• Dr. Frank Wen, DC

A 5 Point Guide to Squatting Smarter and Better

Updated: Aug 25, 2020

If you’re reading this, the squat is clearly an exercise that you don’t need an introduction to. It’s a cornerstone in many training programs because of its ability to recruit so many muscles and it easily carries over to improving many activities of daily living as well as sports performance. It’s also frustrating as hell for those of you trying to avoid pain, or wanting to improve positioning (which may help keep you out of pain). Whatever type of squatting form you choose do, this guide will help you squat smarter and better.

Reading Time: 15-20 Minutes

Man performing deep back squat

1. Listen to Your Knees We'll start things off with the knees as they're an area that tends to worry people the most when squatting, making them a major psychological and physical determinant of your depth and form. Maybe you’ve heard some things about the knees and squatting already, but what you do with your knees depends on what you are trying to accomplish and what the history of your knees are. There are different types of forces your knees must manage when you squat. Let’s take some time to briefly go over these so you can make an informed decision on how to manage depth for your knees.

Compression & Tensile Forces

Compression forces occur between the shin bone (tibia), thigh bone (femur) as well as the knee cap (patella) and femur during the squat. In general, compression forces increase as your squat depth increases. Compression forces between the tibia and femur have largely not been a concern as the amount of force has been measured to be very high with body builders lifting several times their body weight without injury. The risk with increasing compression is that the meniscii and cartilage may be susceptible to injury, but it is unknown what amount of force is needed to cause this in the squat.

Compression forces between the patella and femur have been of more interest as significant compression between the surfaces of the patella and where it glides over the femur may lead to irritation or damage. While the greatest force between the surfaces of the patella and femur occur around 90 degrees of knee flexion in the squat, the amount of contact between the surfaces are found to decrease with increasing depth suggesting a lower risk of injury to these structures.

Tensile forces also occur in the soft tissue that attach to the patella. The patellar tendon connects the bottom of your patella to the tibia and the quadriceps tendon connects the quads to the top of the patella. Like compression forces, the tension in the patellar tendon also increases as you squat deeper, but the ultimate strength of the tendon is estimated to be almost twice the force you would experience with a squat. And because the quadriceps tendon is even thicker than the patellar tendon, it's unlikely that it will experience failure. Furthermore, the quadriceps tendon is believed to help reduce the amount of compressive forces between the patella and femur by helping to disperse and redirect forces.

Shear Forces

Because the opposing joint surfaces of the femur and tibia allow a degree of glide, they are subject to forward and backward forces also known as shear. This motion is checked by the tension provided by the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), quadriceps, and hamstrings. Shear forces will vary depending on your position in the squat but do not necessarily correspond to the forces experienced at the ACL and PCL. Maximum anterior shear forces occur within the first 60 degrees of knee flexion whereas the peak ACL (checks anterior shear) forces occur between 15 - 30 degrees of knee flexion. This means the ACL is more susceptible to injury in light knee bends. Posterior shear forces begin at 30 degrees of knee flexion and max out at the bottom of the squat whereas peak forces on the PCL (checks posterior shear) occur at around 90 degrees of knee flexion. This means the PCL is more susceptible to injury around the half-squat to parallel position. However, as you increase your depth below parallel, the forces on the ACL and PCL actually begin to drop off. Also, as your knee bends further, the motion possible inside the knee begins to become limited as the joint surfaces and soft tissue (fat, muscle, joint capsule) compress.

The Effect of Foot Positioning

Foot positioning can affect forces at the knee as well as muscle recruitment.

  • Squatting in stances beyond shoulder width increases the compression forces that you experience in your knee joints whereas narrow stances reduce compression forces

  • Narrow stance squatting (shoulder width or less) requires increased forward knee translation which increases shear stress in the knees, but results in less compression forces in the knee joint.

  • Wider stances (i.e. sumo squat) increase gluteus maximus recruitment whereas narrower stances recruit more gastrocnemius recruitment.

Check Your Tempo

Descending too quickly into the bottom of your squat can also significantly increase shear and compression forces at the knee. Bouncing out of the hole too quickly can also significantly increase the shear in your knees as well as increase compression forces on the spine. For those trying to avoid overloading their knees or have had prior knee injury, controlling your speed is essential. A 3-4 second descent into and out of the bottom of the squat is ideal.

Considerations For Squatting Depth Based on Your Knees

In the absence of prior knee injury, squatting with depth should not be of concern if you’re following a reasonable training program. It can be confusing to determine what squat depth is appropriate on your own but as the subtleties of an injury can vary person to person, but here are some things to think about:

  • If you have had prior ACL and PCL it wouldn't be a bad idea to make sure you have stability and control in light to parallel knee bends in your squat before you take on more depth and weight

  • If you have osteoarthritis, squats may aggravate your symptoms due to the compressive forces, so squat according what you can tolerate

  • If you have patellofemoral pain, you may want to perform quarter-squats until you have successfully resolved the pain with your health care professional

  • Performing a half-squat is not recommended as the knee experiences many peak forces at the turn around point of the squat

  • Forces experienced at the knee can be fine-tuned with your foot position to find a more comfortable squatting position

  • Control your tempo and don't drop into depth too fast

  • Quadriceps activity peaks at 80-90 degrees of knee flexion, therefore if your interest is in quadriceps development, there may not be much benefit to squatting beyond parallel

  • Gluteus maximus activity increases as you descend deeper in your squat due to it’s eccentric activity in controlling the the descent and its concentric action in the ascent, but if you have unresolved knee pain, you may need to find an alternative

Ultimately, you want to listen to your body. If you're experiencing any knee pain while squatting with or without prior injury, it's best to have it checked out by a knowledgeable health care specialist (like me) instead of working through the pain.

2. Rock Out Your Ankle

Now we get to the fun part. If you haven’t heard it already, ankle mobility is a great place to start, particularly ankle dorsiflexion (allowing your shin to progress over the foot). This is even more important for those who want to achieve more depth in their squat. Why? Because what happens at the ankle will affect what happens at the knees, hips, and spine, ultimately helping to dictate the final form of your squat as you will see below.

The Effects of Ankle Mobility on Squatting

In this example with my trainer friends Donny (left) and Zach (right), we demonstrate how your squat can be impacted by augmenting or limiting ankle dorsiflexion.

Here we have the guys perform a deep body weight squat with feet approximately shoulder width. As you can see in these pictures above and below, Donny’s feet are turned out more (not necessarily a bad thing, but usually attributed to tightness in the thighs and calves), he demonstrates a forward and rounded trunk, and is unable to achieve full depth (this may not be as important depending on the squat you want to do). Zach demonstrates a more ideal squatting position. His knees pass over his feet better, his knees point straighter, and his trunk is better aligned with his shins.

Lets look at our example again now when we utilize a 2"x4" to simulate an increase in ankle dorsiflexion for Donny and a decrease in ankle dorsiflexion for Zach. It almost looks like they traded places compared to the first image. I promise you - we aren't making this up as these results have been replicated in studies before.

With Donny, we augmented his lack of dorsiflexion by elevating his heels. This simulates an increase in dorsiflexion and removes tension from his calves. While not perfect, you can see how his hip flexion and spinal angle have drastically improved. Zach's position was negatively impacted because he was forced to use more hip flexion to obtain more depth, which also impacted his overall spinal angle. Feeling sore in the back and hips from squatting? Lack of ankle mobility might be keeping you from getting into a more advantageous position. This is why weightlifting shoes can be beneficial if you are training with squats. They have an elevated heel which helps to enhance dorsiflexion and reduce tension in the back of the legs. You can try what we did here with the guys on a 2"x4" or plate in the gym in front of the mirror to see and feel the difference for yourself.

The Case For Ankle Mobility