FRIDAY, June 22 (HealthDay News) -- Teens who engaged in more moderate-to-vigorous outdoor activity reported better health and social functioning than their peers who spent hours in front of television and computer screens, a new study in Australia has found.

The teens who had the highest perceived health in the study spent an average of 2.5 hours more per day playing sports or doing other high-intensity activity than their least-active counterparts, according to the researchers.

The research, done at the University of Sydney, found that youths in the study overall spent an average of 3.3 hours a day playing video games, watching television or doing other sedentary activities, compared with only 2.1 hours in physical activity.

The findings suggest that parents need to limit how much time their children spend using electronic media, the lead author said.

"Parents should be conscious of the fact that outdoor physical activity is beneficial to their child's overall health and well-being, and should try to limit the time their child spends in front of the screen," said Bamini Gopinath, a senior research fellow at the university's Westmead Millennium Institute for Medical Research.

Although no causal link was established, the study provides "another piece of evidence" that increasing physical activity and decreasing screen time "would be beneficial" to teens, said Gopinath, adding that "the impact of activity behaviors persists over the long term."

The study, published in the July issue of Pediatrics, was conducted from 2004 to 2009.

Study questionnaires asked how much time 1,216 teens spent on outdoor exercise compared to indoor activities including computer use for recreation and homework. Other sedentary activities such as reading were included. The data were collected at age 12, and again five years later. At that time, another group of 475 teenagers was recruited from the same schools in the Sydney area. Both groups responded to items about their health and general well-being.

The questionnaire included 23 items about the teens' health and physical functioning, as well as self-esteem, peer relationships and school.

Not surprisingly, more time spent reading and doing homework was associated with better school performance.

The more-active teens had significantly better scores relating to social functioning, or getting along with peers. Teens "who rarely exercised" were more likely to report "feelings of loneliness and shyness."

"Improved understanding of these relationships could help in developing interventions to promote general well-being among adolescents," the study authors concluded.

Another expert said he wasn't surprised by the findings.

"It makes sense that these kids who are getting outside, playing sports and running around are going to feel better than those kids who are sitting alone with a screen," said Dr. Michael Rich, director of the Center on Media and Child Health at Boston Children's Hospital.

He cautioned against "over-interpreting" the results because other factors not looked at in the study "may have more influence." For example, he noted that the study did not show whether some teens avoided outdoor sports because they were less healthy to begin with.

But the findings are "worth paying attention to," Rich said.

It also makes sense that kids who spend their time "running around in the fresh air" and playing sports are going to be "not only physically healthier, but socially healthier because they're learning to work things through with other teens," he said.

The study gave "more objective data that supports what your mom always said, which is 'go outside and play,' proving mom was right," Rich added.

More information

To learn more about children and physical exercise, visit the U.S. Centers for Disease Control and Prevention.

Copyright © 2012 HealthDay. All rights reserved.