As drawing begins the archer keeps the string fingers in contact with the bowstring but all of the resistance is being felt at the formaster's red straps on the elbow.  The wrist is actually not under any tension, and again, as the draw proceeds the wrist naturally and easily straightens out because there is almost NO LOAD on the fingers/tab.   The FM  places  the resistance and stimulation on the back muscles of the archer, instead of the arm muscles.  It may sound counter-intuitive, but it actually does transfer load to the back.