Copenhagen Plank for Runners: A Beginner's Guide

The Copenhagen plank is a side plank where your top leg rests on a bench, so the muscles on the inside of your thigh do the work of holding your hips up. For runners, the best way to start is the short-lever version, with your top knee on the bench, holding for 10 to 20 seconds per side, twice a week, and only moving to the harder long-lever version once that feels solid.

It looks simple and feels anything but. Most beginners are surprised by how quickly the inner thigh starts shaking, which is exactly why it is worth doing. This guide walks you through the setup, the cues, a five-level progression ladder, the common mistakes, and a 4-week plan that slots into a normal running week.

What is a Copenhagen plank?

The Copenhagen plank (also called the Copenhagen adduction exercise or Copenhagen side plank) takes its name from the Danish sports researchers who studied and popularised it. You lie on your side, rest your forearm on the floor, place your top leg on a bench, then lift your hips until your body forms a straight line. Your top leg presses down into the bench, and that squeezing action is what holds you up.

There are two main versions. In the short-lever version, the bench supports your top leg at the knee, which makes it much easier. In the long-lever version, the bench supports your top leg at the ankle, which makes the same muscles work far harder. Beginners should always start short.

Why does adductor strength matter for runners?

Running is a long chain of single-leg landings. Each time you land, your adductors help steady your pelvis and stop your thigh drifting inwards, working alongside your glutes. If they are weak or tire quickly, you may lose a little control on every stride, and that can add up over a long run.

Most of the research on the Copenhagen plank comes from football, not running. In one small trial, young footballers who did an eight-week Copenhagen programme increased their eccentric adductor strength (their ability to control the muscle while it lengthens) by roughly a third. A larger trial in semi-professional football teams found that players following a simple Copenhagen-based programme reported groin problems less often than those who trained as normal. Running is a different sport, so treat this as a sensible, low-cost reason to train the area rather than a promise of fewer injuries. For the wider picture, including other inner-thigh exercises, see our guide to adductor and groin strength for runners.

What muscles does the Copenhagen plank work?

• Adductors (top leg): the main target. This group runs down the inside of your thigh and does most of the lifting.
• Obliques and deep core: the muscles down the side of your trunk keep you from sagging or twisting, just like a normal side plank.
• Hip muscles (bottom leg): on harder versions, lifting the bottom leg towards the bench brings in the hip muscles on the lower side too.
• Shoulder stabilisers: your supporting shoulder works to keep you steady over your elbow.

How do you do a short-lever Copenhagen plank?

You need something sturdy and stable at roughly knee height: a gym bench, a solid step, or the seat of a heavy sofa. Make sure it will not slide or tip, and put a folded towel on top for comfort. No bench? A training partner can hold your top leg at the knee instead. If you already find a normal side plank tough, spend a couple of weeks on our beginner's guide to planks first.

1. Lie on your side next to the bench, propped up on your forearm, with your elbow directly under your shoulder.
2. Place the inside of your top knee on the bench. Your bottom leg rests on the floor underneath.
3. Stack your hips and shoulders, as if your back were against a wall. Do not roll forwards or backwards.
4. Press your top knee down into the bench and lift your hips until your body makes a straight line from head to knee.
5. Let your bottom leg hang beneath the bench, or keep its knee lightly on the floor if you need help.
6. Hold, breathing steadily. Push the floor away with your forearm so your shoulder does not sink.
7. Lower with control, rest, then switch sides.

What is the best Copenhagen plank progression?

Think of it as a ladder from easier to harder. Stay on each level until you hit the target with clean form, then move up one rung. Plenty of runners never need to go beyond level 3 or 4, and that is fine.

The long lever puts much more leverage across your knee, because the support is at your ankle. If the inside of your top knee complains on level 4, drop back to level 3 and build more time there first.

How long should you hold a Copenhagen plank?

As a rough guide, most beginners do well with 3 sets of 10 to 20 seconds per side on the short lever, resting about 45 to 60 seconds between efforts. Once you can manage 3 sets of 30 seconds with your hips high and still, you have earned a try at the long lever, starting again at 5 to 10 seconds.

You can also train it in reps instead of holds: lift your hips, pause for two seconds at the top, lower slowly, and repeat for 5 to 8 reps per side. Either approach works. What matters is that the last few seconds are hard but your form stays tidy. If your hips start to drop, the set is over.

What does a 4-week Copenhagen plank plan look like?

This plan is for a complete beginner doing two short sessions a week. All times are per side. If a week feels too hard, repeat it rather than pushing on.

What are the most common Copenhagen plank mistakes?

• Hips sagging. Fix: think about lifting your bottom hip towards the ceiling, and shorten the hold. Ten good seconds beat thirty saggy ones.
• Rolling forwards or backwards. Fix: stack your hips and shoulders. Imagine your back is pressed against a wall.
• Sinking into the shoulder. Fix: keep your elbow directly under your shoulder and push the floor away.
• Rushing to the long lever. Fix: earn it with 3 x 30 seconds on the short lever first. The long lever is a big jump.
• Holding your breath. Fix: breathe slowly and steadily. If you cannot breathe, the level is too hard.
• A bench that is too high or wobbly. Fix: use something solid at roughly knee height, with a folded towel for padding.
• Pushing through sharp pain. Fix: working muscles should burn and shake, but sharp pain in the groin or knee means stop. Go back a level, and see a physio if it does not settle.

How does the Copenhagen plank fit into a hybrid week with running?

The Copenhagen plank takes five to eight minutes, so it is easy to fit in. The main rule is to keep it away from your hardest sessions, ideally not on the same day as or the day before intervals or a long run, because tired inner thighs are not what you want for those. A simple week might look like this:

• Monday: easy run, then a short strength session including Copenhagen planks.
• Tuesday: rest or mobility.
• Wednesday: intervals or a HIIT session.
• Thursday: easy run, then a strength session including Copenhagen planks.
• Friday: rest.
• Saturday: long run.
• Sunday: rest or an easy walk.

Doing it straight after an easy run works well, since you are already warm. If you are unsure whether to lift before or after a run on a given day, our guide to strength training before or after running walks through it. Pair the Copenhagen plank with a glute move and a normal side plank, and you have a compact hip and core routine that covers most of what runners need.

If you would rather not piece this together yourself, Edge builds strength work like this into one hybrid plan alongside your running, HIIT and mobility, and with Edge Pro you can message a real coach whenever you want a second opinion on your form or your week.

This article is general guidance, not medical advice. If you are new to exercise, returning from injury, or managing a health condition, speak to your GP before starting, and see a physio for any niggle that does not settle.