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The clamshell exercise – Benefits, variation, and progressions

This article explains the clamshell exercise’s benefits as well as progressions, e.g. with exercise bands, to make it more difficult. Does the clamshell exercise hurt? We explain why this might be and what you can do instead. Remember, if you need more help with an injury, you're welcome to consult one of our physios online via video call.

Clamshell exercise benefits, progressions and why it may hurt sometimes.

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In this article:

I demonstrate the clamshell exercises described below in this video:

Clamshell exercise benefits

You may have heard some trainers and physiotherapists say, “The clamshell exercise is a waste of time; it's not a functional exercise; you want to be doing functional exercises.” But that's a bit short-sighted, because there are situations in which the clamshell exercise can be valuable.


1. It targets the gluteal muscles

When we do a squat, we use our gluteal muscles in our hips to prevent our knees from collapsing inwards and to keep them nicely in line with our feet.

However, this is quite difficult for people whose gluteal muscles are weak or untrained. Or people simply don’t understand how to do that corrective movement using their glutes. In these cases, the clamshell is an effective way to teach you how to create the turning out movement using your glutes and to strengthen up those gluteal muscles to be able to do proper squats later on.


Also, if you have a hip injury, the clamshell is a good way to compare the strength of your glutes on the injured side to those on the uninjured side, and then to strengthen up those weak muscles until they are on par with the uninjured side.

You may not be able to do functional exercises when you're injured. In which case the clamshell exercise can help you maintain your glute strength.
You may not be able to do functional exercises while you're injured, so the clamshell exercise can help you to maintain your glute strength.

2. When an injury prevents you from doing other exercises

When you have an injury, e.g. to your knee or foot, that prevents you from doing more functional exercises, such as squats, the clamshell can be a good substitute for strengthening the glutes until other exercises are possible again.

3. Core control

The clamshell exercise teaches you to move your leg without moving the rest of your body. This is an important skill to master for controlling your core.

The basic clamshell exercise

The clamshell exercise

📽️ Video demo



  1. Lie on your side.

  2. Make sure your hips are vertical; so, the top one should not be leaning forwards or backwards.

  3. Your thighs can be anywhere from a 30-degree angle to a 60-degree angle to your hips – whatever is comfortable.

  4. Your top foot should be on top of the bottom foot.

  5. Tighten your tummy muscles gently.

  6. Lift your top knee, rotating it backward as far as is comfortable while keeping your feet together and your hips vertical.

  7. Bring the knee back down slowly.


Top tips

  • If you can't get down to the floor because you've got a knee injury, or your hip just doesn't like lying on a hard surface, do it on a bed or anywhere you're comfortable. Later, when you get better, you can move to the floor or use a nice, thick mat.

  • If your head is hanging uncomfortably, put your hand or arm or a pillow under it.

  • You can place the top hand on the floor in front of you for more stability in the beginning.

Clamshell exercise progressions – How to make them more challenging


When you can do three sets of 15 of a specific type of clamshell exercise, you’ve reached the limit of its benefits because you’re now strong enough for it. So now it’s time to make things somewhat harder.


Clamshell exercise with band

Resisted clamshell exercise with band

📽️ Video demo



  1. Put or tie an exercise band around your thighs, just above the knee.

  2. Do the basic clamshell exercise as described above.

  3. Make sure to lower your leg very slowly against the resistance – if you allow the exercise band to drag your leg down quickly, you’ll lose the benefit of the exercise.


Top tips

  • Tie the band so that your legs are close together; you want resistance from the moment that you lift your top leg.

  • Start with a low-resistance band (usually the yellow one) so that you get the full range of motion, but it’s just a bit tougher than without the band.

  • Rest for about a minute when you switch sides so that your muscles are well-rested each time you start.


Progress to an exercise band with more resistance as soon as you can do three sets of 15.

Here is a selection of exercise bands available on Amazon. You can also visit the

TheraBand Store for more options.

Clamshell exercise with unsupported foot

If you don't have an exercise band, you can make the clamshell exercise more difficult by lifting the top foot slightly, so that it doesn’t rest on the bottom one.

📽️ Video demo



  1. Position yourself on the mat as if you're going to do the classic clamshell exercise.

  2. Lift your top foot, so it hovers about 5 cm to 10 cm above your other foot.

  3. Now, rotate your top knee up and back. Try to keep your foot still and hovering in the same spot.

  4. Then reverse the movement, slowly lowering your knee until your knees touch.


Top tip

  • Use your stomach muscles to stabilise yourself. Because your top foot is no longer resting on your bottom foot, this version of the clamshell becomes as much a stability exercise as a strength exercise.


Clamshell exercise with feet lifted

📽️ Video demo


  1. Assume the classic clam starting position.

  2. Then, lift both feet up off the floor – they must remain in this position throughout the exercise.

  3. Perform the classic clamshell movement, slowly turning the top knee up and out.

  4. Complete all your repetitions before lowering your feet to the floor.


Top tip

  • You will feel that your bottom glutes are now also working (as an isometric clamshell, to keep the bottom foot up off the floor), so make sure you rest well between repetitions.

Why the clamshell exercise may hurt


1. Range of motion too big

When you try to open your legs wider than their current range of motion and you strain to lift the top knee quite high, it can cause things to pinch or cramp when you’re at the top.


2. Legs at wrong angle

Also, not everybody's hips have the same range of motion. So, sometimes it doesn't like the angle you place your legs at, and you can then get a pinching in the groin when you do the clamshell movement. So, don't force anything; adjust your leg position if it’s uncomfortable.


3. Not stabilising properly

If you allow your hips to lean backwards and things move in an uncontrolled way, it might put strain on your back, especially if you have a back injury or your back muscles are not strong enough.


4. Injuries that can be aggravated by the clamshell exercise

In my experience, the clam exercise usually makes the following injuries feel worse.


Gluteal tendinopathy and/or hip bursitis

I couldn’t find any research to explain why this happens. Here’s what I think:

  • There is evidence that when you do the clam, it also activates the tensor fasciae latae. This muscle runs over your hip, where the bursa is. So, when you do the clamshell, the tensor fasciae latae rubs over the gluteal tendons and/or bursae which are already irritated.

  • But I think it possibly also pinches the injured tendons when you’re at the top of the movement.


When you have gluteal tendinopathy, there are better exercises to do than the clamshell – here’s an article about that.


High hamstring tendinopathy

Same as with gluteal tendinopathy, I think it's about how the high hamstring tendons attach to the sit bone, and there's something about the clamshell exercise action that just irritates them when you open and close the legs.


Piriformis syndrome

Some people do the clamshell action to try and strengthen the piriformis.

  • First, you don't actually strengthen the piriformis that well in the clam position; it works more when your legs are a bit straighter.

  • But also, when you have piriformis syndrome, your sciatic nerve is often irritated. If you think of the sciatic nerve running either under the piriformis or often through it, doing an action like the clamshell can really irritate it more.


Clamshell exercise alternative


When it really hurts your bottom hip when you lie on your side, or your neck just doesn’t like that position, you can do “clamshells” on your back with an exercise band instead of gravity providing the resistance.

If the clamshell exercise hurts, this variation or alternative exercise may help.


📽️ Video demo



  1. Lie on your back with the exercise band around your thighs just above the knee.

  2. Keep one leg steady while moving the other leg outwards and downwards.

  3. Slowly bring back the leg that you moved; don’t allow the exercise band to let it snap back.


Top tips

  • Put a pillow under your head if you feel that your neck needs it.

  • You can do up to 15 repetitions with one leg at a time, or you can alternate the legs as you go along.

  • When you do this version of the exercise, both your legs are working (the one to stabilize and the other to create the movement). So, you must rest between sets to allow both legs to fully recover.

How we can help

Need more help with your injury? You’re welcome to consult one of the team at SIP online via video call for an assessment of your injury and a tailored treatment plan.

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Maryke Louw

About the Author

Maryke Louw is a chartered physiotherapist with more than 20 years' experience and a Master’s Degree in Sports Injury Management. Follow her on LinkedIn and ResearchGate.


  1. Reiman, M. P., Bolgla, L. A., & Loudon, J. K. (2012). “A literature review of studies evaluating gluteus maximus and gluteus medius activation during rehabilitation exercises” Physiotherapy Theory and Practice 28(4), 257-268.

  2. Moore, D., Semciw, A. I., & Pizzari, T. (2020). “A systematic review and meta-analysis of common therapeutic exercises that generate highest muscle activity in the gluteus medius and gluteus minimus segments” International Journal of Sports Physical Therapy 15(6), 856-881.

  3. Giphart, J. E., Stull, J. D., LaPrade, R. F., Wahoff, M. S., & Philippon, M. J. (2012). “Recruitment and activity of the pectineus and piriformis muscles during hip rehabilitation exercises: an electromyography study” The American Journal of Sports Medicine 40(7), 1654-1663.

  4. Sidorkewicz, N., Cambridge, E. D., & McGill, S. M. (2014). “Examining the effects of altering hip orientation on gluteus medius and tensor fascae latae interplay during common non-weight-bearing hip rehabilitation exercises” Clinical Biomechanics 29(9), 971-976.


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