Side-Lying Internal Rotation Guide | Trapezius Strength

Learn how to perform the side-lying internal rotation with a barbell to improve shoulder stability and strengthen your upper back.

How to Perform

  1. Lie on your side on a flat bench or the floor with your knees slightly bent for stability.
  2. Position your bottom arm perpendicular to your body, holding a lightweight barbell with an overhand grip.
  3. Rest your upper arm across your torso or along your side to keep it out of the movement path.
  4. Slowly rotate your bottom forearm toward your midsection, bringing the barbell toward your floor-side hip.
  5. Maintain a 90-degree angle at the elbow as your shoulder joint rotates inward.
  6. Hold the bottom position for one second before slowly returning the bar to the starting vertical position.
  7. Perform all repetitions on one side before flipping over to repeat the movement with the other arm.

Common Mistakes

  • Using a heavy barbell that compromises controlled rotation
  • Allowing the elbow to drift away from the torso during the lift
  • Jerking the weight upward instead of using smooth muscle contractions
  • Arching the lower back to compensate for limited range of motion

Muscles Worked

Primary movers

  • Trapezius

Stabilizers

  • Rhomboids
  • Infraspinatus
  • Teres Minor
  • Rear Deltoids

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