Is Butt Wink Bad?

Is butt wink bad?  It’s a question we hear quite a bit in the fitness industry.  Typically, butt wink is blamed on hip mobility issues.  Google it and you will surely find resources telling you it’s due to tight hamstrings.  As you know, Google always has an answer, but is it the right one?

The butt wink is considered a dreaded squat movement fault to be avoided at all costs.  It is a term used to describe the pelvis tucking underneath at the bottom of the squat.  It can create a relative flattening out of the lumbar spine, which is why it has been deemed as generally unsafe.  But the actual answer to the question begs the answer that most questions get: It depends.

To answer the question of whether butt wink is bad, we first need an understanding of what it is and why it happens.  Then we can understand within what context it can be potentially bad (or simply not optimal) and how we can fix it.

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WHAT IS BUTT WINK?

Butt wink is actually a normal physiological movement

As you squat down, you eventually run out of room in your hips because your femur runs into your pelvis.  In order to get more depth to sit relaxed at the bottom of the squat, your pelvis will tilt posteriorly – this is a search for more “hip flexion”.

The amount of butt wink and the depth at which it occurs will be different from one individual to another, as it can depend on several factors which we will explore later in the article.  What is important to understand is that some butt wink is physiologically normal and actually unavoidable.

The inherent dangers of butt wink are the relative lumbar flexion that comes with it and the idea that lumbar flexion under load is unsafe for the low back.  For one, losing extension in the lumbar spine under load increases shear force, and second, loaded flexion has been touted as the injury mechanism for disc herniations.  But we also need to remember that the neutral position of the pelvis as well as that of the lumbar spine is a range, and that it is normal and even ideal to have some wiggle room.

WHY DOES BUTT WINK HAPPEN?

Let’s go over this again: butt wink is a normal physiological movement.  That said, if you are seeing butt wink happening very early in the range of motion or an excessive amount of it, then you will want to figure out whether there are other limitations contributing to it.

Regardless of whether you are looking at a low bar back squat, a high bar back squat, a front squat or any other squat variation, these typically require at least 110 degrees of hip flexion.  If the hip cannot get into that amount of flexion, butt wink is a way of getting more depth.

Google will likely tell you that tight hamstrings cause butt wink.  However, at the bottom of the squat, the hamstring is stretched proximally at the hip, but because the knee is flexed, there is some slack at the distal insertion.  For example, if you use a straight leg raise test to assess hamstring length and find some degree of limitation (less than 70-80 degrees of hip flexion), you will usually find that flexing the knee actually increases the range.

On the other hand, if you flexed the knee and did not get more hip flexion range, this would indicate tight glutes, which is the more likely culprit of early butt wink.

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A restriction in the hip capsule could also be a factor in limiting hip flexion and contributing to early butt wink.  It could also be a hip structure issue that requires an adjustment in your squat stance.  I discuss this here.

Now, while we love to jump on the mobility train in this industry, sometimes it’s not a question of mobility, but one of stability. Because butt wink is a normal physiological movement, there is an element of control inherent to limiting excessive posterior pelvic tilt at the bottom of the squat.  Individuals who are hypermobile and/or lack lumbopelvic control may have difficulty limiting butt wink under load.

SO…IS BUTT WINK BAD?

Whether or not butt wink is bad depends on context.  How early does it occur?  How much relative lumbar flexion is occurring along with it?  We have already determined that some butt wink is normal and actually unavoidable at the end range of hip flexion.  Both the pelvis and lumbar spine need to have a neutral range where there is some wiggle room to tolerate movement.

Of course, we don’t want excessive movement in the pelvis, lumbar spine and core for both safety and efficiency reasons.  If the pelvis and lumbar spine move excessively towards the bottom of the squat, it places the body in a sub-optimal position for developing force.  While this might be ok for something like a wall ball with a 14-lb ball, it certainly is not for a heavy loaded squat.

Under heavy load, we are most concerned with the lumbar spine extensors remaining active.  This means a subtle butt wink at the very bottom of the squat with the lumbar spine remaining in relative extension and good control is acceptable and not necessarily “bad”.

HOW DO I FIX BUTT WINK?

Mobilization – Create Space

If you did find that there was a hip flexion restriction in either the glutes or the hamstrings, addressing this in the Mobilization sequence is a good place to start.  If the glutes are tight, a PNF stretch into hip flexion or rolling out on a foam roller is a great way to alleviate muscle tension.

If there is an articular restriction in flexion, use an inferior glide self-mobilization with a band:

Activation – Create Awareness

Once you have created space in the Mobilization sequence, or if you are dealing with an individual who has good mobility but cannot control the pelvis, use an Activation exercise to work on the ability to control the lumbar extensors enough to prevent flexion.  Pelvic rocking is a great exercise to bring awareness to this and also helps dissociate the pelvis from the hips.  This means the individual learns to move the hips on a stable pelvis, much like what needs to happen in the squat:

If you are interesting in learning more about assessing dissociation capacity, I discuss it in my blog article How to Deadlift With Proper Form: The Ultimate Guide.

Integration – Create Behavior

Once we have created space and awareness within that space, we want to maintain these under load.  I have found that using a squat variation where the weight is closer to the center of the torso and even to the hips is helpful, as it allows the individual to really focus on pelvic and lumbar positioning.  Not having to worry about bar path makes a big difference.  A Goblet squat, or even a Zercher squat if you want to load heavier, work well to integrate lumbopelvic control.  As well, using slow eccentrics and integrating pauses at the bottom reinforces that control.  If needed, you could limit depth initially and then progressive increase the range of motion until the individual reaches the optimal depth within which they can maintain solid, safe positioning.

IT DEPENDS

The dreaded answer to many questions is almost always: It depends.  Finding the right answer requires that we understand context.  Where in the range is butt wink happening?  Are we referring to the squat pattern or a loaded squat exercise? How much butt wink is occurring?  Are the lumbar spine extensors still active?

These are all additional questions we need to answer in order to answer the bigger question as to whether butt wink is bad for the specific individual.  These are also the answers we need in order to fix any inefficiencies contributing to early or excessive butt wink.

Remember, Google always has an answer (usually an absolute statement like “butt wink is caused by tight hamstrings”) but it isn’t always the right one.  My advice is to stay away from absolute statements and find your own answers by remaining analytical.

Mai-Linh Dovan M.SC., CAT(C)
Certified Athletic Therapist
Founder of Rehab-U