Bar
An underhand pull-up. The supinated grip puts the biceps in a stronger position, so they share more of the work with the lats.
| Muscle | Role | Action |
|---|---|---|
| Latissimus dorsi | Primary | Extends, adducts and medially rotates the arm |
| Biceps brachii | Primary | Flexes the elbow and supinates the forearm |
| Brachialis | Secondary | Flexes the elbow in any forearm position |
| Brachioradialis | Secondary | Flexes the elbow, especially with a neutral grip |
| Teres major | Secondary | Extends, adducts and medially rotates the arm |
| Lower trapezius | Secondary | Depresses and upwardly rotates the scapula |
| Rhomboids | Secondary | Retract, elevate and downwardly rotate the scapula |
| Posterior deltoid | Secondary | Extends, horizontally abducts and laterally rotates the arm |
| Pectoralis major | Secondary | Flexes, adducts and medially rotates the arm |
| Forearm flexors | Secondary | Flex the wrist and fingers and provide grip strength; the pronator teres pronates the forearm |
Primary muscles are the prime movers; secondary muscles assist or stabilise. The balance shifts with grip, stance, range of motion and technique.