Pilates Open Book: How to Do It and Muscles Worked

How to do the Open Book

Lie on your side on a mat with your knees bent and stacked at a ninety-degree angle. Extend both arms straight out in front of your chest with your palms resting together.

1. Keep your hips stacked and still throughout the movement.
2. Slowly lift your top arm toward the ceiling.
3. Continue moving that arm backward to open your chest toward the sky.
4. Allow your head and upper spine to turn and follow your moving hand.
5. Pause briefly when you reach a comfortable point of rotation.
6. Slowly reverse the motion to bring your top hand back to the starting position.

• Breath. Teachers cue this differently, but you will often inhale as you open your arm back and exhale as you return to the start. Some instructors prefer the opposite, having you exhale to deepen the rotation.
• Where you feel it. You should feel a gentle stretch across your chest and a mild working sensation in your waist and upper back. You should not feel pinching in your lower back or pain in your shoulder joint.
• How many. 5 to 8 slow repetitions on each side

Common mistakes

• Shifting the hips. Keep your knees glued together and your pelvis completely still. The rotation should come from your upper back rather than your lower body.
• Forcing the shoulder. Let your chest lead the rotation instead of just dropping your arm backward. Your arm should only go as far as your spine comfortably turns.
• Straining the neck. Allow your gaze to naturally follow your moving hand. Do not crank your neck backward or leave it staring straight ahead.
• Moving too quickly. Perform the exercise slowly and with control. Momentum will take away the muscular work of the obliques and thoracic rotators.

Make it easier or harder

Easier

• Place a small folded towel under your head to keep your neck aligned.
• Keep your top hand on your ribcage to guide the rotation instead of extending the arm.
• Place a pillow between your knees to help keep your hips stacked and stable.

Harder

• Place your hands behind your head with elbows wide, focusing the rotation entirely on your upper back without the leverage of a straight arm.
• Perform the movement with your bottom leg straight and only your top knee bent and resting on the floor.

Who should be careful

• Twisting under load is something people with osteoporosis are often advised to limit. Keep the rotation small and upright, or ask your clinician.

Related exercises

• Bent Knee Fall Out Beginner
• Mermaid Beginner
• Spine Twist Beginner
• Corkscrew Intermediate to advanced
• Criss-Cross Intermediate

This exercise is part of our pages on Pilates for Lower Back Pain, Pilates for Neck Pain, Pilates for Posture, Pilates for Golfers, Pilates for Flexibility.

When to see a doctor or physical therapist

• Sharp or shooting pain in your shoulder joint.
• Pinching sensations in your lower back or neck.
• Numbness or tingling radiating down your arm.
• Sudden dizziness when turning your head.

This page is general education, not a diagnosis or treatment plan. If you have a health condition, are pregnant or are recovering from an injury or surgery, check with your own clinician before trying new exercises.

How we put this page together. Exercise data (type, level, equipment and muscles) was compiled by our editors from the classical mat order in Joseph Pilates’ 1945 book and from commonly taught mat repertoire. Muscle lists are a general anatomy guide; cueing differs between teachers. Text drafted with AI assistance and checked by the Editorial Team. See our editorial policy. Last checked October 2026.