Think of a simple side plank then make it extreme. Boom- the Copenhagen plank. As with most exercises, there are quite a few variations of this extreme’d outside plank. The most basic is a variation where your top foot is elevated on a bench, your hand or elbow are on the floor helping you get into that plank position, and you bring your bottom leg off the floor. As your foot on the bench and hand or elbow are on the floor, you then bridge your hips up so your body is ideally in a straight line. Now that you have a basic gist of this often-underused accessory movement.

One of the most immediately noticeable muscles worked when performing the Copenhagen plank is your adductors. And, lucky for you, your adductor is a muscle that can often be forgotten about but one that needs to be worked. Any athlete that has dealt with a groin injury knows that the recovery from this can be painful both in physicality but also the length of time it takes to feel good again. So prioritizing a movement like this can be critical in your programming and planning to help not only strengthen the stability in your entire body but also help strengthen your groin. In the most basic sense, the adductor's role is to help move your leg closer and further away from the midline of your body. But when unpacking that a little more, the adductor plays a very important role in stabilizing the pelvis, hips, knees and feet. Weak adductors can change biomechanics, and this often results in decreased athletic performance with an increased risk of injury.

For the sake of this article, when talking “Core” here we are referring to the obliques, transverse abdominis and rectus abdominis.  The Copenhagen plank can help you level up your core strength in so many ways.  And we know as athletes that strengthening your core can and will improve most every aspect of your training in the gym and help you not only lift heavier every week but also you will see improvement in your sport and physique.  

Boulder shoulders anyone? Sure, this is helpful for looks and sport, but what about using the Copenhagen plank as an advantage to get stronger and more stable shoulders? Research shows that those suffering shoulder injury would benefit from better trunk stability and core strength. While the act of holding a Copenhagen plank immediately works the deltoids, you will notice shoulder stability improvements and your smaller stabilizer muscles also get a run for their money with this movement. 

A deceiving movement that might look easier than it is, there are many ways to break a Copenhagen plank down to help match your ability level. A lot of it has to do with lever lengths. And you thought you wouldn't need to use any of what you learned in physics 101, but here we are. The longer the lever (here, that being your leg) the more challenging it is. Breaking down beginner, intermediate and advanced can be helpful when tackling how to appropriately use this movement in your specific training. You can get a huge bang for your buck by adding in most any variation of the Copenhagen plank to your training.

For each of the variations we are about to dive into, a few things hold true across every modification. You will place one leg on a raised platform, typically a bench, with the inside of your ankle, knee or other part of your leg resting on top. The other leg will either remain on the ground, touching the underside of the bench, or with a bent knee. Your upper body will be supported by your forearm on the ground, and you will have a straight line from the top of your head to the lowest point of your body (either your foot or knee). The goal is to maintain a straight line from your head to feet, just as you would a traditional side plank.

The bent knee modification has you set up with your forearm supporting your upper body and resting a bent knee on top of your bench or elevated surface.  The bottom leg is then also bent while resting on the ground underneath the bench.

Similar to your set up for the basic bent knee modification, with the iso hold you are now also bending your bottom leg and holding it up and pressing against the underside of the bench or elevated surface you are using.  Ideally you will hold 10-30 seconds at a time.

Once you have mastered the more beginner modifications, now working on making that lever just a bit longer can help make this movement more challenging in an appropriate progression. Next, your legs will be straight however you will not be resting your foot/ankle on top of the bench just yet, rather your knee or slightly lower near the calf.

Starting with your forearm supporting your upper body, set up so while your legs are straight you will be resting that top leg somewhere around calf height on the bench.  To start, consider keeping the bottom leg straight while resting on the ground.

Just as your initial set up was for the shortened lever, having the calf be placed on top of the bench, now we want to level up a bit and incorporate the activation of that bottom leg.  For the shortened lever Iso Hold Copenhagen, bring that bottom leg up and while keeping it straight, and actively hold it up against the underside of your bench or elevated surface.

The set up of the upper body stays the same for this variation but now your ankle and foot will be responsible for resting on top of the box or bench. To start, keep that bottom leg straight however let it rest on the ground under the bench.

Similar to above, your ankle and foot are resting on top of the bench but now we are changing the set-up of the leg underneath the bench. Choosing an active plank, you will keep the bottom leg straight but pressing up into the underneath of the bench and actively hold it there for the duration of the set.

Throwing this option in there for funsies. As if the active Copenhagen plank isn't challenging enough on its own, you can level up even a bit more and add in an active knee drive of the bottom leg while maintaining that straight line from head to foot and maintaining stability and balance in the trunk. Core stability, dynamic trunk control and dare I say coordination of continuing to breath will all be important in this more advanced version of the plank.

While all of these variations are beneficial, it's important to know that as with any movement, find the one that appropriately challenges you and don't be afraid to think outside the box. Maybe for where you are in your training today, you aren't quite ready to hold the bottom leg up against the bottom of your bench but also resting it on the ground is too easy. Can you then lift your leg up and back down for a set of 8-10 reps? Or perhaps considering a more advanced version with a traditional Copenhagen plank except now you drive that bottom knee up towards your chest for reps? FIgure out what's appropriate for you and have fun with it. Because after all, while the goal is to challenge yourself if you aren’t keeping it fun, what are we doing it for?

The more obvious downside of holding your breath while doing this, or any movement really, is that you may experience dizziness and or lightheadedness. But what about trying to activate some of those deeper core muscles that the Copenhagen plank engages? Particularly your transverse abdominals, your deepest core muscles, will benefit from learning how to engage while still breathing during the exercise. This can translate into bigger compound lifts (think squats and pulls) because your breath and learning how to use it to contribute to your success provides such a big advantage.

As mentioned a few times above, we want to see a straight line from top to bottom. Even the slightest rotation of hips or shoulders can make you lose balance. Maintaining alignment through chest, shoulder and hips is imperative in this exercise.

In the same vein as keeping legs engaged and not rotating your hips or shoulders, we want to continue to emphasize both full body activation as well as proper alignment by ensuring your hips stay up. One simple mistake that is often seen is that while you may be actively pressing away from the ground with your forearm and perhaps even actively engaging your legs, your hips sag, losing that straight line from top to bottom. When the oblique muscles are not engaged you will often find saggy hips occor.

Although there are many variations of this more advanced and challenging movement, even starting at one of the basic modifications can prove to be too challenging for some. While I encourage you to keep working towards mastering this movement specifically, there are a few other exercises you can start with to improve stability, core strength and dynamic trunk control.

A few that may be great places to start and have the same long-term benefits:

Standing inwards cable kicks, side lunges, or the Cossack squat (weighted and unweighted).

Since this is a more advanced movement, it is recommended you ease into progressing and don't toe the line between soreness and strain. Over doing this movement, just like any, right off the bat isn't smart. To play it safe, over time consider working up to 3-4 sets of 30-45 seconds per side, no matter what variation you are starting with.