"My doctor told me that my osteoporosis is better--so I don't need to exercise,"said a resident of the senior apartment complex where I teach strength classes twice a week.

Obviously she doesn't understand what osteoporosis is and what to do to counteract it. Let's review the facts. Bone is active, living tissue that is constantly being built up in your body by cells called osteoblasts and constantly being broken down by cells caused osteoclasts. The idea is to build up new cells while replacing the old.

People with osteoporosis have weak, thin fragile bones because their bodies have not kept up with the rebuilding process. Weak bones are likely to fracture and osteoporosis causes 1.5 million fractures per year in the US. One-third of women over 50 will have a spinal fracture in their lifetime. In women with osteoporosis, spinal fractures can occur from sneezing or heavy lifting. Multiple spinal fractures can lead to severe changes in posture and appearance. Walking becomes difficult and painful, and the compression can cause difficulties and problems with the internal organs. Other symptoms include fracture of the hip or wrist or loss of height. I have had people in my strength training classes who had lost several inches in height because of osteoporosis of the spine. They are usually in almost constant pain.

According to the National Institutes of Health, ten million Americans (80-90 percent of them women) suffer from osteoporosis. Fortunately most doctors are aware of the dangers of osteoporosis and recommend tests to check your bone mineral density. These tests reveal whether you currently have osteoporosis, and can predict your risk of bone fracture. The tests are painless and usually take 15 minutes or less. The equipment uses very low radiation"less than an x-ray"which passes through the bone to measure its density. The results of the test can be helpful if you and your doctor are deciding whether medication is right for you.

When tests are taken at 1-to-2-year intervals, the information can help monitor changes in your condition. If your doctor does not order a BMD test at your annual physical, please talk to him about it.

Now the good news"there is much you can do to protect your body against osteoporosis.

Hormone replacement therapy used to be recommended to help slow down bone loss. But studies link hormone pills to heart risks. In one study, heart attack risk was about 70 percent higher among women taking the pills who were two decades past menopause or had levels of LDL cholesterol above 155.

There are drugs available that slow the process in which your body tears down bone. There is even a prescription drug which needs to be taken only once a month. Space prohibits me from describing here the different drugs which accomplish this, but if density tests show you have osteoporosis, talk to your doctor and if he or she prescribes a drug which will help slow bone loss, take it.

Since bones are living tissue, they are as dependent on proper nutrition as any other part of the body. Dietary factors that contribute to bone loss include a Western diet of processed foods, carbonated soft drinks, caffeine, and high protein, sugar, and salt consumption. Excess animal protein and excess phosphoric acid from soft drinks probably head the list of offenders.

You should make sure your body gets enough calcium, magnesium and other minerals plus vitamin D each day so it will have the raw materials it needs to build new bone. Recommended calcium daily intake for those under 60 is 1200 mg per day and 1500 mg over 60. There are different forms of calcium available in supplements. Calcium citrate is more easily assimilated by older bodies than calcium carbonate. Dietary sources of calcium include milk, yogurt, broccoli, collards, bok choy, kale, sardine and tofu with calcium sulfate.

If you decide to take supplemental calcium, you should know that your body needs much more than just plain calcium--it must balance with magnesium. Some experts are not yet convinced but my studies have led me to believe that your body needs calcium/magnesium in a ratio of 2/1. Carolyn Dean, M.D., author of The Miracle of Magnesium has convinced me that most of us are deficient in magnesium and that our calcium supplements must include magnesium. It is found in cooked spinach, white beans, brown rice, raisin bran, shredded wheat, almonds, artichoke, oatmeal and nonfat yogurt.

Your body must also have vitamin D in order to utilize calcium. The best vitamin D is made by your body by being in the sun. I recommend that you spend 15 to 20 minutes in the sun each day in addition to taking a supplement that contains at lease 400 I.U. Recent studies indicate that older adults need 800 to 1000 I.U.

Bottom line: when you go shopping make sure you get calcium in a product that contains half as much magnesium as calcium. It should also contain vitamin D and boron plus other trace minerals. There are excellent products available in health food stores.

Last, but certainly not least -- exercise is necessary to help prevent and reverse osteoporosis. According to a study done at the University of Arkansas, the two most effective forms of exercise to prevent osteoporosis are weight lifting and gardening. A study done by Miriam Nelson at Tufts University in Boston found that women who participated in a weight lifting program for a year gained two percent in bone mass. The control group that did not exercise lost one percent. I have had many students in strength classes tell me that their bone density is improving.

I cannot recommend too strongly that you participate in strength training. Join a fitness center and learn to use the machines or work out in the free weight area. If you find that too intimidating, you can exercise at home. My book "Over 40 & Gettin' Stronger" contains a simple workout using only dumbbells. I've recently added an audio CD so you can listen to me guide you through the workout. Go to www. strongover40.com for information.

You are not sentenced to suffer from osteoporosis. There is much you can do to prevent and reverse this dreaded disease.