Sitting cross-legged is no problem, but the moment you try to spread your legs wide to the side and bend just one knee to sit into it, the inner groin on the other side pulls so tight you can't put any weight on it at all. That same tightness shows up when you dive sideways for a shot in soccer or badminton, or take one big step to the side while carrying a child. No amount of opening the pelvis with 90/90 stretches or hip flexor stretches seems to touch this particular stiffness, and there's a reason: most stretches only address the front-to-back direction or the inward-outward rotation of the hip, never the side-to-side direction where you actually shift and load your weight.
The Cossack squat fills that exact gap. Standing with the feet wider than the shoulders, you bend one knee fully to sit deep while the opposite leg stays straight with the whole sole planted on the floor, then shift your weight back to the other side. The bent-leg hip goes through deep flexion and external rotation while the straight-leg adductors and hip stretch to their full length, both at once. Unlike a static seated stretch, the act of shifting weight itself loads the lengthening tissue, so you're not just building flexibility, you're building the strength to actually use that new range. This guide breaks the movement into five levels, from an assisted version holding a wall to a full-depth squat with no hands and a brief hold at the bottom, laid out so even someone whose groin is too stiff to sit sideways at all can follow along starting today. If rotational stiffness feels like the bigger issue for you, check this companion piece: hip 90/90 mobility routine
Why Stretching Alone Doesn't Fix It: The Lateral Mobility Gap
Why Stretching Alone Doesn't Fix It: The Lateral Mobility Gap
Adductors don't get short simply because you sit a lot; more precisely, they lose the ability to produce force in a lengthened position because you almost never spread your legs wide to the side. Walking, climbing stairs, cycling, all the movements that fill an ordinary day keep the legs moving front to back, and the moment they spread wide only comes up in sport or a sudden change of direction. That's why someone can walk around all day with no issue, then feel a sudden pulling pain in the adductors the instant they lunge sideways in soccer or try a side lunge on a yoga mat.
Malliaras et al. (2009, British Journal of Sports Medicine) screened 111 professional Australian football players before the season and found that players with lower measured hip adductor strength had a significantly higher probability of a groin injury during the season. It's a prospective cohort study observing an association between strength deficits and injury occurrence, so it can't establish causation outright, and the sample was limited to male professional players in a single season and league, which makes it hard to generalize directly to general recreational adults. Still, the observation that an inability to produce force through a lengthened adductor range travels together with injury risk gets cited often in the design of later prevention programs.
A literature review on groin injury rehabilitation by Delahunt et al. (2011, Physiotherapy Practice and Research) concludes that exercises loading the muscle actively through a wide range of motion, eccentric training like the Copenhagen adduction exercise, carry relatively strong supporting evidence for reducing pain and shortening return-to-play time. The review notes a real limitation too, though: most of the studies it covers were done on athletes who already had an injury, so it's hard to say a healthy person doing the same training preventively would see effects of the same magnitude.
A study by Tyler et al. (2001, American Journal of Sports Medicine) on professional ice hockey players in the United States reported that in seasons where adductor strength was maintained at 80% or more of abductor strength, groin injury rates dropped substantially compared to previous seasons. It's a relatively small intervention study limited to a single team and a single sport, so the same numbers won't necessarily transfer to other sports or the general public, but it's frequently cited as support for the direction that side-to-side strength balance and the ability to produce force with lengthened adductors are tied to injury prevention.
All three sources point to the same conclusion. Lateral mobility of the adductors and hip matters less for how far it stretches than for whether you can support body weight and produce force through that lengthened range. Check your own status with the table below first.
| Check movement | Comfortable range | Possible restriction |
|---|---|---|
| Spreading feet to 1.5x shoulder width and sitting sideways into one side | Both heels stay flat on the floor while shifting weight | A heel lifts on one side, or a sharp pull in the groin |
| Standing, taking a big side step and sitting into it | Both knees track over the toes in a stable sit | A knee caves inward or balance is lost on one side |
If you noticed a clear left-right difference on this check, that's exactly the gap the Cossack squat routine below is designed to close. Worth noting too, if neither leg feels distinctly easier and both sides get stuck at a similar point, the issue may be an overall lack of lateral mobility rather than a left-right asymmetry.
It's easy to assume a side lunge or a sumo squat is basically the same thing since both spread the legs wide to the side, but the actual range and mechanism differ. A side lunge usually only bends the knee about halfway while the opposite heel lifts slightly or leaves the floor entirely, so it ends the movement before the adductor ever reaches its maximum length. A sumo squat bends both knees at the same time, so there's never a phase where one leg stays fully straight and lengthened at all. What sets the Cossack squat apart is the requirement that while one knee folds all the way down, bringing the hip close to that heel, the opposite leg keeps its knee straight with the entire sole planted on the floor. Only when that condition holds do the straight-leg adductors and inner hip actually load with real body weight and lengthen all the way, while the bent-leg hip simultaneously goes through deep flexion and external rotation. That's why the stretch effect drops off sharply the moment a heel lifts, a point worth repeating throughout this guide.
Setting Up the Cossack Squat: Stance Width and Weight Distribution
Setting Up the Cossack Squat: Stance Width and Weight Distribution
Before moving through the levels, get your base stance and foot width right. Starting with feet too narrow or toes pointed the wrong way places unnecessary rotational stress on the knees in every level that follows, so spend the first few days checking your foot position in a mirror, barefoot.
What you need A non-slip floor or yoga mat is enough, along with a sturdy chair or doorframe to hold onto if your balance still feels shaky. No special equipment is required, so you can do this in a corner of the living room, on a conference room floor at work, or on a hotel room floor while traveling, as long as there's space for a single mat, which makes it easier to stay consistent.
Base setup ① Stand with your feet spread 1.5 to 2 times wider than your own shoulder width. It's fine to start wider than feels natural. ② Turn your toes out slightly, about 15 degrees past straight ahead. ③ Bring your hands together in front of your chest, or hold a chair back lightly in front of you if you need the support. ④ Bend your knees and hips slightly into a ready position and check that your weight sits evenly between both feet.
Common mistakes and fixes Starting with the stance too narrow is the most common error; a narrow stance leaves too little room to shift weight sideways, which pulls the knee inward. If your knee caves in, widen your stance by another hand's width and open your toes out a bit more. Letting the heels lift before you even start is another common issue; this makes you unstable during the weight shift, so confirm both heels are firmly planted before you begin.
Stop if you notice Sharp pain in a knee or the groin just from standing in the base stance, or numbness or radiating pain down the leg while standing, means you should skip this session. Forcing a large weight shift while pain is already present can put excessive rotational stress on the knee ligaments or meniscus.
Footwear and floor surface Bare feet or thin, flat-soled shoes work best. Thick-cushioned running shoes let the ankle wobble independently inside the shoe as weight shifts sideways, which makes balance harder to control. Trying this in socks on a hardwood floor or slippery tile risks the foot sliding out from under you the moment you shift weight, so always practice on a non-slip mat or carpet at first.
Levels 1-2: Assisted Side Squat and Shallow Cossack
Levels 1-2: Assisted Side Squat and Shallow Cossack
Once the base stance feels stable, these two levels actually shift weight to the side. Both move in the same pattern, but the first leans heavily on hand support while the second gradually removes it.
Level 1, Assisted Side Squat
Starting position From the base stance above, hold a sturdy chair back or doorframe with your right hand. Keep the same stance width and toe angle you set earlier.
Movement steps ① Bend the left knee and shift your weight to the left. ② Keep the right leg straight, heel flat, not lifting off the floor. ③ Sink only as far as the point where your left hip feels like it's settling toward the left heel; going only halfway down is plenty at first. ④ Push back to center using the chair as support.
Breathing rhythm Exhale as you shift and sink, inhale as you push back to center. If you pause briefly at the bottom, keep breathing in short breaths rather than holding.
Sets, reps, frequency 6-8 reps each side, 3 sets, 4-5 times per week.
Common mistakes and fixes Leaning so much weight onto the chair that the legs barely work is common; gradually reduce hand pressure so the leg muscles take on the body weight. The straight leg's heel drifting back and lifting is another frequent issue; if the heel lifts, cut the depth in half and prioritize keeping the whole foot flat first.
Stop if you notice A sharp, pinching pain in the inner groin of the straight leg, or sharp pain on the inside of the bent knee, means return to center and stop immediately. This is clearly different from an ordinary pulling, achy sensation.
Level 2, Shallow Cossack
Starting position From the same base stance as Level 1, this time bring your hands together in front of your chest or rest them lightly on your thighs, without support.
Movement steps ① Shift your weight left and bend the left knee to roughly 90 degrees only. ② Keep the right leg straight, whole sole planted on the floor, holding steady. ③ Pause briefly, then push back to center using left leg strength. ④ Immediately shift weight to the other side, bending the right knee to 90 degrees.
Breathing rhythm Exhale as you shift weight into the sit, inhale as you return to center. Repeat this rhythm each time you alternate sides.
Sets, reps, frequency 8-10 reps alternating sides, 3 sets, 4-5 times per week.
Common mistakes and fixes Leaning the torso far forward to find balance is common; if you're leaning a lot, cut the depth slightly and keep your chest upright as you continue. The bent knee tracking inward past the toes is another frequent issue; consciously aligning the knee with the second toe helps correct it.
Stop if you notice The knee wobbling side to side or feeling unstable mid-shift, or new numbness or radiating pain down the leg, means drop back to Level 1 and use hand support again immediately.
On your first sessions with either level, prioritize left-right symmetry over maximum depth. If you consistently sit shallower or feel less balanced shifting one direction versus the other, calibrate the depth of the whole set to that weaker side. Training to the weaker side naturally narrows the gap over time; forcing the weaker side to match the stronger side's depth instead tends to load up strain on the weaker knee or groin first.
Levels 3-4: Full-Depth Cossack and Hold-and-Reach
Levels 3-4: Full-Depth Cossack and Hold-and-Reach
From here on you're not just shifting weight side to side, you're sinking to full depth and actively holding there. Give yourself at least two pain-free weeks with Levels 1-2 before moving on to these.
Level 3, Full-Depth Cossack
Starting position From the base stance, widen your feet slightly beyond the width used in Levels 1-2. Bring your hands together in front of your chest, or keep them ready to touch the floor if you need balance support.
Movement steps ① Shift your weight left and sink as deep as possible, until the left hip nearly touches the left heel. ② Keep the right leg's knee fully straight with the whole sole pressed into the floor. ③ At the deepest point, tip the pelvis back slightly to find the point of maximum length in the straight leg's adductors. ④ Push back to center using only left leg strength.
Breathing rhythm Exhale as you sink, exhale again briefly at the deepest point to relax further into the position, then inhale as you rise.
Sets, reps, frequency 5-6 reps each side, 3 sets, 3-4 times per week.
Common mistakes and fixes Lifting the heel to chase more depth is common; if a heel lifts, that's your maximum depth for today, don't force further. The straight leg's knee staying slightly bent instead of fully straight is another common issue; this shortchanges the adductor stretch, so prioritize a straight knee first and build depth after that's locked in.
Stop if you notice Sharp, stabbing pain in the groin or inner hip at the deepest point, or numbness or radiating pain down the leg, means rise to center and stop immediately, then cut the depth in half at your next session.
Level 4, Hold-and-Reach
Starting position Set up the same deep sit into one side as in Level 3.
Movement steps ① Hold the deepest position for 3-5 seconds. ② While holding, reach both hands toward the toes of the straight leg, tilting your torso slightly. ③ Take one more breath in the reached position, then lift your torso back upright and push back to center. ④ Repeat on the other side.
Breathing rhythm Breathe in short breaths through the hold, and a second exhale right as you reach often lets you reach a little further.
Sets, reps, frequency 3-5 second holds, 4 reps each side, 3 times per week. Since this loads the muscle actively, spacing sessions at least a day apart works better than doing it daily.
Common mistakes and fixes Letting the straight leg's knee bend as you reach is common; if that knee bends, shorten the reach and prioritize keeping the knee straight instead. Wobbling forward and backward during the hold and losing balance is another frequent issue; if balance wobbles, cut the hold to 2-3 seconds and lightly touch just the fingertips to the floor for support.
Stop if you notice The knee buckling sideways during a hold, a catching sensation in the groin, or numbness or radiating pain down the leg getting worse, means release the position and drop back to Level 3 immediately.
Even someone who can handle Level 4 comfortably shouldn't expect perfect symmetry every time. Depending on pelvic structure or a past injury history, it's common for one side to consistently hold 1-2 seconds less or reach a bit shorter, and watching whether that gap is narrowing over time is a more useful goal than chasing perfect symmetry itself.
The 7-Week Progression: Building Depth and Volume
The 7-Week Progression: Building Depth and Volume
If you're unsure which level to prioritize on a given day, use the table below as your guide. The rule is to only increase emphasis on the next stage once you can perform the current one comfortably and pain-free; treat this table as a typical pace, not a strict deadline.
| Week | Primary level | Target volume | Criteria to progress |
|---|---|---|---|
| Weeks 1-2 | Level 1, assisted side squat focus | 6-8 reps each side, 3 sets, 4-5x/week | Able to hold half-depth balance without chair support |
| Weeks 3-4 | Maintain Level 1, add Level 2 shallow Cossack | Level 1 volume tapers; Level 2 alternating 8-10 reps, 3 sets, 4-5x/week | Able to sink to 90 degrees without hand support and without the knee collapsing |
| Week 5 | Maintain Level 2, introduce Level 3 full depth | Level 3: 5-6 reps each side, 2 sets, 3x/week | Reaches maximum depth without a heel lifting |
| Weeks 6-7 | Increase Level 3 volume, add Level 4 hold-and-reach | Level 3: 3 sets. Level 4: 3-5 second holds x 4 each side, 3x/week | Able to hold the deep position 3+ seconds without wobbling and reach forward |
Still working through Level 2 after seven weeks is entirely normal. Lateral mobility of the adductors and hip tends to recover even more slowly than rotational mobility, and if you've gone a long time without spreading your legs wide to the side at all, it realistically can take 10 or more weeks. Consistency, a little every day, matters more than forcing depth.
If you want to see progress rather than just feel for it, film yourself from the side at the deepest position each week, same day, same time. Comparing the distance between the bent-leg hip and heel, and whether the straight leg's knee is fully extended, across photos often reveals changes that are hard to feel in the moment but show up clearly as numbers or angles. Placing left and right photos side by side also makes it obvious which side is lagging, so you can add an extra set or two on that side to fine-tune the program.
When you do this in your day also affects how consistent you stay. Try a light Level 1-2 warm-up before a workout, or work through Level 3 on a mat in front of the TV in the evening, folding the routine into something you're already doing rather than carving out separate time. On days before a sport with a lot of lateral movement, like soccer or badminton, dropping down one level and using it purely as a warm-up is also a good approach.
When to Skip This: Contraindications and Stop Signs
When to Skip This: Contraindications and Stop Signs
This routine is designed to restore chronically limited lateral mobility of the adductors and hip, not to replace a diagnosis or treatment for an acute injury. See an orthopedist or physical therapist first if any of the following apply to you.
- A recent groin strain or a diagnosed partial adductor tear that hasn't cleared its acute phase
- A hip or knee surgery recent enough that full flexion range hasn't yet been cleared by your provider
- A diagnosis of femoroacetabular impingement or a labral tear where your provider has advised against deep squat positions
- Dizziness or lower-limb weakness severe enough to cause a major loss of balance just from shifting weight while standing
- Knee ligament or meniscus injury that makes deep knee flexion itself feel unstable
- Late-stage pregnancy, where relaxed pelvic ligaments make deep lateral weight shifts uncomfortable
- Ongoing numbness or radiating pain down the leg that hasn't been evaluated yet
Even if none of these apply, stop and reassess if any of the following happen during a session: new or worsening numbness or radiating pain down the leg, sharp, stabbing pain in the groin or inner hip, or a sensation of the knee buckling sideways or feeling unstable. If the signal keeps showing up even after a day or two of rest, get it checked rather than pushing through on your own judgment.
Near-infrared LED is not a substitute for this lateral weight-shift squat and does not directly treat a joint problem, it's best understood as a wellness tool that supports recovery before or after exercise. Don't shine it directly into the eyes, and check with your physician first if you're taking a photosensitizing medication. Avoid direct application over thin, sensitive skin like the groin; for the inner and outer thigh, a distance of 5-30cm (2-12 in) from the skin for 10-15 minutes, 3-5 times per week, is a common pattern among users, though the right duration varies with skin condition and individual differences.
Exercise order matters too. Using near-infrared light before the squat routine and then immediately attempting a deep position risks mistaking temporarily warmed tissue for genuinely improved flexibility, which can push you to sink deeper than usual. Use the light for recovery after the routine instead, and warm up beforehand with light walking or shallow Level 1 reps, keeping that order for safety.
