‘Lats’ are a short form of the word latissimus dorsi, which are large muscles in your back. In fact, they’re the largest muscle in the upper body and connect to the spine, ribs, pelvis, scapula and upper arm. This muscle performs many different functions, including rotating, abducting, extending your arms, and pulling your arms back and down. The lat muscles are essential for stabilization and good posture. Those with weak lats may find they have a hunched posture or get chronic shoulder and back pain. While of course lat pulldown exercises work the lats, you also use your lats in many exercises, from deadlifts to pull ups and bench presses. For this reason they’re an essential muscle for bodybuilders to work on.