Researchers at Indiana State University in Terre Haute tried a small experiment to test the effects of having kids play with heavier toys. They found that 10 children ages 6 to 8 burned more calories and had higher heart and breathing rates when they moved 3-pound toy blocks instead of unweighted blocks.
So could adding a small weight to stuffed animals and other toys help kids get fit?
"This is not going to solve the obesity problem," said John Ozmun, a professor who did the study with graduate student Lee Robbins. "But it has a potential to make a positive contribution."
Some experts caution that children could hurt themselves trying to lift too much too soon and said more activity is preferable to heavier toys. But all agree childhood obesity is a big problem.
Obesity rates have tripled over the past 40 years for children and adolescents, raising the risk of diabetes and other health problems. Federal health officials say more than a third of American children are overweight; about 17 percent are considered obese.
Squeezing activity into daily routines can be a good way for children to get more exercise and shed unhealthy pounds, said Alicia Moag-Stahlberg, who heads Action for Healthy Kids, an organization that works with schools.
"By adding weights, you're adding some intensity to the action," she said.
Kara Tucker, youth development coordinator for the National Institute for Fitness and Sport in Indianapolis, said active playing helps youngsters work out without realizing it.
Tucker leads groups of children through several fitness stations at the institute, including inflatable obstacle courses, an oversized soccer game and a moving rock-climbing simulator called a "Treadwall."
"Giant soccer is one of my favorites," Tucker said. "If we told the kids, 'Hey, you're going to run up and down the court 20 times,' they would completely be uninterested. Yet when we put a big soccer ball out there, they will just run forever. They're having a great time."
Weighted toys might be another way to sneak in exercise, but not everyone thinks a 3-pound stuffed animal sounds like fun.
Rambunctious kids could throw heavy toys at playmates, said Celia Kibler, president of Funfit, a family fitness club in Maryland. Kibler also fears children could hurt themselves if they lift too much weight before their bodies are fully developed.
"I think that can be more dangerous than beneficial," she said. "There's so much activity that a child can do that can keep them in shape without the use of weights. That's what they should be concentrating on."
The study's authors stressed that their report is a starting point, and involved only a few children under very controlled circumstances.
Weighted toys in the real world would have to be designed to be safe while holding a child's interest, said Ozmun, acting associate dean of Indiana State's College of Health and Human Performance.
Even though weighted toys might not make it to store shelves anytime soon, they could find a niche in specialty applications. Ozmun said he's working on creating 3-pound stuffed animals for physical therapists to try with their young clients.
"Having a 3-pound teddy bear may not only help with strength, but with balance and coordination," he said.