What the Hell Is a ‘Butt Wink’—And Is It Really All That Bad?

It seems like there’s a form adage for everything in fitness, especially for common exercises like the squat. Keep your chest up. Put your weight in your heels. And stop the butt wink.

Wait, what? If that last one threw you for a loop, you’re not alone. While the butt wink might not be in the vernacular of the everyday gym-goer, it’s a pretty popular topic on GymTok and other social platforms. There, trainers and coaches are captioning videos with words like “fixing,” “correcting,” and “mistake”—leading whoever’s scrolling on by to naturally assume this squat technique should be avoided at all costs.

But as we’ve all learned the hard way a time or two (or 10), social media isn’t always the most reliable source of intel. So that raises the question: Is a butt wink really that bad? We dug in to find out.

Wait, what even is a butt wink?

First, let’s get clear on what this really means. A butt wink is when your pelvis tucks under at the bottom of your squat. This causes your lower back to round forward or flex, rather than stay upright—it’s what’s officially known as a posterior pelvic tilt. A butt wink is one of those things that’s hard to explain, but jumps right out if you see it in a photo or a video. The motion itself can appear like a mini booty twerk, which may explain its fun name.

You can butt wink with lots of different types of squats, including front, back, weighted, and bodyweight, and there are several possible factors driving it. One is your mobility: If you don’t have proper ankle dorsiflexion, or the ability to bring your toes closer to your shins, it may be all but impossible to keep a straight spine when sinking into a squat, Carrie Pagliano, PT, DPT, spokesperson for the American Physical Therapy Association and adjunct professor at Marymount University, tells SELF. Tight hamstrings could also be a culprit, since they can pull your pelvis into a tucked position, physical therapist Nicole Haas, PT, DPT, founder of Boulder Physiolab in Boulder, tells SELF.

How you’re squatting may matter too. If your stance is too narrow, it can make it harder to keep an upright spine as you lower down, Dr. Pagliano explains. Squatting past parallel (where your butt is below your knees) can also increase your chances of butt winking. Sinking to that depth challenges your balance, and can cause your pelvis to naturally tuck under as a way to prevent you from falling forward, Craig Secor, PT, DPT, a Richmond, Virginia–based physical therapist, tells SELF.

Or it could also be simple anatomy. Some folks, because of the shape of their hip sockets, are more likely to butt wink in a narrow stance, or conversely, in a wider stance, Dr. Haas explains. Others who have a naturally more flexed forward posture, or who tend to stand in a posterior pelvic tilt—say, their butt tucks under rather than sticks out or stays neutral—will probably also be more likely to do so while squatting, Kellen Scantlebury, DPT, CSCS, founder of Fit Club NY, tells SELF.

Okay, but is a butt wink actually bad?

Here’s the thing: The butt wink is a bit of a divisive topic—not only on the internet, but among trainers and physical therapists too. Some experts, like Dr. Pagliano, say it’s NBD. She doesn’t believe there’s anything actually bad or dangerous about it; rather, it’s more just a form quirk, which some people are simply more prone to than others.