Iliopsoas Explained   The “Give the Psoas a Break” Exercise. A Constructive Rest Position for Everyone! CRP is a supine position that has been taught for many years. The system was developed by Mabel Todd in the early part of the twentieth century in Boston and then in New York City as an alternative to strict military physical education. She called this method Natural Posture. Her ideology was later termed Ideokinesis, an idea of movement used to improve muscular coordination through imagery. Creative yet scientific, it is based on functional anatomy with ease and repatterning of movement, and was...