If you've ever felt a sharp pull deep in your inner thigh while lunging wide for a tennis serve, or cutting hard on the pitch, that's almost certainly the adductor muscles, most often the adductor longus. The frustrating part is how often this injury comes back within the same season. The pain settles, stretching your groin feels fine again, but the moment you sprint and change direction or reach into a wide lunge for a shot, that same pull shows up.
Usually the reason is that the strength you rebuilt during recovery isn't the same kind of strength the sport actually demands. Concentric strength, the force your adductors produce as they shorten to pull the leg inward, comes back fairly easily with gym machines. But the moment you actually get hurt cutting on a football pitch or lunging wide on a tennis court is an eccentric one, when the leg is being forced outward and the adductor has to lengthen under load to control it. If that eccentric capacity hasn't come back by the time you return to play, the muscle can feel fully healed and still fail in the exact same movement. The Copenhagen plank was built to target that eccentric capacity directly: a single side-plank position with your leg resting on a bench loads the adductor eccentrically in a way few other exercises do. To make this safe even if your torso caves the first time you try it, this guide breaks the exercise into four levels, from a short-lever hold up through the full classic plank and a final phase that emphasizes the eccentric lowering, with a clear criterion for when to move up. If you're dealing with a groin injury right now, check the acute-phase guidance first: groin strain adductor rehab
Why Groin Injuries Keep Coming Back: It's the Lengthening Force, Not the Holding Force
Why Groin Injuries Keep Coming Back: It's the Lengthening Force, Not the Holding Force
Ask an athlete who's sprained the same adductor twice and you'll usually hear the same story. The pain went away, stretching into a wide split felt fine, they returned to play, and then the exact moment their leg got forced outward on the court or pitch, the strength just wasn't there. That's rarely because the muscle tissue hadn't finished healing. It's more often because the type of strength rebuilt during rehab didn't match what the sport actually demands in real time.
The adductors work in two distinct ways. There's concentric contraction, where the muscle shortens as it pulls the leg inward, and eccentric contraction, where the muscle lengthens to brake the leg as it's forced outward. The instant a soccer player cuts hard to change direction, or a tennis or badminton player lunges wide to the side, is almost always the latter, an eccentric moment where the adductor has to lengthen under load to control the leg. Gym-based hip adduction machines and resistance bands mostly train the concentric side only, so returning to sport on that alone means stepping back onto the field with the exact eccentric braking capacity you need still missing.
This exercise matters most for athletes in sports with frequent direction changes. In soccer, it's the sudden cut inside during a dribble or the wide lunge to block a cross. In tennis and badminton, it's the wide lateral step to reach a shot. In squash or field hockey, played in tight spaces with constant starting and stopping, this eccentric loading repeats on nearly every rally. By contrast, sports like distance running or cycling, where the leg moves mostly straight forward and back, carry a much lower rate of adductor injury, so this exercise is a lower priority there. Checking whether your sport actually demands frequent direction changes and wide stances is the first thing to consider before deciding to start this program.
Harøy et al. (2019, British Journal of Sports Medicine) ran a cluster-randomized trial with roughly 650 Norwegian male football players, comparing teams that ran an adductor-strengthening program built around the Copenhagen plank twice a week across a full season against teams that didn't. Teams running the program saw groin problems drop by about 41 percent overall. That said, this was a cluster design randomized at the team level rather than the individual level, so differences in coaching style and training culture between teams could have influenced the results, and the researchers also reported that the effect shrank noticeably in teams with poor adherence to the program.
There's also research on how quickly, and by how much, eccentric strength itself can actually increase. Ishøi et al. (2016, Scandinavian Journal of Medicine & Science in Sports) had elite youth soccer players perform the Copenhagen plank twice a week for four weeks, progressing through levels, and found eccentric hip adduction strength increased by an average of about 35.7 percent in the training group, a clear difference from a control group that did nothing extra. The limitations here are a relatively small sample, around 20 per group, a short four-week observation window, and the fact that this study alone can't confirm whether that strength gain actually translates into fewer real-world injuries.
Taken together, these two studies point in a consistent direction: the Copenhagen plank can raise eccentric strength meaningfully in a short window, and sticking with it appears to lower the actual rate of groin problems. But the precise causal link between the strength gains and the injury-prevention effect, along with how much that varies person to person, is still not fully mapped out. If you want a quick sense of where your eccentric strength stands right now, check the table below first.
| Test Position | Target Hold Time | What It Means |
|---|---|---|
| Level 1 position (bent knee, shin on bench), isometric hold per side | 30 seconds | Under 30 seconds: start carefully from Level 1 |
| Level 3 position (straight knee, only the top of the foot on the bench), isometric hold per side | 15-20 seconds | Under 15 seconds: it's too early to move to Level 3 |
If your body shakes badly or your hips sag in the Level 3 position, that itself is a sign your eccentric strength isn't there yet, so don't force it. Work back through Levels 1 and 2 first.
Levels 1-2: Bench-Supported Short Lever, Isometric Hold to Dynamic Reps
Levels 1-2: Bench-Supported Short Lever, Isometric Hold to Dynamic Reps
Most of the Copenhagen plank's difficulty comes down to lever length. Bending the knee and resting your shin on the bench shortens the distance from your torso to the support point, reducing the load on the adductor. Straightening the knee so only the top of the foot rests on the bench moves that support point further away and sharply increases the load. The first two levels build the isometric holding strength at that short lever, then the dynamic control of raising and lowering.
Level 1: Short-Lever Isometric Hold
Starting position Lie on your side next to a bench, low couch, or step at roughly knee height. Bend the top leg's knee to about 90 degrees and rest the inside of the shin on the bench. Keep the bottom leg straight in line with your torso, lifted slightly off the floor. Support your torso on your forearm with the elbow directly under the shoulder.
Movement steps ① Push through the forearm and the top shin to lift your hips until your body forms a straight line from shoulder to ankle when viewed from the side. ② Keep the bottom leg lifted off the floor and hold the position. ③ Once you reach your target time, lower the hips slowly back down. ④ Roll onto the other side and repeat.
Breathing timing Exhale briefly right before you lift the hips and brace your core. While holding, don't hold your breath; keep a shallow rhythm of inhaling and exhaling every 3-4 seconds.
Sets, reps, frequency 20-30 seconds per side, 3 sets, with 30 seconds of rest between sets. Start at 2-3 times a week.
Common mistakes and fixes The most common flaw is the hips rotating backward, with the glutes drifting behind the line of the body. Draw your belly button slightly forward to keep the shoulders and hips squarely in the same plane. Letting the bottom leg rest limply on the floor is also common; it needs to stay lifted the whole time for the top-leg adductor to take the full load.
Stop if you notice Stop immediately if you feel a sharp, stabbing pain deep in the groin, or notice the groin visibly bulging as you set up the position. If you feel tingling or radiating pain toward the groin, that could point to a hernia or another cause, so don't push through it.
Level 2: Short-Lever Dynamic Reps, Level Up Past 20 Seconds, 3 Sets
Level-up criterion Once you can hold Level 1 for 20-30 seconds per side, 3 sets in a row, without the hips sagging, move on to Level 2.
Starting position Set up exactly as in Level 1, but this time you'll switch from a static hold to repeated raising and lowering of the hips.
Movement steps ① Lift the hips into the Level 1 straight-line position. ② Lower the hips slowly toward the floor, stopping just short of touching down. ③ Lift the hips back up to the starting position. ④ Repeat this up-and-down motion for your target number of reps.
Breathing timing Inhale as you lower the hips, exhale as you lift them back up. Holding your breath on the way down stiffens the core and actually makes control harder.
Sets, reps, frequency 8-12 reps per side, 3 sets, 2-3 times a week. Aim for roughly 2 seconds on the way down and 1 second on the way up.
Common mistakes and fixes A common error is dropping the hips fast and bouncing back up off momentum, which erases nearly all the eccentric stimulus. Consciously counting out the 2-second descent and controlling it slowly is the key. Tensing the neck and shoulders is another common issue; keep the neck in line with the torso and your gaze slightly down and forward.
Stop if you notice If groin pain clearly worsens as you go through the set, or if the pulling sensation is still there the next morning while walking, drop back to Level 1 and lower the intensity for your next session. Tenderness right at the pubic bone could point to something like osteitis pubis, which needs a medical evaluation first.
Levels 3-4: Full Long-Lever Plank to Eccentric-Emphasis Dynamic Reps
Levels 3-4: Full Long-Lever Plank to Eccentric-Emphasis Dynamic Reps
Once Level 2 feels manageable, it's time to straighten the knee and extend the lever. Levels 3 and 4 are the classic position most people picture when they hear Copenhagen plank. Because the load jumps sharply with the longer lever, it's safer to start with lower target times and reps than you might expect.
Level 3: Long-Lever Isometric Hold
Level-up criterion Once you can do Level 2 for 8-12 reps per side, 3 sets, with a controlled 2-second tempo and no bouncing, move on to Level 3.
Starting position Lie on your side next to the bench. Keep the top leg's knee straight, resting only the top of the foot or the lower shin on the bench. Keep the bottom leg straight and lifted off the floor, supporting your torso on your forearm.
Movement steps ① Push through the leg on the bench and your forearm to lift the hips into a straight line from shoulder to ankle. ② Hold the position with the bottom leg lifted. ③ Once you reach your target time, lower the hips slowly. ④ Repeat on the other side.
Breathing timing Same as Level 1: exhale briefly right before lifting, then keep a shallow, steady breathing rhythm through the hold. Because the load is higher here, more people unconsciously hold their breath, so pay extra attention to it.
Sets, reps, frequency 10-15 seconds per side, 3 sets, 2 times a week. It's normal for your target time to be shorter than Level 1, so don't force your way to 30 seconds.
Common mistakes and fixes The most common flaw is the hips sagging under the load while the low back bends sideways. Check your side profile in a mirror or your phone camera to confirm shoulder, hip, and ankle form a straight line, and stop just before the point where the form breaks rather than pushing to hit the clock. A slightly bent knee on the top leg is another common issue; the knee needs to stay straight for the lever to actually lengthen.
Stop if you notice Stop immediately and drop back to Level 1 or 2 if you feel a sharp, tearing pain deep in the groin, a throbbing or swollen sensation at a previously injured spot, or pain severe enough to make you limp while walking.
Level 4: Eccentric-Emphasis Long-Lever Dynamic Reps
Level-up criterion Once you can hold Level 3 for 10-15 seconds per side, 3 sets, keeping the body in a straight line, you're at the final level. Level 4 moves beyond a static hold to intentionally extend how long the adductor spends under lengthening tension on the way down, maximizing the eccentric stimulus.
Starting position Set up exactly as in Level 3. This time you'll switch to a repeated up-and-down movement.
Movement steps ① Lift the hips into the Level 3 straight-line position. ② Lower the hips very slowly toward the floor over a 4-second count. ③ Pause for about 1 second just before touching down. ④ Lift the hips back up relatively quickly, over about 1 second, returning to the starting position.
Breathing timing Inhale slowly through the nose during the 4-second descent, then exhale sharply through the mouth as you lift back up. The trick is making sure your descent speed doesn't outrun your breathing.
Sets, reps, frequency 6-8 reps per side, 3 sets, 2 times a week. Holding the 4-second descent matters far more than hitting a specific rep count.
Common mistakes and fixes The most common mistake is counting to 4 in your head while actually dropping in about 2 seconds. Having a partner count out loud, or timing yourself against a phone timer's beeps, helps you match the actual pace. Form often breaks down sharply on the last 1-2 reps as fatigue sets in; it's better to end the set there than push through with poor form.
Stop if you notice Stop immediately, ice the area, and see an orthopedic provider if you feel a sudden snapping sensation in the groin during the eccentric lowering, or a sudden loss of strength along with pain. Bruising in the groin the next day is also a sign of muscle fiber damage, and you should scale back intensity for at least a few days.
What to Emphasize Differs by Sport
In soccer, with its sudden changes of direction and kicking, it's worth paying extra attention to keeping the top leg fully extended through Level 4's 4-second descent, since the eccentric lengthening moment in a kick's backswing lines up almost exactly with that lowering phase. In racket sports like tennis and badminton, with their wide lateral steps, it can help to hold the Level 3 position and add a very small forward-and-back rotation of the top hip, training fine rotational control. Try this variation only once you can perform the basic Level 3 and 4 positions pain-free; adding it too early tends to break down alignment.
The 8-Week Program: Weekly Levels and Level-Up Criteria
The 8-Week Program: Weekly Levels and Level-Up Criteria
If you're unsure which level to run on a given day, use the table below as your baseline. Keep in mind the 8 weeks shown here is just an average-pace example; if you haven't met a given week's level-up criterion, don't move to the next level. Repeat that level for another week or two instead. The jump in difficulty from Level 2 to Level 3 in particular feels much bigger than it looks on paper, and pushing through that transition too fast is a common way groin pain comes back.
| Weeks | Primary Level | Target Time/Reps | Level-Up Check |
|---|---|---|---|
| Weeks 1-2 | Level 1, short-lever isometric | 20-30 sec per side, 3 sets, 2-3x/week | Pass 30 seconds, 3 sets in a row, without hip sag |
| Weeks 3-4 | Level 2, short-lever dynamic | 8-12 reps per side, 3 sets, 2-3x/week | Pass 12 reps, 3 sets, on a controlled 2-second tempo without bouncing |
| Weeks 5-6 | Level 3, long-lever isometric | 10-15 sec per side, 3 sets, 2x/week | Pass 15 seconds, 3 sets, keeping the body in a straight line |
| Weeks 7-8 | Level 4, long-lever eccentric-emphasis dynamic | 6-8 reps per side, 3 sets, 2x/week | Pass 8 reps, 3 sets, holding the 4-second descent tempo |
In the Harøy study, teams didn't stop after 8 weeks; they kept the routine going twice a week for the entire season, and the reduction in re-injury was more pronounced in teams that kept it up consistently. Continuing Levels 3-4 as maintenance work once or twice a week after finishing the 8-week program is more effective for preventing recurrence than stopping cold. Attaching it to the end of a warm-up or the start of a cooldown means you don't have to carve out extra time for it.
Keeping your log as simple as possible helps with consistency. Jot down the date, level, and your hold time or rep count per side in a phone notes app, one line at a time. Looking back over a few weeks lets you see exactly how much your eccentric strength has actually improved, and lining up the dates when pain flared with the dates you increased load helps you trace the cause.
When to Skip This, and Red Flags to Stop
When to Skip This, and Red Flags to Stop
This program is built with chronic groin tightness or re-injury prevention in mind, not an acute injury or a condition that needs a diagnosis first. If any of the following apply to you, see an orthopedic specialist or sports medicine provider before starting.
- You injured the groin less than 72 hours ago and still have swelling or bruising, the acute phase
- A bulge appears in the groin when you cough or strain, suggesting a possible hernia
- Sharp tenderness right at the pubic bone, suggesting acute osteitis pubis
- Deep groin pain that catches when flexing and internally rotating the hip, suggesting possible femoroacetabular impingement
- Pregnancy or the immediate postpartum period, when pelvic joints are unstable
- A recent groin or hip surgery without your surgeon's clearance to return to activity
Even if none of these apply to you, stop immediately and monitor your condition if you notice the following during the exercise: a sharp, tearing pain deep in the groin, a sudden loss of strength that makes you buckle, new bruising or swelling around the groin the next day, or pain with urination or a visibly bulging groin. If these signs keep recurring even after resting a day or two, it's safer to see a doctor and identify the cause rather than continuing to self-manage.
Near-infrared LED should be understood as a wellness tool that supports recovery around this eccentric training, not a medical device that replaces the exercise itself or treats an injury directly. Don't shine it directly into your eyes, and if you're taking a photosensitizing medication, check with your prescribing doctor before use. As a rule, don't apply it directly to open wounds or areas with reduced sensation. For a sensitive area like the groin, many people keep the device 10-30 cm from the skin and use it for about 10-15 minutes per session, 3-5 times a week, though the right duration can vary with skin condition and individual factors.
