HUMAN GROWTH HORMONE: HOW SWIMMING LITERALLY MAKES YOU YOUNGER

According to the life-expectancy test, a regular program of swimming can add up to three years directly to your life expectancy. Not a bad start! But indirectly, its effects can be much greater.

Chapter 3 showed how swimming can lower your blood pressure and increase the amount of “good” cholesterol (HDL) in your blood, decreasing substantially your risk of dying of stroke or heart attack. Chapter 4 outlined how swimming can make you trimmer and keep you trimmer, eliminating the risk factors that accompany obesity. Later chapters will examine some of the psychological effects of swimming: how it will improve your self-image and outlook, factors that affect your longevity. In addition to all this, recent research demonstrates how swimming can retard and even reverse some of the “normal” processes of aging.

In 1990 the world was startled by reports of the youth-conferring effects of human growth hormone (hGH). Human growth hormone, as its name implies, is important in the growth process of young people. During childhood and adolescence, the hormone, which is produced by the pituitary gland, stimulates development of the muscles, bones, kidneys, liver, and immune system and prods fatty tissue to shrink. After adolescence, secretion of hGH begins to decline; by age fifty it has decreased significantly, and ultimately it stops altogether in some people.

For years scientists have speculated that at least some of the changes attributed to normal aging result from hGH deficiency. If so, giving hGH to older people might slow or reverse bodily changes associated with aging. Daniel Rudman, a professor of medicine at the Medical College of Wisconsin, decided to test this theory. What he discovered started a mass media avalanche.

In his 1990 report, Rudman described what happened when twelve men, aged sixty-one to eighty-one, gave themselves hGH injections three times a week for six months. Their lean body mass increased by almost 9 percent, their fatty tissue decreased by over 14 percent, and their skin thickened by 7 percent. These changes, Rudman declared, amounted to washing away the effects of ten to twenty years of living. A larger study published in 1991 reported similar results; it also found that the liver, spleen, and muscles from ten areas had increased in volume by 8, 23, and 11 percent respectively.

Unfortunately, what Rudman did not report is that injecting hGH can result in a wide range of adverse side effects, from swollen joints and enlarged breasts in men to an elevation in insulin or blood sugar (which can lead to diabetes). In addition, once normal individuals begin receiving hGH injections, their bodies stop producing the hormone naturally; it takes months after the injections stop for the pituitary gland to begin secreting hGH again. Finally—and most significant of all—it is not necessary to inject this seemingly magic potion at all: it is produced naturally by the body when you exercise! And without the adverse side effects.

It is thus no wonder people who swim regularly report feeling stronger, sexier, more vital, younger. Aside from all the other positive changes, the release of hGH triggered by their swimming actually turns back the clock.