The pullup is an effective body-weight exercise that targets a variety of muscles in the back and arms. Because this maneuver does not require much equipment, you can perform pullups just about anywhere. Beginning weightlifters can also build foundational strength needed to execute more advanced lifts with this exercise.
Target
Pullups primarily target the latissimi dorsi. Commonly referred to as the lats, these long and wide muscles originate in the ribs and vertebral column and insert just underneath the humerus. The lats are responsible for controlling movements in the shoulders and assist with the depression, rotation and adduction of the scapula.
Synergists
Synergists are muscles other than the primary target that help facilitate the execution of the lift. As with most body-weight exercises, pullups require a multitude of synergists to support the body throughout the lift. The biceps, deltoids, rhomboids, trapezii and a number of other smaller muscles in the back and arms help support the latissimi dorsi to enable you to complete a full pullup.
Dynamic Stabilizers
Stabilizers are muscles that contract during an exercise, but do not significantly lengthen or shorten. Dynamic stabilizers are muscles that provide joint support through the full range of motion of a lift, with a subtle shortening at the target joint and lengthening at the adjacent joint. During a pullup, the triceps brachii serve as dynamic stabilizers to the latissimi dorsi. These muscles are responsible for extending the elbow and both extending and adducting the shoulder.
Pullup Variations
A variety of pullup variations exist, placing different emphasis on certain muscle groups. For example, an underhanded pullup, or chinup, places a greater demand on the biceps. A kipping pullup, or one in which the exerciser first swings forward at the shoulders, requires some additional support from the deltoids. A wide-grip pullup places a great emphasis on muscles in the back, while narrow-grip pullups require more strength in the arms.
