Many children spend too little time outdoors and too much time in front of the TV - and a lack of suitable outdoor spaces seems partly to blame, an Australian study suggests.

The study, of nearly 1,400 10- to 12-year-olds, found that 37 percent typically spent a half-hour or less being active outside. Few were outdoors for two hours or more on a typical day.

On the other hand, researchers found, many children devoted at least two hours per day to the TV or computer screen, with 49 percent of boys and 36 percent of girls doing so.

The researchers did find, however, that certain children were more likely to play outdoors for more than a half-hour at a time - namely, those whose parents allowed them to walk around their neighborhood on their own.

The finding suggests that when parents think their neighborhood is safe, children are more likely to get outdoor exercise, according to Dr. Li Ming Wen and colleagues at the Sydney South West Area Health Service and the University of Sydney.

If more neighborhoods were safe, clean, walkable and offered public areas where children could play, Wen told Reuters Health, that might allay parents’ concerns and help kids be regularly active.

The findings, published in the International Journal of Behavioral Nutrition and Physical Activity, add to evidence of the importance of neighborhood surroundings on people’s activity levels.

Past studies have suggested that, compared with years ago, parents have become less willing to let their children walk to school or play outside - at least in part because of worries over crime and traffic safety, and a general lack of parks, playgrounds and other appropriate places for children to play.

Other studies have tied heavy reliance on cars and neighborhoods that lack sidewalks to higher risks of obesity in both children and adults.

Wen suggested that, when possible, parents not drive their children to school but allow them to walk. Having them walk with their friends, the researcher noted, may help ease parents’ safety worries.

If the path to school includes dangerous road crossings, Wen noted, parents might try lobbying local officials for improvements.

SOURCE: International Journal of Behavioral Nutrition and Physical Activity, online March 16, 2009.