The lat pull down is designed to target many muscles of the back, most notably the latissimus dorsi or lats for short. The latissimus dorsi is the prime mover or agonist muscle. Meaning the Latissimus dorsi brings about the movement in the first place. The antagonist or opposing muscle to the latissimus dorsi is the deltoids.

The pecs are the antagonist muscles in bent barbell rows because bench presses are the opposite movement of bent barbell rows. Yet, in lat pulldowns, the deltoids are the antagonists to the lats because shoulder presses are the opposite movement of lat pulldowns, and vice versa.