What Is Butt Wink and How Do I Fix It?

woman performing barbell squat

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A key component of exercise is proper form in each movement you add to your workout. This applies to everything from a stationary bike to an overhead press. Before you add reps, weight, or change it up, you've got to make sure your form is good enough to stand any additional tests you add to it.

Butt wink is a potentially dangerous form flaw that occurs during the barbell squat. If you’ve never heard of butt wink, it might sound strange, but it is a common phenomenon for experienced lifters.

The risks involved in continuing to squat with butt wink under heavy loads include back injury and loss of power during the squat. Butt wink should be addressed to prevent an injury from occurring and so that you can improve your squat mechanics, increasing your ability to lift more weight safely and progress toward your goals.

If you have any pain or are concerned about your lower back and butt wink, seek the advice of a physiotherapist or other sports-related health care professional.

What is Butt Wink?

Butt wink refers to the rounding of the lower back during the descent of the squat. In anatomical terms, it is spinal flexion and occurs due to the pelvis tucking under near the bottom of a squat.

When the pelvis tucks in this way, it is called a posterior pelvic tilt. Your pelvis and lower back are connected, and so, if your pelvis starts to tilt posteriorly, you will see spinal flexion and rounding of the lower back.

The position where someone may experience butt wink will be different for everyone and can change, depending on your current mobility and whether you have adequately warmed up. 

However, there will be a depth during squatting for some people that cannot be reached without butt wink. In this case, you will need to adjust your depth to avoid your pelvis tucking and causing butt wink.

Butt wink is not a result of tight hamstrings or lack of strength. These two factors have incorrectly been attributed to causing butt wink. The hamstrings do not lengthen with a squat, therefore, hamstring tightness cannot cause it. Strength is also not a factor—anyone can have butt wink due to anatomy or incorrect squat form for their body type.

The Risks of Butt Wink

When starting in the squat, most people can obtain a neutral spinal position with the natural curve of the spine. Maintaining this throughout the entire descent and ascent of the squat is ideal for preventing injury. It also helps increase your power to push heavier weights, thereby improving your performance.

Injury and loss of power occur with butt wink due to the decreased ability to stabilize and maintain pressure in your core because of spinal flexion. It is vital for spinal injury prevention to properly brace your core during any weight-bearing activity. You need to create pressure through your core to stabilize the spine to do this. 

When your spine flexes, especially under load, you can no longer adequately pressurize and stabilize. If you can maintain a neutral spine, the load you are bearing can compress directly down the spine. In this position, the spine is resilient to injury.

However, when your low back begins to flex with posterior pelvic tilt, the load is no longer supported in a straight line and can cause excessive force on the spine, leading to a possible disc bulge. Disc bulges are caused by flexion movement under load, which occurs during a butt wink while squatting.

While a butt wink with no load (just bodyweight) or only occurring once is not a big risk for injury, repeatedly performing heavy squats with a butt wink motion can lead to disc bulges and other back injuries.

The neutral spine position is not one static position of the spine, but rather, a small range that is safe and natural for the spine to be in while bearing load.

The Causes of Butt Wink

It's important to figure out when and by how much butt wink is occurring during your squat—when your low back begins to flex due to the pelvis tucking under. The reasons for the pelvic tilt depend on your anatomy, squat stance and form, and mobility. The cause for each individual may be different and should be addressed depending on personal needs.


Some people may simply be squatting with the incorrect stance for their anatomy. For instance, a stance that is too narrow for the hip or femur anatomy of the individual.

You can test your ideal squat stance width by lying on the floor and having a friend push your bent knee straight back toward your chest. When it meets resistance and the pelvis starts to move, you have reached your mobility limit. Next, move the leg out to a wider angle and try again. Typically, you will be able to raise the knee significantly higher without the pelvis moving.

Deep Hip Sockets

People with deeper hip sockets will have less mobility when it comes to squat depth, as the head of the femur will hit the acetabulum (socket of the hip bone). The hip is a ball and socket joint, and as such, the ball aspect moves within the hip socket.

Deeper hip sockets prevent the ball joint from rotating farther. Shallow hip sockets allow for more movement and a deeper squat depth without hitting the barrier of the socket wall and preventing movement.

When the ball joint cannot move freely in the socket, the pelvis will start to tilt, resulting in butt wink. In this case, the simple fix is to widen your squat stance by moving your feet slightly wider than you normally would. See if this fixes your butt wink by having a friend or trainer monitor your back to see if you can maintain a neutral spine deeper into your squat.

Note that it is still vital not to squat to a depth that brings your spine out of neutral and leads to posterior pelvic tilt and spinal flexion. Review your squat form regularly to be sure you are avoiding a squat depth that causes butt wink.

Exercises to Prevent Butt Wink

One simple way to prevent butt wink is to widen your squat stance, as mentioned above. However, if the stance and hip socket depth are not the cause of your butt wink, there could be issues with mobility and control that can be addressed with specific exercises.

There is no definitive evidence that hip mobility is an issue that causes butt wink, especially at the bottom of the squat. If you believe you have limited hip mobility and want to try an exercise that may help, try the runner's lunge.

Ankle Mobility Exercises

Limited ankle mobility can also cause butt wink. To see if ankle mobility is an issue for you, perform the 5-inch wall test.

Place your foot 5 inches away from a wall while kneeling on the floor. The leg being tested will have the foot flat on the floor, and the leg bent at 90 degrees. The other leg supports you bent under and behind (in a tall kneeling position). Try to touch your upright knee to the wall in this position without your heel lifting off the floor. Test both sides—they may vary.

Stiffness, pinching, or blocked feelings can mean you need to work on your ankles before squatting. Try the following, and be sure to test your ankle mobility with the wall test after each drill to see if they work for you:

Banded Ankle Mobilization

  1. Attach a loop strength band to a fixed point and loop it around your ankle, around the bony parts that protrude. It should rest on the top of your foot, not around your upper ankle.
  2. Place your banded foot out away from the fixed point, so the band becomes taut. You can place your foot on a weight plate for a height boost if that feels better.
  3. Drive your knee forward. You will feel a bit of a stretch in the back of your ankle and relief from the pinching or blocking sensation in the front of your ankle.
  4. Push the knee straight forward for 5 to 10 seconds and release.
  5. Repeat 4 to 5 times.

Goblet Ankle Stretch

  1. Hold a 10-20lb weight plate, kettlebell, or dumbbell in front of your chest.
  2. Get into your normal squat stance and squat all the way down to the bottom position. Hold your weight out as a counterbalance. Rest your elbows on your knees with the weight held out in front of you.
  3. Move your hips to one side while driving the same side knee over your toes. Hold for 5 to 10 seconds and release. Switch and repeat on the other side.
  4. Repeat on both sides 4 to 5 times.

Bench Ankle Stretch

This stretch will be felt in the muscle in your lower calf. Ankle mobility will be limited if it is inflexible.

  1. Place one foot on a bench with the other on the floor.
  2. Drive the knee directly over the toes.
  3. Hold for 5 seconds and release.
  4. Repeat 10 to 20 times.

If ankle mobility isn't your issue, you may find help from using a lifting shoe. Choose a shoe with a bit of a heel lift designed specifically for squatting. This small lift can help you squat deeper without a posterior pelvic tilt.

Lumbo-Pelvic Control Exercises

If your butt wink is not solely due to your hip anatomy limiting your squat depth and your pelvis is tilting early and throughout the descent of your squat, you may have issues with control in your lumbopelvic region. The lumbopelvic region is the area of your lumbar spine (lower back) and pelvis. Here are some exercises that can help you with lumbopelvic control:

Quadruped Rock Back

The quadruped rock back will help you learn how to maintain a neutral spine while moving your hips and shoulders.

  1. Get on your hands and knees and find a neutral spinal position by tucking and arching your low back until you find a comfortable, natural position.
  2. Maintain this position while you hinge back, moving your bum toward the wall behind you.
  3. Push back until you feel your low back may start to round (or pelvis tucking under).
  4. Practice rocking back like this while maintaining a neutral spine.

Counter Balance Squat

Using a counterbalance in the form of a dumbbell, weight plate, or kettlebell, held out from the body, can make descending into a squat with a neutral spine easier.

  1. Hold a light weight (5 to 10lb) such as a small weight plate, kettlebell, or dumbbell in front of your chest while standing with feet in your normal squat stance.
  2. Extend your arms to where you feel comfortable, the farther out, the more you will have a counterbalance.
  3. Lower into a squat with the weight extended while maintaining your neutral spine. Focus on going slowly, with control.

After performing these movement, try practicing your squat again with an unloaded barbell. Progress by using lighter weights than you used to until you are confident you are not allowing your pelvis to posteriorly tilt.

A Word From Verywell

Butt wink during the squat can lead to back injury. It also reduces your power, limiting your ability to lift heavier weights. If you are experiencing butt wink, it's vital that you address the cause and fix the issue.

If you are unsure what is causing your issue or you feel any pain, it's critical that you seek professional help from a physiotherapist or other sports-related health care professional.

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By Rachel MacPherson, BA, CPT
Rachel MacPherson is a health writer, certified personal trainer, and exercise nutrition coach based in Montreal.