Clinical Pearl: Simple Laws of Squatting

By Chris Juneau, PT, DPT, SCS, CSCS

Every year, I have the pleasure of delivering what has now become the “Legendary Squat Lecture,” to our Sports Residents down here in Houston, Texas. It has evolved over the years and has ultimately become two hours of conversation, stimulating discussion, reflection, and problem solving. It’s always rewarding to watch contemplation unfold; it is fun to challenge their rationale in an area that should be fairly well understood and comfortable to them and to most of us as well.

That being said, I wanted to share a couple points that I think make for good reflection and learning. I try and hammer home two simple points: The Law of Give and Take; and Respect the Anatomy. Hope it helps you as well!

The Law of Give and Take

Fry et al. 2003; Table 1

An article was published in 2003 by Fry et al, and it spoke to force (in Newton Meters – Nm) experienced by the lower extremity joints during squatting. Specifically, it reported the joint force experienced when the knees were either allowed, or prevented, from migrating anteriorly over, or beyond, the toes during the squat. (Image 1) The reported data suggested (Table 1) that limiting the knees from moving forward resulted in a decrease in knee force load by around 33 Nm, which is good data to support a posterior biased squat maneuver when attempting to off load the knee, whether it be the patellofemoral joint, the patellar tendon, or the articular surfaces and corresponding soft tissue structures.

What does this have to do with the law of give and take?

Unfortunately, to no intention of the paper, the data set regarding the forces at the hip went relatively under the radar compared to the knee. This data found that force on the hip increased dramatically, around 275 Nm higher, when the knees were limited from moving forward. If you look at Image 1, it becomes really apparent.

Fry et al. 2003 1; Image 1

The torso flexes forward to keep the center of gravity (COG) over the foot, which involves large compression and forces at the hip.

Let’s take it a bit further. What if I allowed the heels to lift upwards off the ground during the squat? Well, it would allow the torso to remain vertical, thus off-loading the hips substantially. However, it would increase the stress on the knee and also significantly increase the stress on the foot! Think about a patient with a Lisfranc injury. Would that style of squat be helpful for them? I would think NOT! Imagine all that force now being moved to the mid foot!

Remember, it is always “give and take.” You can offload one area, but often do so at the expense of another!

The Law of Anatomy

This is a fun one. How do we typically evaluate somebody’s squat form? Is it based on depth? How upright their chest is? Or maybe it is their knee position? Is it simply the “eye test” (some arbitrary agreement about what “good” is)? The fact of the matter is simple: our squat is ultimately the product of our anatomy, our strength, and our neuromuscular control superimposed on the prior two variables.

I want to focus briefly on the anatomy. We cannot change it and it plays a huge role in how we move. Do you often consider it when judging movement patterns? Most do not, and I think that’s a real oversight!

https://bretcontreras.com/how-femur-leng; Image 2

Consider Image 2.

These women are close to the same relative height. However, their anatomic morphology, or bone shape, is not the same. The woman on the left has a longer torso and shorter femur length relative to the girl on the right, who has a longer femur and shorter torso. This actually plays a massive role in how they move, especially when they squat!

Contemplate this: During a squat, your body must account for the horizontal displacement of your femoral length. When you squat, your femur moves from vertical to horizontal which shifts your center of gravity posterior to the value of how long your femur is. We have to counteract this force by imposing an opposite force (an anterior force) to keep from falling backwards! Quite simply, the longer your femur, the more something has to compensate for it to maintain your balance. Most commonly, we achieve this via either a forward trunk lean or by moving the knees forward (the ankle moving into closed chain dorsiflexion). If you lack the dorsiflexion, then we typically see the heels lift upwards to account for that lack of flexibility.

Either way you think about it, something is picking up the slack for your anatomy!

Let’s look at that in a real-world example. The same two women are now in a squat (Image 3).

https://bretcontreras.com/how-femur-leng; Image 3

If we were giving out score cards, most people would praise the woman on the left, and scold the woman on the right. However, they are, in fact, both good squats relative to their body proportions. The woman on the right must lean forward to account for her longer femur length. She can’t help it, and you can’t beat anatomy! Her torso and her dorsiflexion are making up for her femur.

What does that mean for us? Well, it ultimately changes what normal is! Normal is going to be largely dictated by how your built. This is only one single variable of body proportion; let’s not forget about other aspects of anatomy such as rotation, version, and orientation.

We have to remember how force is accounted for during exercise. If we move or shift it from one place, it is likely that force is experienced somewhere else. This is extremely important with pathology and patient care, what type of squat or squat modification are you selecting, and why. What does this mean for the other joints and ultimately, how does this affect them down the road?

Happy Squatting!

-Chris