Exercise Boosts Artery
Health in Obese Teens

Obese teens can reverse early signs of artery disease by exercising even if they do not lose weight, new research suggests.

"What we have is a bad news, good news story," Dr. Daniel J. Green at the University of Western Australia stated.

"The bad news is that the negative effects of obesity on artery health are evident at an early age," Green said. "This is one of the reasons that obesity in young people can become a big problem in later life in terms of cardiovascular disease."

The good news, Green said, is that there is a way to improve children's artery health without medications.

"Exercise reversed the bad effects of obesity and it did so without changing body weight," or changing body mass index (BMI), a measure of obesity that takes into account weight and height, Green said.

Green and his colleagues tested blood vessel function in 19 obese and 20 lean adolescents before and after they participated in an exercise program. The youth were all healthy nonsmokers who had normal cholesterol and blood pressure.

Green's team focused on flow-mediated dilation, which measures how well the endothelium, the lining of the blood vessel, acts to keep blood moving by widening the vessel.

Poor endothelial function is suspected of being an early sign of artery disease. Until this study, the researchers noted, no one had examined whether exercise can improve endothelial function in obese teens.

For 8 weeks, participants completed three 1-hour sessions of aerobic activity and weight training.

At the start of the study, obese adolescents had impaired endothelial function compared with their lean peers. But blood vessel function had improved significantly by the end of the exercise program.

The results of the study appear in Wednesday's issue of the Journal of the American College of Cardiology.

"We believe, on the basis of this and other studies we have performed, that exercise has a direct and beneficial effect on artery health, as well as the indirect but beneficial effect exercise possibly has through decreasing blood lipid levels, blood sugar and blood pressure," Green said.

Obese teens, who were not advised to change their diet, did not lose weight while on the exercise plan. But they did experience healthy changes in their body composition, including increased muscle mass. They also experienced a decrease in fat around the abdomen. This type of fat is strongly associated with an increased risk of cardiovascular disease.

But to keep vessels healthy, teens have to stay active. Exercise quickly improved blood vessel function, but these benefits soon dissipated once teens stopped exercising.

"Exercise is a big factor which is being largely ignored in the obesity debate in young people," Green said. In terms of blood vessel health, exercise is probably more important than diet, Green said, although he stressed that both diet and exercise are critical for weight loss.

Green and his colleagues are currently studying the effects of different types of exercise in obese children and teens to identify the best way to improve blood vessel health and reduce the risk of future cardiovascular disease.

SOURCE: JACC/Journal of the American College of Cardiology, May 19, 2004.

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