Butt Wink, What Is It? And Should You Worry About It?

4 May

Written By Tony Wang

What is butt wink?

Definition: Butt wink occurs as a posterior tilt of the pelvis towards the bottom of the squat (past parallel). The lumbar spine will be pulled into flexion during butt wink. Posterior pelvic tilt is a result of lack in hip flexion range of motion between the femur and the pelvis.
Athletes usually report that butt wink makes them lose power from the body when trying to lift up

Whenever there's flexion of the lumbar spine, it decreases the ability to stabilize and pressurize the core, so when there's a lot weight on the body during squat or a clean, its going to affect the ability of the body to get the weight up.

However if the athlete is just resting, with no/minimal weight and theres a butt wink, it would not affect anything at all.

Is butt wink bad for athletic performance?

Firstly, we must recognise that for spinal mechanics Power = Force x Velocity. This is important because when power is deprived from the spine, it may lead to injury.
- What would that look like in butt wink?
  When squatting down with a neutral spine, there’s a lot of compressive force that goes into the spine
  - A lot of research studies shows that the spine is extremely resilient to injury when its maintained in a relatively neutral position (small range, not static)
  - However when there’s repetitive posterior pelvic tilt during the deep squat, the spine could eventually have a disc bulge (flexion movement under load);
  - so when we have a load which acts as Force (weight on the back) , velocity (movement) , we have increased Power. therefore if someone squats down with a relatively neutral spine, they have minimal power derived, BUT if we add in increased movement at the spine, the force would act on the discs more, and with repetition, it could eventually lead to irritation or a disc buldge.

Myths and Exaggerations

If we see butt wink once, would it blow out your back?
- NO, but if there is greater exposure to power being derived at the spine during heavy loaded squats, there would be increased risk that gets these types of injuries. Because everyones spine is different, there will be difference in the rate of how each person would develop these types of injuries. HOWEVER, the mechanism is the same (load through the spine -> movement -> greater exposure -> increased risks)
Modifications to reduce butt wink

Assess squat stance: assess hip and back relationship, and see where the butt wink starts

Modify stance width (observe the lumbopelvic region, thorax)

Passive range of motion of the hip flexion in supine (normal stance vs wider stance)
Wide and externally rotated stance significantly reduced pelvic tilt at 70° femur inclination. However, when subjects reached femur parallel to ground no statistical differences between squat types were found (3).

2. Ankle mobility, and hence squat height

Greater ankle mobility would help you further squat down without compensations of the chain
Squats on a wedge and wide & externally rotated stance allowed more of the subjects to go deeper in the squat compared to Narrow stance (3).

Discussion

Butt wink is a term that has been used in the gym context where people perform squats. Is it dangerous to have a butt wink? Not necessarily as it really depends on the context. It could be dangerous when a person is pushing heavy weights for higher repetitions due to unideal spinal loading, and may cause irritation or even disc bulge in the long run. However, it isn’t necessarily dangerous if someone is just using minimal/no weight in a squat position, the force in this case is unable to affect our extremely resilient lower back vertebrae.

Hope this helps the gains!

Tony

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