Rocking. There is a video and a picture. The picture shows me doing rocking on an exercise ball. A nice variation and way to train the opening of the front body. The video shows rocking. Watch the head, ideally the rock comes from an activation of the legs, arms and torso. My body likes extension and it likes this but my shoulders need a good warm up before it can happen.
Primary focus: Opening the front body
Secondary focus: Stretch and control