CORONARY RISK FACTORS
The number one cause of death in modern Western society is coronary heart disease. CHD is responsible for 1 in 3 deaths in Australia. However, there has been a very pleasing reduction in deaths from CHD and stroke in the past 20 years because people have made the effort to reduce their risk factors. In the United States heart disease is one of the major causes of death. Lifestyle and activity level play an important role in the prevention of heart disease.
The major coronary risk factors that increase your chance of getting heart disease include:
A: Modifiable risk factors.
1. Hypertension: Approximately 50 million adults in the United States have systolic blood pressure >140 mm Hg and/or diastolic blood pressure >90 mm Hg. Hypertension is a primary risk factor for cardiovascular disease such as stroke, heart failure, angina, renal failure, and myocardial infarction at all ages and in both genders. The ACSM recommends endurance exercise for mild hypertension. The recommended mode large muscle exercises, frequency 3-5 days/week, duration 20-60 minutes, and intensity 50-85% of maximal oxygen uptake are generally the same as those for healthy adults. For individuals with markedly elevated blood pressure, exercise training at somewhat lower intensities 40-70% is recommended after initiated pharmacological therapy.
2. Smoking: According to the Centers for Disease Control, tobacco use is the number one preventable cause of premature mortality, and is responsible for more than 470,000 deaths annually. More people die from tobacco-related deaths each year than from AIDS, alcoholism, cocaine, heroin, traffic accidents, fire, homicides, and suicides combined. Smoking is responsible for cancer of the lungs, trachea, larynx, lip, oral cavity, pharynx, esophagus, bladder, kidney, cervix, pancreas, stomach, and leukemia. Smoking is also a major cause of atherosclerosis and is one of the four major risk factors for cardiovascular disease including coronary heart disease, cerebrovascular disease, abdominal aortic aneurysm, and peripheral vascular disease.
3. High cholesterol: Cardiovascular disease is the leading cause of death in the United States. Atherosclerosis, the primary etiology of CVD, is an accumulation of cholesterol, smooth muscle, and other material in the arterial wall. Blood cholesterol levels above 240 mg/dl is considered high risk, a level of 240 to 200 mg/dl is considered moderate risk and below 200 mg/dl is considered low risk. Total level of cholesterol is comprised of two major components. High density lipoproteins HDL and Low density lipoproteins LDL. HDL is considered a good component and LDL is considered bad. Forty-five minutes of daily aerobic exercise substantially lowers triglycerides. The minimal weekly threshold for caloric expenditure to increase HDL is 1000-1200 Kcals. Several studies report a dose-response relationship between fitness and/or weekly caloric expenditure and increase in HDL. Simultaneous weight and fat loss results in a greater HDL increase. The lower the initial level of HDL, the greater the increase, it often takes several months of regular weekly caloric expenditure >1000 before becoming apparent.
4. Diabetes: Type I diabetes is insulin dependent (IDDM) or juvenile-onset and is the result of insufficient insulin production from the pancreas. Type II diabetes in non-insulin dependent (NIDDM) or adult onset and is caused by the unresponsiveness of the body tissues to insulin. This condition exists with blood glucose levels at or above 140mg/dl during a fasting period. Type II diabetes afflicts about 12 million Americans and is often preventable. Exercise improves glycemic control in Type I diabetes is not well - documented, perhaps because increased caloric consumption or decreased insulin treatment are used to prevent exercise-associated hypoglycemia. Regular physical activity for individuals with Type II diabetes is a current recommendation of the American Diabetes Association. Regular exercise improves insulin sensitivity and maybe responsible for increased insulin receptor affinity.
5. Obesity: Obesity is a surplus of adipose tissue-containing fat stored in triglyceride form, resulting from excess energy intake relative to energy expenditure. Obesity is a serious, prevalent, and growing public health problem. Excess weight is associated with increased risk of mortality and morbidity, including coronary heart disease, Type II diabetes, hypertension, and other illnesses. Exercise reduces morbidity and mortality via a number of possible mechanisms. Exercise has positive effects on blood pressure, serum cholesterol, body composition, and cardio respiratory function, and obese persons are at increased risk for abnormalities in these areas. Consistency, adherence, and enjoyment are the goals rather than intensity or mode of exercise.
6. Lack of exercise: Physical inactivity is recognized as a risk factor for CAD. Regarding the beneficial effect on other CAD risk factors, regular physical activity has been shown to lower resting systolic and diastolic blood pressure, reduce serum triglyceride levels, increase serum HDL, cholesterol levels, and enhance glucose tolerance and insulin sensitivity.
B: Non-modifiable risk factors.
1. Heredity: A parent or sibling who has had a heart attack before the age of 55 if a man, or 65 if a women.
2. Increasing age: 80% of fatal attacks, and 55% of all heart attacks, occur after the age of 65
3. Gender: Before age 55, men have a much higher incidence of CAD than women. At about age 60, women begin to develop a similar level of risk.
4. Race: Because they have a higher risk for hypertension and diabetes, African-Americans have an increased risk for CAD.
References:
ACSM’s Resource Manual for guidelines for exercise testing and prescription.
Douglas S. Brooks, MS Program design for personal trainers