The Cossack squat is a lateral squat variation where the athlete squats deeply to one side while the opposite leg extends straight along the floor. It is one of the most complete single exercises for developing lower body mobility and strength simultaneously, combining deep hip flexion, hip adductor stretch, ankle dorsiflexion, and single-leg stability in a movement that no conventional gym exercise replicates.
The Cossack squat is used by gymnasts, martial artists, dancers, and strength athletes as a foundational mobility-strength exercise, and it is increasingly recognised in athletic training for its direct transfer to cutting movements, defensive stances, and lateral athletic demands. Its reputation for being difficult is partly due to the genuine demands it places on hip, ankle, and thoracic mobility, and partly due to being commonly attempted before the prerequisite mobility exists to perform it safely.
What the Cossack Squat Uniquely Develops
Most lower body exercises develop strength or mobility in the sagittal plane (forward and backward movements). The Cossack squat works primarily in the frontal plane (side-to-side), developing qualities that squats, deadlifts, lunges, and hip thrusts do not:
Deep unilateral hip flexion strength: The squatting leg must control the body’s descent into deep hip flexion (significantly deeper than a standard squat) against the full body weight on a single leg. This develops the hip flexor, quad, and glute strength at end-range flexion that bilateral squats rarely challenge.
Hip adductor flexibility and strength: The extended leg creates a significant adductor stretch as the squat deepens. Unlike passive stretching, the Cossack squat requires the adductors to work eccentrically during the descent and concentrically during the return, developing both flexibility and strength through the adductor range.
Ankle dorsiflexion under load: The deep squat position on the squatting leg requires significant ankle dorsiflexion under full body weight, which is one of the most effective ways to develop functional ankle mobility.
Hip internal rotation range: At the bottom of the Cossack squat, the squatting hip is in deep flexion and internal rotation. This combined position is one of the most restricted movement combinations in most adults and is also the position most associated with hip impingement limitations.
Thoracic rotation and lateral flexion: To maintain balance in the Cossack squat, the trunk must remain upright despite the unilateral loading, requiring thoracic mobility and lateral stability.
Muscles Worked
Primary muscles (squatting leg):
- Quadriceps: Work to control the knee flexion during the descent and drive the return
- Gluteus maximus: Eccentrically controls the deep hip flexion during descent and concentrically drives the return
- Hip adductors (squatting leg): Work alongside the glutes during the deep position
Primary muscles (extended leg):
- Hip adductors: Stretched and eccentrically loaded as the leg extends during the descent
- Hamstrings: Provide tension on the extended leg through the knee and hip
Secondary muscles:
- Gluteus medius: Maintains pelvic level during the unilateral loading
- Core: Anti-lateral-flexion stability throughout
- Calves: Ankle stability during the deep squat position
Prerequisites Before Attempting the Cossack Squat
The Cossack squat requires a baseline of mobility that many people do not yet have. Attempting the full version without the prerequisites typically produces one or more of: heel rising on the squatting foot, rounding of the lower back, inability to extend the other leg, or pain in the hip or knee.
Mobility prerequisites:
- Adequate ankle dorsiflexion: The squatting heel must remain flat throughout. If the heel rises during a standard bodyweight squat, ankle dorsiflexion needs work before the Cossack squat.
- Hip adductor flexibility: The ability to perform a wide-stance sumo squat to parallel with the toes pointed outward is a minimum prerequisite.
- Hip flexion range: The ability to squat to depth in a standard bodyweight squat with a neutral spine.
Strength prerequisites:
- Single-leg squat to a box: The ability to perform a controlled single-leg squat to a low box indicates sufficient unilateral strength for the Cossack squat.
If these prerequisites are not yet met, the progressions described in the progressions section below provide the pathway to developing them.
Step-by-Step Technique
Starting Position
- Stand with feet significantly wider than shoulder-width, approximately 1.5 to 2 times shoulder-width
- Toes can point forward or slightly outward, whichever allows the most comfortable wide stance
- Arms extended forward for counterbalance
- Bodyweight evenly distributed between both feet
The foot position question:
The squatting foot can have the toes pointing forward or turned outward slightly. Turning the squatting foot outward eases the ankle dorsiflexion demand and makes the squat more accessible for most people. As ankle mobility improves, the foot can be progressively turned toward forward. The extended leg foot typically turns upward (toes pointing toward the ceiling) or rests flat on the heel as the leg extends.
The Descent
- Shift the weight toward one leg (the squatting leg)
- Begin bending the squatting knee while the opposite leg extends straight to the side
- As the squatting knee bends, push it outward over the toes
- Lower the hips toward the floor on the squatting side
- The extended leg remains straight with the foot either flat, on the heel, or with toes pointing upward
- The torso remains as upright as possible throughout
- Lower until the deepest comfortable position is reached while maintaining a flat heel and neutral spine
What to feel at the bottom:
A deep stretch in the inner thigh of the extended leg (hip adductors), a quad burn in the squatting leg, and a deep hip flexion sensation in the squatting hip. The ankle of the squatting foot should be under significant dorsiflexion load.
The Return
- Drive through the heel of the squatting foot to return to the starting wide-stance position
- The extended leg draws back in as the weight returns to centre
- Pause briefly in the wide-stance starting position before shifting to the other side
- Transition to the opposite side for the next repetition
Performing as alternating repetitions:
The most common way to perform Cossack squats is alternating sides: squat right, return to centre, squat left, return to centre. This constitutes one complete repetition.
Key Technique Cues
Heel flat throughout: The squatting heel must remain in contact with the floor throughout the entire movement. A rising heel indicates insufficient ankle dorsiflexion and should be addressed with the progressions below rather than accepting the heel rise as a technique compromise. A heel rise during a Cossack squat shifts the loading forward onto the knee structures and away from the hip, changing the training stimulus and increasing injury risk.
Knee over toes: The squatting knee should track over the second and third toes throughout the descent. Knee cave (the knee drifting inward) indicates insufficient hip external rotation control and should be corrected by actively pushing the knee outward throughout.
Torso as upright as possible: The trunk should remain relatively upright rather than leaning significantly over the squatting leg. Some forward lean is natural as the depth increases, but excessive forward lean indicates hip or ankle mobility limitations that are limiting the depth. Use the arms extended forward or overhead to assist with the upright torso position.
Extended leg truly straight: The extended leg should be straight (fully extended at the knee) rather than slightly bent. A bent extended leg reduces the adductor stretch and makes the movement significantly easier, which reduces the training stimulus.
Smooth transition: The movement from the centre position to the squatted position should be smooth and controlled rather than dropping rapidly. The controlled descent develops the eccentric strength component that is one of the primary training values of the exercise.
Common Errors and Fixes
Error 1: Heel Rising on the Squatting Foot
Why it happens: Insufficient ankle dorsiflexion range.
Fix: Elevate the heel of the squatting foot on a small plate (2.5 to 5 kilograms) to reduce the dorsiflexion demand while the ankle flexibility is developed. Work on ankle dorsiflexion mobility separately (ankle circles, wall ankle stretches, calf stretching). As dorsiflexion improves, progressively reduce the heel elevation until the squat can be performed flat-footed.
Error 2: Lower Back Rounding
Why it happens: Insufficient hip mobility (hip flexion or adductor flexibility) prevents the deep position from being achieved with neutral spine, so the lumbar spine rounds to add range.
Fix: Reduce the depth of the squat to the point where neutral spine can be maintained. Use the elevated heel option to reduce the ankle demand. Work on the beginner progressions below to develop the prerequisite hip mobility.
Error 3: Knee Caving Inward
Why it happens: Insufficient hip external rotation strength or control.
Fix: Actively cue the knee outward over the toes throughout the movement. Strengthen the hip external rotators (clamshells, lateral band walks) before progressing the depth.
Error 4: Extended Leg Not Straight
Why it happens: Hamstring tightness preventing full knee extension in the wide-stance position, or insufficient hip adductor flexibility preventing the leg from reaching the extended position.
Fix: Begin with the extended leg slightly bent and work toward full extension as flexibility improves. Hamstring stretching and adductor stretching performed separately will accelerate this progress.
Error 5: Inability to Shift Weight to One Side
Why it happens: The stance width is too wide for the current mobility, or the starting balance is insufficient for the lateral weight shift.
Fix: Begin with a narrower stance (slightly wider than shoulder-width) and progressively widen as mobility develops. Use a support (holding a rack post or doorframe) to assist balance during the learning phase.
Progressions
Level 1: Supported Cossack Squat
For people who do not yet have the mobility for the unsupported version.
How to do it:
- Hold a rack post, doorframe, or TRX handles for support
- Use the support to assist balance and allow the torso to remain upright
- Lower into the Cossack squat position while holding the support
- The support allows deeper positions than the unsupported version and accelerates mobility development
Sets and reps: 3 sets of 5 per side, daily
Level 2: Cossack Squat With Heel Elevation
For people with limited ankle dorsiflexion.
How to do it:
- Place a weight plate or a low wedge under the heel of the squatting foot
- Perform the Cossack squat with the elevated heel reducing the dorsiflexion demand
- Progressively reduce the elevation as ankle mobility improves
Sets and reps: 3 sets of 5 per side
Level 3: Bodyweight Cossack Squat (Standard)
The full bodyweight version as described in the technique section above.
Sets and reps: 3 sets of 6 to 8 per side
Level 4: Cossack Squat With Pause
Add a 3 to 5 second pause at the bottom position. The sustained hold at end-range develops both mobility and strength in the deep position and extends the adductor and hip flexion training stimulus.
Sets and reps: 3 sets of 5 per side with 3-second hold
Level 5: Cossack Squat With Load (Goblet Position)
Hold a dumbbell or kettlebell at the chest (goblet position) to add external resistance.
How to do it:
- Hold a light dumbbell or kettlebell at the chest with both hands
- Perform the Cossack squat with the added load
- The goblet position also assists with keeping the torso upright, which is why some people find a lightly weighted goblet Cossack squat easier than the unweighted version initially
- Begin with a light weight (5 to 10 kilograms) and progress gradually
Sets and reps: 3 sets of 6 per side
Level 6: Kettlebell Cossack Squat (Advanced)
As covered in the kettlebell cossack squat article on this site, the kettlebell adds unique loading options including the racked position and the overhead position that further challenge the movement.
Programming the Cossack Squat
As a mobility drill:
The Cossack squat is one of the most effective lower body mobility exercises when performed daily at low intensity. 2 sets of 5 to 6 reps per side daily, using the supported version if needed, produces consistent mobility improvements over 4 to 6 weeks.
As a strength exercise:
3 to 4 sets of 6 to 8 per side with progressive loading (goblet or kettlebell). 2 times per week as part of a lower body strength programme.
As a warm-up drill:
3 to 5 Cossack squats per side before lower body training, martial arts, gymnastics, or any sport involving lateral movements. The broad range of motion accessed by the Cossack squat makes it one of the most efficient single-exercise warm-ups for the lower body.
In a mobility circuit:
Cossack squat (5 per side), hip 90/90 (60 seconds per side), deep squat hold (30 seconds), hip CARs (5 per side). Performed daily for 10 minutes, this circuit develops comprehensive lower body mobility over 6 to 8 weeks.
Frequently Asked Questions
Is the Cossack squat safe for the knees?
Performed with correct technique (heel flat, knee over toes, controlled descent), the Cossack squat is generally safe for healthy knees. The deep knee flexion of the squatting leg is comparable to other deep squat patterns. The primary knee risk comes from heel rising (which shifts stress to the knee) and knee cave (which creates valgus stress). Both are correctable with the technique cues and progressions above. Anyone with existing knee pathology should begin with the supported version and progress conservatively.
Why do some people find the goblet Cossack squat easier than the bodyweight version?
The goblet position shifts the centre of mass forward and slightly lowers it, which counterintuitively makes balance easier and allows the torso to remain more upright. The weight at the chest provides a counterbalance that assists the deep lateral squat position. This is why the goblet Cossack squat is often used as a teaching tool for people who cannot maintain balance in the unweighted version.
How wide should my stance be for the Cossack squat?
The appropriate stance width is the widest position where the extended leg can be kept straight and the squatting heel can remain on the floor during the descent. Most people find this to be approximately 1.5 to 2 times shoulder-width. Begin narrower and progressively widen as mobility develops rather than starting at maximum width where technique is compromised.
Can I do Cossack squats if I have tight hip flexors?
Yes, and the Cossack squat may help address the hip flexion restriction. The deep hip flexion of the squatting leg develops hip flexion range under load, which is one of the most effective ways to address hip flexor tightness beyond passive stretching. However, very tight hip flexors may make the initial sessions uncomfortable in the deep position. Begin with the supported version and a reduced depth and progress gradually.
How long does it take to develop a full Cossack squat?
For people with typical adult mobility limitations (moderate ankle restriction, moderate adductor tightness, moderate hip flexion limitation), consistent daily practice of the supported version and the heel-elevated version typically produces a full unsupported Cossack squat within 4 to 8 weeks. People with very restricted mobility may take 3 to 6 months. Consistent daily practice produces faster progress than less frequent training for this type of mobility-strength exercise.