Climbing ropes, stationary bicycles and electronic dancing games could join the menu of play options for kids at McDonald's if they prove a hit in a trial launched in several of its U.S. restaurants.

The burger-and-fries company, often accused by critics of contributing to child obesity, is tinkering with the mini-gyms as a possible successor to the popular McDonald's PlayPlace, with its ball pits and crawl tubes.

It opened the first R Gym — that's R as in Ronald McDonald for those who missed the clown plug — last March in Tulsa, Okla., and now has six more, at McDonald's in Santa Ana, Whittier and Elk Grove, Calif.; Broomfield, Colo.; and Chillicothe and Woodridge, Ill.

More are planned based on what the Oak Brook, Ill.-based chain says has been a positive early response.

"As long as our customers see a benefit in it, we will continue to look at this," spokesman Bill Whitman said Monday. "We have for many years supported programs that promote physical activity, and we will continue to do that."

Incorporating more technology than the traditional PlayPlace, McDonald's Corp. says the R Gym is intended to provide a fun, easy way for children to increase their physical activity.

It isn't likely to be confused with mom's or dad's gym. The stationary bikes are attached to video games, and kids shoot hoops on tiny courts that electronically cheer players. Other offerings include air hockey and foosball tables.

R Gyms feature a toddler zone for ages 0-3, where soft balls and slides remain; an active zone for ages 4-8, including an obstacle course and climbing challenges; and a sports zone for ages 9-12, with bicycling, jumping, dancing and other sports-oriented activities.

Analyst Bob Goldin agrees with nutrition advocates who note that it would take a child a long time to burn off the calories from a Big Mac and fries in the R Gym.

"Realistically, I can't imagine it's going to necessarily be that beneficial," said Goldin, of Chicago-based food consultancy Technomic Inc. "It's not truly something that's real physical fitness. But it does take their playgrounds to a new level."

He said McDonald's clearly is eyeing the change as one to strengthen its "well-earned stranglehold on the kids' market" rather than as a health-driven move. "The fact it has positive imagery is just icing on the cake."