It must be admitted that while the risk factors are certainly altered, conclusive long term follow up studies confirming the positive effects of exercise training on susceptibility to coronary artery disease and heart attacks have been slow to materialize.
In the National Exercise and Heart Disease Project, a supervised exercise program displayed only a marginal effect on 3 year mortality and 3 year frequency of repeat heart attacks in patients who had already suffered one. But a recent large follow up study of 16,936 Harvard alumni from 1962 to 1978 did indicate that habitual post college exercise rather than amount of athletic participation as students coincided with a low death rate from heart disease. Sedentary alumni, even former varsity athletes, were at higher risk. But while the death rates declined as the amount of exercise increased from less than 500 to more than 3,500 kilocalories per week, beyond 3,500 the death rate increased slightly. The Pritikin group have presented evidence that their program of diet and exercise inhibits the progression of peripheral vascular disease, coronary arteriosclerosis, and adult onset diabetes. But their studies do not differentiate between the benefits of diet and those of exercise. A common fallacy about exercise and heart disease is that exercise is more effective than diet in preventing an attack. That’s not true. The idea that diet is rather irrelevant as long as you exercise strenuously is a myth. Jim Fixx, author of the 1977 best seller The Complete Book of Running, who transformed himself from a chubby 2l4 pound, two pack a day smoker into a sleek 160 pound marathon runner, died at the age of 52 from .a heart attack while pounding the road in Vermont. He paid dearly for his expressed belief that running all by itself would suffice to prevent heart disease. Do not fall so deeply into the myth of exercise that you neglect other preventive health measures. Diet is the most important, even for heart disease, although exercise provides additional benefit. But there is absolutely no evidence in either animals or humans that exercise influences the rate of cancer, the second major cause of death after cardiovascular disease, and we know that cancer is very heavily influenced by diet.
The Interplay Between Diet And Exercise
Let us consult a study made by scientists at the National Institute on Aging. They allowed one population of mice to eat as much as they wanted, but gave them no access to exercise wheels; a second population ate as much as they wanted but also exercised daily; a third population was calorie restricted and not allowed to exercise, and a fourth, calorie restricted population was allowed to exercise. What were the life spans of these populations? shows the results. Exercise increased the life spans of animals allowed to eat as much as they desired, but decreased the other wise very extended life spans of the calorie restricted animals. This means that the relationship between diet and exercise is complex. They are not simply additive. Exercise does not automatically increase life span, as everyone seems to think. A fine tuning between exercise and diet is necessary for the optimal effects. And people who do crash dieting, or nutritionally unsound dieting, and couple it with vigorous exercise to “burn off” even more calories are doubling the harm of their bad dieting technique. Detailed diet exercise experiments are being performed by scientists at Washington University in St. Louis, in the laboratory of Dr. John Holloszy, whom I consider one of the best exercise physiologists in the world. The studies compare fully fed sedentary rats, fully fed and exercising rats, and calorie restricted sedentary rats. At time of writing, 50 percent of the fully fed exercising rats were alive at months of age compared with only percent of the fully fed sedentary rats. But again the calorie restricted non exercising rats were surviving the longest. The fat cells of fully fed sedentary rats were resistant to insulin, those of diet restricted animals sensitive to insulin, and those of exercisers still more sensitive . Blood cholesterol levels followed the same patterns. So in this important study the exercising rats seem “fitter” than diet restricted sedentary rats, but their survival is less. This can any mean, as I’ve already indicated, that fitness biomarkers are not entirely equivalent to longevity biomarkers. But we must await further studies from Holloszy’s laboratory to clarify these important issues.
The overall evidence suggests that aerobic exercise considerably increases cardiovascular fitness and substantially decreases the susceptibility to heart attack and that it improves some features of carbohydrate metabolism. But at the same time possibly owing to an increased generation of free radicals or a temporary increase in metabolic rateit may slightly accelerate the basic rate of aging. Exercise definitely has a good effect and possibly a mild bad effect. The fitness effect increases rapidly up to a certain point as you exercise more and more, but beyond that point the benefit may level off. According to Dr. Kenneth Cooper of Dallas, running tops out its aerobic benefits at 15 miles a week. He says, “If you run more than that, it’s for some thing other than fitness.” Others agree with this assessment. My own view is that the optimal combination for health and longevity is the high low diet plus the equivalent in aerobic exercise of about 15 miles of jogging per week, coupled with a modest amount of weight resistance training .