Pull-ups are a classic exercise for building upper-body strength, especially in the muscles of your upper back. To perform the exercise, hang from a bar with your hands at least shoulder-width apart and palms facing away from your body, pull your body upward until your chin is over the bar by flexing your arms and moving your elbows toward your sides. Then, slowly reverse back to the starting position and repeat. Pull-ups are effective because the muscles that produce these movements have to contract powerfully to overcome the force of gravity acting on your body.
Brachialis
The brachialis muscles cross your elbow joints on the front of your arms. They attach to the ulna bones of your forearms below your elbows and to the front of the humerus bones, about halfway between your elbows and shoulders. It is the major elbow flexor, especially when your forearms are pronated as they are during pull-ups. For this reason, they are sometimes referred to as "the workhorse of the elbow," according to Susan Hall, author of the textbook "Basic Biomechanics." When you perform pull-ups, they contract to flex your elbows so you can lift your body and also as you lower your body to help control the speed of your descent.
Latissimus Dorsi
The latissimus dorsi muscles, or lats, are on either side of your spine. They attach to several structures in the lower to middle part of your back on one end, and to the front of the humerus bones of your upper arms on the other. The lats facilitate several arm movements, including adduction, extension, horizontal adduction and inward rotation. When you perform pull-ups, they help adduct your upper arms, or move them downward and toward your body.
Pectoralis Major
The pectoralis major muscles are on either side of your chest. They attach to the inside of the humerus bones, just under your shoulder joints, and then split into two parts, with one part attaching to the clavicle and the other to the sternum. The part that attaches to the sternum is important for the pull-up exercise because it contracts to assist with shoulder adduction.
Teres Major
The teres major muscles are on either side of your upper back. They attach to the inside and lower portion of the scapula bones on one end and to the anterior, or front, part of the humerus on the other. They assist with adduction, extension and inward rotation of the humerus. For pull-ups, like the latissimus dorsi and pectoralis major muscles, they help draw your elbows toward your ribs as you pull yourself upward.
References
- "Basic Biomechanics (Fifth Edition)"; Susan J. Hall; 2007
- "Grant's Atlas of Anatomy (Eleventh Edition)"; Anne M.R. Agur and Arthur F. Dalley; 2005
- Get Body Smart: Teres Major Muscle
Member Comments