Animals, such as pet hamsters, really do enjoy exercise wheels, suggests a new study that found most small wild creatures voluntarily use the wheels when they encounter them.
The study, published in the latest issue of Proceedings of the Royal Society B, is the first to look at wheel running in the wild.
The study “puts a nail in the coffin” of the debate over whether mice and rats will run on wheels in a natural setting, says Ted Garland, an evolutionary physiologist at the University of California, Riverside, who was not involved in the work. More importantly, he says, the findings suggest that like (some) humans, mice and other animals may simply exercise because they like to. Figuring out why certain strains of mice are more sedentary than others could help shed light on genetic differences between more active and sedentary people, he adds.
Even before Meijer got creative in her yard, researchers knew that captive mice are exercise maniacs. In laboratories and bedrooms, they frequently log more than 5 km per night on stationary running wheels. But scientists didn’t know why the animals did it.
One thing was clear: They seem to enjoy it. Mice find exercise rewarding; just as they can be trained to press a lever dozens of times to release a pellet of food or a dose of cocaine, the rodents will go to great lengths to unlock a running wheel when it has a brake on, and get back to spinning, Garland says. But is the drive to run normal, or is it an aberrant, obsessive behavior triggered by living in a shoebox-sized cage?