Clamshells

Clamshells are a side-lying exercise for the outer hips. With your hips stacked and your heels together, you lift the top knee and lower it with control. Use them for activation work or in a conditioning session.

Also called the clamshell exercise or clam shells.

Works: Outer hips
Time: About 30 sec each side
Kit: None. A light band is optional
Intensity: 2 of 5 on Prep's scale

Do this in Prep

Updated 13 Oct 2026 · By the Prep team

How to do it

How to do clamshells.

Work each side for about 30 seconds. A higher knee is not the goal: stop the lift before your hips roll back.

Step 1
Stack your hips
Lie on your right side with your head supported by your bent right arm. Bend your hips and knees comfortably, stack your knees and feet, and keep your left hip above your right.
Step 2
Open and lower
Keep your heels together and slowly lift your left knee only as far as you can without rolling your hips back. Lower with control and repeat.
Step 3
Change sides
To change sides, lower your knee, turn onto your left side and reset with your hips stacked and heels together. Repeat with your right knee.

Form

Clamshells form.

Work around the outside of your top hip.

Keep

Stack your hipsKeep the top hip directly above the bottom one.
Keep the heels touching
Lift and lower slowlyUse the range you can control.

Common mistakes

Rolling the pelvis backA higher knee is not the goal.
Forcing the knee openStop the lift before your hip rolls.

Easier version: Use a smaller openingLift only a little, without a band.
Harder version: Add light band resistanceKeep the same small, controlled opening.

Questions