May 18, 2004 -- Exercise may counter the effects of obesity on
May 18, 2004 -- Exercise may counter the effects of obesity on the hearts of children and help reduce their future risk of heart disease, a new study suggests.
Researchers say tests show that obese but otherwise healthy adolescents have abnormal blood vessel function, which could be an early sign of heart disease. But after participation in an eight-week exercise program, their test results matched those of normal-weight children even though they were still obese.
"We were able to essentially normalize endothelial function [blood vessel] in a short period using the exercise training program," says researcher Daniel J. Green, PhD, of the University of Western Australia, in a news release.
Endothelial function tests measure how well blood vessels expand and contract in response to changes in blood flow. Impaired endothelial function is considered an early sign of atherosclerosis, or hardening of the arteries.
"This paper adds another piece to the jigsaw puzzle which says that exercise is beneficial not only because it may improve your risk factors, like lipids [cholesterol] and blood pressure, but it also probably has a direct effect on your blood vessels that makes them more fit," says Green.
Exercise May Counter Effects of Obesity
In the study, published in the May 19 issue of the Journal of the American College of Cardiology, researchers compared the effects of exercise in a group of 19 obese adolescents who ranged in age from 12 to 15 and weighed an average of 212 pounds.
All of the children had normal blood pressure and cholesterol levels and were not on any medications. However, compared with a group of similarly matched non-obese children, the obese children had impaired endothelial function.
The obese children were then enrolled in an eight-week exercise program consisting of one-hour exercise sessions three times a week using a stationary bicycle and strength training with light weights.
The study showed that after participation in the exercise program, the endothelial function of the obese children matched that of the lean children. Researchers say it's important to note that the children had not lost weight, but their body composition had changed in a healthy way.
"We found a decrease in abdominal obesity in this group. And the reason that they didn't lose weight, even though they lost body fat, is that their lean muscle mass went up," says Green. "So we were really seeing a very beneficial change in the composition of the body without changes in gross measures like body weight."
Green says the results suggest that focusing on weight loss alone may be doing a disservice to obese individuals. This study shows that exercise may produce heart healthy benefits even if it doesn't produce rapid weight loss.
But the study also showed that although the healthy effects of exercise were immediate, they may disappear just as fast. Eight weeks after the obese children ended the exercise program, the benefits of exercise on blood vessel function were gone.
