Exercise in the primary prevention of coronary artery disease.

Since the 1950s there has been a steady accumulation of data from observational studies and clinical trials identifying a lack of physical activity, either in the industrial or leisure setting, as an independent major risk factor for coronary artery disease, with a similar relative risk as smoking, hypercholesterolemia and hypertension. More recently, poor cardiorespiratory fitness has also been shown to increase the risk of cardiovascular mortality significantly. Regular exercise is now known to have beneficial effects on peripheral and central circulation, skeletal muscle and myocardium, as well as lipid and carbohydrate metabolism. Individuals who become active in later life, for example, by way of a moderate intensity walking program, and who make only modest gains in fitness, nevertheless share in many of these health benefits and reduce their coronary artery disease risk. It is estimated that 60% of Canadians are physically inactive, a higher prevalence than for the other major risk factors. Consequently, efforts to encourage a more active lifestyle can have a significant impact on cardiovascular morbidity and mortality, with a marked reduction in costs to the health care system.