Here is a link to article I wrote on the Plank and its twin sister Mountain Pose aka Tadasana. Understanding the mechanics and principles of these movements will help clear up many common dysfunctional movement patterns and help hone skills that apply in additional movements. Coordination, synchronization, linkage, connection, etc. are all key to understanding the body and how the fascial structure works together through joints and muscles. For more info please open the PDF Link below.