(HealthDay News) -- Even when they're playing outside, children tend not to be physically active at preschool, a new study says.

In fact, the researchers found that 89 percent of so-called physical activity by 3- to 5-year-olds was found to be sedentary at community-based preschool programs, as were more than half of their outdoor activities.

The children also received little encouragement from their teachers to be physically active, the study found. The results were published in the January/February issue of Child Development.

The finding comes at a time when childhood obesity, especially at younger ages, continues to rise in the United States.

"The low levels of children's activity and the lack of adult encouragement point to a need for teachers to organize, model and encourage physical activity," lead author William H. Brown, an education professor at the University of South Carolina, said in a news release issued by the journal's publisher. "Because children's health and physical well-being are an important part of development, their physical activity needs to be increased in order to promote healthy lifestyles, particularly for preschoolers who are growing up in low-income families and who are at greater risk for poor health outcomes."

The researchers did find that children tended to be more active when balls and other items were made available to them, especially when outdoors and when open space for play was available.

More information

The American Heart Association has more about healthy lifestyles for children.

-- Kevin McKeever

SOURCE: Society for Research in Child Development, news release, Feb. 6, 2009

Last Updated: Feb. 06, 2009