Modern Hula-Hoops are plastic rings you twirl around your body by moving your hips. This swiveling motion is similar to that ...

To keep a Hula-Hoop aloft, it helps to be in shape — literally. Experiments with gyrating, hoop-slinging robots have revealed how these spinning rings stay up despite the pull of gravity.

The Hula-Hoop is one of the most famous toys in history, but the science behind it has gotten little attention. Some of us are master twirlers, while others can't manage more than one spin.