• By Maureen Williams, ND

Exercise Builds Bones in Teens

Few teenagers think much about osteoporosis, but science suggests that adolescence is a critical time for accumulating bone mass and preventing osteoporosis in the future—and getting exercise may play a role. A new study found that teens who engage in regular vigorous physical activity have higher bone mass than teens who exercise moderately or lightly, which may have implications for their osteoporosis risk in adulthood.

Eat a mineral-rich diet, including green vegetables, nuts and seeds, canned fish with bones, tofu and other soy foods, as well as some dairy foods.

Measuring bone size and strength

The study, published in the Journal of Clinical Endocrinology and Metabolism, included 1,748 boys and girls. They are part of a large ongoing study examining the factors affecting the health, growth, and development of children beginning at birth. The data used for this report was collected at their 15.5-year physical exam.

Researchers measured the teens’ bone mass and density through a test that determines the geometry and strength of a bone as well as its mass and density (peripheral quantitative computed tomography). They were each given an accelerometer, a device that measures the amount and intensity of physical activity, to wear for seven days.

Vigorous exercise builds bone

After examining the data they collected, the researchers found:

• Light and moderate physical activity had little bearing on bone mass.
• Only the children who engaged in vigorous physical activity had higher bone mass.
• Vigorous exercisers also had more bone volume and greater bone strength.

“Our findings suggest that adolescent participation in vigorous physical activity, but not moderate physical activity or light physical activity, may have long-term benefits for skeletal health,” researchers summarized.

Keeping bone all your life

During childhood and young adulthood, we build new bone faster than we break down old bone. But after about age 30, the trend reverses and we begin to slowly lose more bone than we build. Having more bone mass at the time this reversal occurs makes it less likely that we will develop osteoporosis in our senior years.

The results from this study show that intense exercise accelerated the building of bone mass in adolescence. Moderate and light exercise didn’t show the same protective effect, but any physical activity could still be important in establishing a healthy habit that will prevent bone loss in middle and old age.

Help your kids keep their bones healthy throughout life by encouraging good habits, like engaging in regular exercise and following these other tips:

• Eat a mineral-rich diet. This includes green vegetables, nuts and seeds, canned fish with bones, tofu and other soy foods, as well as some dairy foods.
• Cut out colas. These soft drinks are high in phosphoric acid and caffeine, both of which can increase calcium loss.
• Don’t smoke. Smoking increases osteoporosis risk.
• Take vitamin D. Most healthcare providers recommend that children and adults supplement with vitamin D, especially those who live in northern latitudes and particularly in winter.

(J Clin Endocrinol Metab 2011;96:E793–802)