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Heart Court - BY PETER BRUNO, M.D

Players often talk about giving their lives to the game. And some of them do.
Professional sports don't seem as safe as they used to be. An alarming number of athletes have died on the job lately, stunning sports fans and making weekend warriors nervous. What exactly happened to these people, and what are the implications for the amateur sportsman?
The relationship between the heart and athletics is a fascinating one. The function of the heart is to get adequate oxygen to the muscles so that work can be performed. One standard that doctors use to measure this process is cardiac output, or the amount of blood the heart can pump per minute. At rest, the cardiac output of the average adult is five to six liters per minute. During exercise, the rate can be raised to as high as 40 liters per minute. For a tennis player, that can be quite an advantage.

One way to get this effect is by hypertrophy, or enlargement of the heart muscle. Hypertrophy increases the force of the contraction of the heart muscle, which allows the heart to pump blood with increased efficiency. The other method of increasing cardiac output is by dilation, where the ventricles, or the chambers of the heart, become
enlarged and thus can accommodate more blood.

Interestingly, aerobic activities will tend to dilate the chambers of the heart, while anaerobic activities tend to enlarge the heart muscle itself. Marathon runners are the prime example of the former and weightlifters of the latter. Tennis players fall somewhere in between, benefiting from both types of conditioning.
A study done on men aged 30 to 65 showed that the incidence of sudden death during jogging was only one per year for every 7,620 joggers. If joggers with known heart disease were excluded, the incidence dropped to one in every 15,240 joggers. These figures underestimate the true incidence of cardiovascular events, however, because non-fatal events were not recorded.

According to this and other studies, the risk of sudden death is greater during exertion than it is at other times. But the risk of heart attack during exercise is much greater for men with a sedentary lifestyle than it is for men who are habitually active. Most important, an ongoing exercise regimen greatly reduces the risk of a man dying suddenly when he is at rest.

Women appear to be relatively safe from sudden death at all ages, possibly because of their higher levels of estrogen and lower leve.ls of vigorous activity. The most common cause of sudden death is pre-existing coronary artery disease, or CAD. In fact, most of the athletes who have died suddenly-Hank Gathers, Reggie Lewis, Pete Maravich and Flo Hyman-had some form of CAD. Both CAD and sudden death are rare among people age 35 and under, however. When sudden death does occur in this population, congenital heart disease is usually the culprit. And hypertrophic cardiomyopathy is the most common of such diseases. But wait a minute. Isn't hypertrophy, or enlargement of the heart, supposed to be a good thing in athletes? True, a heart that is symmetrically or equally enlarged appears to be a good response to exercise. But this needs to be carefully distinguished from a more uneven enlargement of the heart, as seen in congenital cardiomyopathies. In such diseased states, the electrical system of the heart muscle is more likely to cause potentially fatal arrhythmias, or extra heartbeats. In some cases, this kind of hypertrophy will actually squeeze blood out of the heart chambers and cause the heart to fail. A good physical examination and an E KG will suffice as a screening exam. Exercise stress testing is warranted only in older patients, people with abnormal EKGs and those with risk factors for heart disease. An echocardiogram, or soundwave test on the heart, which shows the size of the muscles and chambers, will help the serious athlete but is not really cost-effective for the average recreational player.

In short, exercise increases life expectancy. The risk of sudden death .from exercise is very low in men and even lower in women. Although the majority of us will never perform at the level of Reggie Lewis, we need not worry too much about exercising moderately after getting a basic medical screening.

 





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