Lean teens are ones who get vigorous exercise, study finds

Tuesday, April 12th 2005, 12:28 pm

By: News On 6

ATLANTA (AP) _ Lean teenagers are more likely to be the athletes who have a lifestyle that can overcome the effects of hours on the computer or watching TV, a study of Georgia students suggests.

Reserchers at the Medical College of Georgia outfitted 421 teens ages 14 to 18 with accelerometers _ pedometers that not only measure steps taken but also intensity of activity. During the five-day study, they tested the teens for cardiovascular fitness with a treadmill and measured students' body fat.

The study in this month's issue of the American Journal of Clinical Nutrition found that the fittest students were those who got high amounts of moderate and vigorous physical activity. But the leanest students (lowest body fat percentage) were only those who participated in vigorous activity, the study found.

Because many teenagers have sedentary lives filled with large amounts of time spent in front of computers and TV, they have to somehow ``make up'' the exercise deficit to avoid becoming overweight, said Kelly Brownell, a Yale University obesity expert.

``The results of the study show pretty clearly that kids who do make up for it are less likely to struggle with weight problems. But there's a lot to make up for, so much so that moderate activity may not get the job done,'' Brownell said. ``The sad thing is we've created conditions for our children where they have to go out of their way to be vigorously active to make up for the sedentary conditions they face.''

In the middle of a national obesity epidemic in which up to 30 percent of U.S. children are overweight or obese, health officials have been concerned about how much exercise children actually get.

A previous study by medical college researchers and Healthcare Georgia found that 41 percent of Georgia teens failed to get 20 minutes or more of exercise three or more days a week; the government recommends children get at least an hour of moderate activity each day. Less than a third of Georgia middle and high school students attend physical education classes daily.

Although teens should exercise in the daily recommended amounts, those who aren't fit or are overweight need to ease into the routine, said Dr. Paule Barbeau, a study author and exercise physiologist with the medical college.

``They should start with more moderate activity. As they get more fit, they are able to do more and more. You want to maximize the fun and the sustainability and you want to decrease the chance of injury that anyone would sustain starting an exercise program,'' she said.