous training or performing schedule may create a stress condition in the body that alters hormone levels, shuts down the reproductive system, disrupts the normal menstrual cycle and begins to weaken bones. The combination of amenorrhea (cessation of your period), disordered eating and osteoporosis is known as the “Female Athlete Triad.” (For more on amenorrhea, see “Problem: Missed Periods” in DS November 2005). It’s possible for a 20-year-old woman to have bones as if she were 60.

MYTH #3: Osteoporosis isn’t a very common or serious disease.
According to the National Osteoporosis Foundation, an estimated 10 million Americans are affected by osteoporosis and 34 million more by osteopenia (low bone mass, not yet osteoporotic). Twenty percent of those affected by osteoporosis are men. The consequences are life-changing and can include stress fractures (small breaks in the bone), particularly of the hips, spine, wrists, shins and, especially for those who dance on pointe, the toes. Spinal fractures generally manifest later in life. Weakened bones can fracture spontaneously without any injury or trauma, simply because they are too fragile to support the weight of the body. While the relationship between bone density and stress fractures remains unclear, poor nutrition and amenorrhea increase the risk, as does a sudden change in frequency, intensity or duration of training. One study of ballet dancers showed a significant increase in fracture risk when they trained more than 5 hours a day.

MYTH #4: If I had osteoporosis, I would know it.
Not necessarily. This silent disease progresses slowly and painlessly over time without symptoms. As the bone gradually diminishes in strength and structure, it becomes increasingly fragile. In fact, the first sign that you have osteoporosis may be a fracture. The only way to know for sure is to have a bone density test, which is generally recommended for women around the time of menopause, but may be performed on young individuals depending on circumstances. Certain people are more likely to develop osteoporosis than others. Risk fractures include being female; family history of osteoporosis; having a small, thin frame; smoking; personal history of multiple stress fractures; and amenorrhea. If you take the injectable contraceptive Depo-Provera, you may experience a loss of bone density. (Research shows that this loss appears to be temporary and reverses when the drug is discontinued.) If you have several risk factors, speak to your doctor to see if you should be tested. The gold standard of bone density tests is the dual-energy X-ray absorptiometry, or DXA. Once you’re positioned on a special table, a scanner moves over your body measuring bone density at your spine, hips and wrists. It’s completely painless, takes about 15 minutes and emits approximately five percent the radiation of a standard chest X-ray.

MYTH #5: The more I dance, the stronger my bones will be.
The effect of exercise on the bones is site-specific. As weight-bearing exercise that involves high-impact jumping, dance provides an excellent stimulus to the upper region of the thighbone or femur, provided that training isn’t excessive. Dance provides less stimulus to the spine, because the effect of ground-vibration forces diminishes as they travel up the skeleton. Additional strength training for the upper body may be necessary for dancers who don’t use their arms in a weight-bearing fashion. (For exercises, see “Awesome Arms” in DS September 2005.)

MYTH #6: If I don’t eat enough calcium, I can compensate by exercising harder to increase bone density.
Adequate calcium plus regular exercise have an additive effect on bone. In other words, you can’t compensate for a deficiency in one by increasing the other. Calcium needs change over the course of a lifetime, being greatest (1,200–1,500 mg) during childhood and adolescence, pregnancy and breastfeeding, and after age 50. From ages 25 to 50, the recommended daily intake is 1,000 mg, provided you aren’t pregnant or breastfeeding. (One cup of nonfat milk has about 300 mg of calcium; one cup of spinach has about 245 mg.) Make up the difference for calcium shortages in your diet by taking a supplement.

MYTH #7: Since osteoporosis runs in my family, I can’t do much about it.
It’s true that your ability to make bone is strongly influenced by genetics, but good nutrition and exercise habits during formative years can significantly lower your risks. Even if you don’t have a family history of osteoporosis, unhealthy behaviors during peak bone-building years, including smoking and excessive alcohol consumption, may override any genetic tendency toward higher bone mass. Both smoking and alcohol depress the bone-building function at the cellular level. Smoking increases bone breakdown, while alcohol abuse is associated with numerous other factors that contribute to low bone mineral, including poor nutrition, malabsorption of calcium, vitamin D deficiency and parathyroid dysfunction.

Joan Pagano is certified by the American College of Sports Medicine and manages Joan Pagano Fitness Group, a group of health and fitness specialists in NYC.