Assessing Squat Form. Part 1

This is the post excerpt.

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Alright guys, this is going to be my first post and I am going to start it with a tad text heavy discussion relating variables within assessment and teaching squat form.  I anticipate this to entail a three-part post.

The first part will cover the basics of why we should generally coach specific aspects of the squat and the injury-risk rationale.  The subsequent blog posts will detail how anatomical differences among patients necessitating variance in form, how to determine mobility and stability issues on a joint-by-joint bases, and then how to coach the squat.

Key Points in Part 1:

  • Human movement, including the squat, are variable and adaptable but this variability should diminish under load.
  • Everybody should have a motor engram (movement memory) for a loaded squat.
  • Ideal squat form reduces injury risk and produces efficiency promoting performance.
  • Repeated spinal flexion and loaded spinal flexion are proven mechanisms for spinal injury.
  • Consistency in knee alignment and squatting to depth are critical for knee health while squatting.

If you’re reading this you likely do not need me to extol the virtues of squatting or the prowess inherent in the efficient execution of a loaded squat.  As a physical therapist I find myself coaching the squat to help patient’s in pain move better and as a strength and conditioning professional I’ve coached many athletes the same movement strategy for performance goals.

Human movement is inherently variable and adaptable, this includes the squat.  There is not one way for any person to squat, reach, run, jump, etc.. The movement patterns within those activities all depend on internal factors relating to the individual (body dimension, motor control, strength, etc.) and external factors, or environmental situations, for which they may need to adapt their squat pattern for functionality.  So within these adaptable patterns of movement should exist a motor engram, or a movement memory, for a “loaded squat.”  The stability requirements change in the squat with load.

Loaded squat is parenthesized because “loaded” is a relative term relating to the difficulty in executing a squat.  Some patients may be loaded with 6-lbs and some with 600.

Squat Goals

Because individual anthropometric differences may dictate variance in form from one individual to another, patterning is judged on the ability to maintain certain segmental movement patterns.  These movement patterns are derived from known mechanism of injury with injury risk reduction and movement efficiency and performance hand in hand with these goals.  I will keep in simple and discuss the two most common areas of injury although there are a couple other areas I will bring up as well.

1.  Eliminate (limit) lumbar flexion

I’ll explain the need for parenthetical shortly.  Avoiding lumbar flexion is obvious to anybody in the training and rehab world.  Dr. Stuart McGill, renowned spine researcher, has clearly revealed that repeated spinal flexion is a mechanism for disc injury (see Study.)  Another McGill article (here) shows that spinal flexion increases the anterior shear force on the spine and is a mechanism for injury.  In addition, we know that the spine tolerates load better in a neutral position (see Study.)

To play devil’s advocate a bit, and the point of the parenthesized “limit” above, is that there is research suggesting that we cannot fully eliminate spinal flexion during functional movements such as the squat.  This again comes from McGill’s lab showing subjects have a tendency to still flex the lumbar spine with kettlebell swings (study) and squatting (study.)

So to counter the above findings I will say that whether spine flexion occurs or not the goal should be to avoid flexion as this focus and intent will inherintely decrease the power which is exerted towards the spine.  Power, the physics term, is Force times Velocity.  High power exerted between spinal segments is said by McGill to be a primary spine injury mechanism.  So in instances where there is a high amount of Force, such as a loaded squat, velocity between vertebrae should be minimal.  This also presents the idea that unloaded, or lower load, situations can safely incorporate intersegmental flexion/extension of the spine.

The goal of reducing intersegmental power to the spine has important implications with how a person should set up prior to squatting.  I will go over this in part 3.

2.  Maintain knee alignment and squat to DEPTH.

The knee is the second area that inadequate form can cause issues.  But let’s be clear, squatting to, and below, parallel is not “bad” for your knees.  While it is true that patellofemoral forces increase as knee flexion increases, the contact area of the patella also increases which mitigates any focal pressure on the patella.

In fact, it is likely better to squat to this full depth position than to do partial squats where the hip stops above the level of the knee.  Here’s why:

So firstly what I mean by “to depth” is to squat to or if possible below parallel.  Parallel is defined when the hip descends to the level of the knee.  The rationale for squatting to parallel is two-fold.  To start, when a partial squat is performed above parallel often the quadriceps take on an increased role to decelerate and reverse the motion because the posterior chain musculature was not appropriately tensioned.  This increased quad dominance without posterior chain recruitment will increase the anterior sheer on the knee.  Secondly, achieving full depth should allow the tension to develop in the hamstrings which will balance the anterior pull of the quads with a posterior pull on the tibia.

It is also important to maintain good knee position in the frontal plane.  There is a long-established link between dynamic knee valgus and the development of knee pain (Study.) The mechanism appears to be poor hip stability yielding excessive femoral internal rotation (Study.)  I will describe variances in form outside of the sagittal plane so understand that maintaining knee alignment should be relative to the amount of hip abduction when using a wider stance.  In other words, your feet should be parallel to your femurs and the knees should not fall inwards of this starting position at any point.

Stay Tuned for Part 2 where I will discuss anthropmetric considerations of the squat and how to assess range of motion, stability, and mobility requirements for successful squatting.

 

Feature Image from: Starting Strength 2nd ed. by Mark Rippetoe