Move it or lose it.

"When they're 50 or so, most people start to wonder: `Will I have enough money for my retirement?'" says Frank Booth, professor of biomedical sciences at the University of Texas Health Sciences Center in Houston.

"Well, they should also ask themselves: `Will I have enough muscle left when I'm 80 to hit the golf ball or play tennis or pick up my grandchildren or have fun?'"

Most people know that eating a healthy diet can cut the risk of heart disease, cancer, diabetes, stroke, and osteoporosis. Physical activity can help prevent the same killers.

But while few of us can go even a day without eating, it's easy to go days, weeks, or even years without exercising.

This month, Nutrition Action's David Schardt asked three experts how physical activity can improve the bones, muscles, sleep, and quality of life of older people.

Says Booth: "Our society isn't set up to encourage people to exercise, but we need to do it."

STAYING YOUNG

Q: What can strength training do for bones?

A: One year of doing high-intensity strength training can lower a woman's risk of osteoporotic bone fractures in more ways than any other single thing she can do for herself.

Q: How did you show that?

A: We recruited 39 sedentary white women, aged 50 to 70, and randomly assigned half of them to a program of exercise and the other half to a control group that remained sedentary.(1) Twice a week, for 45 minutes each session, the exercise group worked out on weight machines.

After one year, the women who exercised had better balance, stronger bones, and more muscle than the women who didn't exercise. So they were less likely to fall and break a bone.

Balance is a very complex activity. It takes in eyesight, hearing, and coordination, but a big factor that many investigators haven't really thought about is muscular strength. When someone's stronger they have much better balance.

I've been in the field of osteoporosis and bones for 13 years now, and when you think about calcium, vitamin D, estrogen, and the drug Fosamax, they are all critically important, but they only affect bones. Exercise strengthens muscles as well as bones.

Q: Did it change their lives?

A: Yes. We've seen now in three different studies in a variety of ages that once women become stronger, they take up lots more physically demanding activities that they enjoy doing. "Revitalized" is not a very scientific term, but that's what happens to the people in our studies who do these exercises. This is a side effect that we scientists never believed we would see.

I've had numerous women tell me they started gardening again, or ballroom dancing a couple of nights a week, or they were canoeing on weekends because it was now easy for them to help their husbands get the canoe up on the car. One woman took up rollerblading, another goes white-water rafting regularly with her daughter. It's been really exciting.

Strength training even helps people sleep better and relieves depression and improves the mood of people who were mildly to moderately depressed.(2,3)

Q: Is it ever too late to start?

A: Absolutely not. My oldest volunteer is 95.

I like to think of the aging process in three different segments. If you're 30 or 40 years old, you want to maximize what you have and make sure that those weekend activities that you love to do are easy and you don't injure yourself.

Then at 40 or 45, you start to lose bone and muscle. At 50, the losses accelerate and your physiology really changes. That's especially true of women going through menopause. So it's critical to minimize the loss of muscle and bone at this time.

In your 60s, 70s, 80s, and 90s, you want to maintain your vitality and independence for as long as possible. And all exercise, especially strength training, will help you do that.

Q: Do men benefit, too?

A: Yes. The exercises are the same, but men might start out with a little heavier weight because they're stronger to begin with.

But building strength is particularly important for women. We start out smaller and we naturally have less muscle and more fat. What's more, we live longer than men on average and so we disproportionately have osteoporosis and become dependent on others. So, if any group should be doing strength training, it's women.

Q: Do people notice that they're losing muscle?

A: No. Both men and women lose about a third of a pound of muscle each year after age 40. And they gain that much fat, if not more. People usually stay about the same weight, or they gain a little bit. But inside the body, muscle is being replaced by fat So, after ten years you realize: "Oh my gosh, I'm not nearly as strong or as trim as I was ten years ago."

Aerobic exercise, like running or brisk walking, is important, and we need to get more people doing it. But it doesn't affect the muscles nearly to the same extent that the strengthening exercises do.

(1) J. Amer. Med. Assoc. 272: 1909, 1994.

(2) Journal of Gerontology 52A: M27, 1997.

(3) Sleep 20: 40, 1997.

Miriam Nelson is associate chief of the Physiology Lab at the U.S. Department of Agriculture's Jean Mayer Human Nutrition Research Center on Aging at Tufts University in Boston.

STAYING ACTIVE

Q: Why do we become less active as we age?

A: As people get older, a vicious cycle occurs. Because some daily tasks get harder for them, they choose not to do as much. And because they choose not to do as much, the tasks become harder for them. So if you can break that sequence, then they're apt to be more active and enjoy their lives more. The quality of life is going to be greatly improved.

Q: How can someone break the sequence?

A: Through weight training. Before the women in our study started weight training, it took on the average about 65 to 70 percent of the maximum strength in their thigh muscles to be able to stand from a chair. After weight training, it took only about 35 percent.(1)

The women ranged in age from 60 to 77. Eventually, if people live long enough, they'll probably all have difficulty getting out of a chair. But after the weight training, these ladies were probably at least 10 years, if not more, further away from that day than they were before.

Q: Did other simple tasks became easier?

A: Yes. Before weight training, walking while carrying the equivalent of a 10- to 13-pound bag of groceries took about 55 to 60 percent of the women's strength. After weight training, the amount their muscles had to work decreased by about 60 percent. The women were stronger and their muscles were better able to do the task, so they didn't have to work nearly as hard.

Q: How do you know?

A: We did electromyography to look at the electrical activity in their muscles. In other words, we looked at how active their muscles really were.

Q: Did the strength training have other benefits?

A: Yes. Not only did the muscles not have to work nearly as hard, but the women's blood pressure and heart rates were much lower while they were doing these activities. That reduces the stress on the heart. So we were pretty darned sure that these ladies were going to be much less apt to have a heart attack or stroke while doing daily activities like carrying a granddaughter or a bag of groceries upstairs.

Q: What did the weight training program consist of?

A: For 16 weeks, three times a week on alternate days, they did 12 exercises that just worked the major muscle groups of the body, both upper and lower body. They were doing things like leg presses, knee extensions, two different kinds of leg curls, bench presses, overhead presses, elbow curls, and rowing exercises.

Q: Do people have to do these exercises in a gym?

A: Ours was done in an exercise facility, but I think you could do exactly the same thing at home. It's probably a little bit easier with machines, but if you had a barbell and indoor dumbbells, you could devise an exercise program doing most of the same movements.

For example, you could do squats instead of leg presses. You could do almost all of the other exercises with just a barbell. If you didn't have any of those things, you could probably even devise resistance type training using things around the home. It's a little more difficult, because it's not easy to go up in very small increments of weight, to get progressive resistance. But using a little imagination, you could do some substitute things without any equipment at all.

Q: Did the women continue after the study ended?

A: Some of them have and some of them haven't. Obviously, if you don't persist, you're going to lose the effects.

Q: Did the women lose weight?

A: No, but they lost fat. We found an increase in resting metabolism and an increase in fat oxidation. They were burning more fat at rest. That was very dramatic.

We also saw an increase in muscle, and since they maintained the same body weight, there was a decrease in fat. And we saw a shifting of fat away from the abdominal area, which is the most-harmful fat.

Q: Did anyone get hurt?

A: We had only one injury and that was in a woman who aggravated a previous abdominal surgery. She dropped out of the study.

(1) J. Amer. Geriatrics Soc. 43: 756, 1995.

Gary Hunter is an exercise physiologist at the University of Alabama at Birmingham 

EXERCISE & SLEEP

Q: Can exercise help you sleep better?

A: Yes. Surprisingly, our new study was among the first well-designed ones to look at whether physical exercise can help older people who were complaining of poor sleep. As many as half of middle-aged and older adults have this problem. The study was also unique because it focused on moderate-intensity activity. Many sleep and exercise studies have focused on vigorous forms of exercise such as jogging or running. We wanted to test something like brisk walking, which older people prefer.

Q: What did you do?

A: We recruited 43 sedentary men and women aged 50 to 76 who complained about their sleep. Then we randomly assigned half of them to four months of a moderate exercise program and the other half to a "wait-list" where they didn't do anything different.

Q: What kind of exercise?

A: Twice a week they attended a YMCA class of low-impact aerobics that was set up specifically for seniors. It was a one-hour class that included 30 minutes of moving in small steps to music from side to side and up and down.

Q: What happened?

A: Instead of taking about 30 minutes to fall asleep, the exercisers were falling asleep within 15 minutes. And they slept 50 minutes longer than they did before. They also reported feeling more rested in the morning. As they age, most folks tend to sleep less and complain more about it. So these people were able to regain some of their lost sleep, which is good.

Q: How long did it take for the exercises to start working?

A: After two months we saw some improvements. But it didn't become statistically significant until we looked again at four months. So, you probably have to keep up the exercise for at least a few months before you see the benefits on sleep.

Q: Should people not exercise right before they go to sleep?

A: The data suggest that exercise has an energizing effect. We know from studies that within an hour or two after exercise sessions, people report feeling more energy, feeling more alertness, and that's not good if you want to get to sleep. So what we tell people is to try to do their exercise prior to dinner time. In our study, they pretty much did their exercise in the middle of the day.

Q: What's next?

A: We'd like to look at whether people who exercise are able to get off their sleep medicine.

(1) Journal of the American Medical Association 277: 32, 1997.

Abby King is a behavioral psychologist at the Stanford Center for Research in Disease Prevention in Palo Alto, California.

Getting Strong -- at Home

"You don't need special clothes or fancy equipment," says Miriam Nelson in Strong Women Stay Young ($23.95, 1997, Bantam Books, New York).

"All that's necessary are a couple of dumbbells and some ankle weights, which you can buy at a sporting goods store or through mail-order. These are small enough to fit in a small bag that can be stowed away in a closet. Plus you'll need a sturdy chair. And that's it.

"You'll start with relatively light weights--one to three pounds for each arm and three to five pounds for each leg, depending on your current strength. In the beginning you'll add weight every week. Within a few weeks you'll be training at the proper intensity: You'll be able to lift each weight eight times in good form, but this effort should be close to your limit. When the eighth lift is no longer a challenge, it's time to increase the load.

"Each lift takes about nine seconds: four seconds to raise the weight; a one-second pause; and four seconds to lower the weight."

Here are three of Nelson's "Eight Exercises That Will Make you Strong."

KNEE EXTENSION

This exercise strengthens the quadriceps, the large muscles in front of your thighs. You '11 notice a power difference when you walk, climb stairs, rise from a chair, bike, or engage in any sport that uses your legs.

Starting position: Sit back in the chair. Your feet should be shoulder-width apart, with your knees directly above them--your knees shouldn't touch each other. Put a towel under your knees to pad them. Your toes should just brush against the floor; if necessary, raise your knees by doubling up or rolling the towel. Rest your hands on top of your thighs or let them dangle at your sides; or lightly hold the edge of the chair seat.

The move:

* 1-2-3-Up: Slowly raise your right leg until the knee is as straight as possible. Keep your toes gently flexed up toward your body.

* Pause for a breath.

* 1-2-3-Down: Relax your ankle so your toes are no longer flexed up. Slowly lower your leg to the starting position.

* Pause for a breath. Then repeat the move with your left leg.

Where you will feel the effort: On top of your upper thighs, with a stretching feeling in the backs of your thighs.

Reps (repetitions) and sets: Repeat, alternating right and left legs until you have done eight knee extensions with each leg--this is one set. Rest for a minute or two and do a second set.

Checklist:

* Posture: Don't arch your back as you do the exercise.

* Straighten your leg as far as possible at the end of the lift--the last part of the muscle contraction is the most important.

* Don't hold your breath.

UPWARD ROW

This exercise strengthens the deltoid (shoulder muscle), trapezius (upper back muscle), and biceps. The shoulder joint is one of the most important--and vulnerable--in the body. Strong shoulder muscles help stabilize this joint, allowing you to lift and carry heavy objects.

Starting position: Stand with a dumbbell in each hand. Move your hands so that the dumbbells rest on the fronts of your thighs, with your palms facing your thighs.

The move:

* 1-2-3-Up: Slowly pull the dumbbells upward along your torso until they are just below your chin. Keep your hands in the same position during the move; your wrists will bend to the side so your knuckles remain pointing down. At the end of the lift, your elbows will be at shoulder height and pointing out to the side; your forearms and the weights will be parallel to the floor.

* Pause for breath.

* 1-2-3-Down: Slowly lower the dumbbells to the starting position.

* Pause for a breath, then repeat.

Where you will feel the effort: In your forearms, biceps, and shoulders.

Reps and sets: Perform eight upward rows--one set. Put the weights down and rest for a minute or two. Then do a second set.

Checklist:

* Don't scrunch your shoulders! This is the most common problem with this exercise.

* Make sure that your elbows and wrists are not above shoulder level.

* Maintain good posture.

* Don't hold your breath.

TOE STAND (WITHOUT WEIGHTS)

This is a three-purpose exercise. It improves your balance, makes your ankles more flexible, and strengthens the gastrocnemius and soleus muscles in the backs of your lower legs. You'll feel the difference when you're on your feet all day, because you use these muscles whenever you're standing.

Instead of dumbbells and ankle cuffs, this exercise uses your body weight. Start with Level I. If your calf muscles are weak or inflexible, you may not be able to raise yourself very much. Work on improving the strength of these muscles until you can lift yourself all the way; up onto your toes. Then go to Level 2--the same exercise but without help from your hands.

Starting position: Stand twelve inches away from a wall, with your feet about twelve inches apart.

* Level 1: Rest your fingertips lightly on the wall to help maintain your balance.

* Level 2: Stand in the same place, with your hands ready to support you if you lose your balance. As you improve, try to become less reliant on the wall. For safety's sake, always perform this exercise with a wall in front of you.

The move:

* 1-2-3-Up: Slowly raise yourself as high as possible on the balls of both feet.

* 1-2-3-Hold: Remain on your toes for another count of three, breathing normally.

* 1-2-3-Down: Slowly lower yourself to the starting position.

* Pause for a breath and repeat.

Reps and sets: Repeat eight times--one set. Only one set is required for this exercise.