In this video, I will discuss the significant role of exercise in reducing the risk of heart disease. Cardiovascular disease is a general name for more than 20 different diseases of the heart and its vessels. This video will focus on coronary heart disease which remains the most common cause of death around the world in both men and women. I will conclude by examining the role of exercise in the treatment and prevention of hypertension and stroke. In the United States, heart disease remains the number one killer, accounting for approximately 25% of the deaths. That's over 600,000 people every year. Coronary heart disease is the most common type of heart disease killing over 370,000 people annually. The major culprit in coronary heart disease is atherosclerosis which is defined as a disease of the arteries characterized by the deposition of plaques of fatty material on the inner walls. The inside of the arteries becomes narrow which lessens or blocks blood flow. While it frequently occurs in the coronary arteries leading to heart attacks, it can affect other arteries in the body such as the carotid and cerebral arteries causing a stroke. Shown here is the progression of atherosclerosis in a coronary artery. It begins with fat and cholesterol deposits in the lining of the artery. Over time, this will result in the development of plaques which will obstruct blood flow, eventually resulting in blockage of flow through the artery. As the coronary arteries deliver oxygen and fuel to the heart muscle itself, a complete or near complete blockage can result in the death of that portion of the heart muscle receiving its blood supply from that vessel. Such blockages can produce chest pains or angina and can eventually result in a heart attack and death. Shown here on the left is an example of a human heart that has coronary artery blockages. The image on the right indicates the localized death of the heart muscle or myocardial infarction shown in brown of the area of the heart muscle affected. When this atherosclerotic process occurs in the carotid or cerebral arteries supplying blood flow to the brain. It can result in a complete or partial stroke. Here's an example of a clean and healthy artery. This is how we want our arteries to look. Shown here is an artery in the early stages of fat and cholesterol deposits. Notice the yellowish color coming from the fatty deposits. The eventual progression of those artery clogging plaques as shown here. This is a very unhealthy artery and if left untreated, will eventually result in a heart attack. The major risk factors for coronary heart disease include obesity, physical inactivity, smoking, elevated blood lipids or fats, hypertension, and type 2 diabetes. These are all considered modifiable risk factors which means the individual can make lifestyle changes to reduce the severity of these risks. The most abused of all the risk factors for coronary heart disease is that for physical inactivity. This is unfortunate because as we'll see increasing one's level of physical activity not only reduces the risk factor itself but also reduces many of the other major risk factors associated with heart disease including obesity, elevated blood cholesterol, hypertension, and type 2 diabetes. The risk lowering effects of exercise for heart disease and subsequent health benefits and outcomes have been repeatedly demonstrated in multiple studies. In the Nurses' Health Study, which was among the largest and longest running investigations into the risk factors for major chronic diseases in women. It was clearly found, the more physically active a woman was, the lower was her risk for coronary heart disease. A second major landmark study, the Women's Health Initiative, begun by the National Institutes of Health found the similar relationship between the degree of physical activity and the relative risk for cardiovascular disease in general. Thus, regular physical activity reduced the morbidity and mortality rates for heart disease. In examining the role of exercise in reducing their major risk factors for heart disease, I have already discussed its role in the treatment and prevention of obesity in the previous video. In the next video, I will cover exercise and diabetes. That leaves hypertension and abnormal blood lipids as the remaining major risk factors. If your total serum cholesterol levels are abnormally high, regular aerobic exercise has been shown to be beneficial in lowering those levels. More specifically, aerobic exercise can reduce the low density or LDL levels. LDL is considered the bad cholesterol because it is the cholesterol that deposits in the coronary arteries leading to plaque formation and blockade. Regular aerobic exercise can also raise the High-density Lipoprotein levels or HDL. HDL is considered the good cholesterol because it helps remove LDL cholesterol from the blood. Even if your total serum cholesterol levels are normal, there is still a beneficial protective effect from regular aerobic exercise. While your total cholesterol levels may not drop with exercise, most studies suggest that exercise will lower LDL and increase your HDL levels. Thus, when presented as the HDL to LDL ratio, significant protective benefits from atherosclerosis are demonstrated for regular runners when compared to sedentary controls of the same age and sex. Animal studies would support this claim, when monkeys were put on a high fat atherosclerotic diet for 24 months, these sedentary control group showed signs of plaque build up and narrowing of the coronary arteries, while the monkeys that exercise daily had clear arteries despite being on the high fat diet. Exercise studies performed on humans are consistent with these findings. In patients with coronary heart disease tested before and after one year of regular exercise, any further progression of the plaque build up and subsequent lesions in their arteries was inhibited. This was not the case with patients in the control group. In fact, some heart patients in the exercise group actually demonstrated plaque and lesion regression in their coronary arteries. The final risk factor to consider is hypertension. Here's the classification of blood pressure for adults. When resting systolic blood pressure is 140 millimeters of mercury or greater and/or the diastolic pressure exceeds 90 millimeters of mercury or greater, an individual is considered to have hypertension. Left uncontrolled, the health consequences associated with chronic hypertension are many including heart failure, heart attack, stroke, and kidney disease. Regular aerobic exercise has been shown to be an effective intervention to reduce both systolic and diastolic blood pressure in hypertensive subjects. In most cases, exercise is just as effective in reducing blood pressure when compared with anti-hypertensive drugs but without the side effects associated with these medications. In the studies shown here, nine months of aerobic training significantly reduce both the systolic and mean arterial blood pressure in previously hypertensive individuals. Notice that this training effect was quickly reversed after just one month of detraining. Thus in review, participation in a program of regular exercise can reduce the severity of five of the six major modifiable risk factors for heart disease. In summary, physical inactivity is a major risk factor for heart disease. Physically fit individuals have a lower relative risk for coronary heart disease when compared to their sedentary counterparts. Participation in a regular exercise program lowers many of the other risk factors associated with heart disease.
