Damn good. In addition to improving your fitness and giving you more energy to carry out your everyday activities, regular exercise can limit your chances of suffering from a number of deadly - and not-so-deadly - diseases.
Of course, the biggest health problem partially controlled by exercise is heart disease, the number- one killer in the United States and Britain. In the US alone, heart trouble accounts for half a million deaths a year, a staggering number which could be lowered drastically if more people exercised. In fact, health experts are now saying that over 30,000 of these yearly deaths are unnecessary - in other words, they wouldn't occur if more people engaged in regular physical activity.
This link between exercise and improved cardiovascular health is not exactly a new revelation. In fact, it's been over 40 years since a British doctor called Jeremy Morris completed a ground-breaking study which showed that London bus conductors were far less likely to suffer from heart attacks than their bus driving peers. The simple act of moving up and down the double-decker steps each day made the conductors' hearts less prone to disease.
The Paffenbarger analysis
Since then, numerous studies have verified that exercise can provide protection against cardiac problems. Best of all, these studies show that moderate exercise is enough to provide benefits (you don' t have to be a serious athlete to have a really healthy heart). Perhaps the best-known of these investigations is Ralph Paffenbarger's analysis of 17,000 Harvard University alumni which was published in 1986. In his survey of men who had enrolled at Harvard between 1916 to 1950, Paffenbarger found that individuals who regularly jogged, walked, climbed stairs, or engaged in sports had about a 25 per cent lower risk of heart disease compared to sedentary men.
Paffenbarger's research provided a good foundation for the idea that you don't have to be a highly motivated athlete to get healthy. After all, Harvard alumni who burned a mere 500-999 calories per week during exercise (the number of calories required to walk five to 10 miles) benefited from a sizeable decline in cardiovascular mortality.
Heavy-duty exercises weren't left out of the-picture, however; for Harvard graduates, cardiovascular death rates dropped steadily as-exercise levels increased. For example, alumni who burned more than 2000 calories a week (which is roughly equivalent to jogging more than 20 miles per week) tended to live a full year longer than people who expended 500- 1999 calories weekly and TWO-AND-ONE-HALF years longer than fully sedentary men. 68 per cent of Harvard graduates who burned at least 2000 calories a week during exercise lived past the age of 80, as against just 58 per cent of the less active men.
Lowering cholesterol
New studies concerning exercise and cardiovascular health demonstrate that it's never too late to derive cardioprotective benefits from exercise. For example, a recent study carried out at the University of Florida followed a group of men over a 20-year period, as they aged from 50 to 70. Normally, this is a time period during which the risk of cardiovascular disease climbs, but these men participated regularly in jogging and racewalking and actually lowered their chances of heart problems.
For instance, the exercisers' blood cholesterol levels declined significantly during the 20-year study. Eleven of the subjects had cholesterol readings over 200 at the beginning of the research while only four had such high levels at the end. Body fat levels usually rise after the age of 50, yet the Florida men remained lean throughout the 20 years, averaging only 17 per cent body fat at the end. In fact, their body weight stayed exactly the same - 154 pounds - throughout the period.
In addition, there was decreased frequency of high blood pressure, and none of the subjects developed diabetes mellitus. The lesson is that individuals who stay active in their 50s and 60s can control their risk of heart disease and prevent an array of other health problems.
Exercise reduces risk of some cancers
In addition to lowering the probability of some heart maladies, there's also good evidence that exercise can help prevent some forms of cancer. Paffenbarger's original investigation with the Harvard alumni was one of the first studies to link exercise with fewer malignancies. He showed that individuals who burned more than 2000 calories a week had a lower cancer death rate than those who expended fewer than 500 weekly calories.
Paffenbarger's results were a pleasant relief to advocates of exercise because some of the earlier research on exercise and cancer hadn't been too encouraging. For example, a study published in the 1950s which looked at death rates of Cambridge University athletes versus non-exercising 'intellectuals' over their lifetimes actually detected higher cancer death rates among the athletes. Other investigations produced similar results, but researchers gradually began to realise that athletes were actually living longer than sedentary people, and it was their increased age, not their active lifestyles, which made them more vulnerable (cancer rates increase with age).
Good news for women
In recent years the news about cancer and exercise has generally been positive. As an example, a new University of Southern California study indicates that women who exercise several times a week have a significantly lower risk of breast cancer than those who don't exercise.
Specifically, the.study, conducted with over 1000 women as subjects, showed that females who exercise from just one to three hours per week reduce their breast cancer risk by 30 per cent, while women who work out four or more hours a week lower their breast cancer chances by 50 per cent! That's great news, since breast cancer is a huge health problem; about I in 10 women may develop it in her lifetime, and the disease claims about 50,000 lives a year in the United States alone.
The Southern California study suggested that a large number of activities probably have equally protective effects against breast tumours. Running, cycling, swimming, soccer, aerobics, vigorous walking, and a variety of other sports are likely to be breast- cancer antagonists.
Lung and colon cancer, too
It's likely that exercise may limit the risk of other kinds of cancer as well. Moderate exercise tends to activate your immune system and can temporarily boost the activity of a unique immune-system cell called the NK ('natural killer') cell. Since one of the NK cells' chief duties within /our body is to destroy cancer cells before they can develop into full-blown tumours, regular exercise may offer some generalised protection against cancer.
In fact, it's a good bet that it can lower the risk of lung cancer. In recent research completed at Harvard (again by the ubiquitous Paffenbarger) 17,775 men were studied over a 28-year period between l 962 and 1990. The activity levels of the men were assessed using mailed questionnaires, and the subjects were classified as either inactive (expending fewer than 1000 calories a week during exercise), moderately active (burning between 1000-2500 calories per week, which is the equivalent of running 10-25 miles per week), or highly active (expending more than 2500 calories weekly during exercise). Factors which tend to increase the risk of lung cancer - smoking, age and body mass - were controlled statistically.
A total of 354 lung cancers actually occurred during the research, but analysis of the data revealed that physical activity was linked with an appreciably lower risk of lung malignancy, especially in the men who were highly active throughout the 28-year study. This latter group had only HALF the risk of lung cancer compared to inactive males. Since lung cancer accounts for about 20-25 per cent of all cancer deaths, and kills 100,000 men in the United States each year, these protective effects of exercise are much needed.
In addition, a number of studies (including Paffenbarger's classic research) have shown that exercise can reduce the risk of colon cancer. It's possible that exercise does this by helping to move materials through the intestines more quickly. Such quicker movements might flush bile acids and other potential carcinogens out of the digestive system before they can transform normal colon cells into malignancies.
Bringing down blood pressure
Preliminary research has also suggested that women who burn more than 1000 calories a week during exercise have lower rates of reproductive-system cancer, Iymphoma, leukemia, myeloma, Hodgkin's disease, thyroid cancer, and cancers of the bladder, eye, and mouth compared to sedentary women. That' s a huge chunk of disease prevention - and all for just 10 miles of walking or jogging per week!
Can exercise also help to control blood pressure in people with mild to moderate hypertension (high blood pressure)? This is an important question, since high blood pressure is common in Britain and the United States. In fact, an estimated one in four adults in the US suffers from hypertension, and half of them (about 30 million people) aren't aware that they actually have the condition. Untreated hypertension can dramatically increase the risk of stroke and congestive heart failure.
The available evidence suggests that, in fact, exer. cise can reduce the risk of developing high blood pressure - and in some cases can bring down pressure in people with mild to moderate hypertension.
In a recent study which followed blood pressure over time in a group of 30 hypertensive women, pressure dropped significantly when the women maintained a regular exercise programme, only to rise again when exercise ceased. Investigators at the famous Cooper Clinic in Dallas, Texas, have also been able to show that individuals with low levels of fitness have a 50 per cent greater risk of developing high blood pressure than those who exercise regularly. Again, such studies suggest that you don't have to be a serious athlete to have good blood pressure; regular, moderate exercise will do just.fine.
Why does the exercising person tend to have lower blood pressure? First, well-trained muscles usually have many more capillaries (small blood vessels) than untrained muscles. These capillaries 'drain off ' blood from the arteries, lowering overall pressure. The veins of fit people also tend to have greater capacities, again preventing pressure from building up in arteries.
Exercise can prevent high blood pressure indirectly by reducing the risk of obesity and insulin resistance, both of which increase one's chances of hypertension. Exercise has also been strongly linked with reductions in stress, which may help to keep blood pressure at moderate levels.
Exercise makes people happier
Speaking of stress, there's also lots of scientific evidence that exercise can reduce tension and make people happier. The first studies in this area were conducted in the 1970s and generally showed that physically fit people were more likely to report that they felt 'very happy'_' while the less-fit more often indicated that they were 'not so happy'.
Since then a number of studies have shown that exercise can reduce anxiety, and 'exercise therapy' has been used successfully to treat people with chronic nervousness. Some studies have actually shown that a 15-minute bout of exercise is better than a tranquilliser at relieving muscle tension. Surveys also reveal that compared to non-runners, runners tend to have less anxiety about death.
More than half-a-dozen separate pieces of research have shown that exercise can be helpful in the treatment of depression; these studies suggest that symptoms of depression decrease as exercise levels increase. Some psychologists have gone so far as to suggest that inactivity is itself an independent risk factor for depression.
It might even improve your personality!
Can exercise actually change your personality for the better? A classic piece of research completed in the 1960s revealed that individuals who exercised regularly exhibited more humour,-optimism, ambition, patience and energy than did non-exercisers. The study also found that regular exercisers were more easy-going and good-tempered. Follow-up studies asserted that regular exercisers were more imaginative and had more self-assurance and emotional stability than sedentary individuals.
Such surveys have often been criticised on the ground that happy, confident people might simply be more likely to decide to exercise than unhappy ones - in other words, that exercise might be an outcome, not a cause, of happiness. However, subsequent research has been able to show that exercise programmes can indeed produce gains in self-confidence, emotional stability and self-sufficiency, and that exercise can also increase overall vigour and reduce fatigue and tension. Studies have also shown that incarcerated delinquent adolescents can elevate mood and increase their self-esteem by completing a regular exercise programme, and people who exercise regularly also seem able to develop improved body images.
Why it happens
How does exercise produce all these important psychological effects? Well, it can actually change the concentrations of 'neurotransmitters' - chemicals that nerve cells use to communicate with each other - in the brain. Most intriguing is the fact that exercise can dramatically increase the levels of a group of chemicals called the 'endorphins'. Endorphins are a compound with a structure similar to opium: they reduce sensations of pain and tend to induce a sense of tranquillity. Happily enough, you don't have to exercise for very long to get an endorphin 'rush' in your own gray matter; studies suggest that just 30 minutes of vigorous activity is often enough to bathe your brain cells in the opiate-like chemicals.
Since exercisers seem to have more opiates bubbling around in their brains than sedentary people, it' s not surprising that research has shown that those who exercise regularly are less 'stressed out' by unpleasant events like exposure to loud noises-or cold temperatures. This resistance to stress seems to be particularly pronounced during approximately a six hour period which follows every workout. Exercisers also seem better able to cope with life's major negative events such as divorce, the death of a loved one, or a large financial loss. It's not that exercisers are not bothered by such events; instead, they seem less debilitated and more able to construct their lives following an emotionally damaging experience.
It might even make you cleverer
In addition, there's even evidence that exercise can make you smarter. Individuals who exercise throughout life seem to have better memory retention when they get older, and studies have also shown that people who undergo exercise programmes often simultaneously improve their mathematical and reasoning abilities.
Getting back to the physical benefits of exercise, we know that regular exertions can strengthen your skeletal system, downplaying your chances of developing osteoporosis, a bone-thinning disease that affects about one out of every two women and one out of five men during their lifetimes. The best form of exercise for osteoporosis prevention is probably strength training, although other forms of weight-bearing exercise are also very good (see page 7 for how to build spine density) .
And there's even evidence to suggest that regular exercise can lower your risk of coming down with that bane of mankind, the common cold. Various studies indicate that individuals who exercise from about one to three hours a week have a reduced risk of upper respiratory infection, compared to individuals who exert themselves for less than that. At this time of year, when everyone on the train or bus seems to be hacking or sneezing, what could be better than that?
The bottom line? Even if you're not exercising to achieve super-fitness, regular exercise can help you attain super-health. What's the absolute-best level of exercise to most effectively promote health? Exercise experts aren't exactly sure, but it's clear that too little exercise doesn't give your immune system a boost or clear out your coronary arteries; likewise, too much exercise can deplete your immune system and leave you overtired and overstressed. Probably the best level of exercise for health is somewhere between one and three or four hours a week. It's pleasant to know that just 20-30 minutes of daily activity can have a big impact on how you feel - and lower your risk of developing some pretty deadly diseases.
Owen Anderson