‘Even though we now have only the beginning of what was once a real mammalian tail, it behaves the same. Untucking the tailbone opens the pelvic outlet, tucking it closes it — tightening the pelvic floor. The dog with his tail down between his legs is an equivalent of you sitting on your sacrum, the back supported by a chair or a couch. If you spend multiple hours a day in this position, your pelvic floor doesn’t really have a chance to release and allow the muscle fibres to regain their natural length at resting state. So gradually it shortens.’ From Yoga with Ivana blog
