One knee bends against the ball while your straight arms pull Yoga poses upside down the ball against your knee to create the opposition to engage the upper back and scapula for Yoga poses upside down stability. Lift your other leg, keeping it as straight as possible, up to hip level. Keep your hips level if possible, to establish the stretch on the side of your hip and thigh that are supporting your body. Straighten your bottom leg and roll the ball out in front of you as you stretch your torso out long. Hold your top leg up, pointing and flexing your ankle joint and activating your calf as well. Do this 4 times. Repeat with your other leg. This is advanced.
It is my impression that hatha-yoga represents a Tantric yoga which was not only metaphysically different to the old ascetic-wisdom types of yoga but also practically different. Both the referent and the signified of this yoga culture represented an epistemic rupture from previous examples. But like so many other systems, it would also suffer from being included in hegemonic elite theologies. This is the subject of the chapter on hatha-yoga.