In this video tutorial, viewers learn how to perform hanging knee ups. This exercise targets the abdominal muscles. Users will need to use a smith rack for this exercise. Begin by hanging on the top of the smith rack. Users should have a bar behind the rack that will support the back area. While hanging, users will point the chin down and bring the knees up. Then raise the chin up and bring knees down. Continue performing this movement in a series of sets and repetitions. This video will benefit those viewers who want to lose fat on their stomach and build abdominal muscles.