The Copenhagen plank (also commonly referred simply as an “adductor side plank”), is one of the most effective adductor-strengthening exercises available, and one of the most underused outside of professional sport.
Popular with strength coaches and physiotherapists alike, it builds the kind of hip stability that carries over to athletic performance, injury resilience, and healthy movement in everyday life.
Named after FC Copenhagen, the football club where the exercise was popularised, the Copenhagen plank targets the often-neglected adductor muscles of the inner thigh. These muscles play an important role in hip stability, and research consistently shows that weakness here is a significant risk factor for groin injuries.
Done correctly, it’s a remarkably effective exercise. Done poorly, it can place unnecessary stress on the lower back.
This guide covers how to perform it properly, the muscles worked, benefits, and how to progress or regress the movement based on your current level.
Quick Summary
- Copenhagen planks primarily target the hip adductors, the muscles of the inner thigh responsible for drawing the legs toward the midline.
- They improve stability around the hips and are well-supported by research for increasing adductor strength, which is closely associated with reduced groin injury risk.
- They also strengthen the core, particularly the obliques.
- The exercise is isometric, meaning you hold a fixed position for a set duration rather than performing repetitions.
What is a Copenhagen Plank?
A Copenhagen plank is a side plank variation that involves resting your top leg on a bench or raised surface. The bottom leg hangs underneath the bench. Lifting your hips off the ground until your back is straight, you simply hold this side plank position for the duration specified.
The exercise is isometric and involves a “squeezing” movement to keep your legs together.
You can make the exercise easier by resting the bottom leg on the floor, or positioning yourself closer to the bench.
To make things harder, you can also include a dynamic hip movement by lowering and raising your hip to the ground or using a suspension trainer instead of a bench.
Copenhagen Adduction Exercise
The Copenhagen plank is a practical adaptation of the “Copenhagen adduction exercise”, which involves a training partner holding the top leg (as opposed to resting it on a bench).
How to do Copenhagen Planks
To do the Copenhagen plank:
- Start by lying on your side, like you would for a regular side plank.
- Place your top leg onto a bench or raised surface. The closer your body is to the bench, the easier the movement becomes.
- Bracing your core and keeping your obliques and abdominals tight, lift your hips off the floor so your back is straight.
- Lift your lower leg off the floor so it hangs under the bench, unsupported.
- Squeeze your thighs to hold this position.
- Repeat on the other side.
Coach’s Tip – Ensure you use a bench or raised surface that is roughly the same height as your head when you hold the side plank. This will mean as you place your leg on the raised surface, and lift your hips, your back should naturally be nice and straight.
Muscles Worked
The Copenhagen plank primarily targets the adductor muscles of the hip. These muscles are responsible for moving your legs to the center of your body.
These adductor muscles include the adductor longus, adductor brevis, adductor magnus, pectineus, and gracilis.
It’s worth noting that several of these muscles have secondary functions beyond adduction… the adductor longus contributes to hip flexion, the posterior head of the adductor magnus assists with hip extension, and the gracilis also contributes to knee flexion.
This means the Copenhagen plank has broader functional carry-over than its simple appearance might suggest.
As well as hip adduction, Copenhagen planks will also help develop overall core strength by engaging the abdominals and obliques.
Benefits of Copenhagen Planks
Adductor Strength
The Copenhagen plank is one of the most effective exercises available for developing adductor strength.
Research consistently shows it produces significant increases in eccentric hip adduction strength, the type of strength most closely associated with injury resilience in the groin.
Stronger adductors support better athletic performance, particularly in activities involving running, cutting, and kicking, and also contribute meaningfully to stability during squats, deadlifts and other compound movements.
Reduce Groin Injury Risk
Weaker adductors are a well-established risk factor for groin injuries, particularly in sports involving running and kicking.
Research shows that training the Copenhagen adduction exercise consistently is associated with meaningful reductions in the prevalence of groin problems in athletes.
It’s worth being precise here: what the research clearly demonstrates is a significant increase in adductor strength from this exercise, and that increased adductor strength is associated with reduced injury risk.
Whether the exercise directly prevents time-loss groin injuries remains an area where more large-scale research is needed, but the evidence base for including it in training and rehabilitation programmes is strong.
Better Kicking Power
Stronger adductors allow the leg to move with greater power and precision. For athletes, this is a meaningful competitive advantage, particularly in football, hockey, and rugby, where kicking power and change-of-direction speed rely heavily on adductor strength and control.
Adduction/Abduction Balance
Many standard training programmes naturally favour the hip abductors… exercises like clamshells, lateral band walks, and many glute movements all train the outer hip. While abductor strength is important, a significant imbalance between the two can compromise overall hip stability and increase injury risk.
Research has shown that when adductor strength falls considerably below abductor strength, the risk of groin injury increases substantially. Actively training adduction strength alongside abduction helps create the balanced hip stability needed for healthy, resilient movement.
An interesting study that Physio-Network highlights in this article showed that groin injuries increased by 17 times when adductor strength was less than 80% of abductor strength.
Activate Core Muscles
As well as developing hip strength, the Copenhagen plank is also a great way to activate the core muscles, especially the obliques.
Similar to a standard side plank, your obliques are required to help create stability as you hold the position.
Strengthening the obliques helps to better stabilize the torso and spine, helping to promote better posture, as well as rotational strength.
Lateral Power and Movements
Any sort of lateral movement will involve careful coordination between adductors and abductors to move meaningfully in a sideways direction.
This ability to strengthen the adductors helps to ensure your lateral movements aren’t solely reliant on your abductors.
This helps to improve exercises like lateral side squats too.
Copenhagen Plank Progression
The key to getting the most from Copenhagen planks is starting at the right level and building up gradually. Beginning too advanced is one of the most common mistakes, it leads to form compensation and reduces the training stimulus on the adductors.
Regression — Modified Floor Version: Rather than placing your top leg on a bench, rest it on the floor in front of you. This significantly reduces the load on the adductors and is a good starting point for beginners or those returning from injury.
Standard Version: Top leg rests on a bench or raised surface, bottom leg hangs unsupported beneath it. This is the main version described in this guide and the appropriate starting point for most people with a reasonable base of fitness.
Progression — Dynamic Hip Dips: From the standard position, lower your hips toward the floor in a controlled manner and raise them back up, adding a dynamic element to the isometric hold. This increases the demand on both the adductors and the core.
Advanced Progression — Suspension Trainer: Using a TRX or similar suspension system instead of a bench means the surface is unstable, forcing the adductors and core to work significantly harder to maintain position. This is a meaningful step up from the standard version and should only be attempted once you can hold the standard variation comfortably for 45–60 seconds.
Research suggests building toward 1–3 sets of 12–15 repetitions (or equivalent time under tension), 2–3 times per week over the course of 8 weeks for meaningful strength gains. If you’re using it as a general training tool rather than a structured injury prevention programme, 2–3 sets of 6–15 reps or holds, 2–3 times per week, is a reasonable target.
Bottom Line
The research behind Copenhagen planks is consistently positive. The exercise is highly effective at building adductor strength, which plays an important role in hip stability, athletic performance and groin injury resilience… making it a valuable addition to training programmes for athletes and non-athletes alike.
To see meaningful results, aim to build toward 2–3 sets of 12–15 repetitions or equivalent holds, performed 2–3 times per week. Start with a regression if you’re new to the exercise, focus on maintaining a straight back and neutral hips throughout, and progress gradually over several weeks. The adductors are often undertrained relative to the rest of the lower body… Copenhagen planks are one of the most efficient ways to address that.
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Featured image and video demonstration credit – AchieveFitnessBoston