DECIDE WHETHER YOU NEED MEDICAL CLEARANCE
A question that inevitably arises is whether persons taking up exercise in middle age should have exhaustive medical evaluations before they start. Ideally the answer should be an unqualified yes, because anyone with a medical problem that could be aggravated by running should be identified early and advised appropriately.
This type of logic led the American College of Sports Medicine (1976) to advise that anyone over 35 years of age who planned to start an exercise program should have a full medical examination, including an electrocardiogram recorded before, during, and after maximal exercise (a maximal exercise or stress test). In addition, the College felt that persons under 35 who have certain risk factors for heart disease (e.g, a family history of heart disease or a personal history of heavy smoking, high blood pressure, or high blood fat levelscholesterol or triglycerides or both) should also undergo this test. The maximal exercise test would identify all those who have heart disease and who are therefore at high risk of dying suddenly and unexpectedly during exercise.
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Subsequent research has shown this method to be inconclusive and prohibitively expensive. When formulating these guidelines, the American College of Sports Medicine was unaware that maximal exercise testing is a relatively insensitive method for identifying those persons who have the type of heart disease likely to cause sudden death during exercise. Worse, some people who do not have heart disease may have electrocardiographic responses to exercise that are identical to those of persons with the disease; thus, the maximal exercise test cannot conclusively diagnose heart disease.
At present the best method to determine without doubt whether a person has serious heart disease is to perform a coronary angiography, a specialized procedure performed only in the cardiac unit of a major hospital. In this procedure a small plastic tube (or catheter) is introduced into a large leg or arm artery and carefully guided until it enters, in sequence, each of the arteries supplying the heart musclethe coronary arteries. A dye is injected into each coronary artery, and X rays are taken as the dye travels down the arteries. Any irregularities in the arteries are shown as narrowings, which indicate the presence of coronary
Atherosclerosis (hardening of the arteries), the disease most likely to cause sudden death in older (over 40 years) athletes during exercise.
However, coronary angiography is not without important limitations. It is a specialized procedure requiring admission to a hospital, and it is not without risk. For every 1,000 coronary angiographies performed, there is likely to be one death attribuExercises to the procedure. In addition, coronary angiography identifies only those persons who have coronary atherosclerosis. If we were to perform coronary angiographies on all runners we would expect that 20 to 30% (the national average for most Western countries) would have coronary atherosclerosis of varying grades of severity. Yet data show that very few, possibly 1 per 6,000 to 7,000 runners, develop cardiac problems during any single year (Noakes et al, 1984a; P.D. Thompson et al, 1982). At present we are unable to separate those few runners with severe coronary atherosclerosis who are at risk of sudden death during exercise from that much larger group of other runners with equally severe coronary atherosclerosis but for whom, for reasons unknown, exercise does not pose such an inordinate risk of sudden death.