MUSCLES ENGAGED Biceps Biceps are the pair of muscles on the front of the upper arm connecting the shoulder to the elbow. Your biceps are used in everything from turning a doorknob to lifting heavy items. Strengthening your biceps can greatly reduce the "flabby arms" look. Shoulders The shoulder is the most movable joint in the body. However, it is an unstable joint because of the range of motion allowed. This instability increases the likelihood of joint injury, often leading to a degenerative process in which tissues break down and no longer function well. Equipment Used Pull Up Bar A pull-up bar is a straight steel bar that mounts on a wall, door frame, squat rack or cable machine. It is one of oldest and most effective strength tools and is used to target the latissimus dorsi muscle (lats) along with the rhomboids, shoulders and biceps. Exercise Instructions Step 1 Jump up on the bar using a chin-up grip, palms turned in approximately shoulder width apart. Step 2 Hold your chin over the bar as long as you can. Step 3 Lower yourself back down when your muscles are fried and you are no longer able to hold the position.