In case you missed it, here is the piece I wrote for my buddy Dr. Dan Pope's site FitnessPainFree.com:
Proper squatting forms the basis of any performance system and is essential to meaningful function as an athlete and human - which includes the elderly (might need to scale though, bro). As an athlete and as a practitioner who treats fellow CrossFitters frequently, one of the things I love is the emphasis on the squat pattern. But with high squatting volume in any performance system we need to ensure it’s reproducible.
I understand and share the pride that comes with the ability to squat deep while lifting some serious weight. However, many athletes are unable to squat deep with load due to hip or low back pain. Femoral-acetabular impingement is often the culprit here, where the neck of the femur is literally jamming into the acetabulum of the pelvis. Dan goes into much greater detail in one of his prior posts on FAI. These same biomechanics also cause butt winking where there is a reversal of the lumbar spine causing a loss of segmental control. This spinal shear under load is dangerous and never okay - a butt wink is an immediate fault and nobody gets a pass. Altering squat width is a strong start to fixing these train wrecks.
So how do we determine best squat width for depth and performance (and to help prevent hip pain and butt winking)? “Shoulder width” is often used however that differs for each individual. Many times we just start with a random width and that becomes the default. However, factors such as motor control of the entire system (particularly the over-extended spine), hip and ankle mobility, and individual structural differences in acetabulum and femur alignment all influence squat width and depth.
The sooner the femur runs into the pelvis, the less depth you’ll achieve and squat numbers will plateau. But you don’t need an x-ray to determine how you should squat. Rather, we need to find the best squat width that allows the most depth while maintaining movement integrity (such as a neutral spine). The best position yields the best performance and the fewest injuries. The test below helps find where these limitations are least restrictive and determines the best starting squat width.
I like this test (originally from Dr. Stu McGill, spine biomechanist) as a screen for new lifters, those who are having hip or low back pain, and athletes whose squat numbers are plateauing.
Things to consider with this test:
1) Performing this test on your hands and knees allows you to assess the hip and core without bringing other structures into the equation. You’re also performing this in an unloaded position (i.e. not standing) which helps eliminate movement inefficiencies you might find while standing.
2) Demonstrates lumbopelvic motor control. If a strong contraction of the anterior core allows greater depth prior to butt winking or decreases pinching in the front of the hip, motor control deficits are present. This is not an anatomical variation, you need to improve trunk stiffness as the lumbar spine is over-extended causing the pelvis and femur to meet prematurely. In so many cases, we can prevent butt winking and un-impinge the hip with appropriate movement patterns and control rather than rushing to surgery to correct bony deformities. Improve motor control first and foremost regardless of structure.
3) Once you’ve found the width that allows the most depth without impinging or butt winking, this is where you should start when squatting. Can use this screen for those new to squatting as a way to determine the most effective width to start while you work on motor control and mobility to allow for a variable squat program.
4) Those who show poor motor control in this test and have hip or low back pain will most likely need to correct this for successful rehabilitation and return to squatting.
So ultimately, what is the best squat width? The one that allows the best depth while preserving a neutral spine. Regardless of starting squat width or structural variation, this does NOT change the essential movement principles of the squat. Feet should be straight, knees tracking over the foot, shins vertical as possible for as long as possible, hips externally-rotated. You MUST prioritize and control the lumbar spine and pelvis, above all else. In my opinion, the ability to control the spine and pelvis is a prime determinant in the performance ceiling of athletics and human function so don’t lower that ceiling with improper movement patterns. Squat depth and width do not matter if these principles are not upheld.
Acknowledge what we can’t change (structural alignment), optimize the many variables we can change including squat width, and then vary it for an effective motor program.