“Butt wink” refers to the moment at the bottom of a squat when the pelvis begins to rotate backward and slip under your body. You’ll also hear it referred to as “posterior pelvic tilt” or just “pelvic tilt,” and when it’s severe, it can be bad news for your lower back. In this video by ATHLEAN-X™, they show us what is “butt wink” and how to prevent it.
Learning how to squat properly or how to squat without butt wink is a matter of first understanding what actually causes the flaw in the first place. To do that, I put together this squat video to cover both the root causes of butt winking when squatting and also half of the solution for how to fix the butt wink during a squat.
The butt wink is one of the most common squat flaws, particularly as you get lower and lower in the squat. As you approach parallel and beyond (ATG squats) there is a tendency of the pelvis to quickly switch positions from an anterior tilt to a posterior tilt to compensate for a lack of mobility and flexibility elsewhere in the kinetic chain.
Some mistakenly think that this is caused by a weakness in the quads or hamstrings. This is not the case. The butt wink is actually a problem with the length and flexibility of the hamstrings on either one of both legs.
As you get lower into the squat exercise, the distance between your ischial tuberosity and your knee joint gets further and further apart if you are properly maintaining the natural anterior tilt and arch in your lumbar spine. The second this length becomes maxed out however, the hamstrings are no longer able to stretch any further and in an effort to keep you moving in your squat, will pull on the pelvis into posterior rotation. This compensation immediately relieves the tension on the hamstrings and allows the lifter to finish the squat.
Once you begin your ascent again, the length tension on the hamstrings is back to normal and you are able to again resume your anterior tilt. This quick switch back and forth makes it look like a quick wink.
The second cause of the butt wink and something you need to know if you want to know how to squat without winking is related to your thoracic mobility. Most people have a hard time getting full extension (or maintaining it) in their thoracic spine during squatting. This is why it’s harder to do an overhead squat while keeping your trunk upright than it is a typical back squat. If your t-spine mobility is compromised at all, you’ll want to be sure to include foam rolling or other self mobilization techniques to help restore that. If the thoracic spine falls into flexion, it will pull the rest of the spine as well by virtue of it’s interconnectivity.