Exercise as it relates to Disease/Effect of aerobic exercise training on atherosclerosis

Atherosclerosis
Atherosclerosis is a disease of arteries where white blood cell accumulations and lipid aggregations of the endothelium start forming a plaque in the arterial wall, following by thickening of the vessel wall. Later, within decades, to may start causing stenosis in the lumen This results in smaller amount of blood flowing in the arteries which leads to lower levels of oxygen running in the arteries. In the heart atherosclerosis predisposes to coronary heart disease and possible myocardial infarction later but it can also cause serious consequences in the brain, kidneys and prevent oxygen supply also in the periphery causing claudication (pain in the feet caused by ischemia in the tissue) and impairing the healing of wounds, especially with diabetics.

Inflammation factor
As a background for stenosis is a damage in the endothelium caused by hypertension, hyperglycemia (pre-diabetics and diabetics), inflammation and toxins from smoking, for example. The low-density lipoprotein (LDL) -particles get into the vessel wall and attract monocytes and other white blood cells to the sub-endothelial space which cause chronic inflammation in the intima layer of the vessel.

Lipid aggregates
The monocytes are activated into macrophages by different cascades and they start absorbing the oxygenated LDL-aggregates in. If there is not enough high-density lipoprotein (HDL) -particles reducing the amount of fat in the vessel wall, the macrophages become bigger foam cells and the plaque formation continues. Within the time, there is calcification and fibrous tissue formation among the smooth muscle cells in the arterial wall and a fibrous cap is formed around the plaque.

Prevalence
The inflammation process and the plaque formation may start at an early stage in life but the people can be asymptomatic for decades until the stenosis is big enough to cause symptoms. In developed countries atherosclerosis is a leading cause of death and is a big factor behind many other diseases. In 2005 the prevalence of cardiovascular diseases in the general practice patient population of Australia was 30%.

= Risk factors =
 * Obesity
 * Hypertension
 * Dyslipidemia
 * Hypertriglyseridemia
 * Hypercholesterolemia
 * Diabetes
 * Smoking
 * Alcohol
 * Genetic factors
 * Inactivity
 * Psychological stress

= Possible Consequences of atherosclerosis =

= Effect of aerobic exercise training on atherosclerosis = It has been difficult to prove the beneficial effect of exercise training on atherosclerosis but studies show that aerobic exercise prevents the development of coronary artery disease (CAD) and reduces symptoms in patients with established cardiovascular disease, pointing to the health benefits of exercise training. It also reduces the concentration of total cholesterol (TC), triglyserides (TG) and LDL-cholesterol, as well as increases the good HDL-cholesterol. Triglyserides are reduced for up to 72 hours after finishing the exercise and acutely, vigorous exercise decreases systolic blood pressure. Exercise is also beneficial for diabetics, as well as pre-diabetics by controlling the blood glucose. It was noticed that the intensity of exercise didn't make such a big difference but the health effects increased as the weekly amount of time spent exercising increased.

= Summary and recommendations = Exercise is an important factor when it comes to preventing atherosclerosis and the diseases following it. Since the development of atherosclerosis starts at an early stage in life, it is important to start preventing it by exercising, avoiding sedentary behavior and eating healthy, even if you don't have any illnesses diagnosed. According to the Australian Government Department of health physical activity guidelines, adults (18–64 years) should do aerobic exercise preferably everyday consisting of 150–300 minutes of moderate intensity exercise or 75–150 minutes of vigorous intensity exercise per week.

=Further Reading =
 * Sharon A. Plowman; Denise L. Smith (1 June 2007). Exercise Physiology for Health, Fitness, and Performance. Lippincott Williams & Wilkins. p. 453-484.
 * Australian Government Department of health physical activity guidelines: http://www.health.gov.au/internet/main/publishing.nsf/content/health-pubhlth-strateg-phys-act-guidelines#apaadult

= References =