June 29, 2000 DALLAS, June 27 -- The blood vessels of older athletes behave like those of people half their age, according to a new study in Circulation: Journal of the American Heart Association.
Researchers studied sedentary individuals and athletes, both young and old. The athletes were long-distance runners, cyclists and triathletes, who combined running, cycling and swimming. Both groups of young people, sedentary and athletic, averaged 27 years of age. The average ages for the older groups were 63 for the sedentary participants and 66 for the athletes. The study found that the older athletes' blood vessels functioned as well as those of the participants in either of the two younger groups.
"This study demonstrates that regular physical activity can protect aging blood vessels," says the study's lead author, Stefano Taddei, M.D., an associate professor of internal medicine at the University of Pisa in Italy. "Long-term exercise protects the inner lining of the blood vessels from age-related changes and makes them behave more like those of a young person," he says.
And it may not take a triathlon to reap benefits, Taddei says. A study by the Honolulu Heart Program published in Circulation last year showed that regularly walking more than 1.5 miles a day reduced heart disease risk in older individuals. "You do not need to be an athlete to get these beneficial effects from exercise," he says. "Aerobic activity five days a week -- rather than intensive training -- might just do the trick." Blood vessels need to be able to expand in order to accommodate increases in blood flow. A protective layer of cells, called the endothelium, forms the inner lining of blood vessels and produces substances that help the vessels expand, or dilate.
In healthy blood vessels, the endothelium produces a substance called nitric oxide that helps the vessels dilate when the heart needs more blood. Nitric oxide also protects the vessel walls from developing atherosclerosis -- the buildup of fatty substances that thicken the arteries and block blood flow -- and thrombosis, the formation of blood clots that can block small or narrowed vessels and cause heart attacks, explains Taddei. Aging can cause alterations in the endothelium, he says, making older individuals more prone to atherosclerosis and thrombosis.
Previous studies have linked aging to problems in endothelium responsiveness and have shown that exercise can make the endothelium dilate more efficiently, even for patients with chronic heart failure, says Taddei.
Taddei's team studied 12 young and 12 older sedentary subjects and compared them to 11 young athletes and 14 older athletes.
The researchers gave the study subjects a substance called acetylcholine, which causes the blood vessels to dilate if the endothelium is producing nitric oxide properly.
The young subjects, whether sedentary or active, had similar strong responses to acetylcholine and their vessels dilated. Among the older participants, athletes showed greater blood vessel dilation than the sedentary group.
Another age-related change in the endothelium is increased free radicals in the blood. Free radicals are highly unstable, reactive oxygen molecules that circulate in the blood and damage tissues. These reactive molecules play a major role in the formation of artery-blocking fatty build-up when they come in contact with LDL cholesterol -- the "bad" cholesterol. Scientists believe that exercise and certain vitamins have antioxidant effects by blocking free radicals.
The researchers found in this study that older athletes had low blood levels of free radicals similar to the younger study subjects. However, the older sedentary individuals had high levels of free radicals -- their blood vessels showed dilation only when the researchers administered high doses of the antioxidant vitamin C.
Co-authors are Fabio Galetta, MD; Agostino Virdis, MD; Lorenzo Ghiadoni, MD; Guido Salvetti, MD; Ferdinando Franzoni, MD; Costantino Giusti, MD; and Antonio Salvetti, MD.
For more information on exercise, visit the section of the American Heart Association's Web site on physical fitness at http://www.justmove.org .
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