In our studies we keep seeing how difficult it is for traumatized people to feel completely relaxed and physically safe in their bodies. We measure our subjects HRV by placing tiny monitors on their arms during shavasana, the pose at the end of most classes during which practitioners lie face up, palms up, arms and legs relaxed. Instead of relaxation we picked up too much muscle activity to get a clear signal. Rather than going into a state of quiet repose, our students muscles often continue to prepare them to fight unseen enemies. A major challenge in recovering from trauma remains being able to achieve a state of total relaxation and safe surrender. Bessel A. van der Kolk, The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma

The Body Keeps the Score by Bessel van der Kolk