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Healthwise

Tuesday, February 04, 2003

By Virginia Linn, Post-Gazette Staff Writer

The tea kettle is too heavy to lift when filled with water. The Sunday paper is canceled because it is too massive to carry.

	Virginia Linn

Turning the knob to wind up an alarm clock is impossible. Pushing yourself up from a chair is a struggle. Walking outside during winter becomes a trek of terror.

Simple, everyday tasks become insurmountable feats when aging takes away our strength and balance and weakens our bones.

But a new study we reported recently provides more evidence that it doesn't have to be this way.

Weight-lifting exercises monitored by University of Arizona researchers showed that women can maintain and build their bone mass and muscle strength in the hip and spine areas, where most fractures occur from the brittle bone disease of osteoporosis.

"This is really much more about prevention," said lead researcher Timothy Lohman, who urges women to begin strength training by age 45.

The Bone, Estrogen and Strength Training (BEST) study published in the January issue of the American College of Sports Medicine journal, Medicine & Science in Sports & Medicine, tracked 140 post-menopausal women who lifted weights for a year. Half were on hormone replacement therapy, which are supplements of estrogen that keep bones strong. All took calcium supplements of 800 milligrams a day.

The women warmed up with stretching and weight-bearing activities and then performed eight core exercises with free weights and machines. Bone scans of the pelvic area were done before and after the study period.

Lohman said the combination of HRT, calcium and exercise built the most bone mass, but "exercise alone has some effect." And the more weight the women lifted during the year, the greater the effect. That's particularly important for women who don't want to deal with the expense and potential side effects of bone-building medications.

The study also showed these exercises help build and preserve the muscle mass lost during aging.

Strength and balance training is a message that Miriam Nelson from the School of Nutrition Science and Policy at Tufts University has been pushing for years.

A book that should be in every woman's home library is her "Strong Women, Strong Bones," (Putnam paperback, $12) which describes the important link between strong muscles and bones and exercises that prevent bone thinning. (Be aware it was published before the latest studies showing the dangers of long-term HRT use).

She says three processes are involved in exercise:

Bone-building osteoblasts are stimulated by the mechanical forces that exercise generates. Each time your feet hit the ground when walking, your bones are stimulated to grow. The higher the impact -- with jogging or jumping -- the more the growth.

The chronic force of muscles pulling against bones also promotes osteoblast activity. The stronger your muscles, the more stimulation they give to your bones.

Physical activity increases secretion of growth hormone, as well as other hormones that encourage bone and muscle growth. You'll have higher levels of these hormones if you get plenty of exercise.

These changes are seen in elite athletes, according to Nelson. One investigation compared the left and right arms of professional tennis players. The bones in their racket arm were 15 to 20 percent denser than bones in the other arm. Another investigation that measured the leg bones of cross-country runners and those of nonrunners the same age, found that the runners' bones were 10 to 20 percent denser.

The lesson: The more stimulation our bones receive, the denser they will be.

Lohman, in his study, found that certain exercises provide more benefit to the hip and spine than others. The weighted squats (from a standing position a person lowers the weighted upper body to a 90-degree angle at the knees and hips) had the greatest impact on building bone in the hip area at the upper thigh. The military press from a sitting position (pushing weighted dumbbells upward to an unlocked straight elbow) and the leg press helped to strengthen the spine and back muscles.

It's important to gradually increase the weight in these workouts. When you have reached the maximum amount you can lift, vary the routines so you're putting different forces on muscles and bones.

Nelson's book also includes exercises to improve balance, which can start declining in your 40s. Balance training protects our bones by preventing falls.

Before beginning, get a doctor's checkup. While her book provides good descriptions of the exercises, have qualified staff or a personal trainer at your gym, fitness center or Y guide you through the exercises.

Lohman also encourages women in their 40s to get a baseline bone scan called a dual X-ray absorptiometry that will measure the density of the hip and spine bones. Bone density is the best predictor of future fractures, and accounts for 80 percent of the strength of your bones.

These tests, available at hospitals or imaging centers, cost between $150 to $300, but are generally not covered by insurance unless you have reached a certain age or have certain risk factors or conditions.

"Don't wait until your insurance pays for it," he said. "This is the best test you can do if you're prone to osteoporosis. You can know in your 40s."