Heart disease, or cardiovascular disease (CVD), comprises diseases of the heart and its blood vessels. Heart disease is not a single disorder, but a general name for more than 20 different diseases of the heart and its vessels. The American Heart Association has reminded us that although we have made tremendous progress in fighting CVD, it has been the leading cause of death among Americans in every year but one (1918) since 1900 (1). Every 33 seconds, an American dies of CVD, the underlying cause of just under 1 million deaths annually. Four of every 10 U.S. coffins contain victims of CVD (1). Cardiovascular disease accounts for almost a third of global deaths. More than one in three people in the UK die from CVD, mainly CHD and stroke. About one third of CVD deaths occur prematurely (before the age of 75 years). Deaths, however, do not tell the whole story, in that of the 280 million Americans alive today, nearly one in five live with some form of CVD. Also, one survey of 90,000 adults in the United States found that only 18% reported having no risk factors for heart disease. In other words, an alarming number of Americans either have CVD or are headed in that direction (1).
Cancer, according to most surveys, is the disease people fear the most. CVD deserves more respect, however, maintains the National Centre for Health Statistics. According to their most recent computations, if all forms of major CVD were eliminated, total life expectancy would rise by nearly 10 years. If all forms of cancer were abolished, the gain would be just 3 years (1). Atherosclerosis, the buildup of fatty, plaque material in the inner layer of blood vessels, is the underlying factor in 85% of CVD (3, 6). When atherosclerotic plaque blocks one or more of the heart's coronary blood vessels, the diagnosis is coronary heart disease (CHD), the major form of CVD.
Risk Factors for Heart Disease
Risk factors are defined as personal habits or characteristics that medical research has shown to be associated with an increased risk of heart disease. Up until 1992, the American Heart Association did not include physical inactivity in its list of "major risk factors that can be changed", which included cigarette smoking, high blood pressure, and high blood cholesterol. Inactivity was listed along with obesity, stress, and diabetes as "contributing factors" (1, 2). In 1998, obesity and diabetes were upgraded from "contributing" risk factors to "major" risk factors.
Cohort studies that started in the late 1960s discovered that, as an epidemic condition in Western countries, coronary heart disease (CHD) (the cardiovascular disease with the highest prevalence) is mostly due to environmental influences. These can be modified, so this finding opened the way for prevention. These studies developed the concept of risk factors. More than 30 years on, numerous other risk factors have been identified. Risk factors interact synergistically. For instance, the excess risk of CHD death attributable to high cholesterol and high blood pressure is much greater for cigarette smokers than for non-smokers.
Heart Disease and Exercise
The observation that physical activity can protect against heart attack was first made in cross-sectional studies comparing incidence rates in men in a variety of occupations. Jeremy Morris and colleagues studied the drivers and conductors of London's double-decker buses. The conductors (who walk up and down stairs 11 days a fortnight, 50 weeks a year, often for decades) experienced roughly half the number of heart attacks and 'sudden death' due to heart attack as the drivers. Similar differences in CHD attack and death rates were found between physically active postmen (who spent 70% of their shift time walking, cycling and climbing stairs) and their sedentary colleagues who sorted the mail (4). The self-selection bias in such studies is obvious, however: did leaner, generally healthier men seek the more physically active jobs? Morris and colleagues subsequently published data on the waist size of the uniform trousers issued to the men- a crude measure of what is now termed central obesity. Lean, average and portly conductors all experienced CHD rates about half those of the sedentary drivers. It appears therefore that the protective effect of physical activity was independent of body fatness (at least as crudely assessed).
In 1987, a landmark review article was published by researchers from the Centers for Disease Control and Prevention (CDC) (5). Forty-three studies were reviewed, and not one reported a greater risk for CHD among active participants. Two thirds of the studies supported the finding that physically active versus inactive people have less CHD, and the studies following the best research design were the ones most likely to support this relationship.
In general, the risk for CHD among physically inactive people is twice that of people who are relatively active (5, 7). This risk is similar to that reported for high blood pressure, high blood cholesterol, and cigarette smoking. According to the CDC, regular physical activity should be as vigorously promoted for CHD prevention as for blood pressure control, dietary improvements to lower serum cholesterol and control weight, and smoking cessation (5). The CDC feels that given the large proportion of people who do not exercise at appropriate levels, the incidence of CHD that can actually be attributed to lack of regular physical activity is significant.
If you have or are at risk of getting Heart Disease, learn about how Heart Disease is a chronic disease which is eligible to receive a Medicare Rebate when seeing an Accredited Exercise Physiologist:
Did you know you could get up to 50% off with a Medicare Rebate?
Learn how an Accredited Exercise Physiologist can help you to begin and maintain exercise in your life, so you can enjoy the health benefits of Exercise for Heart Disease:
What Does an Exercise Physiologist Do?