Essentially a Pull Up is carried out in what is known as a pronated position which requires an overhand grip. Reverse the hand grip to underhand or Supinated and what you are now doing is a Chin Up instead. To really perfect a Pull Up the key is to be able to retract your scapular – basically to isolate and pull down your shoulder blades. Master this action and you are well on your way to mastering the Pull Up and impressing the hell out of everyone.