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Pilates Clam: Steps, Muscles and Common Mistakes

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The Clam, also known as the pilates clam or clamshell pilates, is a beginner contemporary mat exercise. It focuses on side-lying hip rotation while keeping your pelvis perfectly stacked.

This movement targets your gluteus medius and deep hip rotators to build strength and control. As you hold a steady, neutral spine, your obliques also work as supporting muscles to keep your torso stable on the mat.

Exercise data

Type
Contemporary mat
Level
Beginner
Equipment
Mat
Main muscles
gluteus medius, deep hip rotators
Also working
obliques
Spine
neutral spine held steady
Focus
Side-lying hip rotation with the pelvis stacked
Also searched as
pilates clam, clamshell pilates

How to do the Clam

Lie on your side on the mat with your knees bent, resting your head on your bottom arm and keeping your spine neutral.

  1. Stack your hips and shoulders so your body forms a straight line from your head to your tailbone.
  2. Keep your feet resting together on the mat.
  3. Slowly lift your top knee toward the ceiling while keeping your heels touching.
  4. Maintain a completely still pelvis as the leg rotates outward.
  5. Pause briefly at the top of the movement to feel the work in your hip.
  6. Lower your top knee back down to the starting position with control.
  • Breath. Teachers cue breathing differently, but a common pattern is to exhale as you lift your top knee and inhale as you lower it back down.
  • Where you feel it. You should feel the work deep in the side and back of your working hip, as well as light effort in your obliques. You should not feel pinching in your lower back or the front of your hip.
  • How many. 8 to 12 slow repetitions per side

Common mistakes

  • Rolling the hips back. Keep your top hip pointing directly up at the ceiling, using your obliques to prevent your pelvis from tilting backward.
  • Lifting the knee too high. Only open your leg as far as you can without moving your spine or pelvis.
  • Dropping the waist into the mat. Keep a small lift under your bottom waistline to hold a neutral spine.
  • Tensing the neck and shoulders. Relax your upper body and rest your head completely on your bottom arm or a small pillow.

Make it easier or harder

Easier

  • Perform the movement with a smaller range of motion, only lifting the knee a few inches.
  • Lie with your back against a wall so you can feel if your pelvis starts to roll backward.

Harder

  • Hover both feet a few inches off the mat while keeping your bottom knee down, then open and close the top knee.
  • Slow down the pace, taking three full seconds to lift the knee and three seconds to lower it.

Who should be careful

This is one of the gentler exercises in the repertoire, but the usual rule applies: work in a pain-free range and stop if something feels wrong.

Related exercises

This exercise is part of our pages on Pilates for Back Pain, Pilates for Sciatica, Pilates for Osteoporosis, Pilates for Seniors, Pilates During Pregnancy, Pilates After Pregnancy, Pilates for Knee Pain, Pilates for Hip Pain, Pilates for Arthritis, Pilates for Hypermobility, Pilates for Runners, Pilates for Golfers, Pilates During Menopause, Pilates for Balance.

When to see a doctor or physical therapist

  • Sharp or shooting pain in your lower back.
  • A pinching sensation deep in the front crease of your hip.
  • Numbness or tingling traveling down your leg.
  • Pain in your knees when resting them together or opening the leg.

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.