Here's what you need to know...

It's ignorant to say that everyone should squat to the same depth. Some lifters inherited awesome levers, possess just the right hip anatomy, and are able to squat butt-to-floor with no issues. Serious squatters should perform the kneeling rock-back movement screen to see where they fit in on squat depth. One problem directly related to squat depth is "butt wink." The butt wink is just a less fancy way of saying posterior pelvic tilt. Butt wink and squat depth can be improved by working on crappy ankle mobility, including glute work in every session, and doing slow goblet squats.

Let's make one point clear: It's completely asinine to say that everyone should squat to the same depth. Some people picked the right parents, inherited awesome levers, possess the appropriate hip anatomy, and are able to squat ass-to-grass with no issues at all. And we all hate those people.

Conversely, there are others out there who, because they're told to do so (usually from some internet jockey who claims to squat over 400 pounds, ass-to-grass, for reps, while juggling chainsaws) or because their manhood is somehow called into question, try to squat deep no matter what. And well, bad things happen. Not everyone is the same, and it's important to understand this. As a coach my "end game" is to work with what I have and to get every single one of my athletes or clients to squat to depth. However, it's not always a good idea to force someone to squat deep when they just don't have the ability to do so safely. While admirable, the end goal for every person shouldn't be to squat deep.

Rather, the goal should be to develop proper squat mechanics, groove technique in a safe range of motion that's applicable to a particular individual's limitations and anatomy, and most important of all, keep the spine safe. Admittedly, it's not a sexy approach. I'm not going to sit here and wax poetic about some super secret squatting protocol or bust out my protractor and discuss some advanced algorithm to follow. The answer, simply, is to work on "stuff," and eventually squat depth will improve. One problem directly related to squat depth, however, and one that I see far too often, is "butt wink."

What Is Butt Wink?

The butt wink, tuck under, or "Celtic hip," as it's known in some circles (FYI: it's been stated that Scottish people tend to have deeper hip sockets, which affects - in this case limits - their "usable" hip flexion range of motion), is just a less fancy way of saying posterior pelvic tilt. For the visual learners out there, the farther one goes into hip flexion during a squat, the more the pelvis will posteriorly tilt, and with it, cause the lumbar spine to rotate into flexion. Put another way, as the femurs ride up during the squatting motion, the trainee runs out of hip range of motion, and going deeper will result in compensation patterns such as the butt wink.

Before I state the obvious, let's get one thing out of the way so that everyone doesn't shit an EMG study: It's important to realize that compression forces, to some degree, are completely normal and acceptable. I know some will immediately cower in the corner at the mere sight of the word compression, especially as it relates to our spine, but unloaded compression is fine, as is spinal motion in general. Where it becomes problematic is when loaded compression enters the equation and we include a barbell into the mix.

Someone with limited hip flexion that attempts to squat deeper than their anatomy allows inevitably tucks their hips under at the bottom. This leads to lumbar flexion under a significant load.

And this is what we'd want to avoid whenever possible. Mind you, alittle bit of tucking is acceptable, especially if someone happens to get to a good depth and they're pushing some appreciable weight. However, if there's excessive tucking at the bottom, or someone begins to tuck before they even reach parallel, that can spell trouble.

What (Probably) Doesn't Cause the Butt Wink

Funnily enough, everyone's "go to" culprit for the butt wink is flexibility, or, more specifically, a lack of hamstring flexibility. Your low back hurts? Must be tight hamstrings. Knees are cranky? Tight hamstrings. Bad hair day? It's gotta be tight hamstrings. Here's the deal: Only Sith Lords deal in absolutes, so I won't dismiss the notion altogether, but as far as the butt wink is concerned we can't lay the blame on the hamstrings or the hip flexors, for that matter.

The hamstrings, with exception of the short head of the biceps femoris, are a bi-articular muscle group which cross both the knee and hip joints. When you squat, you're shortening the hamstrings at the knee while simultaneously lengthening at the hip, giving a net result of almost negligible length change. Likewise, with regards to the hip flexors, when we go into deep hip flexion, the iliopsoas shortens (anteriorly tilts the pelvis), not lengthens (posteriorly tilts).

Moreover, the rectus femoris, like the hamstrings, is a bi-articular joint. Concurrently, as we squat it lengthens at the knee and shortens at the hip. Again, the net result is not much length change and thus has little (if any) effect on posteriorly tilting the pelvis in deep(er) hip flexion. To reiterate: stiffness or shortness in either muscle group can enter the equation and affect pelvic positioning during a squat, I just don't feel it's as much of a player as many believe.

Of more prevalence is one's bony limitations and anatomy! Hip anatomy isn't the same for everyone. And one's pelvic arch - width, breadth, and angulations - can play a key factor in how (and how deep) someone should squat. Below is a figure that illustrates how much we can differ in anatomy.

Some people only have so much hip flexion - as the femoral head sits in the acetabulum differently - and this is something you of course cannot control.

What Can We Control?

A good starting point is attempting to figure out where proper depth is for any one individual. One screen I like to use during my athlete assessment in the kneeling rock-back. In fact, any serious squatter should perform these screens to see where they fit in on the squat-depth issue. I'll have someone start in the quadruped position with a neutral spine. Slowly, I have him or her sit back towards their heels to see if or when their spine hinges.

As I sit back, my spine stays relatively neutral the entire time. In this event it's safe to assume that squatting "deep" probably won't be an issue. Conversely, it's common to see something like this:

It's clear that there's something - most likely a motor control issue, but could be a bony adaptation/blockage - that's preventing them from maintaining a neutral spine while going into deep hip flexion. Nonetheless, using this screen does give us some valuable insight as to what would be an acceptable or safe depth to work in while we address other issues.

And Those Other Issues Are?

1. Crappy Ankle Mobility

Limited ankle dorsiflexion is a huge factor! We need roughly 15-20 degrees of ankle dorsiflexion in order to go into deep hip flexion. As we descend into a deep squat and the ankles are locked up, the body has no choice but to lean excessively forward and compensate by posteriorly tilting the pelvis and getting the ROM through lumbar flexion. This is why wearing Olympic shoes or shoes with a heel lift can be advantageous as it shifts the body center of gravity and allows the knees to migrate forward to a greater extent. Just realize that this is only a temporary fix and is akin using a Band-Aid. Taking an aggressive approach and attacking tissue quality not only in the calves, but also anteriorly, in the shin area, can pay major dividends.

Two of my favorite drills include:

Your standard self-myofascial release using a foam roller, ball, or barbell on the gastrocs and soleus muscles A Kelly Starrett favorite, the bone saw calf smash, which targets the tibialis anterior and is pretty much the worst thing ever

Ankle mobility drills will also factor in here. One drill is the banded distraction ankle mobility drill:

Adding the distraction of the band essentially pulls the tibia back and "clears" the impingement and allows for more space and ankle ROM.

2. Weak Glutes/Improving Glute Activation

Because of the attachment points, the glutes - not the hamstrings - have a bigger play on the femoral head and controlling it. Simply put, get your glutes stronger and/or work on better glute activation and the result will be the glutes having a more profound rearward pull on the femoral head, which in turn will help to clear more space to squat a bit deeper.

I like to take a grenade approach here and try to include some form of direct glute work with every training session. Barbell glute bridges, barbell hip thrusts, one-legged hip thrusts, kettlebell swings, pull-throughs, and GHRs are all fair game. Similarly I like to include a high volume of glute activation as part of an extended warm-up.

3. Get Better at Squatting

To be more precise: Get better at squatting lighter loads. Even better, you need to learn to controlyour squat! The butt wink arises because most people are flat out unstable and aren't used to squatting to depth. They lack ample stability and motor control within that range of motion. This is one of the many reasons why goblet squats are so valuable. Here I can groove a rock-solid squat pattern - sit back, push the knees out, keep the chest tall, and more importantly, learn to brace the abs harder.

Simultaneously, goblet squats make it easier to slow people down. Implement a lot of controlled slow-eccentric squats to force yourself to stabilize and to still keep time under tension high. This video shows the same athlete from the butt wink example above, and how slowing things down and forcing him to control his squat and own his position drastically cleans things up.

You can still use front and back squats here, but it's important to keep a few things in mind:

You need to "own" your rib position. Think about there being an imaginary line between your belly-button and nipple line. When we over-arch, that line gets longer, and we want to try to avoid this as it reduces (posterior) compressive forces on the spine.

As you sit back, brace your abs and think about crushing a can between your hamstrings.

Another way to think about it is to "pull" yourself down into the hole, making sure to maintain proper spinal alignment throughout the rep.

Likewise, it helps to "spread the floor" with your feet. This will elicit more of an external rotation torque in the hips, which in turn helps to provide more hip stability.

Also, as a reminder, use the kneeling rock-back screen from above to help dictate what your appropriate depth is!

Summary

The butt wink is a common problem when squatting, but something that can be easily remedied. Despite popular belief, it's generally not about stretching or improving your hamstring flexibility. Instead, it comes down to three main points:

Addressing limited ankle mobility. Tackling weak glutes. Improving motor control - spinal alignment - during the squat.

We must need to account for individual differences in anatomy. Not everyone is meant to squat deep, and if anatomy won't allow it, attempting to squat deep regardless may cause problems.