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IS FRAILTY INEVITABLE AS WE AGE?

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