Master Your Hip Function with The Copenhagen Plank

Dr. Joel Seedman, Ph.D.

Proportional strength between sides of a joint is critical not only for overall muscle function and athletic performance but also for joint health. Although this topic is frequently discussed in terms of anteroposterior portions of the body such as the hip flexors and extensors or knee flexors and extensors, the same concept is just as applicable to medial and lateral sides of the joints particularly the hips. In this case having a solid balance of strength between the inner and outer thighs or adductors and abductors can play a critical role in hip health, lumbopelvic hip function, low back issues, and even knee health.

Over the years more attention has been given to the abductors. That’s likely because falling into valgus collapse or manifesting significant inward knee collapse is arguably more problematic than having too much external rotation or lateral knee spread although neither is desirable. Unfortunately this trend has given rise to a common scenario where many athletes tend to overspread their knees and hips when squatting, produce excessive external rotation of the hips, display a poor ratio of abductor/adductor strength, and produce excessive external rotation of the feet (outward toe flare). This can lead to groin injuries, inflammation of the IT band, various knee and hip issues (particularly near the outer regions), and low back pain.

Although proper coaching, cueing, and instruction of foundational movement patterns such as squats, hinges, lunges, and lateral lunges will help remedy a majority of these issues particularly when employing eccentric isometrics, periodically implementing exercises that target the hip adductors and groin musculature is also warranted. Although there are a number of various drills that can be used including basic adduction drills, one of my favorites is the Copenhagen plank and variations thereof.

Although the Copenhagan plank is similar to the side windmill plank I’ve posted in the past as both target the obliques and side musculature of the core, the primary difference is witnessed in the inner and outer hip activation patterns. Here’s one of my awesome figure athletes Leslie Petch demonstrating it with textbook form.

Rather than placing the outside/lateral portion of the foot on the top of the bench as you would during a traditional side windmill plank, the Copenhagen plank requires the athlete to place the inside/medial portion of the foot on the bench. This ultimately targets the inner thighs, adductors, and groin as opposed to traditional side windmill plank variations that target the outer hips and abductors. Essentially what’s happening here is you’re holding a side plank while resisting abduction of both legs particularly the top leg which intensely activates the adductor muscles. Additionally, the lifter is attempting to adduct and squeeze the bottom leg close to the bench which further targets the adductors of both legs.

The Copenhagen plank can also be regressed and progressed based on strength and fitness levels. Here are some of my go-to variations.

Forearm Copenhagen plank

As with traditional side planks the most simple and basic regression is to perform the movement on the forearm rather than the hand as this shortens the lever arm of the upper body thereby minimizing the level of instability. Most athletes will find it easier to balance and control their body with this position making it an ideal starting point for Copenhagen planks.

Bottoms Up Copenhagen Plank

Once the basic variations of the Copenhagen plank have been mastered, one of the most effective methods for increasing the intensity, load, instability, and overall level of difficulty is using the bottoms up loading method on the top arm as shown by my awesome bodybuilding athlete Ben Lai.

Besides increasing the overall force and load on the adductors and core, this also exponentially magnifies the level of rotational forces on the body that the lifter muscle resist.

Copenhagen Plank 2.0

If you really want to get the most bang for your buck from Copenhagen planks try performing them with half your foot or forefoot off the bench as I have MLB pro baseball player Austin meadows doing here. I call this the Copenhagen plank 2.0.

With that said here’s why the Copenhagen plank 2.0 is superior to the traditional Copenhagen plank and why I’ve actually used it to replace a majority of the Copenhagen planks my clients and athletes perform.

The primary goal when using the Copenhagen plank is to target the adductors. However to fully engage the adductors and inner thighs requires 2 primary functions to be completed, one obviously being the execution of an adduction force (squeezing the legs together), the other less commonly known being internal rotation of the hip accompanied by foot adduction. In fact, to fully engage the adductors requires the hip and foot to be slightly internally rotated or pointed inward (i.e. pigeon toed) as this allows a slight but natural degree of internal tibial torsion that’s necessary for fully activating the inner thigh musculature. In fact when performing adduction motions particularly when the foot and ankle complex move near the midline of the body, prohibiting the hip and foot from slightly internally rotating represents a dysfunctional position as inward rotation of the hip and foot should almost always accompany complete hip adduction.

When the entire medial portion of the foot is anchored into the bench this prohibits the athlete from completing the last several inches of internal rotation of the hip and adduction of their foot. As a result they’re unable to fulfill the various functional tasks associated with the musculature of the hip adductors. Once the forefoot or top half of the foot is free to adduct and rotate inwardly several inches, this not only maximally engages the hip adductors but it also feels exceptionally more natural and comfortable as the hip is no longer being torqued or pulled on but instead can settle into its most biomechanically natural position.

In fact, one of the most common complaints about Copenhagen planks is how they hurt the knees especially the inner region. The Copenhagen plank 2.0 addresses this and fully remedies it.

As an added bonus, the level of instability is exponentially more challenging during the Copenhagen plank 2.0 since the lifter inevitably has less surface area on the bench therefore less total support. Simply put, the level of motor control, balance, and stability needed to lock these in is exceptionally high making them a truly effective and functional core stabilization exercise.

Copenhagen Plank on Suspension System

If you want to take the intensity and difficulty of the Copenhagen plank up several notches, try performing them with your top foot on a TRX or suspension system strap as my awesome client Leslie Petch does here.

Similar to the Copenhagen Plank 2.0 this also allows the top half of the foot or forefoot to slightly adduct and internally rotate since it’s not compressed against a bench. Additionally, the level of instability is significantly greater making these a highly advanced hip adduction and core combination exercise. These are also exponentially more challenging than they look and require mastering the more basic versions before attempting.

Chaos Copenhagen Plank

Not only is the chaos Copenhagen Plank the most advanced variation of the Copenhagen plank drill there is, it’s also one of the most brutally difficult full body stabilization core exercises I’ve ever attempted. In fact, when I first tried these I wasn’t quite sure they were feasible as the level of instability was through the roof not to mention the degree of forces and torque on the adductors and core.

Besides the incredibly intense stimulus they provide to the targeted musculature, the chaos Copenhagen plank also requires near perfect body alignment, positioning, and posture as anything less will make it impossible to control. If you have trouble locking in your Copenhagen planks or simply need a more intense stimulus to the adductors and core, these are sure to fit the bill.

To master this drill there are two very important cues. First, keep the hips and core tall and high, if they drop it will be impossible to stabilize. Secondly, adduct the daylights out of your bottom leg. It might not look like it but I’m literally squeezing my bottom adductor muscle (of my right leg) with maximal effort. This helps lock both hips in and prevents sagging hips which in turn helps stabilize the entire body

On a side note, you’ll notice how these allow my top foot to slightly internally rotate and adduct. Similar to the Copenhagen plank 2.0 on a bench, this slight internal rotation of the foot and foot adduction (inward rotation), allows maximal activation of the adductors while also creating the most comfortable and natural position for the hips.

Copenhagen Cable Adduction Side Windmill Plank

Perhaps the only downfall of the traditional Copenhagen plank is that it simply involves an isometric contraction rather than repeated concentric and eccentric contractions of the adductor muscles. Although the basic version can be modified to allow the hips to move up and down to target the adductors isotonically, this position tends to feel a bit unnatural as the lifter must disengage their core musculature and essentially allow their hips to collapse and sag for this respective motion to occur. One simple and superior remedy to this is the Copenhagen cable adduction side windmill plank exercise as demonstrated here by my awesome clients Leslie Petch with 3 different variations.

Also huge shoutout to Leslie for coming up with this awesome exercise as it truly is ingenious and incredibly effective. In fact this has 4 unique benefits.

1. As previously mentioned it allows the adductor muscles to be targeted via concentric shortening as well as eccentric elongation throughout the set rather than simply an isometric hold. For those who need both stretching and strengthening of their adductors (something a majority of athletes could use) this one is a gem.

2. Most adduction exercise that involve concentric and eccentric phases (i.e. standing or seated adduction machines), rarely involve a stabilization component not to mention a significant degree of core activation. This variation has both.

3. This is one of the few exercises that simultaneously targets both the adductors and abductors at once. That’s because the bottom leg is holding a traditional side windmill plank thereby targeting the abductors and outer hips of that leg, while the top leg is performing adduction motions thereby targeting the adductors and inner hips of that side. In other words it represents the perfect 2-in-1 exercise.

4. In order to produce a perfectly vertical force on the cable or band during the adduction phase, this variation requires the lifter to find a perfectly in-line side plank position (something many athletes struggle with) otherwise he or she will pull at an angle and destabilize his or her body.

Modified Regression

Here I have one of my awesome clients Mitch performing a modified regression of the Copenhagen plank as he's performing it with his knee, shin, foot, and ankle on the bench rather than the more difficult straight leg version that only involves the foot and ankle.

Even if clients are capable of performing the standard more difficult version I periodically like to include this regression so they can focus on dialing in their form and squeezing their adductors (inner thighs), and core musculature especially the obliques. If it's too easy add a chain or weight vest as shown here.

Additional Notes About Copenhagen Planks

1. You’ll often see many therapists and trainers performing the bent-knee version of the Copenhagen plank. Many variations are also performed with the inner leg/thigh on a bench rather than the foot. Besides minimizing tension and force to the targeted musculature due to enhanced leverage, these less-challenging variations are also less functional. That’s because when it comes to working the adductors or any region of the hips, the foot and ankle complex plays a large role. Any variation that eliminates or minimizes the contribution of the foot and ankle complex is inevitably going to have less transfer to functional tasks whereas variations that involve the foot and ankle complex will have greater transfer to sport and everyday functional tasks.

2. Knee pain is a common complaint regarding Copenhagen planks. This is often a result of 3 factors. 1) The athlete is unable to properly resist the strong abduction forces against their hips and therefore some of this tension goes to the knee. In this case the individual may want to build up their core and adduction strength before attempting these. The cable adduction side plank shown above by Leslie although semi-advanced also places less tension on the knees. 2) The core strength is lacking and as a result the hips are dropping which creates much greater torque on the knees. 3) The Copenhagen plank 2.0 should help remedy a majority of the knee pain for reasons mentioned above.

3. Lifters who demonstrate significant valgus collapse might want to avoid Copenhagen planks until they correct this imbalance and strengthen the outer hips to a greater degree.

4. Although the Copenhagen plank effectively targets the inner thigh, groin, and adductors, individual with groin strains and groin injuries should take extreme caution when performing these drills due to the very high levels of forces placed on the injured site. The drills should only be included once the athlete has largely recovered from their injury and is taking every pre-caution to avoid future re-occurring injuries.

5. Copenhagen planks can and should also be implemented for figure athletes and bodybuilders as the inner thighs periodically need to be worked to maintain optimal proportionality and physique dimensions of the lower body.

6. For most athletes super-setting these with traditional side windmill planks that target the abductors is ideal as this creates optimal balance between sides of the hips.

7. While this isn’t a drill that needs to be included on an overly-frequent basis for most lifters, periodically incorporating it into your routine (i.e. 1-2x per week for 2-3 sets), can help ensure optimal hip function and muscular development in the lower body.