Type 2 diabetes and its often-associated high blood pressure present a double-whammy to the heart, causing abnormalities in the organ's structure and function, and damage to blood vessels throughout the body. Now a Johns Hopkins exercise physiologist suggests that exercise, mainly aerobic activity and weight training, may provide multiple solutions to these heart problems.
Writing in the Oct. 2 issue of the Journal of the American Medical Association, Kerry J. Stewart, Ed.D., director of clinical exercise physiology at Hopkins, says that regular aerobic and weight-lifting activities not only control blood sugar and lower blood pressure, but also provide cardiovascular benefits. As an added bonus, exercise training reduces total and abdominal fat, both of which lead to improvements in insulin sensitivity, blood pressure and blood vessel function.
Because Type 2 diabetes can double or quadruple the risk of cardiovascular disease, most diabetic patients die of heart-related complications, including coronary artery disease and stroke, Stewart notes.
"There's a great focus on the search for genetic methods of treating diabetes and other chronic conditions," he says, "but although gene therapy is not yet available for diabetics, 'gym therapy' is. The benefits of exercise go way beyond controlling blood sugar. Physicians should urge their patients to become more active."
The prevalence of diabetes in the United States rose from 4.9 percent in 1990 to 7.3 percent in 2000, an increase of 49 percent, the report says. Health care costs associated with diabetes were $98 billion in 1997.
For his review paper on the cardiovascular benefits of exercise training on diabetes and hypertension, Stewart did a computerized search of studies performed between 1985 and 2002 of exercise training, type 2 diabetes and high blood pressure. He examined 235 reports, placing them into categories of heart health measures: functioning of the endothelial cells lining the inside of blood vessels (blood vessels' ability to dilate, allowing more blood to flow during periods of stress); functioning of the left ventricle (the heart's ability to fill with blood and pump it out to the rest of the body); blood vessel stiffening (a sign of early heart disease); and inflammation and size of the left ventricle (indicators of infection/disease).
Analysis of the studies indicates that the strongest evidence for exercise benefits lies in improvements in endothelial and left ventricular function. Exercise also may improve blood vessel stiffness, inflammation and heart size, but the evidence there is weaker. This may be due to fewer studies available in these categories, Stewart says, rather than because of any information showing exercise is not beneficial.
The American College of Sports Medicine and the American Diabetes Association have developed exercise guidelines for type 2 diabetics. Patients should get aerobic exercise such as walking, cycling or swimming three days a week for up to 45 minutes per session. In addition, resistance training using light weights and frequent repetitions should be performed at least twice a week, with a typical workout consisting of a minimum of one set of eight to 10 exercises to cover large muscle groups of the upper and lower body.
Stewart cautions that all diabetic patients check with their health care provider before engaging in a strenuous exercise program, but almost all patients can at least benefit from walking.
Stewart, Kerry J., "Exercise Training and the Cardiovascular Consequences of Type 2 Diabetes and Hypertension," Journal of the American Medical Association, Oct. 2, 2002.
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