Chest Expansion: Technique, Muscles Worked and Modifications

How to do the Chest Expansion

Kneel on the reformer carriage facing the footbar, holding the straps in your hands with your arms reaching forward.

1. Keep your spine in a neutral position and look straight ahead.
2. Pull the straps back past your hips by engaging your back and the backs of your arms.
3. Hold your arms steady behind you while balancing on your knees.
4. Turn your head smoothly to look over your right shoulder.
5. Turn your head to look over your left shoulder.
6. Return your head to the center.
7. Control the carriage as you slowly release your arms back to the starting position.

• Breath. Teachers cue breathing differently, but you will often inhale as you pull the straps back, pause briefly for the head turns, then exhale as you return your arms.
• Where you feel it. You should feel your latissimus dorsi, triceps, and posterior deltoids working hard, along with your spinal extensors supporting your back. You should not feel pinching in your lower back or strain in your neck.
• How many. 3 to 5 repetitions, alternating the starting direction of the head turn

Common mistakes

• Losing neutral spine. Keep your spinal extensors engaged to prevent your lower back from arching or rounding.
• Shrugging the shoulders. Focus on engaging your latissimus dorsi to draw your shoulders down away from your ears.
• Rushing the head turn. Move your neck slowly and deliberately rather than snapping your gaze side to side.
• Bending the elbows. Keep your arms straight to ensure the work stays in your triceps and posterior deltoids.
• Leaning forward. Keep your weight centered over your knees and avoid letting the springs pull your torso forward.

Make it easier or harder

Easier

• Sit cross-legged on the carriage instead of kneeling.
• Perform the arm pull back without the head turn to focus on balance.
• Use a lighter spring setting to reduce the resistance on your arms.

Harder

• Kneel with your knees closer together to challenge your stability.
• Perform the movement on a heavier spring setting to demand more from your upper body.

Who should be careful

• Kneeling can be uncomfortable with knee pain; use extra padding or choose a version that keeps you off the knees.
• Reformer springs and the moving carriage add load and instability. Learn it with a qualified instructor, who can set the springs for your body and goals.

Related exercises

• Pulling Straps Beginner to intermediate
• Supine Arm Series Beginner
• Down Stretch Intermediate
• Kneeling Arm Series Beginner to intermediate
• Coordination Intermediate

When to see a doctor or physical therapist

• Sharp pain in your shoulder joints when pulling the straps back.
• A pinching sensation in your lower back that does not improve with posture adjustments.
• Dizziness or vertigo during the head turn.
• Numbness or tingling traveling down your arms.

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 reformer 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.