Hula hoops rotate by rolling around your body, like a wheel on the road, except that they roll on their inside edge instead of the outside.
If you gyrate your hips in sync with this rotation, your waist will push against the hoop at just the right point to apply a force that keeps the hoop spinning.
The hoop stays up because your hips are wider than your waist, so pushing sideways also causes the hoop to slide up this slope to the narrowest point.
A 2024 study at New York University confirmed that an hourglass waist was the best figure for hula hooping.
This article is an answer to the question (asked by Nikki Costa, via email) 'How do hula hoops stay up?'
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