Exercise movement reviewed by:Cody Lockling, MS, CSCS

How Iridium Programs This

Iridium recognizes this movement imposes load on the posterior deltoids alongside the biceps, contributing to accumulated volume for both muscle groups. The AI analyzes your 7-day training history to ensure your rear delts are sufficiently recovered to stabilize the external rotation during the curl. To encourage strict execution, Iridium emphasizes RPE targets rather than rapid load progression for this accessory lift.

Form Cues

Keep your elbows glued tightly to your ribs throughout the set
Rotate your forearms outward as you curl up, like opening double doors
Squeeze your shoulder blades together slightly to stabilize your posture
Lower the weights slowly, resisting the pull of gravity
Keep your wrists neutral or slightly extended, avoiding excessive curling

Don't

Don't let your elbows flare out or drift forward away from your body
Don't swing your hips or arch your back to generate momentum
Don't shrug your shoulders up toward your ears as you lift
Don't rush the lowering phase of the movement
Don't allow your shoulders to roll forward at the bottom of the rep

Common Mistakes

Using too much weight, forcing the elbows to separate from the torso
Failing to fully rotate the palms outward at the top
Performing the movement too fast and losing tension
Allowing the wrists to curl inward instead of the biceps doing the work
Leaning backward to counterbalance the weight

Muscles Worked

This exercise primarily targets the short head of the biceps brachii, which contributes to the thickness of the inner arm. Secondarily, it heavily recruits the external rotators of the shoulder (infraspinatus and teres minor) and the posterior deltoids, making it excellent for correcting rounded shoulders.