Exercise guide
Side Lying Internal Rotation
- Beginner
- Isolation
- Rep-based
- Back
- Shoulders
This isolation exercise specifically targets the subscapularis, the largest muscle of the rotator cuff, to improve shoulder stability and internal rotation strength. It is a vital movement for shoulder health, injury prevention, and balancing the joint's mechanics.
Reviewed by the Crucible Fit team · Updated June 2026
Muscles worked
Setup
- Lie on your side on a flat, comfortable surface.
- Position your bottom arm (the working arm) bent at a 90-degree angle with the elbow tucked into your side.
- Rest your head on your top hand or a small pillow to keep your spine neutral.
- Stack your hips and shoulders vertically so your torso is perpendicular to the floor.
How to do it
- Start with your bottom forearm resting on the floor, palm facing upward.
- Exhale as you rotate your forearm upward toward your chest, keeping your elbow pinned firmly against your ribcage.
- Inhale as you slowly lower your forearm back to the starting position under full control.
- Perform the movement with a controlled 2-0-2 tempo (2 seconds up, 2 seconds down).
Form checklist
- Keep your elbow glued to your side; do not let it drift away from your body.
- Maintain a neutral wrist throughout the entire range of motion.
- Ensure your torso remains still; do not roll your chest forward or backward to create momentum.
- Only rotate as far as your natural range of motion allows without pain.
Pro tips
- Place a small rolled-up towel between your elbow and your ribs to provide a pivot point and ensure better subscapularis recruitment.
- Focus on the 'deep' feeling in the front of the shoulder rather than trying to use your chest or bicep to lift the arm.
- Keep your shoulder blade retracted and depressed (down and back) to stabilize the joint.
Make it harder
- Hold a light household object, such as a water bottle, to add incremental resistance.
- Add a 3-second isometric hold at the peak of the contraction (when the forearm is closest to the chest).
Frequently asked
- What muscles does the side lying internal rotation work?
- The side lying internal rotation primarily targets the deltoids and rotator cuff, and also works the biceps and serratus anterior as secondary muscles.
- What equipment do you need for the side lying internal rotation?
- The side lying internal rotation requires no equipment — just your body weight.
- Is the side lying internal rotation good for beginners?
- Yes. The side lying internal rotation is a beginner-friendly movement and a strong foundation to build on.
Related exercises
- Band Warm Up Shoulder StretchBeginner · deltoids and rotator cuff
- Cable Kneeling Shoulder Internal RotationIntermediate · deltoids and rotator cuff
- Dumbbell Lying External Shoulder RotationIntermediate · deltoids and rotator cuff
- PVC Front Rack StretchBeginner · deltoids, lats, rotator cuff, and triceps