Clamshell Exercise: How To, Benefits, Variations

The oddly named clamshell exercise, sometimes called “clams”, is quite possibly one of the best hip-strengthening exercises out there. This is because it is widely used and extremely beneficial for a number of physiotherapy treatment protocols. In this article, we will cover how to properly do the clamshell exercise, along with its benefits and progressions.

Muscles targeted during the clamshell exercise

The primary muscle used and strengthened by doing the clamshell exercise is the Gluteus Medius. This is a smaller and lesser-known muscle compared to the Gluteus Maximus muscle. Gluteus Medius is responsible for abduction and external rotation movements of the hip.

Functionally, the gluteus medius helps stabilize the pelvis when standing on one leg. This is extremely important for sports that involve running and jumping from one leg.

An everyday implication for this muscle is to provide stability and motor control to the pelvic girdle when going up and downstairs. In fact, a weak gluteus medius can cause the knee and lower extremity to fall out of a normal alignment when descending stairs.  This would become quite obvious when someone is having difficulty with the eccentric step down exercise.

Benefits of the clamshell exercise

There are many reasons why people may need to do the clamshell exercise as part of their physiotherapy workout routine.

Because the gluteus medius is the strongest lateral stabilizer of the lower extremity, it is the best muscle to control side to side movements.

The clamshell exercise can be used to correct a Trendelenburg gait, which is when one hip drops as you take a step when walking.

Aside from gait correction, the clamshell is often prescribed for a multitude of injuries including:

  • IT Band Syndrome
  • Patella Femoral Pain Syndrome
  • Osteoarthritis of the knee or hip
  • Knee sprains
  • Post-op Total Hip Replacement
  • Ankle Sprains
  • Low BackPain
  • And more…

How to do the clamshell exercise

  1. Start by lying on your side with the target hip up.
  2. Keep both legs stacked and knees bent to ninety degrees.
  3. Flex your hips to roughly sixty degrees.
  4. Roll forward slightly so that your belly button approaches the ground.
  5. Raise the top knee up while keeping your ankles together and your trunk rolled forward.
  6. Hold the top knee at the highest point you can achieve for 2 to 3 seconds before lowering back down.
Clamshell Exercise Video Instruction

Common mistakes

It is almost too easy to cheat when doing clamshells. Follow the directions carefully in order to get the biggest benefit from this hip strengthening exercise.

When performing the clamshell exercise avoid:

  • Rolling your trunk or back while your hip is moving.
  • Separating your ankles
  • Holding your breath

You should also make sure you are raising your knee as high as you can go. This may require an addition gluteus medius contraction at the very top of the movement.

Progressions to the clamshell exercise

Strengthening exercises need to be challenging and cause some level of fatigue by the end of the workout. Here are a couple ways you can make the standard clamshell exercise ore difficult.

Clamshell Exercise with Band

You can add resistance to your standard clamshell exercise by using an elastic exercise band (I.e. theraband). Cut and tie the elastic band so that it can be wrapped around your legs. The ideal placement for the loop is just above your knees.

You can proceed to perform the clamshell against the band resistance. Be sure to control the leg on the way down as well and not depend on the recoil of the band.

You will need to be mindful of the varying band tensions and select the resistance level that is right for you. These are typically colour coded, with darker colours offering more resistance. Latex free options are also available in there are allergy concerns.

Hip Abduction in Sidelying

Another way to challenge your clamshell exercise is with a sidelying hip abduction exercise. In this variation you will straighten the top leg instead of bending the knee to ninety degrees. Raise the straightened top leg up towards the ceiling in an abduction movement.

The straight leg will act as a longer lever and require more muscle power. You will want to more precisely target the gluteus medius by adding external rotation during the abduction movement. This can be achieved by rotating your leg so that your toes are pointed up towards the ceiling.

Clamshell Pearl

Here is a bonus tip or pearl of wisdom to help you perfect your form while doing the clamshell.

Set up in your standard clamshell position but place your back and bum against a wall. Roll forward so that your top cheek is off the wall but the bottom one is still touching.

Next, raise your knee up towards the ceiling without rolling back and keeping your top bum cheek from touching the wall. This will ensure you are using gluteus medius and not rotating through your back.


A study from the Journal of Orthopaedic & Sports Physical Therapy shows that:

“…gluteus medius activation was greatest when the hip was flexed to 60°”


By the end of this read, you should now know how to properly perform the clamshell exercise and avoid common mistakes. If you perfect this motion, you will improve your running, jumping, and day to day activities, requiring better pelvic motor control.

You will avoid injuries by improving hip mobility on a stable core, as well as encouraging proper lower extremity alignment during functional tasks.

Remember to focus on form and precision before progressing to more challenging exercise variants.

As always, consult with your physiotherapist to make sure this exercise is right for you and help guide you through your recovery or performance goals.

Improve Running with the clamshell exercise


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