Playgrounds for the elderly are catching on in Europe, where the population is aging. After watching 40 people ages 65 to 81 use swings, seesaws and jungle gyms over a three-month period, researchers at Finland's University of Lapland found that such play improved balance, speed and coordination.

Senior playgrounds also create a sense of fun and increase social interaction, says Fabio Comana, an exercise physiologist with the American Council on Exercise.

And, he says, they're accessible even to people who might be intimidated or embarrassed about going to a gym.