Inactivity Rampant Among Teen Girls

Sept. 4, 2002 -- By the time girls reach their teen years, they're exercising much less than when they were younger. Though maybe not surprising, this is an alarming finding in light of the obesity epidemic among American youth.

A large study -- the first of its kind -- shows that by the age of 16 or 17, 56% of black girls and 31% of white girls are getting no regular physical activity.

"When we're talking about an obesity epidemic, this is what's responsible -- lack of physical activity," says lead author Sue Y.S. Kimm, MD, MPH, professor in the department of family medicine and clinical epidemiology at the University of Pittsburgh School of Medicine.

"Other studies looking at food intake have shown no increase over the years," she tells WebMD. "We have to surmise that lack of physical activity is responsible for this obesity epidemic that's overtaking us. I don't think anyone has been aware of the extent of this decline in physical activity."

Kimm's study appears in the Sept. 5 issue of The New England Journal of Medicine.

In their study, researchers tracked nearly 2,400 girls from ages 9 or 10 until they reached 18 or 19.

At the study's beginning -- and at several more times during the years -- the girls completed surveys with information about activities they were involved in. This included sports, recreational activities (bicycling, basketball, and walking) and lessons ( swimming, dance, and gymnastics).

Throughout the study, black girls had significantly higher body mass index -- indicative of too much fat on the body. By the age of 16 or 17, pregnancy was keeping black girls from getting much activity. For white girls, smoking was more likely the reason.

Kimm's study "confirms some of what we've been finding," says Monica Baskin, PhD, research assistant professor at the Rollins School of Public Health at Emory University School of Medicine in Atlanta.

With white girls, there may be misguided thinking at work -- the idea that smoking may be one way to lose weight, Baskin tells WebMD. "We've certainly heard it on college campuses -- the Diet Coke/cigarette diet."

Though elementary and middle school children get structured PE classes, it's minimal, says Baskin. Also, "the majority of Atlanta public high schools no longer have mandatory physical activity. Unfortunately, that's a trend across the nation."

When it comes to extracurricular sports activities, many girls run into financial problems, she says. "It's whether they can afford to get into sports outside of school -- whether they have to pay for the activity or a gym membership."

Also, there are potential cultural issues that drive a girl's perception of weight. "Numerous studies have looked at the differences between black and white girls, and what is viewed as healthy and attractive," says Baskin. Black girls always say that a full-figured shape is most appealing to them and to boys, she says.