The Short Story About Your Bones

Our bones are very much living tissue. Your entire skeleton is replaced every 7 to 10 years. In the bones, cells called osteoclasts break down bone, while osteoblasts build bone. When these are in balance, bone density remains stable.

The greatest gain in bone density occurs between age 12 and 20. With adequate nutrition, and physical activity, we hit adulthood with excellent bone density. People who are weightlifting during this time start out with wonderfully strong bones. Density stays pretty much stable until menopause, unless other factors contribute to loss or gain. Bone loss can be caused by smoking, excessive alcohol, inadequate nutrition, eating disorders, excessive exercise - to the point of menstrual cessation- and a sedentary lifestyle. Further bone growth can result from good nutrition, and an active life that includes weightlifting. Bone growth is influenced by hormones, especially estrogen, and that makes menopause a risky time for some people. During the first 3 to 5 years after menopause, you can lose 3% to 5% of your bone density EACH YEAR. If this happens, you will have Osteoporosis.

Wayne Wescott, PhD., did some interesting studies on weightlifting and bone density. People weightlifting during adolescence gain much more bone that those who are not weightlifting. And during the decades up to age 50, modest bone growth can still occur in weightlifters. During the decade from age 50 to age 60, a very small (less than 1%) increase in density occurs. But, wait. Compare that to the 3% to 5% loss, each year, that occurs without weightlifting, and you now can see why lifting at this time is so important. In some people, weightlifting and good nutrition can help regrow bone that has thinned, but if the bone loss is substantial, medication is a good idea too.

How do weightlifting and medication help bone density? The medications (Fosamax, Actonel, Boniva, etc) work only on the osteoclasts, so they inhibit the breakdown of bone. Exercise stimulates the osteoblasts, so it stimulates the growth of bone. It is weight bearing exercise that has this effect. Many people believe that walking alone will stimulate bone growth, this is only true if you are quite heavy or walk 20 miles a day. Bones need intensity, not lots of repetition, to stimulate growth. An exercise that helps stimulate growth at the hip is a side lying leg lift. You benefit more from doing 15 repetitions with 10 lbs on your ankle than you would from doing 45 repetitions with no weight. Do not jump into an unguided exercise program if you have osteoporosis, because the wrong exercise can hurt you. If you don't have access to a gym, or your gym does not have knowledgeable trainers (and many know nothing about osteoporosis), buy both Miriam Nelson's book, Strong Women, Strong Bones and Osteopilates by Karena Lineback. Work with someone watching you to observe that your form is correct. You want to do exercises not just for the sake of your bone density, but also to improve balance, the key to preventing falls.

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