Clamshells: The Best Exercise You're Probably Doing Wrong...

If you’re coming to see us for a knee, hip or low back injury one of the most common exercises we prescribe is the clamshell. However, it’s also one of the exercises that most people do incorrectly.

Why: Most adults spend more than 7 hours per day sitting which causes glutes to weaken and hip flexors to tighten. Hip mobility only declines as we age. The less mobility we have in our hips, the more force we take in the low back. The back can be a punching bag for the hips when they’re not moving. It’s not designed to bend all the time, it’s meant for stability and support. If your hips aren’t moving, something else must absorb the force…

The clamshell exercise not only keeps the hips moving, it strengthens both the gluteus medius AND gluteus maximus.

GLUTEUS WHAT? Here's a quick anatomy lesson:



The gluteus medius is the main abductor (movement away from the midline of the body) and external rotator of the hip.

The gluteus maximus extends the hip and assists with abduction and external rotation (toes out) of the leg.

The gluteus minimus serves as the primary internal rotator (toes in) of the hip joint. The gluteus minimus helps with abduction and medial (inward) rotation of the thigh at the hip.

Still with me? Great! Now, let’s learn how to do the clamshell properly…


Lying on a bed on your side, keep the heels together and the hips stable. Make sure your heels, hips and shoulders form a straight line. Some of our patients find it helpful to lie with your back against a couch.

Lift the top leg 3 – 4 inches while maintaining that contact of the ankles and ensuring that the HIPS ARE NOT ROTATING. If your hips rotate or move, try lessening the range of motion.

Movement should be slow and controlled throughout.  Up Slow/Down Slow

DO NOT HOLD at the top 

Try 10 repetitions in a row, switch sides, then repeat.

Did you know that if you rotate the hips you lose engagement of the muscles we’re trying to strengthen? You may have heard one of our Exercise Therapists say that once or twice.

Feeling like you’ve mastered the clamshell? Ask one of us to check it out, we might even be able to make it harder 😉