The butt wink is the posterior tilt of the pelvis that occurs towards the bottom of the squat. When this occurs, it causes the lumbar spine to round and go into flexion.
There are a number of risks associated with this...
Failing to hold neutral spine in the bottom of the squat and letting the pelvis posteriorly tilt increases the loading of the spine which may increase the risk of SI joint issues or disk herniations.
The picture below illustrates the difference between the correct and incorrect squatting technique.
Figure 1: Incorrect vs Correct Technique
The butt wink can occur in all squat variations: the back squat, front squat, overhead squat or the goblet squat.
Tight hamstrings is one of the most common reasons you may of heard for the butt wink but unfortunately it is not that simple due to the
fact that there is no real change in length of the hamstrings during a squat.
This is because the hamstrings are biarticulate muscles, meaning they cross two joints and when there is equal hip and knee flexion occurring at the same time, there is no change in hamstring length. This is explained by a concept called Lombard's Paradox.
The truth is, there is not one sole cause of the butt wink.
"The cause of the Butt Wink is not limited to just mobility and stability issues but also structural issues such as the depth of the hip socket."
The two main reason the butt wink occurs is because of a stability issue or a mobility issue.
If you have a structural issue, this is something that cannot be changed and will not be altered by any amount of mobility or stability drills.
For the purpose of this post, we will explain the difference between a mobility or a stability issue and how to assess which is causing the butt wink in the squat.
To assess if the butt wink occurs from a mobility restriction, start in a quadruped position on the floor. Rock back toward the heels and perform a horizontal squat (see in the video below).
Perform 5 reps and observe if there is a posterior tilt of the pelvis.
If you can rock back without restriction, you have sufficient mobility to squat. This assessment resembles what happens at the ankles, knees
and hips in a deep squat and is indicative of not having significant mobility restrictions.
To assess if the butt wink occurs from a stability issue, perform a body weight squat.
Either film or have someone observe 5 reps and note the point at which the butt wink occurs.
The next step is to do the same but hold a weight plate out in front.
Observe if holding the weight plate either stops or improves the butt wink.
If the butt wink disappears or improves, it is clear that it is caused by a stability issue.
The counter balance squat increases the anterior core recruitment and will give you a false sense of stability.
If the movement improves, it is a clear indication that you need to improve your ability to brace and hold Lumbo-Pelvic alignment as you
lower down into the squat.
From these two simple assessments you will be able to determine if the butt wink occurs from a mobility or stability issue.
The first assessment will indicate if it is caused by a mobility issue.
The second assessment will indicate if it is caused by a stability issue.
If after these two test there is no improvement, this may indicate there is a structural issue at the hip joint.
If you have a mobility restriction the key areas to focus on are ankle mobility, hip mobility and thoracic mobility.
Check out our other articles below!
Ankle Mobility: 5 Exercises For Ankle Mobility
Hip Mobility: 5 Exercises for Tight Hip Flexors
Thoracic Mobility: 5 Exercises for Thoracic Mobility
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