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The clock ticks for everyone, and with each tick comes change. For those who manage to avoid major medical problems, the changes are slow and gradual, but they do add up.

Some of the changes of aging start as early as the third decade of life. After age 25–30, for example, the average maximum attainable heart rate declines by about one beat per minute, per year, and our heart's peak capacity to pump blood drifts down by 5%–10% per decade. That's why a healthy 25-year-old heart can pump 2½ quarts of blood a minute, but a 65-year-old heart can't get above 1½ quarts, and an 80-year-old heart can pump only about a quart, even if it's disease-free. In everyday terms, this diminished aerobic capacity can produce fatigue and breathlessness with modest daily activities.

Starting in middle age, our blood vessels begin to stiffen and blood pressure often creeps up as well. The blood itself changes, becoming more viscous (thicker and stickier) and harder to pump through the body, even though the number of oxygen-carrying red blood cells declines.

Most Americans begin to gain weight in midlife, putting on 3–4 pounds a year. But since we start to lose muscle in our 40s, that extra weight is all fat. This extra fat contributes to a rise in LDL ("bad") cholesterol and a fall in HDL ("good") cholesterol. It also helps explain why blood sugar levels rise by about 6 points per decade, making type 2 diabetes distressingly common in senior citizens.

The loss of muscle continues, eventually reducing our musculature by up to 50%, which contributes to weakness and disability. At the same time, muscles and ligaments get stiff and tight. We have an increased risk of fractures due to a drop in muscle mass and bone density.

The nervous system also changes over time. Reflexes are slower, coordination suffers, and memory lapses often crop up at embarrassing times. The average person gets less sleep in maturity than in youth. Not surprisingly, spirits often sag as the body slows down.

If this sounds grim, don't fret, there is a solution!

While we cannot stop the clock, we can slow its tick. Research shows that many of the changes attributed to aging are actually caused in large part by disuse.

Exercise is not the fountain of youth, but it is a good long drink of vitality, especially as part of a comprehensive program. And an old study from Texas shows just how important exercise can be.

The Dallas Bed Rest and Training Study

In 1966, five healthy men volunteered for a research study at the University of Texas Southwestern Medical School. The individuals were confined to bed rest for three weeks. After the bed rest, the men were instructed to exercise. Testing the men before and after exercise, the researchers found devastating changes that included faster resting heart rates, higher systolic blood pressures, a drop in the heart's maximum pumping capacity, a rise in body fat, and a decrease in muscle strength.

In just three weeks, these 20-year-olds developed many physiologic characteristics of men twice their age. Fortunately, the scientists didn't stop there. Instead, they put the men on an 8-week exercise program. Exercise did more than reverse the deterioration brought on by bed rest, since some measurements were better than ever after the training.

A second look

The original subjects all agreed to be evaluated again at the age of 50. All five remained healthy, and none required long-term medication. Even so, the 30-year interval had not been kind. Over the years, the men gained an average of 50 pounds, or 25% of their weight at age 20. Their average body fat doubled from 14% to 28% of body weight. In addition, their cardiac function suffered, with a rise in resting heart rate and blood pressure and a fall in maximum pumping capacity. In terms of cardiac function, though, the toll of time was not as severe as the toll of inactivity; at 50, the men were far below their 20-year-old best, but they were not quite as feeble as when they emerged from three weeks of bed rest in 1966.

The researchers did not ask the 50-year-old volunteers to lie in bed for three weeks; that could have been hazardous. But they did ask them to begin an exercise program, and they constructed a gradual 6-month regimen.

At the end of the six months, the men averaged only a modest 10-pound loss of their excess weight, but their resting heart rates, blood pressures, and their heart's maximum pumping abilities were back to their baseline level from age 20. All in all, exercise training reversed 100% of the 30-year age-related decline in aerobic power. Even so, exercise did not take the men back to their peak performance after 8 weeks of intense training at age 20. The clock does tick, after all, but exercise did slow the march of time.

Endurance exercise is the best way to improve cardiovascular function. It helps keep the heart muscle strong and the arteries flexible, lowers the resting heart rate, and boosts the heart's peak ability to deliver oxygen-rich blood to the body's tissues. A related benefit is a fall in blood pressure.

Endurance exercise is also the best way to protect the body's metabolism from the effects of age. It reduces body fat, sensitizes the body's tissues to insulin, and lowers blood sugar levels. Exercise boosts the HDL ("good") cholesterol and lowers levels of LDL ("bad") cholesterol and triglycerides. And the same types of activity will fight some of the neurological and psychological changes of aging. Endurance exercise boosts mood and improves sleep, countering anxiety and depression. In addition, it improves reflex time and helps stave off age-related memory loss. All in all, many of the changes that physiologists attribute to aging are actually caused by disuse. Using your body will keep it young!

The key is regular activity

Start slowly if you are out of shape, then build up gradually to 3–4 hours a week. A program as simple as 30 minutes a day will produce major benefits.

Resistance exercise using light weights or exercise machines will enhance muscle mass and strength and preserve bone calcium.

Flexibility training will help keep you supple as you age. Stretching exercises are an ideal way to warm up before and cool down after endurance exercise. Like strength training, 30 minutes of dedicated time two or three times a week is ideal.

Exercises for balance will also help retard some common effects of aging. They will help you move gracefully, avoid injuries, and prevent the falls that cripple so many older Americans.

To keep your body as young as possible for as long as possible, keep it moving. As usual, Hippocrates got it right about 2,400 years ago, explaining, "That which is used develops; that which is not wastes away."

Exercise, illness, and longevity

A proper exercise program will help delay many of the changes of aging, particularly when combined it with a healthy diet.

Heart disease a leading killer of Americans. Because exercise helps improve so many cardiac risk factors (cholesterol, blood pressure, diabetes, obesity, and stress), it should have a powerful protective influence on heart attacks — and it does. Back in 1978, the Harvard Alumni Study found that those who exercise regularly are 39% less likely to suffer heart attacks than their sedentary peers. It was a groundbreaking observation, and it's been confirmed many times over.

Stroke is the third leading cause of death in America. Like heart disease, many strokes are caused by atherosclerosis, which is why heart attacks and stroke share so many risk factors. It's no surprise, then, that exercise can reduce the risk of stroke. Twenty-four years after its report on exercise and heart disease, the Harvard Alumni Study linked mild exercise to a 24% risk reduction; moderate to intensive exercise was even better, reducing risk by 46%.

Harvard's Health Professionals Follow-Up Study found that highly active individuals are 47% less likely to develop cancer than their sedentary peers, and many other studies agree.

Aging Americans vs. Aging hunter-gatherers

As we get older, we know that strength declines rapidly. By the time people are in their 60s and 70s, they're often somewhat frail, but hunter-gatherers remained physically active as they aged.

Age doesn't naturally lead to frailty. Older individuals may not be as strong and swift at 63 as they were at 23. However, the reason so many seniors in the developed world become weak is because they believe loss of strength is inevitable and they give up on exercise. This belief is a myth.

As a result of this false belief, many older Americans stop exercising, which leads them to become less fit, which in turns causes them to exercise even less. It's a vicious circle that leads to "sarcopenia," or loss of muscle mass and strength.

Boosting brains and brawn

We tend to think of this loss of muscle mass as an inevitable part of getting older, but it's not. And you don't have to hang out with hunter gatherers to prove that's true.

It's worth noting that separate studies show that regular (but modest) weight training helps keep the brains of older adults functionally younger.

Exercise precautions

Exercise is wonderful for health — but to get gain without pain, you must do it wisely, using restraint and judgment every step of the way.

Here are a few tips:

  • Get a medical check-up before you begin a moderate to vigorous exercise program, particularly if you are older than 40, if you have medical problems, or if you have not exercised previously. Although treadmill stress tests were once considered an important precaution, they are not necessary for most people who are healthy, even if they are senior citizens.

  • Eat and drink appropriately. Don't eat for two hours before you exercise, but drink plenty of water before, during, and after exercise, particularly in warm weather.

  • Warm up before you exercise and cool down afterward.

  • Exercise regularly. Unless you are ill or injured, try to exercise nearly every day, but alternate harder workouts with easier ones. Give yourself enough time to recover from injuries and illness — and remember that recovery may take longer as you age.

  • Listen to your body. Learn warning signals of heart disease, including chest pain or pressure, disproportionate shortness of breath, fatigue, or sweating, erratic pulse, lightheadedness, or even indigestion. Do not ignore aches and pains that may signify injury; early treatment can often prevent more serious problems. Do not exercise if you are feverish or ill. Work yourself back into shape gradually after a layoff, particularly after illness or injury.

Helping to prevent heart disease, cancer, stroke — exercise is worth the effort. Physical activity can help reduce your risk for many of the chronic illnesses that produce so much distress and disability as we age.

Regular exercise helps people age more slowly and live healthier, more vigorous lives. And it also helps people live longer. Calculations based on the Harvard Alumni Study suggest that those who exercise regularly can gain about two hours of life expectancy for each hour of exercise. Over the course of a lifetime, that adds up to about two extra years. Maximum benefit does require regular exercise over the years, but it doesn't mean a trip to the gym every day. In fact, just 30 minutes of brisk walking every day will go a long way toward enhancing your health.

It's never too late

One of the most impressive things about this research is that people responded nearly as well to exercise training at 50 as they did at 20! You can benefit from exercise at any age, though senior citizens do need to take extra care, especially if they are just getting started. Perhaps the most dramatic example comes from a Harvard study that demonstrated important improvements in 87- to 90-year-old nursing home patients who were put on a weight-lifting program. This study evaluated muscular function, but the Harvard Alumni Study examined mortality. The latter study found that previously sedentary people who began exercising after the age of 45 enjoyed a 24% lower death rate than their classmates who remained inactive. The maximum benefits were linked to an amount of exercise equivalent to walking for about 45 minutes a day at about 17 minutes per mile. On average, sedentary people gained about 1.6 years of life expectancy from becoming active later in life.

Exercise is one way to slow the aging process, but it works best in combination with other measures. Here are some other tips to help you age well:

  • Avoid tobacco in all its forms.

  • Eat properly. Reduce your consumption of saturated fat, trans fatty acids, and cholesterol. The omega-3s and monounsaturated fats in fish, nuts, olive oil, and possibly canola oil are desirable in moderation. Eat lots of fruits, vegetables, whole grains, and nonfat dairy products. Favor complex carbohydrates and high-fiber foods, but reduce your consumption of simple sugars. Get about 15% of your calories from protein. Cut back on salt and processed foods. Keep your caloric consumption down and stay as lean as possible.

  • If you choose to drink, be responsible, and limit yourself to two drinks a day.

  • Keep your mind active and stimulated. Mental exercise is an important complement to physical exercise.

A balanced program is best. That's why Cicero proclaimed, "Exercise and temperance will preserve something of our youthful vigor, even into old age."

Beat the clock

Aging is inevitable, but it has an undeservedly fearsome reputation. No person can stop the clock, but most can slow its tick and enjoy life as they age with grace and vigor.

If you expect to get weaker as you age, you probably will. Thankfully, the opposite is also true -- a modest commitment to keeping up your strength will prevent much of the age-related declines in fitness too many people see as inevitable.




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