Latissimus dorsi is the widest muscle in the body. It is also the one most people pull with their arms instead of their back.
Lats — Biceps, Rear delts, Traps
PrimarySecondaryNot worked
What it is
The lats run from the pelvis and lower spine to the humerus. They do two things: bring the arm down (adduction) and back (extension). Hence the split that structures all back training — vertical pulls bias adduction, horizontal pulls bias extension. You want both.
How to load it
The back tolerates more volume than most groups: fifteen to twenty-five weekly sets sit well, because the work is shared between lats, traps and rear delts. Alternate vertical and horizontal within the week. Single-arm work earns its place — it allows a range a barbell forbids.
The recurring mistake
Pulling by bending the elbows first. The movement starts at the shoulder blade: it depresses and retracts, then the elbow follows. If your biceps burn before your back, the order is reversed.