Build a Stronger Skeleton

To build bone, you have to beat it up.

Your bones are nothing like the frame of a building. If a skyscraper's steel skeleton is shaken by an earthquake, it weakens. But shocks to bone only make it stronger. Bone is living tissue, and it responds to your activities. Mechanical stress -- the impact of your feet pounding pavement, the weight of a barbell, or the shock that travels up your arm when you whack a baseball -- creates microscopic fractures. Your bone not only repairs the tiny fractures, but it also responds by building more bone on top of them.

Doctors have known this for over a century, ever since a German surgeon named Julius Wolff proposed the idea, which became known as Wolff's Law.

Most of us, however, are ignorant of how our bones behave. "I don't think this information has really hit people," says Nicholas DiNubile, an orthopedic surgeon in suburban Philadelphia. He consults for the Pennsylvania Ballet and the 76ers basketball team about their bones.

If you hope to live to a ripe old age and be active during your golden years, you must pay heed to Wolff's Law.

This is especially true for women. After menopause, women start to lose a lot of bone. The end result can be osteoporosis: bones so brittle that even the stress of ordinary activities can snap them. Men aren't immune, either. The rapid bone loss that leads to osteoporosis starts about 10 years later in men -- around age 60.

DiNubile says it is crucial to build up as much bone as you can during the first 20-30 years of your life, so that when you reach the age when bone loss accelerates, the effect won't be devastating. He compares it to investing in the stock market. If you have $1 million and you lose 90% of it in a market crash, you're still left with more than most people earn in a year. If you've only invested $10,000, what's left probably couldn't cover a month's rent.

Train Smart

To build healthy bones, you need the raw material calcium. Eating foods rich in calcium is a good start, but you also have to make sure your bones can use it. You may get enough calcium in your diet, but you rob your bones of it if you drink lots of soda. The phosphorus in soft drinks inhibits calcium absorption.

Good Vibrations

Clinton Rubin, PhD, a scientist at the State University of New York in Stony Brook, thinks he may have found another way to build bone: vibration. His experiments have shown that gentle, high-frequency vibrations greatly increase bone growth. In a recent study, he had sheep stand on a vibrating platform for 20 minutes, five days a week, over the course of one year. The density and volume of their leg bones increased by more than 30%.

Rubin's research is funded by NASA's National Space Biomedical Research Institute. NASA is interested because bone loss is a bane to astronauts. According to Rubin, we lose about 2% of our bone per decade here on Earth. Astronauts lose about 2% of their bone per month in space. Under no stress from gravity, bone dissolves. "It's doing exactly what it thinks it should do," Rubin says. That is, a weightless body doesn't really need bones. It's responding to the environment.

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