Thinking about HOW to do your clamshells is the important part! And that will vary from person to person.
But an awesome starting place is to think of the motion as the rotation of the top of your leg bone in your hip socket. That’s a good way to get past two of the common mistakes in clamshell: overuse of the quads and hip flexors and rocking back your whole pelvis instead of isolating the rotation.
Looking at the pics above, see if you can envision getting past the big surface muscle, the gluteus maximus, and accessing those little muscles in the next two pictures.
The middle image includes gluteus medius at the top (only the posterior fibres contribute to external rotation), piriformis next and then the smaller ones are superior gemellus, obturator internus (which is a bigger muscle than you can see- the rest of it wraps around the pelvis and lies underneath the extenus shown in the next picture), inferior gemellus and quadratus femoris.
The last one is obturator externus, which you can’t see from the back (and which has the internus in about the same shape underneath).
Why is all this important?
Because how your legs are placed, supported and moved from your hip joints by all those deep little muscles is crucial for hip health AND because your hips affect your knees. Your feet also affect your knees, but we’ll get to that in a couple of weeks! : ))
If your knees tend to track in towards centre when you move through the world, then changing them needs to start from either end. Trying to change it while you’re actually doing the thing (walking, running, jumping, squatting, etc) is really complicated and maybe not possible. If your feet are on the ground, then the whole foot-shin-knee-thigh-hip chain is dictated by the need for your foot to meld to the unyeilding surface.
And here’s where the humble clamshell shines!
When you lie on your side, with your feet not required to meet the ground, you remove a limiting condition. When you bend your knees, you shorten the lever of your leg and thus lessen the load for your hip muscles. That makes it an easier place for your tissues to do the work and your brain to connect to what might be an unfamiliar motion.
Doing a set of focused, finicky, mindful clamshells BEFORE you head out and do your bigger, more fun and functional thing is a fantastic way to introduce a motor skill, activate support, wake up your brain and prepare to load your muscles, joints and other tissues to serve you for awesome, lifelong, resilient, durable, sustainable, lifelong health and wellness. And isn’t that what we all want?
I know I do!
Look at how much I changed the position of my leg in one short, targeted session!
The left pictures show how when I orient my feet forward, my knee pits are so internally rotated that you can only see one of the two connecting ligaments that should be facing straight back.
On the right, can you see how different my left leg looks? It’s aligned more to centre, so when I move around, my knee is better settled between my thigh and my shin and won’t get strained or stressed unnecessarily.