[tetris11]

I think its to so with how small the wheel is, and how hard it is for the animal to take damage when things go wrong.

Cats, rodents, ferrets, anything capable of running fast would enjoy this. Humans too if we could hop on and off without breaking any bones

[onionisafruit]

We have human sized hamster balls, that are pretty popular with the younger humans…or at least the subset that went to my kids’ elementary school carnivals. So there’s a little support for your theory.

We also have treadmills and stair masters with a similar concept of infinite running or climbing, but they are not nearly as attractive to humans as wheels are to rodents.

[TheLML]

Isn't a treadmill basically that?