The findings run contrary to the notion that people get more exercise and are healthier when they have access to outdoor recreation, researchers said.

It's possible, they added, that urban neighborhoods with few parks may instead have lots of cafes, schools and community centers that facilitate walking for transportation.

But regardless of what explains the results, they "provide important evidence that the relationship between park area and levels of walking is far from straightforward," according to Tania King from the University of Melbourne and her colleagues.

The researchers used data from 2003, when about 2,300 people living around Melbourne were asked how often they walked for at least ten minutes at a time.

They compared those answers with data from Geographic Information Systems, which showed how much designated parkland was within one-quarter of a mile, half a mile or three-quarters of a mile of participants' homes.

About 80 percent of people reported going on a walk at least once per week; the rest walked twice per month or less.

There wasn't much of a difference in people's walking frequency based on the amount of parkland within a quarter-mile of their homes, the researchers reported in the International Journal of Behavioral Nutrition and Physical Activity.

But people with the most parks and fields within a half-mile or larger radius were 35 percent less likely to walk at least weekly than those with the least amount of parkland in the area. That pattern held when King's team looked solely at parks that were four acres or bigger, the size of an Australian football field.

The researchers didn't factor in other aspects of participants' neighborhoods, such as walkability, or any details about the parks themselves. And that's an important limitation, according to Ariane Rung, who has studied parks and physical activity at the Louisiana State University School of Public Health in New Orleans.

"It may not matter how close the park is if you're living in a neighborhood that you can't walk easily in, maybe (because) there are no sidewalks… or it's not safe," Rung, who wasn't involved in the new research, told Reuters Health.

"There's lots of other stuff in there that make it a more complicated thing than whether there's some open land and how much in your neighborhood," she added. For example, some parks may be in poor condition, and others more conducive to socializing than exercising.

Rung said the theoretical benefits of parks go beyond encouraging physical activity. They include fostering social ties within a community and boosting the mental health of people who spend time there.

King and her colleagues agreed the new findings don't mean living near outdoor public space isn't beneficial.

"While parks may not have an effect on walking levels, there are likely to be many other health benefits of having access to parks," they wrote.

SOURCE: bit.ly/QL66xg International Journal of Behavioral Nutrition and Physical Activity, online September 19, 2012.

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