Hip circles are a chi kung practice discussed here. They are a great practice for strengthening and stretching the hips and lower back. They are like the big circles one might use when first learning to hula hoop. A different, but similar practice is sacrum spiraling.
The sacrum spiraling practice can feel foreign when we first learn it. To ‘get the gist’ it is helpful to place the finger tips of one hand on the pubic bone and the finger tips of the other hand on the sacrum. Then, rotate the sacrum in one direction, switch hands and switch directions. In this practice, the circles are smaller and more subtle than hip circles. In sacrum spiraling, the hips are mostly stationary while the sacrum moves in a small circle, as if the coccyx is drawing a circle on the ground between the feet.
Some of the most popular and sensual dance moves involve this sacral movement. Just seeing Elvis Presley spiral his sacrum derailed the morality of a whole generation of teenagers in the U.S. Belly dancers also have this practice mastered and expert hula hoopers use the sacrum and don’t need to move the entire hips.
Moving the body in this way unlocks the energy of the root and sexual energy centers/chakras. While practicing this chi kung form, imagine the powerful energy of the reproductive region spirals up the spine to nourish the organs, heart, and brain. Modern people sit so much. This practice is one way to help reverse the damage caused by sitting.