Hips · 30–60 seconds of controlled repetitions per side
The clamshell, for the side of the hip
A small movement aimed at a muscle that keeps your pelvis level every time you take a step.
Gluteus medius sits on the outside of the hip and does an unglamorous job: it stops the pelvis dropping every time you stand on one leg, which is most of walking. The clamshell isolates it in side-lying, where the bigger muscles cannot easily take over.
How to do it
- 1
Lie on your side with your knees bent to roughly forty-five degrees
Hips stacked, one directly above the other. Head supported on your lower arm or a cushion.
- 2
Keep your feet together and lift the top knee
Open the knee like the hinge of a clam. The movement is small — this is not about how far the knee travels.
- 3
Lower with control and repeat
You should feel it on the outside of the top hip. If you feel it in the front of the thigh, the leg has rotated — reset and go smaller.
Make it easier
Reduce the range to a few centimetres and slow it down. This muscle responds to being isolated, not to being pushed.
Make it harder
Pause for two seconds at the top of each repetition, or lift the whole bottom side slightly off the floor to add a stability demand.
The mistake that undoes it
Rolling the pelvis backwards to open the knee further. It makes the range look bigger and takes the load straight off the muscle you came for. Keep the hips stacked.
When this one tends to help
Walking that tires one hip before the other, and hips that ache after standing for a long time.
Sharp pain at the outside of the hip, or pain that lingers afterwards, is worth having looked at rather than working through.
Also part of sessions for
Each of those explains what the condition is, what the published guidance recommends, and where this movement fits.
Common questions
What muscle does the clamshell work?
Gluteus medius, on the outside of the hip. It is the muscle that stops your pelvis dropping each time you stand on one leg, which is most of walking. Side-lying keeps the bigger muscles from taking over.
How many clamshells should I do?
The library doses it at 30 to 60 seconds of controlled repetitions per side. Slow and small beats fast and wide, so count quality, not reps.
Where should I feel a clamshell?
On the outside of the top hip. If you feel it in the front of the thigh, the leg has rotated. Reset with the hips stacked and go smaller.
Why is my pelvis rolling back when I open my knee?
Rolling back makes the range look bigger and takes the load off the muscle you came for. Keep your hips stacked, shrink the range to a few centimetres and slow it down.
How do I make the clamshell harder?
Pause for two seconds at the top of each repetition, or lift the whole bottom side slightly off the floor to add a stability demand.
When should I stop?
Sharp pain at the outside of the hip, or pain that lingers afterwards, is worth having looked at rather than working through.
Also called clamshell exercise, clam shell, side-lying hip. Drawn from the clinically authored Vinys exercise library. Read how the method works. General movement guidance, not medical advice.