Pull ups using a doorway pull up bar are and a great way to strength major muscle groups of your upper body, but too many pull ups too often can lead to injury. One are of the body that is particularly prone to injury during pull ups with a doorway pull up bar is the rotator cuff. The rotator cuff is a group of muscles that allow you to elevate and rotate the shoulder joint. Hanging from a pull up bar or over articulating the shoulder during exercises like kipping can lead to injuries in this area. Wide grip pull ups on a straight bar are great for developing the “v” shaped back muscles but it is important not to hang from the pull up bar or allow your shoulder to rotate out in excess. Pull ups done behind the head can also lead to rotator cuff injuries. If you plan on doing any of these exercises using a make sure to use a smooth controlled motion and do not hang too long from the bar or allow your shoulders to rotate all the way out. Finally, make sure to allow at least one days rest between pull up bar workouts.