By Carl Valle
While the backlash over the Nordic hamstring exercise is nearly over, we are now seeing a little disagreement in the coaching community over Copenhagen exercises. The same lesson we learned from hamstring injuries can be applied to adductor injuries: Strength still has relevance in injury reduction.Hamstring and #adductor injuries both teach us that strength still has relevance in injury reduction, says @spikesonly. Click To Tweet
I was not a fan of Nordics because athletes simply didn’t like them, and it was difficult to place them into a program because they created soreness that was far from welcome. Eventually, we did modifications as a part of a program, but the Copenhagen adduction exercise was slightly more difficult to include because it didn’t have the same support from the coaching community.
The promise of this article is straightforward: I will dissect the Copenhagen adduction exercise in detail and leave you with more information to work with if you decide to use the exercise in your training.
What Is the Copenhagen Adduction Exercise
Similar to the Nordic hamstring exercise, the Copenhagen adduction exercise (CAE) is a bodyweight movement popularized by Danish researchers and sports therapists. The origin of the exercise is a bit of a mystery, but it’s safe to say it was invented way before the early 2000s. The reason the Danes get credit for the exercise is that they are doing incredible research in the area of groin injuries in sport. One of the leaders in groin injuries is Kristian Thorborg, a Danish therapist, who is one of my favorite sports medicine educators.
Video 1. This video shows an experienced adopter of the Copenhagen adduction exercise. This is a solid technique and smooth enough to provide the right stress to the adductor system.
The exercise resembles a partner-assisted plank, with the only real difference that the support is held inside to overload the top leg adductor system. The athlete doing the exercise performs a repetition by raising their hip up and then dropping the lower leg down to the ground and back up again. While it may look like an isometric action, the exercise is dynamic in nature. European soccer clubs were the main users of the exercise, but due to the globalization of sport and science, it’s used everywhere now.
My suspicion is that the exercise was boosted by the use of dynamometers when therapists tested adductor strength, and the visual connection encouraged its use in sport. While the exercise is technically a bodyweight movement, some practitioners have used weight vests, ankle weights, and bands to overload the movement more. Several derivatives have been promoted as either replacements or prerequisites to the CAE.
Does Scientific Evidence Support the Use of the Copenhagen Adduction Exercise?
The most common approach to implementing an exercise is determining how it helps the intended goal. When I look at any exercise, there are four questions I ask myself before moving forward. I do follow up with additional questions, but for the most part you should ask these key questions for any intervention in sports training.
- Does the exercise help create an adaptation that matters, such as strength?
- Does the exercise improve outcomes in performance with the athletic population?
- Does the exercise decrease injury rates to specific joint or muscle systems of the body?
- Does the exercise have a better result compared to other practical options?
As you can see, I want to know if an exercise does what is intended, and whether it is the best option available. Too often, interventions don’t do anything beyond improving strength tests or changes in the load used in the exercise. While I like a muscle group to improve, I would rather see a field test make a positive change. Also, I don’t care if an intervention helps compared to what I call “a phantom control” (read: nothing), as anyone in sport will likely want to use something to create a positive change. Still, we should always include controls to get a sense of how rest or just not tinkering with any other variable influences training outcomes.
Generally, the impact of the Copenhagen adduction exercise is promising, meaning every study notes a positive aspect of the exercise, whether an EMG study or eccentric strength effect over time. However, it’s not proven to be better than a holistic program that includes other options. Coaches are expected to know what exercises may develop similar benefits and how all of the training mingles together. Often, a good exercise helps in isolation, but it isn’t congruent in a program as it could overload one area or neglect something else.A good exercise may help in isolation, but then overload or neglect something when in a program, says @spikesonly. Click To Tweet
So what we know is very simple: Yes, the exercise is likely a great asset to adduction strength, and that strength may help with outcomes in sports where groin injuries occur. While it’s similar to Nordic exercises, it’s not as straightforward anatomically and biomechanically, because the region is a little more difficult to model with the available science. If you look at all of the evidence, the CAE is a good choice with athletic preparation.
How Science Evaluates Hip Adduction Strength
The force testing of individual muscles or simplified patterns of movement is not a true representation of adduction function. Instead, they are nice summaries that are very useful for clinical settings or coaching environments that just need a good indication of change in strength. Electromyography is commonly used to evaluate activity of the muscles of the inner thigh, but even that approach is still limited, since most studies only test a single muscle as a representation of a very complex and congested area.
The adductor group is more than a handful of muscles that connect to the pelvis and femur—you can argue that the series of muscles are part of a kinetic chain rather than an anatomical zone. A full evaluation of the true strength of the adductor muscles is not complete at this time, but the research community is making progress every month as new studies come out with fantastic information.
The primary way to measure adductor strength is either from manual muscle testing or an isokinetic machine. Other tools like strain gauges and similar are available, and now tools like the GroinBar are getting traction in the sports testing arena. Force plates are helping model some high analysis with athletic actions like cutting, but even those models are not helping sports like soccer that still have to equate for no ground contact patterns like kicking. The support leg may have some value, but kicking requires more than just one measure to fully explain its injury mechanism. A simple hand dynamometer is an inexpensive way to estimate adduction strength, and various devices that resemble blood pressure cuffs are available as well.
I predicted the GroinBar by Vald Performance, as it was clear the similarities to the Nordbord would make sense for other muscle tests. The GroinBar was a good move by Vald for several reasons. First, the machine tests strength of the upper body as well, making it more useful to teams than just testing legs. Second, it tests more than just adductor strength, and comparing abduction strength was a wise move.
You can use the GroinBar to score the CAE, but it will take some time to determine if that movement will be a significant measure with injury risk and performance in the future. Lastly, the system is very portable because the main sensor is removable, making it a practical option on the road. I am more of a fan of the GroinBar because it’s more versatile than the NordBord, but keep in mind other options exist that are just as valid and accurate. The company does a good job with a top-notch user experience, and the brand is very popular internationally.
What About Other Copenhagen Exercises?
I have experienced three major exercises that I consider part of the Copenhagen family: the plank, the ball squeeze, and now modified options like bent knee versions. Nick Tumminello has done a great job making exercises either more effective or more easily accessible by fine-tuning the motions and the teaching of them. In fact, I would make an argument that Nick has the best talent for really ensuring that exercises are taught better by coaches than most of the education out there.
The above three options—a squeeze, a plank, and a modified family of similar patterns—are great alternatives if you can’t use or don’t like using the CAE for some reason. Here is an expanded review of the other options similar to the Copenhagen adduction exercise:
The Copenhagen Squeeze
Nearly everyone in soccer and sports performance is aware that a squeeze pattern with the athlete’s legs is a valid and reliable option to measure adductor performance. Coaches like it because some balls and pads have sensors to give instant feedback, but the core problem with squeezing is determining the resistance.The core problem with squeezing is determining the resistance, says @spikesonly. Click To Tweet
Foam products, bands, and resistance tools are nice options to start a program, but I don’t like spending too much time with the types of movements that they utilize. Usually, an athlete sees them as a crutch or places too much hope that they will reduce pain or injury, and education and careful inclusion are necessary to explain the process of rehabilitation or training when they are taken away. The exercise is usually a five-second burst of isometric squeezing, followed by additional sets or another trial if it’s used as a test.
The Copenhagen Plank
Similar to the full experience, the Copenhagen plank is more isometric in nature and less stressful to the adductor system. Remember, the benefit of the full movement is eccentric strength of the adductors, a really important adaptation. Two variables that generally change with planks are the removal of the partner in favor of a box or bench, and a more-level angle of the exercise so there is less strain on the adductors. Those two changes are enough to merit caution in progressing directly to the next exercise.
Modified Copenhagen Exercises
There are a few exercises that use a bent knee or add resistance modalities to the movement, either partner-assisted or solo. I believe this species of exercise is ripe to grow if the variations have purpose and are not just mindless permutations for entertainment.
One of the primary reasons that many coaches find the bent knee useful is that it usually decreases the lateral strain to the knee, and athletes can use slightly more load comfortably. I have found that the adductor exercise is more individualized than any other movement, and sometimes we need to figure out the right position for the athlete so that they’re comfortable. Sometimes, revisiting the conventional movement later is fine after a slow transition with similar exercises.
Video 2. The plank is a great starting point, and this modification combines a less aggressive angle from the box, a bent knee for comfort, and a more stable position. Fluttering the lower bottom leg up and down is the next progression to the exercise.
I don’t have enough experience with the exercises above to give any practical takeaways on how interchangeable they are or say whether they make a big difference in performance or injury resilience. My expectation is they are part of a program that can add more robustness to the groin area and are worth exploring. Remember, just because an intervention has value in research or someone else’s program doesn’t mean it will fit neatly in yours. Trial and error are still part of the necessary learning curve with new exercises.An intervention may have value in research or someone else’s program, but not fit neatly into yours, says @spikesonly. Click To Tweet
How to Better Progress into Copenhagen Exercise
I thought the controversy over the CAE would be in the science, but I will make a case that the real friction of the exercise is not validity or efficacy, but integration. There has been a rash of athletes with these injuries to the groin early in the pre-season because the coaches jumped on the bandwagon without education or experience. A new exercise requires actual experimentation with yourself before placing it haphazardly or even intelligently into an athlete’s training program. Even with experience, the insertion of a new exercise can sometimes lead to unexpected bad results.
Rarely do I add a new exercise into a program without some adjustment weeks before. I used to add a new movement by doing a set of the exercise with the lowest effort necessary to remove soreness or possible incompatibility, but even that was too primitive to hit my personal standards. I find that it’s better to know all of the requirements of good performance of the exercise and make sure the athletes have those qualities first. Planking is an obvious prerequisite, because a partner holding their legs is also similar to the suspension training that athletes are not used to.
Video 3. The first time someone starts the Copenhagen adductor exercise (staged here for education purposes), you will see typical small movement strategies to mask or compensate that they are new to the exercise. Look for bends at the hip, external rotation of the femur, and loss of tension.
I like very few suspension movements, and technically the Copenhagen adduction exercise is a suspension movement. TRX training does get a lot of criticism, but sometimes a few benefits emerge from the use of that modality. General planking is not going to change much in sport, but I don’t think it’s a good idea to toss out planks because they don’t transfer to sport.
Sometimes an exercise is valuable because it acts like a stem cell, meaning that those fundamental patterns can form into other useful exercises that do have the ability to translate to performance or injury reduction. Other suggestions to prepare for the movement are general leg and core exercises, as just doing low load movements like band work seems to have baggage with irritating attachment sites to the region. I thought this was unique to me, but when I ask other coaches, most say that isolation exercises are not their cup of tea either.
Tips on Better Copenhagen Adduction Exercise Coaching and Training
Three overarching principles of exercise application exist with nearly any movement pattern or sporting action. They are coaching or teaching the exercise, programming it in training, and monitoring the loading interaction. At first, I would have said it was simply instruction and program design, but it’s really about how to teach the CAE, how to throttle the load, and how to mix it in a weekly cycle over a season.
Even if you incrementally include progressions to the exercise, you still need to instruct the athlete and make sure they are use the right contributions of muscles and engage not just the adductors, but the lateral chain of muscles all the way up the hip and torso. Some coaches see the movement as a sequence of planking to pushing down the adductor—I see it as the opposite. A good Copenhagen based on force transmission is pressure on the inside of the foot and raising the force down through a bridging movement. The lowering of the non-supporting leg is more a challenge of maintaining tension with coordination than a continual overload.
Some activity in other supportive muscles is normal and expected, but it’s ineffective when the overload of the desired muscle groups is decreased by compensation or selective recruitment of the athlete. To reduce the chance of cheating the movement or allowing errors to reduce the efficacy of the exercise, the placement of the foot is a major factor.The placement of the foot is a major factor in reducing the chance of cheating or allowing errors, says @spikesonly. Click To Tweet
Athletes can engage hip extensors or knee extensors if the foot is externally or internally rotated. We tend to see this when athletes have a nagging chronic injury, meaning it’s not preventing them from competing, but it’s reducing their training abilities so that they are managed with rest and pain medications. To safeguard from compensation, watch for slight twisting at the hips to torso, as the hamstrings sneak in when athletes lean back or the quads compensate when athletes tilt towards their anterior.
The bottom leg is often seen as the free scissor of the exercise, meaning it closes and opens as part of the repetition. The purpose of this addition is more motor control than overload, but I don’t have much research or personal instrumentation data to make a strong conclusion on what this does or fails to do.
Note: My suspicion is that the dropping of the leg adds some challenge to the exercise by removing a co-construction bracing that the legs held together can provide. I would be interested to hear from others to theorize and investigate with evidence as to what the bottom leg exactly does.
Where you hold the athlete is also a priority due to both repeatability of the movement and comfort. Just holding onto the edge of the foot tends to place lateral stress on the knee, a common complaint that has led to the bended knee options. Some coaches find that holding with two hands near the shin and at the knee makes this far more comfortable. My only issue is that the way you teach it must be reproducible over time, otherwise you are comparing the progress of an exercise that has enough variance to potentially throw off conclusions.
Other than these mechanical recommendations, communication between the coach and athlete, and the athlete and partner, is important. If an athlete uses a suspension trainer they will likely be more confident because any time you rely on a partner some trust issues will surface.
Try the Exercise and Evaluate It Yourself
This exercise movement is easily accessible because it’s a bodyweight pattern, so any coach can try it immediately. I like using it with skilled athletes who are at naturally high levels of strength, as it’s hardly useful for beginner trainees. Some athletes seem to be a good fit for the exercise and can do similar movements or alternative exercises with ease and without complaint.The #CopenhagenAdductionExercise is valuable for sports that have a problem with groin injuries, says @spikesonly. Click To Tweet
Regardless of what you have heard, the Copenhagen adduction exercise is a valuable option in any sport that has groin injuries as a problem. I would still use it in track and field, but focus on hurdlers as that injury is more common to them than flat sprinters. I am also curious how CAEs can help swimming, as breaststroke is very adductor-centric with the leg kick action. As always, experiment with the exercise and judge for yourself if it makes a difference in your program.