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
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
The more you can improve your ankle dorsiflexion the easier it will be for you achieve depth
Limited ankle dorsiflexion can increase hip flexion in trying to achieve depth, thereby increasing forward lean or spinal flexion which will increase forces to the back if you are squatting with weight as well as over-activation of the hip flexors
If you can’t rock forward on your ankle, this may encourage your foot to pronate more, causing more knee valgus
Increased knee valgus has been associated with pain in the knee because the patella is not tracking as ideally as it should
Knee valgus has also been implicated to increase stress on the ACL
Ankle mobility can also be deceptive though. Some people don’t rock as straight through the ankle joint because their feet are flat or flatten more (pronation) causing changes in joint articulation. If the pronation is not dealt with, it can also compromise dynamic positioning of the knee (inward deviation AKA valgus), possibly leading to knee pain. This is where foot arch exercises may be helpful (which I will cover in another article), but for some individuals, a custom foot orthotic by a podiatrist can be beneficial.
Simple Homework for Ankle Mobility
A good place to start for ankle mobility is to get your knee to pass in a straight line over your toes without lifting your heels that is distance of at least a fist width, if not more. While easy conceptually, it can take a lot of time to develop this. Some people have more ankle joint tightness they must work through whereas some have more soft tissue tension. Typical approaches to work on improving ankle mobility are ankle rocking exercises (more than I can shake a stick at on YouTube), and stretching, foam rolling, or sticking your calves. Ankle manipulation, mobilization, or massage therapy can also help speed this process along. You can also practice your squats with elevated heels on a plate or platform while you are working to improve your mobility.
Using a fixed resistance band to help mobilize the talocrural joint as you rock the knee forward is a popular method for working on ankle dorsiflexion. Try to keep your knee inline over your foot without lifting your heels if you use this method. Hold the knee in front of the toes to help stretching the muscles of the calf.
Self myofascial release with a stick roller or rolling on a high density foam roller are ways to take tension off your calves which may be limiting your dorsiflexion.
3. Mobilize and Power Up the Hips If you're trying to squat with more depth, some focused mobility and motor control work to the muscles of the hip would be beneficial.
Good hip flexion is required during squatting especially if you want to go deeper. This means you should be trying to get your thighs as close to your torso as possible. This may require some backside work to stretch the glutes, hip external rotators, and hamstrings so you can drop into your bottom position more comfortably, but working on overall mobility in the lower extremity is usually beneficial for most people.
Foam rolling the hamstrings, glutes, and hip external rotators (i.e. piriformis) are fairly straightforward methods for self-myofascial release.
Passive stretches such as the figure-4 can be helpful in opening up the glutes and external rotators.
Hamstrings are found to be only moderately active throughout the squat and their length does not change much. They are most active in first 70 degrees of knee bend and the outer hamstrings are more active. That said, you still want to make sure you have the most length available to use going into the squat as their tightness have been implicated in contributing to the dreaded butt wink.
My favorite active stretch for the hamstrings is the reverse toe touch. Start with your knees bent and keep your fingers touching the ground while you try to straighten your legs. Do this daily for a couple minutes and you might be surprised how flexible your hamstrings become.
For many people, their day-to-day consists of many hours of sitting. Sitting maintains the hip flexor muscles in a short and contracted state that the brain becomes accustomed to. It also facilitates a lengthened and inhibited gluteus maximus as well. Stretching the hip flexors will help counter the tightness and help you work towards achieving developing better hip extension. This is important if you will be doing a high volume of squatting.
This commonly prescribed stretch with a band is a twofor. It will help elongate your deep and superficial hip flexors.
Gluteus maximus activation also goes hand-in-hand with hip flexor mobility work as it naturally opposes the hip flexors. Glute max activation increases as you squat deeper, because it helps to stabilize and control your descent as well as ascent. That's why it may be beneficial to do isolated glute max exercises to help achieve balance in activation of each glute.
This single-leg bridge complements the hip flexor stretch by helping to achieve dynamic flexibility of the hip flexors while isolating individual gluteus maximus action. It also incorporates core stability into the mix. A great exercise to help improve hip drive coming out of the hole of a squat.
While a large part of squatting occurs in the forward/backward plane, we can't ignore the multi-directional nature of the hips. Some people may struggle with the knees buckling inward (valgus) when squatting down. While ankle mobility should be troubleshooted first as it can be the source of poor dynamic knee alignment (possible reason for knee pain), strengthening of the gluteus medius and minimus may help. They are the hip abductors and work to stabilize and check unwanted motion at the hip, and thereby the knee in many movement patterns we are trying to improve (i.e. single leg stance in gait, single leg squat alignment, double leg squat alignment, lunging). To improve their function I like to use an approach called reactive neuromuscular training technique (RNT). RNT is useful in trying to correct movement dysfunctions without having to explain or cue movement excessively- the person simply reacts. The beauty of these techniques are that they are open to your creativity.
While straight leg hip abduction in standing or side-lying, along with clamshells are frequently given exercises to improve hip abductor function, the exercise I've come up with (or like to think so) to help reacquaint people with their hip abductors is a side-lying resisted march. The person raises their upper leg up to be aligned to their torso against gravity and the resistance of the band. While maintaining that position they simply bring their hip and knee to 90/90 position and return to full hip extension at a medium pace.
Try doing this for 30 seconds to 1-minute. If you are feeling a burn on the upper side of your butt, you are probably doing it right. The key is if you are looking at your feet your thigh is coming straight at you and, not tilted to the ceiling or floor. While technically not as functional as a single leg squat due to the open chain nature, I believe it is functional in teaching neuromuscular control of knee alignment with full hip flexion activities. If you want to incorporate your core, use the bottom hand to go into side-plank position.
4. Find Your Neutral Spine You’re also probably already aware that squatting with a rounded low back poses a risk for a strain or disc herniation. This is because the roundness of the back will reduce the ability of the back muscles to act effectively, shifting the load to the ligaments and your spinal discs. All of this together reduces your back’s ability to handle the compressive and shear loads in the spine if you’re squatting with weight. But did you also know? It’s also not good to squat with too much arch in your low back as the it can cause excessive compression to the back of your spinal discs too as well as your spinal joints. That's why most recommendations suggest trying to maintain as close to a neutral spine as possible.
Start with Thoracic Spine Extension Clinically, many patients present with poor upper back mobility because we are a very forward flexion society (phones, computers, desks). In the process of trying to maintain a neutral spine when squatting it’s just as important to work on improving upper spine mobility and control because it contributes to your overall ability to keep upright during a squat without using too much of your low back, especially when weight is added.
There are many exercises to improve thoracic extension mobility. The easiest place to start is simply by foam rolling combined followed with back extensions from your mid to upper back to loosen up your spinal joints.
Stabilize Your Core After you've improved your passive thoracic extension, you want to work on improving your core/spine stability to take advantage of that mobility to help keep your back stacked well. The more upright you can keep your spine, the less shear forces occur in your back and the less sore your back extensor muscles will feel. Bracing your core (different from abdominal hollowing) also helps to increase your intra-abdominal pressure which will act as a cushion on the front of your low back to help you stabilize better. To do that, imagine being punched in the gut and try to harden your abdominal region to protect your internals.
While there are countless ways to work your core/spinal stability, I prefer to take a more direct approach to the squat by using RNT again.
One popular RNT method is to take a strong resistance band and attach it well to a fixed point and then loop it around under your armpits and step back far enough to where you just feel the band pulling your torso forward but not far back enough where you can lay back against it. As you squat, the band tries to pull you more into your dysfunction, which you will react by trying to stabilize your spine.
I like to combine the band technique with holding a 10-15 lbs Kettlebell or plate out with your arms locked. The moment created by the outstretched weight helps to counter a moment wanting to tip you backward if you have poor mobility. It also forces you to engage upper spine stability which leads to more upright positioning. As you can see, Donny's upper back positioning improved even more from the band alone. For those with a keen eye, you can see his 4th and 5th toes are now completely relaxed because he has stability in his squat now.
Don't Forget To Look Up
Lastly, where you’re looking also influences the spine’s position, especially so with increasing loads. Looking down has been shown to increase trunk flexion and hip flexion by a few degrees compared to looking straight or upward. So if you want to be more upright, keep your eyes up.
5. Setting the Bar We finally get to address weight. I saved this part for last because I believe it's more important to develop good form before adding more weight otherwise you are building strength on top of dysfunctional movement. While squats and Olympic lifts share commonalities, I will let your coaches and trainers work with you on the lifts.
There are essentially two main positions you can adopt for your weighted squat. These are the front or back squat.
Front Squat
In the front squat, the barbell is placed in the front of the shoulders over the collar bone and deltoids while the elbows are up so that the arm is parallel to the ground and extending the wrist so that your fingers lightly hook the bar for balance.
Some people struggle to get their elbows up due to tightness in the wrist flexors. Using the wall is a simple way to stretch them. If mobility is too hard to achieve, wrist straps can be helpful for some.
Back Squat
The back squat comes in two subtle flavors: the high back squat (AKA Olympic Squat) or the low back squat (AKA Power Lifting Squat). The high back squat has the bar placed across the top of the traps and rests on top of the C7 vertebra's spinous process (the prominent bump at the base of your neck).
The low back squat is placed on the mid trap just over the posterior deltoid, along the spine of the shoulder blade.
What's Are the Differences?
Shear forces at the knee do not vary between front and back squat
You elicit the same degree of muscle activity in front squat as with the back squat but the back squat will let you take on greater loads, although you may isolate the quads better in the front squat
The front squat is a viable alternative for a good leg workout for those with knee problems where extra weight will increase compressive forces
The low bar back squat may help to engage the gluteals more, but aside from that there is no significant difference in high bar or low back technique
Overhead Squat
While this position is generally found in Olympic lifts, I include it as some of you may choose to incorporate this squatting form. I consider this the pinnacle of squat positions as it requires good mobility and stability from your ankles to your hands.
Like our thoracic spine, many of us have difficulty obtaining full shoulder flexion due to tightness from daily activities. We also generally don't spend much time overhead either which doesn't help develop good motor control. The following are a few simple exercises to help improve overhead shoulder mobility.
A simple stretch laying on your stomach with wrist on top of a foam roller can help to stretch anterior chest musculature and the lats to help passive shoulder flexion.
Performing a thumbs up reach up in quadruped position and holding for a few seconds has been shown to best engage the muscles that bring the shoulder into a flexed position.
Likewise, you can go into a child's pose position and perform a reach, roll, and lift with the arm to accomplish the same.
Conclusion
Don't expect to have a perfect squat in one day. Just as it takes time to develop strength, speed, and endurance -- effort must also be taken to develop good squatting form. Putting the basic knowledge and simple techniques that I covered here will put you on the path to squatting smarter and better. But remember, when in doubt, seek a professional.
After our picture shoot for the blog, Donny decided to perform the RNT exercise with the resistance band and kettle bell for 3 sets of 10 to compare his free body squat to his first one. As you can see in the right picture, he still has room for improvement, but just a few minutes of work has already generated a small but appreciable change in his form compared to his initial squat on the left.
A special thanks to my friends and Kirkland personal trainers, Donny Mateaki & Zach Foster for being our examples for this post. They train youth, collegiate, and professional athletes with a focus on non-contact injury prevention and incorporate many of the tips from this blog post in their training. You can check out their website here www.dmathletics.com.
For more comprehensive care, check out the rest of our website or visit our office, to experience the difference of a Kirkland chiropractor who is there to guide you on your journey to wellness.
Thanks for reading and happy squatting!
References
Butler R, Plisky P, Southers C, Scoma C, Kiesel K. Biomechanical analysis of the different classifications of the Functional Movement Screen deep squat test. SPORTS BIOMECHANICS [serial online]. 2010:270.
CHARLTON J, HAMMOND C, COCHRANE C, HATFIELD G, HUNT M. THE EFFECTS OF A HEEL WEDGE ON HIP, PELVIS AND TRUNK BIOMECHANICS DURING SQUATTING IN RESISTANCE TRAINED INDIVIDUALS. Journal Of Strength & Conditioning Research (Lippincott Williams & Wilkins) [serial online]. June 2017;31(6):1678-1687.
Mark R. M, Brendan J. B. Overhead shoulder press – In-front of the head or behind the head?. Journal Of Sport And Health Science, Vol 4, Iss 3, Pp 250-257 (2015) [serial online]. 2015;(3):250.
Dill K, Begalle R, Frank B, Zinder S, Padua D. Altered knee and ankle kinematics during squatting in those with limited weight-bearing-lunge ankle-dorsiflexion range of motion. Journal Of Athletic Training [serial online]. November 2014;49(6):723-732.
Gullett J, Tillman M, Gutierrez G, Chow J. A biomechanical comparison of back and front squats in healthy trained individuals. Journal Of Strength And Conditioning Research [serial online]. January 2009;23(1):284-292.
Hartmann H, Wirth K, Klusemann M. Analysis of the Load on the Knee Joint and Vertebral Column with Changes in Squatting Depth and Weight Load. SPORTS MEDICINE -AUCKLAND- [serial online]. 2013:993.
Hirth C. Clinical evaluation & testing. Clinical movement analysis to identify muscle imbalances and guide exercise. Athletic Therapy Today [serial online]. July 2007;12(4):10-14.
Johanson M, Baer J, Hovermale H, Phouthavong P. Subtalar joint position during gastrocemius stretching and ankle dorsiflexion range of motion. Journal Of Athletic Training (National Athletic Trainers' Association) [serial online]. March 2008;43(2):172-178.
Lee J, Koh D, Kim K. The kinematics of the lower leg in the sagittal plane during downward squatting in persons with pronated feet. Journal Of Physical Therapy Science [serial online]. January 2015;27(1):285-287.
Lima Y, Ferreira V, de Paula Lima P, Bezerra M, de Oliveira R, Almeida G. The association of ankle dorsiflexion and dynamic knee valgus: A systematic review and meta-analysis. Physical Therapy In Sport [serial online]. January 2018;29:61-69.
List R, Gülay T, Stoop M, Lorenzetti S. Kinematics of the Trunk and the Lower Extremities During Restricted and Unrestricted Squats. Journal Of Strength & Conditioning Research (Lippincott Williams & Wilkins) [serial online]. June 2013;27(6):1529-1538.
Macrum E, Bell D, Boling M, Lewek M, Padua D. Effect of Limiting Ankle-Dorsiflexion Range of Motion on Lower Extremity Kinematics and Muscle-Activation Patterns During a Squat. Journal Of Sport Rehabilitation [serial online]. May 2012;21(2):144-150.
Medeiros D, Martini T. Chronic effect of different types of stretching on ankle dorsiflexion range of motion: Systematic review and meta-analysis. The Foot [serial online]. September 23, 2017
Neumann D. Kinesiology of the Hip: A Focus on Muscular Actions. Journal of Orthopaedic & Sports Physical Therapy. 2010 Feb;40(2):82-94
Power V, Clifford A. The Effects of Rearfoot Position on Lower Limb Kinematics during Bilateral Squatting in Asymptomatic Individuals with a Pronated Foot Type. Journal Of Human Kinetics [serial online]. March 2012;31:5-15.
Schoenfeld B. Squatting Kinematics and Kinetics and Their Application to Exercise Performance. JOURNAL OF STRENGTH AND CONDITIONING RESEARCH [serial online]. 2010:3497.
Stiffler M, Pennuto A, Smith M, Olson M, Bell D. Range of Motion, Postural Alignment, and LESS Score Differences of Those With and Without Excessive Medial Knee Displacement. Clinical Journal Of Sport Medicine [serial online]. January 2015;25(1):61-66.
Tsuruike M, Ellenbecker T. Serratus Anterior and Lower Trapezius Muscle Activities During Multi-Joint Isotonic Scapular Exercises and Isometric Contractions. Journal Of Athletic Training (Allen Press) [serial online]. February 2015;50(2):199-210.