What muscles start a pull-up?

From a still hang, the lower trapezius, latissimus dorsi and serratus anterior set the shoulder blades down and on the ribs before the elbows bend.

The lower trapezius is one of the first muscles to work in a strict pull-up: it pulls the shoulder blade down and helps draw the shoulder blades down from a hang before the elbows bend.

The latissimus dorsi is the largest pulling muscle in a pull-up. It pulls the arm down and back towards the body and helps draw the shoulder blade down. In a strict pull-up it has to start the pull from a still hang, with no swing to help.

The serratus anterior holds the shoulder blade flat against the ribcage while hanging, so the load goes through muscle rather than hanging on the joint.

Once the shoulder blades are set, the elbows bend and the teres major, brachialis and biceps join in. Each structure has its own page with where it runs, what it does, and the drills that work it.

This is general anatomy, simplified. It describes a pull-up, not anybody's shoulder.

Warning signs: see a clinician first

Do not start, or stop, if any of these apply to you:

The pain started with a fall, a dislocation, or a sudden pop or tear, and you cannot lift the arm since.
Numbness, tingling or pins and needles running down the arm or into the hand.
Weakness that is getting worse, or the arm suddenly much weaker than the other.
Pain that wakes you at night and does not ease when you change position.
Swelling, redness, heat or a fever with the pain.
Pain in the chest, jaw or left arm with breathlessness or sweating — call emergency services.
A visible lump, change in shape, or the shoulder looking different from the other.

These are general reasons to have a shoulder examined. They are not a complete list.

Drills for this

Camera checks it

Scapular pull-up

Repeat the active hang as reps: shoulders down, pause, back up to a relaxed hang.

3 × 5–10

Camera checks it

Active hang

From a relaxed hang, draw the shoulders down away from the ears and hold, arms still straight.

3 × 10–20 s

Filmed, counted by hand

Prone Y raise

Lying face down, thumbs up, lift straight arms in a Y shape.

3 × 8–12

Filmed, counted by hand

Scapular push-up

In a push-up position with straight arms, let the chest sink between the shoulder blades, then push the floor away.

3 × 10–12

What it works

In the program

Phase 1 — Set the shoulder blades — Shoulder: kipping works, strict pull-ups do not

Hang again without pain, and learn to draw the shoulder blades down from a hang with straight arms.

Film a set Read the program

The pain rule

0–3 out of 10 during the drill: fine, carry on.
4–5: do less — a smaller range, fewer reps, or the easier version.
6 or more: stop that drill for today.
Worse the next morning than before the session: that session was too much. Step back.
6 or more on waking, any morning: rest the shoulder that day.

Sharp or catching pain, or pins and needles, means stop regardless of the number.