SI Vault
David Noonan
March 11, 1996
In highly conditioned athletes, a big heart—the literal, not the metaphorical kind—is a sign of health and power. But in some cases, it can be a deadly burden, often too heavy to bear
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March 11, 1996

The Heart Of The Matter

In highly conditioned athletes, a big heart—the literal, not the metaphorical kind—is a sign of health and power. But in some cases, it can be a deadly burden, often too heavy to bear

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Blockage of the coronary arteries is the main cause of sudden death in athletes over 35, but it rarely kills younger athletes. It is, nonetheless, what doomed Grinkov, 28, who collapsed on the ice in Lake Placid, N.Y., while skating with his wife and partner, Ekaterina Gordeeva. Grinkov's father had died of the same thing at age 56, which means the skater had a family history of premature coronary artery disease (CAD)—one of the major risk factors for developing the condition. Such a critical detail, routinely picked up in a standard medical history, often leads to further testing that might diagnose CAD. Other causes of sudden death in young athletes include Marian's syndrome, a detectable disorder of the connective tissue that killed U.S. Olympic volleyball star Flo Hyman in 1986, at age 31, and myocarditis, or inflammation of the heart muscle, which is often due to viral infection and is usually discovered only after a cardiac incident.

Loyola Marymount basketball captain Hank Gathers, 23, died in 1990 from what is believed to have been myocarditis, and Boston Celtics star Reggie Lewis, 27, died in 1993 from a combination of heart ailments. While both players knew they had heart problems, both collapsed and died playing basketball.

Whatever the cause, the sudden death of a young athlete in the gym or on the field is uncommon. In the U.S. the accepted minimum figure is around 15 fatalities per year (though experts believe considerably more go unreported) among roughly eight million trained and competitive athletes at all levels. But such deaths are "a public health problem out of proportion to the numbers," says Maron. He attributes this to the central role of sports in U.S. culture. Maron has been investigating sudden death in athletes for close to 20 years, and again and again he has seen how such deaths "strike to the core of our sensibilities," he says. "The public makes them important, the press makes them important, everybody makes them important, because sports in this country are important. So you don't have to have 10,000 kids collapsing every year for this to be an important issue."

Unfortunately it's an issue that isn't going away. Improved screening programs might avert some deaths, but there will always be a certain number of young athletes who harbor deaden ly heart conditions, and some of them are going to die—suddenly and without warning. That is the cruel truth of the matter.

The condition known as athlete's heart has captured the interest and imagination of medical researchers, just as athletes' performances have captured the interest and imagination of sports fans. It was first described in the medical literature at the end of the 19th century by a European physician who had examined a group of cross-country skiers. Since then athlete's heart has been the subject of dozens of studies. "It's an adaptation process," says Maron. "The heart is adapting to a different lifestyle."

"Everything gets bigger: the size of the chambers, the thickness of the walls," says Dr. Michael H. Crawford, chief of cardiology at the University of New Mexico Health Sciences Center. "It's the same as when you work out your biceps. The heart muscle has a different function, and it's structurally somewhat different, but it's still basically muscle, and it will get bigger when it's confronted with having to work more."

The heart's work is to pump blood throughout the body, delivering oxygen (and other things) to the muscles (and other things, including the brain). The delivery of oxygen to the muscles and the consumption of oxygen by the muscles are the key physiological processes underlying all athletic performance; sports are as much about cardiovascular function as they are about speed, strength, agility and skill. The harder the muscles work, the more oxygen they need, so the heart of a serious athlete grows to meet the demands placed on it by rigorous activity.

The human heart is complicated meat, for sure. The transformation of an average heart into an athlete's heart is a complex process involving changes at the structural, biochemical, metabolic and neural levels, and it can be as hard to understand as a Casey Stengel monologue. On the other hand, there are only two ways for the heart to increase the supply of blood to exercising muscles: Either it can beat faster or it can pump more blood with each beat. "From a biological point of view," says Crawford, who has been studying athletes' hearts since the late 1970s, "it's more efficient to pump a big volume than to pump faster. Your heart uses a lot more energy beating faster." Which is why it's the size of the heart, rather than the maximum heart rate, that increases with conditioning. An Olympic marathon runner has the same maximum heart rate during exercise as an out-of-shape couch jockey of comparable age. The runner's cardiac superiority is due to the fact that he pumps substantially more blood per beat than the tater does. (To figure your maximum heart rate, subtract your age from 220.)

While it's the entire heart that becomes enlarged in athletes, researchers focus most of their attention on the left ventricle, the chamber that pumps oxygen-rich blood out of the heart to the rest of the body. (Instant anatomy lesson, one time around the horn: Oxygen-depleted blood returns from the body and enters the right side of the heart. It is then pumped out of the right ventricle to the lungs, where it picks up oxygen before returning to the left side of the heart. It is then pumped out of the left ventricle to the body. Tinker to Evers to Chance. End of lesson.) The size of the left ventricle when it is fully expanded, the thickness of its walls and the amount of blood it pumps with each beat (which is called the stroke volume) are all key stats in the assessment of athlete's heart.

Until the early 1970s athlete's heart was identified somewhat crudely by a combination of physical examination, chest X-ray and electrocardiogram (EKG). With the introduction of echocardiography (box, page 75) in 1972, a new era began. Echocardiography, based on ultrasound technology (the tool used to look at babies in the womb), is an easy, noninvasive way to gather these stats. Using echo, as it is commonly called, researchers can watch the heart in action, then freeze the picture and take the precise measurements needed to establish athlete's heart.

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