The project, which examined 50 parks across Los Angeles, found that simple interventions such as increased signage boosted physical activity by 7 to 12 percent over the study period in relation to parks that did not make changes. The findings are published online by the American Journal of Preventive Medicine.

"The study shows that environmental cues influence and change individual behavior, including physical behavior," said Dr. Deborah A. Cohen, the study's lead author and a senior natural scientist at RAND, a nonprofit research organization. "When physical activity opportunities and reminders become more obvious, whether they are overt signs or notices for classes or new walking paths, they may lead people to becoming more active, especially if they are already in a park."

Although most Americans live in a community with a network of parks and recreation facilities suited to exercise, most do not meet the national guidelines for physical activity. Those recommendations suggest adults engage in physical activity for 150 minutes per week, while children should do so for 60 minutes per day.

An increase in physical activity among people in Finland over the past few decades has been attributed, in part, to an increased focus on local parks and sports facilities. In contrast, many U.S. municipalities -- including Los Angeles -- have trimmed support for public physical activity programs and parks.

RAND researchers wanted to examine whether, given limited resources, parks could adjust their programming and outreach efforts to increase activity if they had better information about local use and activity preferences. The second question was whether the involvement of park advisory boards composed of community members would help improve the decisions made by park directors.

To conduct the project, 50 parks in the City of Los Angeles that included a recreation center and full-time staff were randomized into three groups. In the first group, the park director worked with the research team to determine how to attract more park users and increase physical activity. The research project made $4,000 available to each park for marketing, outreach and programming activities.

In the second group, the research team worked with the park director and an existing local park advisory board to collect and analyze information about park usage and decide how to spend the marketing funds. The third group of parks did not receive any additional help.

In both groups, most of the money was spent on improving signage that encouraged people to participate in park-sponsored activities. Each park was monitored to assess the characteristics of the park and its users, including physical activity levels. The study period ran from 2007 to 2012.

Among the parks that received project funding, there was no substantial difference in the amount of additional physical activity observed between those that involved park advisory boards and those that didn't.

Researchers say most of the increase in activity appeared to be concentrated among existing park users, suggesting that putting reminders and signs in areas outside the park may be necessary to recruit new users to the park.