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  1. Home
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  3. Exercises
  4. /
  5. Shoulders
  6. /
  7. Standing 90 Degrees Arms Rotation

Exercise guide

Standing 90 Degrees Arms Rotation

  • Beginner
  • Compound
  • Rep-based
  • Shoulders

This isolation movement enhances shoulder joint health and mobility by engaging the rotator cuff, deltoids, and pectorals through controlled internal and external rotation.

Reviewed by the Crucible Fit team · Updated June 2026

Watch the Standing 90 Degrees Arms Rotation demonstrationVideo and instructions for every movement are in the Crucible Fit app.

Muscles worked

Primary

  • Deltoids

Secondary

  • Serratus anterior
  • Trapezius

Equipment

  • Body weight

Setup

  1. Stand tall with your feet shoulder-width apart and your core engaged.
  2. Raise your arms out to the sides at shoulder height, bending your elbows to a 90-degree angle into a 'goalpost' position.
  3. Position your upper arms parallel to the floor with your palms facing forward.

How to do it

  1. Inhale and slowly rotate your forearms downward until your palms face behind you, keeping your elbows pinned at shoulder height.
  2. Exhale as you rotate your forearms back up to the starting position, focusing on the squeeze in the back of the shoulders.
  3. Maintain a controlled 2-second tempo for both the downward and upward phases of the rotation.

Form checklist

  • Keep your elbows aligned with your shoulders; do not let them drop toward your ribs.
  • Maintain a neutral spine and avoid arching your lower back as you rotate.
  • Keep your shoulders depressed and away from your ears to avoid shrugging.
  • Ensure the movement occurs strictly at the shoulder joint without bending the wrists.

Pro tips

  • Imagine your upper arm is a fixed rod; focus on rotating the forearm around that axis to maximize rotator cuff activation.
  • At the top of the movement, slightly retract your shoulder blades to increase engagement in the rear deltoids.

Make it harder

  • Hold light dumbbells or small weighted objects to increase resistance throughout the rotation.
  • Slow the tempo to a 4-second eccentric (downward) phase to increase time under tension.

Frequently asked

What muscles does the standing 90 degrees arms rotation work?
The standing 90 degrees arms rotation primarily targets the deltoids, and also works the serratus anterior and trapezius as secondary muscles.
What equipment do you need for the standing 90 degrees arms rotation?
The standing 90 degrees arms rotation requires no equipment — just your body weight.
Is the standing 90 degrees arms rotation good for beginners?
Yes. The standing 90 degrees arms rotation is a beginner-friendly movement and a strong foundation to build on.

Related exercises

  • 45 Degrees Arms PlankIntermediate · abs, deltoids, obliques, and pectorals
  • Across Chest Shoulder StretchBeginner · deltoids, lats, rotator cuff, and trapezius
  • Alternate Front Kick In Place With Arm CirclesBeginner · abs, calves, deltoids, and pectorals
  • Alternate Knee Raise Side ReachBeginner · abs, deltoids, and obliques

Train it with Crucible Fit.

Every movement in this library is in the app with video and instructions, ready for your own sessions on the days between Crucibles. Your first Crucible is on us.

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