Exercise guide
Seated Shoulder 90 Degrees Internal Rotation
- Beginner
- Isolation
- Rep-based
- Back
- Shoulders
- Waist
This isolation exercise targets the internal rotators of the shoulder, specifically the subscapularis, while engaging the anterior deltoid and pectorals. It is highly effective for improving shoulder stability and rotator cuff health using self-applied manual resistance.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Sit upright on the edge of a flat bench with your feet planted firmly on the floor.
- Raise one arm out to the side at shoulder height (90 degrees abduction) and bend the elbow to 90 degrees so your forearm is parallel to the floor.
- Place the palm of your opposite hand on the inside of the wrist of the elevated arm to provide manual resistance.
How to do it
- Exhale as you rotate your forearm downward toward the floor, using your shoulder to push against the resistance of your opposite hand.
- Maintain a 90-degree angle at the elbow and keep your upper arm horizontal throughout the movement.
- Inhale as you slowly return to the starting position, maintaining constant tension and a controlled 3-second eccentric tempo.
- Complete all repetitions on one side before switching to the other arm.
Form checklist
- Keep your elbow aligned with your shoulder; do not let it drop toward your ribs.
- Maintain a tall, neutral spine and avoid shrugging your shoulders toward your ears.
- Ensure the rotation occurs strictly at the shoulder joint, not by flexing the wrist.
- Keep your shoulder blade pinned back and down throughout the set.
Pro tips
- Focus on the 'mind-muscle connection' by visualizing the humerus rotating inward within the shoulder socket.
- Adjust the pressure of your resisting hand to ensure the muscle is challenged through the entire range of motion, not just at the start.
Make it harder
- Increase the manual resistance applied by the non-working hand to its maximum manageable level.
- Add a 3-second isometric hold at the point of maximum internal rotation (when the forearm is closest to the floor).
Frequently asked
- What muscles does the seated shoulder 90 degrees internal rotation work?
- The seated shoulder 90 degrees internal rotation primarily targets the rotator cuff, and also works the abs, deltoids, lats, and serratus anterior as secondary muscles.
- What equipment do you need for the seated shoulder 90 degrees internal rotation?
- The seated shoulder 90 degrees internal rotation requires no equipment — just your body weight.
- Is the seated shoulder 90 degrees internal rotation good for beginners?
- Yes. The seated shoulder 90 degrees internal rotation is a beginner-friendly movement and a strong foundation to build on.