Physiological interactions between diet and exercise in the etiology and prevention of ischaemic heart disease.

Modern eating habits and sedentary life-style interact to promote atherosclerosis and increase risk of ischemic heart disease (IHD). Apparent sites of interaction affecting severity of coronary atherosclerosis are body weight, blood lipid-lipoproteins, blood pressure, glucose-insulin dynamics, and platelet aggregation. In addition the conditioning effects of physical activity on the heart and adrenergic system reduce myocardial oxygen and coronary blood flow requirements, and raise the threshold for ischemia and ventricular dysrhythmias in the presence of existing coronary atherosclerosis. Dietary recommendations to reduce risk factors for IHD are to decrease intake of total and saturated fat, cholesterol, and sodium, increase intake of complex carbohydrates of plant origin and polyunsaturated fatty acids from vegetable oils and fish, adjust energy intake to maintain or achieve desirable body weight, and keep alcoholic consumption low. Epidemiologic evidence also suggests that risk of IHD can be further reduced with 30 to 60 minutes/day of even light or moderate intensity physical activity, including working around the home and yard, walking, exercise or sports. An optimal daily energy expenditure for IHD prevention appears to be between 150 and 300 kcal/day.