Exercise as it relates to Disease/Exercise and Thrombosis

Thrombosis is the formation of a clot in the blood that either blocks, or partially blocks a blood vessel. The thrombus may lead to infarction, or death of tissue, due to a reduced blood supply. When a blood vessel is damaged, the body prevents blood loss by using platelets and fibrin to form a clot. A clot that detaches itself from the site and travels throughout the circulatory system is known as an embolus. Thrombosis can occur in arteries (arterial thrombosis) and veins (venous thrombosis).

Prevalence
Thrombosis effects about 1 in 1000 individuals worldwide. This rate rises rapidly in individuals over 45 years of age and appears to slightly effect men more than women.

Causes
Thrombosis is thought to be induced by one or a combination of the below factors, known as Virchow’s Triad:


 * Disturbed blood flow
 * Endothelial cell damage
 * Hypercoagulability

Complications
Complications of thrombosis are often ischemic-related that lead to a significant reduction or complete restriction of blood flow resulting in damage or potential death to a particular tissue. The most common complications are pulmonary embolism, myocardial infarction, stroke and cor pulmonale.

Exercise
It is well documented that individuals engaging in regular physical activity are less likely to experience a cardiovascular event. Changes in lipid profile, insulin sensitivity and other physiological mechanisms in conjunction with lifestyle habits are thought to reduce this likelihood. There are a number of mechanisms of how exercise alone can reduced the likelihood of suffering a cardiovascular event.

Mechanisms
The hemostatic and fibrinolytic systems appear to play an important role in cardiovascular health. Fibrin is an insoluble, fibrous protein involved in the formation of a blood clot. Elevated levels of fibrin pose an increased risk of thrombosis. Fibrinolysis or the fibrinolytic system is the enzymatic breakdown of the fibrin in blood clots. Chronic exercise may decrease coagulation potential and increase fibrinolytic potential in healthy individuals and cardiovascular disease (CVD) patients. It can be concluded that chronic aerobic exercise may induce favourable adaptations that reduce the likelihood of an ischemic event occurring both at rest and during physical exertion.

Exercise may also reduce thrombotic tendency due to an increase in nitric oxide (NO). This increase in NO is the result of enhanced expression of endothelial nitric oxide synthase (eNOS) mRNA by which exercise is thought to induce. The synthesis of NO results in the phosphorylation of several proteins that cause smooth muscle relaxation and subsequent vasodilation. Lower blood pressure as a result of vasodilation is a favourable outcome in reducing thrombotic likelihood as well as other cardiovascular diseases.

It is also well-documented that exercise improves one's insulin sensitivity. This is favourable in that individuals possessing poor insulin sensitivity can often lead to too much insulin being released from the pancreas, this is known as hyperinsulinemia. Hyperinsulinemia as an independent factor, has been shown to contribute to endothelial damage and initiate an atherosclerotic process, which can subsequently lead to thrombosis. Therefore improving one's insulin sensitivity through exercise may reduce thrombotic tendency.

Changes in lipid profile is another favourable outcome by which exercise causes. A reduction in low-density lipoproteins (LDL) is important in decreasing the likelihood of atherosclerosis. Atherosclerosis and thrombosis are closely related vascular problems and a reduction in atherosclerosis is likely to reduce thrombotic tendency.

Recommendations
There is a lack of evidence for exercise recommendations for thrombosis as a stand-alone disease. Thrombosis however is considered a cardiovascular disease and thrombotic individuals are advised to follow the same exercise recommendations of:


 * 30 minutes or more of moderate-intensity physical activity on most, if not all days of the week,
 * Moderate-intensity resistance training on at least two days per week.

It is important to cease exercising if experiencing:
 * Feelings of nausea
 * Chest pain
 * Dizziness
 * Headaches
 * Numbness

These are potential early signs of a cardiovascular event.