How many reps of the side plank with clamshell should you do when you are new to the exercise?

Aim for 2 sets of 8 to 10 clamshell openings per side while holding the plank the whole time, resting a minute between sides. If the hold breaks down before you reach 8 clean reps, shorten the hold time rather than rushing the reps, and build the hold first.

How do you make the side plank with clamshell easier or harder?

Make it easier by lowering the hips to the floor between openings, or by doing the clamshell without the plank first. Make it harder by adding a light resistance band around both knees or by extending the hold time before you add reps.

What is the side plank with clamshell good for, and who should skip it?

It builds the lateral hip and side-core strength behind stable single-leg landings and pain-free running by making the bottom-side glute hold the plank while the top-side glute produces the clamshell motion. It is not the best choice if you cannot yet hold a plain side plank for 20 to 30 seconds with a stable pelvis, since adding the leg motion on top of an unstable hold just trains the compensation.

Intermediate

Side Plank with Clamshell

The side plank already forces the down-side glute medius to hold the pelvis up. Adding a clamshell on the top leg makes the top-side glutes produce movement at the same time, layering a rotational demand on top of the frontal-plane hold. It is a compact progression that builds the lateral hip strength behind stable single-leg landings and pain-free running.

Equipment: Body Weight
Body part: Abs, Glutes
Type: Balance, Strength
Browse by muscle: Gluteus Medius
Browse by movement: Core Brace, Hip Abduction

How to do it

1
Set up a side plank on your forearm with knees bent and stacked.
2
Lift the hips so the body forms a straight line from shoulder to knee.
3
Keep the feet together and the down-side glute working to hold the pelvis up.
4
Open the top knee toward the ceiling like a clamshell without rolling the pelvis back.
5
Pause at the top, then lower the knee under control while keeping the hips lifted.
6
Finish the reps, then switch sides.

Tips

Keep the pelvis stacked, do not let it roll backward as the knee opens.
Do not let the hips sag toward the floor between reps.
Open only as far as your control allows, quality over range.
Regress to a plain side plank hold first if the pelvis keeps dropping.

Variations

Common mistakes

The bottom elbow drifts out in front of the shoulder as the set goes on, letting the whole plank sink toward the floor instead of staying propped.
The knee opens by swinging fast rather than lifting under control, so momentum does the work the glute medius is supposed to do.
The top hip rolls backward as the knee opens, so the first few degrees of the clamshell come from the pelvis turning rather than the hip rotating.
Holding the breath through the hold stiffens the trunk in a way that makes the hips wobble more, not less, by the end of the set.
The top foot lifts along with the knee, turning a hip rotation drill into a small kick that swings from the knee joint instead.

Frequently asked

How many reps of the side plank with clamshell should you do when you are new to the exercise?: Aim for 2 sets of 8 to 10 clamshell openings per side while holding the plank the whole time, resting a minute between sides. If the hold breaks down before you reach 8 clean reps, shorten the hold time rather than rushing the reps, and build the hold first.
How do you make the side plank with clamshell easier or harder?: Make it easier by lowering the hips to the floor between openings, or by doing the clamshell without the plank first. Make it harder by adding a light resistance band around both knees or by extending the hold time before you add reps.
What is the side plank with clamshell good for, and who should skip it?: It builds the lateral hip and side-core strength behind stable single-leg landings and pain-free running by making the bottom-side glute hold the plank while the top-side glute produces the clamshell motion. It is not the best choice if you cannot yet hold a plain side plank for 20 to 30 seconds with a stable pelvis, since adding the leg motion on top of an unstable hold just trains the compensation.

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