Deep Squats and Back Injuries


Backs are ruined by defective execution of squats, and the squats are blamed instead of the incompetent instruction. The chief mechanical cause of back injury while doing weighted squats is posterior tilting of the lifter’s pelvis, called “butt wink,” which during the squat causes reflexive flexing (bending forward) of the lifter’s lumbar spine. Those two moves together, posterior pelvic tilt and lumbar flexion, stretch the spinal erectors (muscles straightening the spine) while they are working to keep the trunk from collapsing under the weight of the barbell. Additionally, the resulting spinal alignment puts a strong squeeze on the intervertebral discs, making them susceptible to injury.

The butt wink, or posterior tilt, of the pelvis happens when one leans forward under the weight. The more one leans, the more difficult it is to prevent the butt wink, and vice versa–the less one leans forward, the easier it is to prevent it. Butt wink and the damage it may cause to the spine can be prevented by correct teaching of the squat–that is, beginning with forms in which the wink is easy to control (for an example, see instruction for the wall squat on the DVD Flexibility Express). The more one abducts and rotates the thighs externally, the deeper one’s pelvis can sink below the knees without tilting, and so the closer to vertical one can keep the trunk. To put it simply: The wider the squat, the less one leans forward. Here is a guide for teaching progression of squats:

–The lighter the weight, the less the trunk leans forward.

–The wider the stance, the less the trunk leans forward.

–When holding the weight in front of the trunk (goblet squat, front squat), the trunk leans forward less than when the weight is behind the trunk (back squat).

So here is such a progression:

goblet squat => front squat => back squat

Begin with a wide stance (like the five-step horse-riding stance) and a light weight. Practice the three forms of the squat in the above sequence, within the same workout if possible to better transfer the sense of proper position of the pelvis and spine from easier forms to more difficult forms. If you can’t do all forms well enough, then stick with the form you can do until you are ready for the next one. When comfortable, add weight. As weight increases, eventually you will have to narrow the stance while maintaining the natural lumbar lordosis–not tilting the pelvis–and keeping the trunk’s forward lean to a minimum.

Each step of the progression is to be done until the habit of keeping the natural lumbar lordosis under the weight is firmly ingrained.

If your ankle dorsiflexion is poor, you can begin the above sequence with heels on supports and then gradually lower the supports.

To learn more about squats read “Martial Arts and the Squat” at

Flexibility Express DVD by Thomas Kurz

Explosive Power and Jumping Ability for All Sports: Essential Strength and Jumping Ability Exercises for All Sports

Science of Sports Training, 2nd edition, by Thomas Kurz

The Unbreakable® Umbrella — A peculiar mix of genteel elegance and chilling weaponry...

10 Responses to “Deep Squats and Back Injuries”

  1. This is really useful, thanks for posting.

  2. 2 Michael

    Mr. Kurz,
    how can I find out if I have a “butt wink”?
    Can I see it in a mirror?
    On Flexibility Express you show a deep squat and call it “losing control of the lower back” is that a butt wink?
    Thank you very much.

  3. A deep squat is not “losing control of the lower back” but the butt wink is. So yes, the error I talk about when showing the deep squat on Flexibility Express is the butt wink.

    To make it clear for you what the butt wink is, here is a lecture on it by Bret Contreras:
    Squat Biomechanics and “Butt Wink” by Bret Contreras

  4. 4 Jacob Fields

    How much flexibility is required in front and side splits for a karate-ka to hold his or her leg in a 180° vertical side kick (a display of static-active flexibility, required for certain forms/kata)? Is it necessary to have an amount of flexibility reserve, i.e. would one need to develop the ability to do “oversplits” to achieve this feat?

  5. So much valuable information in this video… simply knowing that the depth of the squat is so related to individual anatomy is priceless for us to protect our lumbar – we’re not all built like Asians!

  6. 6 martin

    Very interesting information. If you cannot do a full, deep squat due to your anatomy ie if you do have Celtic hip, is it still possible to achieve a full side split? Or, is it only necessary to be able to squat until your thighs are parallel to the ground, in order to achieve a side split?

  7. @Loren Greig

    So much valuable information in this video…”

    Except any mention how thigh abduction and external rotation delays the butt wink.

  8. @martin:
    Make sure your inability to do a deep squat is due to your anatomy and not to ignoring instructions in the post.

    To see whether you can achieve the side split read my article Misconceptions on Stretching and Flexibility and the Method of Testing Your Potential to Do a Side Split.

  9. 9 Pat Pawlowski

    Excellent video by Brett!

    As a competitive weight lifter, powerlifter and college sprinter I can say in my experiences that butt wink, if not directly related to anatomical issues, has been related to inadequate spinal erector strength relative to hip/leg strength. As a lifter the remedy I have been taught and as a coach use are primarily glute/ham raises and reverse hyper extensions. These exercises work the entire posterior chain of muscles require coordinated movement so we have a direct impact on strength and the coordinated use of it as Brett comments on. In a few cases with imbalances I have used single leg stiff leg deadlifts to improve balance. If we ever do stretching, it is minimal and based on relaxation of muscles under moderate tension to reset golgi relex.

    I do have a great memory of reviewing several sets of hips while studying hip injuries. Without labeling it was often difficult to identify the hips as all being human due to the huge variances in structure at the femur head / socket.

    I am not a martial artist so have my limitations there. As a lifter, sprinter, and coach though, I have found very few circumstances where a sport requires anything more than parallel or just above parallel in competition. We always try to keep to competition requirements.

  1. 1 Deadlifts and Back Injuries | Tom Kurz's Weblog

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