Authors: Jörg Blech
For many years, researchers had a hard time identifying the causes of this age-related decline of the basal metabolic rate. After a lot of guesswork, they discovered how body composition plays a crucial role. When a person has a small muscle mass—as is typically the case with middle-aged people who have neglected to exercise for many years—then the metabolism needs less oxygen and energy; fat tissue requires less fuel than muscle tissue.
This difference points to two ways to avoid gaining weight over time. One can cut back consumption of calories by exactly the amount the metabolic rate sinks, which would amount to 100 fewer kilocalories per day for every decade of life after age 20. The second option would be to get moving and increase one’s basal metabolic rate.
Relative Body Fat
Even when people are not adding weight while aging, their body fat usually increases. Rosenberg and colleagues examined hundreds of elderly people and quantified this tendency: The average 65-year-old sedentary woman consists of 43 percent body fat, whereas a 25-year-old woman typically has 25 percent fat. For men, things are similar: 65-year-olds average 38 percent fat, whereas 25-year-old men average 18 percent.
For older people to achieve a more youthful ration, other than eating less, they have to remain physically active. If they walked every day for two kilometers, they would burn 140 kilocalories respectively each day. After one year, that would be 51,000 kilocalories, and nearly 18 pounds of fat tissue would have melted away.
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Aerobic Capacity
To keep living, to refresh our blood, humans must breathe oxygen. Aerobic capacity measures the consumption of oxygen in a given time. Compared to young adults, people at age 65 have an aerobic capacity that is 30 to 40 percent lower.
Once again, we can slow down this decline with physical exercise. Aerobic capacity indicates our fitness level. Moreover, muscle type also influences it. The healthful oxidizing muscle type virtually sucks oxygen out of the bloodstream. Thus if you are elevating your aerobic capacity by physical activity, it is a sure sign that you have increased the percentage of desirable oxidizing muscle types.
Blood Sugar Tolerance
This describes the body’s ability to control the amount of glucose in the blood, thereby avoiding the damaging effects seen in diabetic individuals. Strength training and physical exercise increase muscle mass, which (by way of insulin signals) can soak up glucose. On balance, this improves the blood sugar tolerance.
Bone Density
Bones grow when they are used. The bigger the effort, the stronger they get. A study from Finland revealed that professional squash players have bone densities 15 percent higher in the arm they play with compared to nonplayers. Physical activity boosts the incorporation of calcium ions into bones, making these more robust and sturdier. The rate of this incorporation is directly correlated to the number of years training.
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Internal Temperature
“Our bodies come with a built-in thermostat,” says Rosenberg.
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Whether it is humid or chilly in our environment, the body is always able to keep its working temperature of about 98 degrees Fahrenheit. Sweating cools us down, while shivering warms us up. This control system is closely related to the aerobic capacity and the balance of electrolytes in the body, which in turn can be positively influenced by exercise.
Cholesterol: Amount and Type
Our bodies cannot function without cholesterol, and they are even capable of producing it when cholesterol is absent from food. The human brain consists of 10 to 20 percent cholesterol (based on the dry mass), and depends on a steady supply. Because the substance is too fatty to circulate by itself through the bloodstream, certain proteins, called lipoproteins, must transport it. However, when the concentration of certain lipoproteins is highly elevated, it creates a risk of cardiovascular diseases.
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William E. Kraus at the Duke University Medical Center has found that a certain type of exercise is especially good at keeping lipoproteins in check: longer spells of moderate exercise seem to be more beneficial than shorter, more intensive workouts. Jogging 12 miles per week reduces the number of small, unwanted lipoproteins, but jogging for 20 miles per week produces even better results.
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Blood Pressure
The pressure inside the blood vessels and the lungs is determined by the capacity of the heart, viscosity of the blood, and the resistance created by the blood vessels. Researchers have demonstrated in more than 50 trials that regular endurance training lowers blood pressure, and that even rather modest everyday activities translate into measurable improvements. Exercise is thus a proven and reliable remedy for people with hypertension, although this is not widely appreciated. For one thing, many people with high blood pressure lack motivation to work out. But frequently the treating doctors are to blame, says Hans-Georg Predel of the Sports University in Cologne, Germany. He has made the sobering observation that physicians “often don’t consider the effectiveness of an intervention without drugs and that they lack a sufficient expertise in prescribing lifestyle changes.”
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Biological Age
The sports physicians at Tufts were among the first to demonstrate that all of these biomarkers will improve when an out-of-shape person starts to exercise.
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They came up with a mix of light endurance (brisk walking and bicycling) and modest strength exercises that can be easily done at home. Time and again, researchers found that anyone who really follows the program for 16 weeks will reap the benefit of many improved bodily functions. It is important not to focus on these biomarkers as risk factors but rather as motivating numbers used to document gains.
What if you didn’t know your age? That’s a question Irwin Rosenberg asks. He tells the story of Satchel Paige, the legendary twentieth-century baseball player. Paige grew up poor in Alabama, and his parents had not noted his date of birth. Later in life, the pitcher used to say folks should guess his age by judging his performance in the ballpark. According to this measurement, Paige hardly aged at all because his outstanding career lasted for three decades.
Where Paige had his scores to show off, we have the biomarkers that reveal our true age. If you don’t like the verdict of the biomarkers, you can change it. Just get moving.
What the Heart Desires
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IFTY YEARS AGO, PEOPLE WHO SURVIVED A HEART ATTACK WERE prescribed up to six months of bed rest. Walking and running, the doctors feared, would only trigger more infarctions, damaged areas of the heart. This mind-set was prevalent when President Dwight Eisenhower suffered a heart attack in 1955. A cardiologist named Paul Dudley White treated the ailing president.
White and Eisenhower were convinced the president would overcome his condition and live a long life. But many other doctors and wide segments of the American population were skeptical, especially after learning about the procedures White advocated. The doctor turned out to be an unusual fitness devotee who rode his bicycle to work and considered bed rest for patients to be nonsense. Instead, White prescribed his presidential patient doses of physical activity. Before long, sensational photographs were printed in newspapers showing heart patient Eisenhower playing golf. But White had done the right thing: Eisenhower recovered and, after being re-elected, was able to serve a second term.
Since then, physical activity has been considered a reliable remedy to slow down, halt, and even reverse heart disease, as well as a prophylactic that keeps a healthy heart young and resilient. Walking and training regularly decreases the risk of heart disease by 35 to 37 percent. Quitting smoking, shedding body fat, and switching to a balanced diet can dramatically enhance this effect, lowering the risk for coronary disease by 83 percent.
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In many trials, researchers have assessed the relationship between physical fitness and life expectancy. The lower the fitness level, the shorter the life, on average. Being out of shape is, according to these studies, as dangerous as smoking cigarettes. However, poor fitness is not a death warrant. In one study, sedentary people were retested after five years. Those who had started to exercise were rewarded for their lifestyle changes, with a mortality rate declining by 44 percent.
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SPORTS AS MEDICATION FOR THE HEART
Heart disease occurs when the small vessels in the heart muscle, the coronaries, are not sufficiently supplied with blood, a condition typically caused by arteriosclerosis. If the blood supply is interrupted for more than 20 minutes, the cells in the affected area will start to die—an infarction, which can be fatal. In sum, nearly half of the deaths in the United States and other industrialized countries are caused by cardiovascular disease.
In the fight against this killer, physical exercise has been found to trigger physiological changes that mirror the pharmacological effects of standard drugs. Consequently, in Germany, men and women suffering from heart disease train together in more than 6,000 sports groups supervised by physicians and professional personnel.
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The participants benefit greatly, as revealed in a survey including 48 trials, with 8,940 patients: regular exercise reduced mortality attributable to heart disease by 26 percent.
In addition, physically active heart patients have significantly fewer heart attacks, fewer bypass operations, and fewer angioplasty procedures for widening atherosclerotic arteries. In effectiveness, physical exercise compares to established drugs like ACE-inhibitors (given after an infarction), but without adverse side effects.
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Although sudden physical exhaustion, especially when occurring after years of inactivity, might increase the risk of heart attacks and strokes, regular aerobic training is beneficial for thinning the blood. Moderate training not only improves cholesterol levels, blood pressure, and glucose tolerance, but also has a beneficial impact on the viscosity of the blood and reduces its tendency to form dangerous clots.
Exercise also helps individuals suffering from narrowed arteries and impaired circulation in the legs. Patients with this problem find that walking causes terrible aches in their legs, known as ischemic pain, forcing them to rest frequently. Yet using these legs helps to cure this disease because regular walking incrementally improves the endurance of the legs. In clinical studies, exercise helped increase the maximum distance a patient could walk without feeling ischemic pain by 179 percent, while the maximum distance a person could walk at all went up by 122 percent.
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In a survey comparing walking to angioplasty, the common treatment of dilating and sometimes placing a stent in the affected vessels, angioplasty seemed slightly more effective than walking. But angioplasty can cause severe side effects. Another trial examined whether open-heart surgery is superior to exercise. The result was that both treatments were equally effective, but surgical interventions gave rise to complications in 18 percent of the cases. In the case of blood-thinning pills, exercise came out well ahead. Taking such drugs increased the period of pain-free walking by 38 percent, but patients who simply exercised more improved by 86 percent.
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OPENING UP BLOOD VESSELS
In looking at biological rather than chronological age, one can say that we are as old as our arteries. The health of arteries is a complex matter in which the inner lining of the blood vessels, the endothelium, plays a key role. This thin layer of cells controls the muscle tone of the vessels. A malfunction of the endothelium is one of the first symptoms of the onset of arteriosclerosis, as plaques build up inside the vessels.
In one remarkable trial published in the
New England Journal of Medicine
, individuals with heart disease trained on stationary bikes, for ten minutes at a time, six times per day—and significantly improved their endothelium function and thus the blood supply to the heart. The study showed that physical activity can reverse the initial hardening of the arteries.
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Even when arteriosclerosis has progressed significantly, as is often the case with older people, exercise is a felicitous remedy. The American researcher Dean Ornish became famous after finding that regular exercise and a low-fat diet can widen narrowed vessels by approximately 5 percent.
Since then, researchers at the University of Göttingen, Germany, have confirmed that exercise does cause favorable changes in the condition of blood vessels. They experimented with mice genetically engineered to suffer from arteriosclerosis. Some mice were kept sedentary as controls, others were active. After running on treadmills five days per week for one hour, over a three-week span, the mice were deliberately injured at the left carotid artery, then put back on the treadmill program for three more weeks. Finally these mice were thoroughly examined. In comparison with the sedentary mice in the control group, the active runners had fewer atherosclerotic plaques and fewer constricted arteries. Furthermore, their wounds had healed better because connective tissue cells had grown to stabilize them.
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Although physical exercise cannot completely prevent the slow progression of arteriosclerosis with age, these results show that it can significantly reduce the problems the disease may cause.