Core · Anti-lateral flexion
Copenhagen Plank
The Copenhagen plank is a side plank where your top leg rests on a bench and your bottom leg hangs free. Lifting your hips means the top inner thigh must work hard to hold you up, so it is one of the most direct ways to strengthen the adductors and the obliques together.
Also known as: Copenhagen side plank, Adductor plank, Side plank with leg on bench
- Muscle group
- Core
- Movement pattern
- Anti-lateral flexion
- Type
- Compound
- Equipment
- Bench
- Difficulty
- Advanced
What muscles does the copenhagen plank work?
Primary movers
- Hip adductors
- Obliques
Assisting muscles
- Quadratus lumborum
- Gluteus medius
- Transverse abdominis
- Rotator cuff
The adductors of the top leg are the main target. They squeeze the leg against the bench to hold your hips up, which loads the inner thigh in a way few other exercises do. The adductor longus and magnus both contribute.
The obliques and quadratus lumborum stop your trunk from sagging sideways. This is the same job they do in a standard side plank, but here the long lever of the legs makes it noticeably harder.
The gluteus medius of the bottom leg and the stabilising muscles of the supporting shoulder keep your body in a straight line. The shoulder is under load throughout, so the rotator cuff works to hold the arm steady.
Placing the knee on the bench shortens the lever and makes the exercise easier. Placing the ankle on the bench makes it harder. Many athletes use it because strong adductors support the groin, but build up gradually since the inner thigh fatigues quickly.
How to do the copenhagen plank
Setup
- 1
Lie on your side next to a bench, with your top leg resting on it and the inside of your knee or ankle against the bench.
- 2
Prop yourself up on your bottom forearm with your elbow directly under your shoulder.
- 3
Let your bottom leg hang free below the bench.
- 4
Brace your core and stack your hips and shoulders so your body is in one line.
Execution
- 1
Squeeze your top inner thigh against the bench and lift your hips until your body is straight.
- 2
Keep your hips stacked and facing forward, not rolling backward.
- 3
Hold the top position for a few seconds for an isometric challenge.
- 4
Lower your hips slowly toward the floor.
- 5
Keep your supporting shoulder pressed away from your ear.
- 6
Finish your reps or hold time, then switch sides.
Common copenhagen plank mistakes
Letting the hips rotate backward
The obliques and adductors lose tension and the exercise turns into a twist.
The fix: Stack your hips and shoulders and keep them facing forward.
Dropping the hips quickly
You lose the lowering phase, which is a big part of the training effect.
The fix: Lower over two to three seconds with control.
Shrugging the supporting shoulder
The shoulder sinks into the joint and tires early.
The fix: Press the forearm into the floor and push your shoulder away from your ear.
Going straight to the ankle version too soon
The longer lever overloads the inner thigh and groin before they are ready.
The fix: Start with the knee on the bench and progress to the ankle over several weeks.
How many sets and reps?
| Goal | Sets | Reps | Load | Rest |
|---|---|---|---|---|
| Strength | 3 | 6–10 per side | Ankle on bench, slow lowering | 60–90 s |
| Endurance | 2–3 | 15–30 s hold per side | Knee on bench | 45–60 s |
| Beginner | 2 | 10–20 s hold per side | Knee on bench, bottom leg bent | 60 s |
Use the Copenhagen plank as a core and groin-strength exercise once or twice a week. Start with a short hold from the knee position and build slowly, because the inner thigh can feel sore for a day or two when you first try it.
Running the copenhagen plank in your next block? Hercules logs every set, shows last session's numbers before you lift, and suggests when to add weight.
Get it on Google PlayCopenhagen Plank variations and alternatives
Side Plank
EasierA simpler side-on hold with both feet on the floor.
Plank
EasierA basic front hold to build trunk stability first.
Cable Hip Adduction
AlternativeIsolates the inner thigh with adjustable cable resistance.
Hip Adductor
AlternativeA seated machine option for training the adductors.
Human Flag
HarderA far more demanding side-body skill that builds on side plank strength.
Frequently asked questions
What does the Copenhagen plank work?
It works the inner thigh adductors and the obliques, with the glutes and shoulder stabilisers helping.
How do I make it easier?
Rest your knee on the bench instead of your ankle, and bend your bottom leg if needed.
Is it good for groin injury prevention?
It is widely used to strengthen the adductors, which support the groin, but build up gradually and stop if you feel sharp pain.
How long should I hold it?
Beginners can aim for 10 to 20 seconds per side, and stronger lifters can work up to 30 seconds or slow reps.
Hercules tracks every copenhagen plank you log, shows you last session's numbers before you lift, and flags when your progress stalls.
Get it on Google Play