← EXERCISE LIBRARYMobility
Clamshell
Side-lying knee opening that isolates the glute medius — the muscle that keeps the knee tracking and the pelvis level under load.
- 01Lie on one side, hips and knees bent to about 45 degrees, heels in line with the spine.
- 02Stack the hips vertically and rest the head on the lower arm.
- 03Keeping the heels touching, open the top knee as far as it goes without the pelvis rolling back.
- 04Pause at the top, then lower under control.
- 01The pelvis does not move — only the knee.
- 02Feel it in the side of the hip, not the front.
- 03Small range done honestly beats a big range done by rolling.
- 01Rolling the top hip backwards to open further — the range comes from the spine and the glute medius stops working.
- 02Letting the heels separate, which turns it into a hip flexor drill.
- 03Rushing the reps — this is a low-load activation, and speed removes the only stimulus it offers.
Note: Reference material, not a prescription. Load, volume and whether this movement suits you at all depends on your assessment — if something hurts, stop and get it looked at.