The rocking motion of the sacrum (tailbone)-- a feature of most yoga styles — helps to stimulate full body relaxation, calms the nervous system, releases endorphins, increases circulation to the pelvis and clears the energy centres of the body. (womenshealthandfitness.com.au)
Those kinds of very proximal so like in a centre of your body, a very Gross Motor like big movement kinds of things. (pregnancymagazine.com)