The Copenhagen Plank: A Groin-Strengthening Exercise for Injury Prevention

Groin strains are one of the most common yet most under-trained injury risks in sports involving sprinting, cutting, and kicking — soccer, hockey, and similar activities. Despite how frequently they occur, most gym-goers and even many recreational athletes have never deliberately trained the adductor muscles (inner thigh) that are most often involved. The Copenhagen plank is a targeted exercise specifically designed to close that gap.

Named after research conducted at a sports science institute in Copenhagen, this exercise has gained traction among physical therapists and strength coaches as one of the more effective tools for building adductor strength and reducing groin injury risk, though it comes with a learning curve worth understanding before diving in.

Why the Adductors Are Often the Weak Link

The adductor muscle group runs along the inner thigh and is responsible for pulling the legs toward the midline of the body, as well as stabilizing the hip during single-leg movements like sprinting, cutting, and kicking. Despite this constant demand in athletic movement, adductors are rarely trained directly in typical gym programs, which tend to emphasize the quads, hamstrings, and glutes.

This imbalance — high demand on the adductors during sport combined with low direct training — is part of why groin strains remain common in field and court sports. Research consistently shows that athletes with weaker adductor strength relative to their hip abductor (outer hip) strength face a meaningfully higher risk of groin injury, and meta-analyses suggest that structured adductor-strengthening programs performed consistently over a full season can meaningfully lower groin injury rates in sports like soccer and hockey compared to no targeted adductor training at all.

What the Copenhagen Plank Actually Trains

The Copenhagen plank is a side-plank variation where the top leg is supported on a bench while the bottom leg does the work of holding the hips level, placing significant, targeted load on the adductors of the supporting leg. It’s considered one of the more effective exercises specifically for building eccentric adductor strength — the ability of the muscle to control lengthening under load, which is the exact demand placed on the groin during a sudden change of direction.

• Targets the adductor muscle group directly and intensely
• Trains eccentric strength, which is particularly protective against strain injuries
• Also engages the core and hip stabilizers to maintain a straight body line

How to Perform the Copenhagen Plank Safely

Because this exercise is demanding, most people should start with an easier regression rather than the full version:

1. Beginner version: Lie on your side, bottom knee bent and resting on the floor, top leg extended and supported on a bench. Lift your hips off the floor, forming a straight line, holding briefly before lowering.
2. Full version: Both legs extended, top leg supported on the bench, bottom leg unsupported, hips lifted into a full side-plank position with the working leg doing the stabilizing.
3. Progression: Add slow, controlled repetitions (raising and lowering the hips) rather than just static holds once the basic hold feels manageable.

Because the adductors are a commonly under-conditioned muscle group, starting conservatively — short holds of around 10 to 20 seconds, the bent-knee regression, and 2 to 3 sets per session — and progressing gradually over several weeks helps avoid excessive soreness or strain from an unfamiliar, demanding new stimulus.

Who Should Consider Adding This Exercise

The Copenhagen plank is particularly relevant for people involved in sports with frequent sprinting, cutting, or kicking — soccer, hockey, basketball, martial arts, and similar activities — where groin strain risk is elevated. It’s also a reasonable addition for general strength trainees looking to address a commonly neglected muscle group and build more balanced hip strength.

People currently recovering from a groin strain or with existing hip pain should approach this exercise cautiously and ideally under the guidance of a physical therapist, since the demanding nature of the movement could aggravate an existing injury if introduced too early or too aggressively.

Building It Into a Balanced Program

The Copenhagen plank works best as a complement to broader lower-body training, not a replacement for squats, lunges, or hip-hinge movements. A well-rounded lower-body program addresses the adductors, abductors, glutes, hamstrings, and quads so that no single muscle group becomes a disproportionate weak link.

• 2x per week is a reasonable starting frequency for adductor-specific work like the Copenhagen plank
• Pair with hip abductor exercises (like side-lying leg raises or banded walks) for balanced hip strength
• Allow adequate recovery, since eccentric-focused exercises often produce more delayed soreness than typical strength work

How to Apply This: A Sample Progression Plan

A practical 6-week introduction for someone new to adductor-specific training:

1. Weeks 1–2: Bent-knee regression, 2 sets of 15–20 second holds, 2x per week
2. Weeks 3–4: Bent-knee regression, 3 sets of 20–30 second holds, or begin introducing short full-version holds
3. Weeks 5–6: Progress toward the full straight-leg version, 2–3 sets of controlled repetitions or longer holds

Athletes with a history of groin injuries should consult a physical therapist or sports medicine professional to tailor progression safely to their specific history. The WHO’s general injury-prevention guidance for sport emphasizes that structured, gradual strength progression — rather than sudden spikes in training load — is one of the most consistently effective ways to reduce soft-tissue injury risk across nearly all sports.

Is the Copenhagen plank safe for beginners?

With the bent-knee regression and conservative progression, yes, though it’s still a demanding exercise and beginners should start with short holds and low volume.

How often should I train the Copenhagen plank?

Twice a week is a common starting frequency, allowing adequate recovery time given how demanding the exercise is on the adductors.

Can this exercise help if I’ve had a groin strain before?

Adductor strengthening is commonly recommended as part of injury-prevention and rehabilitation programs, but anyone with a history of groin strain should work with a physical therapist to time the introduction appropriately.

Do I need a bench to do this exercise?

A bench or elevated sturdy surface works well, but any stable elevated platform of similar height — like a low box or step — can substitute.