Adolescent girls who live within half a mile of a public park are significantly more physically active than other girls, University of North Carolina at Chapel Hill researchers have found.

The study found that physical activity was higher for girls who lived within a mile of parks and showed highest levels among girls who lived less than one-half mile from a park, said Dr. Diane Catellier, a study investigator and research associate professor of biostatistics in the UNC School of Public Health. The researchers found that girls only got about 114 minutes a week of intense physical activity outside of school hours, or about 16 minutes a day.

Dr. Deborah Cohen, a senior natural scientist at RAND Corporation and lead author of the study, said the U.S. surgeon general recommends that all children and adolescents get at least 60 minutes of exercise a day. “We still have a long way to go in encouraging girls to be active.”

The results appear in the November 2006 issue of Pediatrics. The study was led by the RAND Corporation, a nonprofit research organization. Researchers from UNC-Chapel Hill, the University of Arizona, the University of South Carolina and San Diego State University participated. Funding was provided by the National Heart, Lung and Blood Institute, part of the National Institutes of Health.

In the wake of growing national concern about increasing rates of obesity and health problems brought about by Americans’ diets and sedentary lifestyles, the study findings could have implications for both males and females in other age groups as well, Catellier said.

“The study suggests that having access to parks in neighborhoods and communities can make a significant difference in the level of physical activity girls get,” Catellier said. “More research may show that the trend is also true for boys and others in a neighborhood. We believe neighborhood parks are particularly important for adolescents who are too young to drive.”

To examine the relationship between parks and physical activity, the researchers used baseline data from the Trial of Activity for Adolescent Girls. The trial is a national research study led by the UNC School of Public Health focusing on middle school girls.

The study team tracked 1,556 girls in the sixth grade in six cities and counted the average number of public parks within a half-mile radius of the homes of girls in the cities. The girls were fitted with accelerometers - devices that measure physical activity - and were monitored for six days.

The study sites include Minneapolis, Minn. (2.2 parks within a half-mile radius of participants); Baltimore, Md. and Washington, D.C. (1.8 parks); San Diego, Calif. (1.2 parks); New Orleans, La. (0.9 parks); Columbia, S.C. (0.7 parks); and Tucson, Ariz. (0.34 parks).

The researchers found that parks with active amenities such as basketball courts, playgrounds and walking paths were associated with more physical activity than parks with passive amenities, such as picnic areas and lawn games.

The study suggests that communities should make parks a higher priority, particularly ones with amenities like running tracks or walking paths, Catellier said. Previous studies have shown that girls become less physically active once they reach adolescence, and that girls are generally less physically active than boys, she said.

Study authors include: Dr. Kelly R. Evenson, research associate professor of epidemiology at the UNC School of Public Health, J. Scott Ashwood, Molly M. Scott and Adrian Overton, of RAND; Dr. Lisa Staten, co-director of the Southwest Center for Community Health Promotion and associate professor of family and child health at the Mel and Enid Zuckerman College of Public Health at the University of Arizona; Dr. Dwayne Porter, associate professor and graduate director of environmental health sciences at the Arnold School of Public Health, University of South Carolina; and Dr. Thomas L. McKenzie, professor emeritus of exercise and nutritional sciences at San Diego State University.