A new study shows that if a city wants healthier residents, it should install new signs in its parks and take other simple measures to get people to be more active.

"There is a large body of evidence indicating that environmental cues influence and change individual behavior, including physical activity," researchers wrote.

A Rand Corp. conducted the study over a five-year span by picking 50 parks in Los Angeles, giving a select few $4,000 a piece to spend in efforts to increase use of the parks, then observed the activity in the parks from 2007 to 2012.

The study found that spending on marketing and outreach increased physical activity by 7 to 12 percent compared to the parks that did not make changes.

Most of the parks receiving money spent it in several ways, the researchers told the Los Angeles Times. About half of it went to signs to entice people to take part in activities, 28 percent of it went to materials and labor for activities, and a fifth to incentives such as giveaways.

Researchers kept track of who used the park and how over the course of the day and early evening. The 50 parks were divided into three groups.

In one, the park director worked with the researchers to get more people into the park and increase activity; in the second, the park director and a local park advisory board worked with researchers; and in the third, the parks got no extra help.

During the study, all parks had their budgets cut, which led to staff cuts and reduced hours, the Times reported.

Researchers said some of the people they interviewed suggested the new signs placed outside of the park could attract new people. Public health officials say a person should be physically active for at least 150 minutes a week, and that children should be active for at least an hour a day.