Sometimes you might think you've moved as much as you can, but one subtle movement of intelligent action can reveal a whole new level of opening. (yogajournal.com)
The release of the organs draws your energy down into the pelvic floor, which in effect rebounds up and triggers subtle movement in the spine. (yogajournal.com)
You could try this while side lying, standing, and even, with subtle movements, on your back WITH your knees bent. (spinningbabies.com)