The correct way to squat (and solve the “butt wink” problem)

Some things can’t be debated, like whether it’s a crime to hide a raisin cookie in a batch of chocolate chips. Other acts are a little less safe. And, when it comes to exercising movement, there is no shortage of disagreements about which movements are safe and which should be limited.

Squats are one of the most controversial exercises. Some people suggest they are the best movement (period), while others, notably respected trainer Mike Boyle, suggest they are many times abused and unnecessary.

At Born Fitness we work with our online training clients to determine which move is best for them. We love squats, but not everyone needs to do them. General recommendations are dangerous. One person’s path to better performance may be another person’s path to injury.

And, if you do, it certainly doesn’t have to be on two legs (you can do 1-leg variations) or with a barbell on your back.

Let’s say you want to squat (remember, it’s still a primary move). All you need to do is figure out how deep to go and what is dangerous for your body.

Many people will suggest that any type of “butt wink,” a rounding of the lower back, is dangerous.

It’s not that simple, but we can offer you an easy way to help you figure out what’s best for your body.

Is Butt Wink bad?

Some trainers want you to do rear-on-grass (ATG) squats. While others, notably Dr. Joel Seedman ( screenshot below), claim that he should stop his squat at around 90 degrees.

Dr. Joel Seedman's Squat Form
Source: Advanced Human Performance

The two camps disagree primarily on what is dangerous to the spine. And, the move most often in question is the “butt wink.”

As you lower into a squat, there is a point where you dive in so far that your lower back (lumbar spine) begins to round out.

butt wink vs no butt wink
Source: Girls Gone Strong

If you want to see what this looks like on your own body, find a mirror and it’s easy to assess. Roll onto your side toward the mirror, and then slowly lower yourself into a squat with your body weight. As you reach the bottom of the squat, watch your lower back. If you’re like most people, you’ll see this area slowly “flash” as you go deeper.

This rounding of the spine, called spinal flexion, is not inherently dangerous. Our spines are made to flex, extend, and rotate like human beings. That’s why you probably don’t need to worry about this rounding during movements like the bodyweight squat.

So what’s the problem? Rounding without weight on your back is not a big problem. But, once you start adding weighted back flexion, and do it for high reps, such as during a heavy back squat, that’s when the story changes.

Rounding your lower back with a load (such as a barbell) is considered by most spine experts to be risky to the lumbar spine, which means you are at greater risk of disc injury and back pain. back.

Here’s why: Between each bony segment (the vertebrae) in your spine is a gel-filled disc that helps absorb shock. This means that when there is weight on your back, you can safely transfer it along your spine.

When you load your spine, you create a compressive force that pushes the vertebrae together and squeezes the intervertebral discs. This is not dangerous if you have a healthy spine. (Fun fact: your spine is quite resistant to compression.)

The problem is when you compress and flexes the spine at the same time. This combination of loading and bending increases another force (shear) on the spine. And the cut plus compression could increase your chance of injury.

neutral vs arched spine
Source: Stronger for Science

We all have different anatomy, so for you, that injury could take years. But, flex your spine under load rep after rep and eventually you could have a problem on your hands.

That’s why a butt wink while squatting under load not a good idea for the vast majority of us.

What causes the butt wink?

People love to blame “tight hamstrings” for the difficulty in squatting. It’s likely not the cause of the butt wink, so stretching them before lifts won’t help you avoid it.

As Dr. Aaron Horshig discusses in this videothe hamstrings attach to both the pelvis and the knee, which means they don’t actually lengthen much during the squat.

Try this: Lie on your back with your legs stretched out. Now lock your knees and slowly lift one leg up.

I take it you didn’t get high? This is because, with your leg straight, you lengthen your hamstring, eventually reaching your end range.

Do it again, but let the knee bend 90 degrees as you lift the leg.

Feel the difference? You have more range of motion because as you flex the hip (lengthening the hamstring), you also bend the knee (shortening the hamstring). All of your muscle stays relatively the same length, like during a squat.

Instead, the butt wink often comes down to the squat and ankle mobility. And to know about both, it’s time to analyze how you move.

Shakira would be proud, but your hips don’t lie.

Each of us has a unique angle at which our femur (the large thigh bone) fits into the hip socket. And this angle determines your squat.

Let’s say your stance is too narrow or wide (depending on your individual hip genetics). In that case, you will run out of hip socket space when you bring your legs into hip flexion (lowering into a squat).

When you try to force the range of motion, your body compensates. As you run out of hip room at the bottom of the squat, your pelvis tilts back (called the posterior pelvic tilt) and your lower back rounds. Hey, rear wink.

You got to the bottom, but was it really worth it? (More on that in a moment).

Butt wink can also be caused by ankle mobility problems. If you don’t have the range of motion in your ankle, your body can’t drive your knees forward as you squat. Just like when you run out of hip room, your body has to find range of motion elsewhere and prefers the lower back.

How To Fix Butt Wink

Before we show you how to fix the butt wink, we need to talk about the neutral spine. Since that sounds painfully boring, just think of this as your “safe to squat” zone. (Or STS Zone)

When we refer to your STS (also known as your neutral spine), we are referring to the position of your lower back during the movement. For most, this means a slight curve in the lower back.

Finding your STS is encouraged by most trainers and physical therapists because it offers the most protection to your spine during loaded movement. But, and this is important, it does not completely reduce the risk of injury. You’ll still have to check your ego at the door and be smart with the progressive overload of your moves.

neutral spine position
Source: Back forever

Your spine moves a bit during the exercises, even if you are in your STS zone. Things get dangerous when you stray too far from this area. In other words, that’s when the butt wink gets more aggressive.

Our goal is to squat as deep as possible without rounding the lower back too much. You will need to find the proper squat stance to do this.

This is how this is done:

  • Sit in a bodyweight squat. Don’t worry about rounding your back; just drop to the bottom.
  • Play around with the width of your squats and the angle of your feet until you find what feels most comfortable for you.
  • Hold this pose and do a couple of squats to see what the full range of motion feels like.

Sitting at the bottom of the squat in this manner will not be comfortable for some. Feel free to hold onto a support. Do you want to see this process in action? Check out our Instagram post here.

You will also want to experiment with different squat variations. Unless you’re a powerlifter, there’s no rule that requires you to do back squats.

If you love back squats, try sliding small plates (like 2.5 or 5 pounds) under your heels, or stand on a wedge. This changes the angle of your hips and allows you to go deeper into a squat without worrying about winking.

If you’re looking for alternatives to squats, the goblet squat is a better option for most. This is a variation of the front squat, which helps activate your core and keep that spine neutral. Once you’re comfortable with the goblet squat, you can also do the more traditional version of the front squat.

You can also try endless variations of single-leg movements, such as split squats or Bulgarian split squats, which help reduce the likelihood of butt winking.

No matter what, your best guide is usually comfort and pain. If something feels off, don’t force the movement. Find a way to move without pain, and then add load to make it more difficult.


  1. Why do squats hurt? (And how to fix the problems)
  2. Valsalva maneuver: a technique that can save you from back pain
  3. The Squat Mystery: How Low Should You Really Go?

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