How to Do the Clamshell

The gluteus medius is often overlooked — and underworked. Responsible for hip abduction, the so-called side butt is essential for activities like running and squatting. The clamshell is one great way to activate and strengthen this small-but-mighty muscle.

The clamshell looks exactly like it sounds: Lying on one side, ankles together, hinge at the hips to raise and lower the top knee — a move that resembles a clamshell opening and closing. This low-impact move requires little space and no equipment.

It sounds simple — easy, even — but the clamshell’s apparent simplicity is exactly what can stand in the way of its effectiveness.

The clamshell isn’t simply raising and lowering the knee. It requires engaging the glute med of the top leg to initiate the open–close motion.

Moreover, it is not just the top leg that is working. To maximize the clamshell’s benefits, it’s important to engage the bottom leg, too, creating tension by pressing it gently against the floor.

For some people, building the mind–body connection to isolate the glute med will be the first (and possibly ongoing) challenge. Start with body weight only. Once you can control the full movement, progress by looping a small resistance band around your thighs just above the knees.

Another common pitfall is focusing on raising the knee as high as possible while ignoring the need to keep the hips stacked and squared in front of you. Rocking, swaying, or otherwise moving the hips and pelvis to achieve greater knee height not only diminishes the glute med’s work, but it can result in discomfort. Move slowly and with control, keeping the focus on the hips rather than on the knees.

Get the most out of your clamshell with the following tips:

1. Lie on one side with your knees bent and feet in line with your shoulders and hips. Make sure your ankles, knees, and hips are stacked. Prop yourself up or rest your head on your bottom arm.
2. Keeping your body squared in front of you and your feet together, engage your hips to spread your knees open. Maintain an active bottom leg by gently pressing it into the floor and keep your core engaged throughout the movement.

3. Raise the top knee only as high as you can without rocking or shifting the hips. When you reach the end of your range, hold the top position for a moment. Then reverse the movement with control.

4. Repeat for reps. Begin with three sets of 10 reps per side and build up to three sets of 20 per side.

4 Clamshell Variations

1) Banded Clamshell

2) Elevated Clamshell

3) Clamshell Bridge

4) Clamshell Bridge With Dumbbell