A lat pulldown machine consists of a long bar suspended by a cord that is attached to a stack of weights, and a chair positioned directly under the bar. Sit upright on the chair and extend your arms overhead to grasp the bar with your hands wider than your shoulders and equidistant from the middle of the bar. To perform the exercise, lean back slightly, pull the bar in front of your face to your chest by flexing your elbows and lowering them toward your ribs. Then reverse back to the starting position. The lat pulldown exercise strengthens several muscles in your upper back and arms.
Latissimus Dorsi
The latissimus dorsi is the muscle for which the lat pulldown exercise is named. It is a long muscle that spans most of your back on either side of your spine. It attaches to the anterior, or front, part of the humerus bone of your upper arm, crosses under your shoulder, and reattaches to the lower thoracic and lumbar vertebrae of your spine, sacrum, iliac crest and lower ribs, according to Susan Hall, author of "Basic Biomechanics." It is one of the primary adductors of the humerus bone, so it helps pull the humerus bone toward your ribs during the lat pulldown exercise.
Teres Major
Like the latissimus dorsi, the teres major muscle attaches to the anterior humerus, in nearly the same location, and crosses under the shoulder. However, the teres major is much shorter than the latissimus dorsi. Instead of moving down the length of your back, it reattaches to the lower inside part of the scapula bone on your upper back. Although it is much smaller than the latissimus dorsi, it is also one of the primary adductors of the humerus bone. During the lat pulldown exercise, it assists the latissimus dorsi in moving your elbows toward the sides of your body.
Pectoralis Major
The pectoralis major consists of two parts, one that attaches to the clavicle and one that attaches to the sternum. Both adjoin as they move away from the center of your body and attach to the inside of the humerus, just below your shoulder joint. The sternal portion of the muscle is also one of the primary shoulder adductors. Therefore, it helps the latissimus dorsi and teres major during the lat pulldown exercise.
Brachialis
The brachialis is located on the front of the humerus bone. It attaches to the ulna bone of your forearm, crosses the front of your elbow joint, and reattaches on the lower half of the humerus. The brachialis is the primary elbow flexor, especially during lat pulldowns when your palms face away from your body. It contracts to flex your elbows during the downward pulling phase of the exercise, although it doesn't have to work very hard due to the downward momentum established by the shoulder adductors before the elbows flex considerably.
References
- "Essentials of Strength Training and Conditioning (Second Edition)"; Thomas R. Baechle and Roger W. Earle; 2000
- "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: Latissimus Dorsi Muscle
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