Ever heard of a butt wink? Luckily for you, it doesn’t mean you’ve got a flirty third eye in your pelvis (hah). A “butt wink” is the term for lumbar flexion and pelvic tuck that happens at the bottom of a squat.
You can check out this video for what a butt wink looks like. It’s described as a wink because of the downward shift of the pelvis.
Biomechanically, what’s actually happening?
Like I said above, this is lumbar flexion, the fancy way of saying the low back is rounding, and the pelvis is “tucking under” in posterior tilt.
It’s pretty common, but why does it happen, and what (if anything) can it cause?
The why is pretty simple, coming into two common forms.
When we come into a low squat, we need full range of motion at our ankles, knees, and hips. The ankles must come deep into dorsiflexion (knee over toes), the knee must bend fully, and the hip must bend fully, all while keeping our center of mass over and between our feet.
If we lack any of this motion, with stiff ankles, or poor rotation at the hips, our center of mass ends up behind our feet. That’s why most people feel like they’re going to fall back when they come into a deep squat.
The rounding of the low back is quite common, and quite normal at the end or very bottom of a squat. It’s simply function of our anatomy, that with exaggerated hip flexion and posterior tilt of the pelvis, the lumbar spine will round to accommodate. However, the butt wink can be ‘abnormal’ if it’s a large motion (excessive tuck) OR if happens early in the squat, when the knees are still at 90 degrees for example.
Why does it happen? When it falls outside of the more “typical range,” the curling of our pelvis and rounding of our low back shifts more of our mass forward; this is a compensation that helps prevent us from falling backwards. It is most often compensating for limited ankle mobility, limited hip mobility, or poor neuromuscular control.
Now, let’s actually talk about if it’s a problem or not.
If someone has back pain with squatting, I tend to include butt wink in my assessment because if it happens too early, it’s a sign of energy leakage. I especially take a look at it if it’s a large motion. As I mentioned above, there’s a normal amount of lumbar flexion as we come deeper into a squat; a small wink is perfectly normal. However, if it’s a big dramatic shift, or it happens early, I consider that energy leakage. Rather than using your spine as a rigid bar to transfer load from legs to upper extremity, you’re trying to transfer energy through a bendy bar, and that isn’t as efficient.
There’s a fascinating thesis of various barbell squats and deadlifts that assess lumbar flexion and lumbar shear forces. It found significant lumbar flexion in squats, which was consistent across individuals, and that the type of loading has a significant impact on the amount of shear force. High bar squats were found to have to least amount of lumbar flexion, while deadlifts had significant increased lumbar flexion. What’s great about this study is that it highlights how this low back flexion is normal under load.
The second thing that’s exciting about this study is that the maxmum shear force did not correlate with the amount of lumbar flexion. IE, how much the spine bent did not track with the shear force registered at the joint. What this means is that lumbar position does not necessarily directly translate to forces, which flies in the face of so many clinical assumptions.
We’re wading into complex waters here, so I want to emphasize a few things
1) If you’re training, and you have no pain, and you’re making progress, don’t fix what isn’t broke.
2) If you have a significant butt wink early on in your squat, try a few mobility exercises and see if it doesn’t change your form and improve your heavy loads.
3) Lumbar flexion is not necessarily bad, but not being able to control our motion leaves us vulnerable to injury. Which brings me to another point
4) Butt wink can be caused by poor control, not necessarily mobility or strength limitations.
5) In deadlift and squats, lumbar flexion =/= lumbar force.
The control piece is huge. If you don’t ‘know’ where neutral spine is, how can you control it? That’s why I often pair deadlifts or squats with a cat cow, or a banded cat-cow exercises to help them find that low back neutral and control it. You wouldn’t expect to be able to load a heavy bicep curl if you can’t control lowering your arm, right?
So, how else can we improve our control?
I also prescribe “The Egg.”
What’s The Egg? You’re gonna love it.
It’s a deep squat. You’re going to think about pushing your knees out, pulling your knees forward, and keeping your chest upright. You’re also going to think about lifting your chest, and you can play with how much you can control that lumbar spine.
If you need support, you can use a rack, or a weight in front to help hold you upright. Muscles, joints, and ligaments respond to load, so we need to start getting your body comfortable here. With proper form, those knees leaned forward, and your chest upright, hips engaged, we’ll start acclimating your body to this position.
What’s great about the egg is that with the knees driving forward, you’re working that deeper ankle position, and with knees pushed forward and out, we’re addressing some hip rotation and deep flexion.
Now, we’ve talked before about getting your ‘perfect squat,’ and the top reasons you might not be able to squat as low as you want to, so feel free to check out that post for more resources!
In particular, if you’ve got pinching in the front of your ankle, and feel like you’re going to fall backwards, try a banded ankle dorsiflexion stretch to help adjust the bones in your ankle and promote more motion from the joint. Do 12-20 rounds before a round of squats, and see if it isn’t easier to get yourself into a more upright position and that your low back doesn’t stay more stable.
Secondly, you can try a banded hip mobilization for a similar purpose, to promote healthy movement in the joint. With deep flexion, the femur actually needs to slide down and back to allow the upward motion around the knee. We can support this motion with a band as well.
You can check out our blog posts on squat exercises and strategies as well, and see if they don’t change the way you think about squatting, and reduce your butt wink!
And of course, if you’re having pain, contact us to schedule an appointment ASAP so we can address the root cause of your problem!
