3 Squatting Myths That Refuse To Die

High bar back squatThe squat probably gets more of a bad rap than any other strength training movement, especially the barbell back squat. Many people choose the leg press machine instead, blaming the squat on their knee or low back injuries. Others will only perform partial squats, fearing injury if they go too deep. Avoiding injury is always good, but avoiding the squat is like refusing to walk because you’ve seen other people trip and fall on the sidewalk. Millions of professional and amateur athletes around the world somehow manage to squat regularly without hurting themselves.

The fact that a properly performed squat is inherently safe has been presented many, many times by others who are much more qualified than I am. In spite of this, the misconceptions persist, so I believe that the available evidence bears repeating. This article will deconstruct what may be the three most common squatting myths: Squatting below parallel is bad for your knees, your knees should never go past your toes and squatting is bad for your back. I will also present two very basic guidelines that should keep just about anyone injury-free when squatting.

Myth #1: Squatting below parallel is bad for your knees

Despite the ability of the knee joint to provide an average of 140 degrees of flexion, the idea has been promoted that knee flexion should be limited to 90 degrees during a squat. This myth can be traced back, at least in part, to a single study published in 1961 by Dr. Karl Klein at the University of Texas. Dr. Klein determined that a group of competitive weightlifters displayed greater laxity at the knee joint than a group of non-lifters, and issued a blanket recommendation against squatting below parallel. The study was of very low quality, though, and Dr. Klein was seeking to validate his bias against squatting below parallel. Somehow, this erroneous belief was adopted by the general population and has remained standard dogma ever since, even though it’s been disproven many times over.

Powerlifters squatting double their body weight, to depths of 130 degrees of knee flexion, have been shown in studies to have more stable knee joints than individuals who do not squat. In fact, separate studies have revealed that the knees of those who regularly squat deep are more stable than distance runners and basketball players! In one study of female volleyball players, researchers concluded that there was no statistically significant increase in peak forces at the knee when squatting to depths of 70, 90, and 110 degrees of knee flexion. Yet another study showed that forces on the ACL are reduced as the knee is flexed beyond 60 degrees, and forces on the PCL are reduced as the knee flexes past 120 degrees. Still further studies show that powerlifters who are squatting over twice their body weight experience shearing forces on the knee that approximate only 25% of the maximal tensile strength of the ACL, and 50% of the maximum strength of the PCL.

Quarter Squat

If you only do partial squats, then you can only receive partial benefits

Obviously, this doesn’t mean that just anyone should attempt to squat with a load equaling twice their body weight on their back. While those feats clearly demonstrate what the human knee is capable of, the important point is that forces on the knee are actually reduced as squatting depth progresses beyond parallel. How deep should you go, then? Well, once you are able to drop below parallel, meaning that the crease at the top of your hips is below the top of your knees, then you should only squat as deep as you can without losing form. If your lower back starts to round, that’s your stopping point. And if you can’t squat below parallel without rounding your lower back, then don’t increase the resistance until you can. It’s also worth mentioning that you should utilize a stance that allows you to squat between your legs and not on top of them, because pressing the hips directly against the calves under a heavy load can create a dislocating effect on the knee.

Squatting below parallel has the additional benefit of significantly increased activation of the gluteal muscles. The deeper you squat, the greater the glute activation. Whether you’re seeking to improve your performance or your appearance, you’re not doing yourself any favors by leaving the glutes out of the picture.

Myth #2: Your knees should never go past your toes

This one is about as mythical as you can get, as it’s hard to find much information at all regarding it’s origin. Search online and what you will find are numerous references to one study from 1978 at Duke University which found that keeping the lower leg as vertical as possible reduced shearing forces on the knee. I wasn’t able to find the actual paper and there’s no available explanation I’m aware of as to why those researchers believed the knee was incapable of sustaining those forces, or how they performed their study. Whether this is the actual origin of the myth or not, an obscure study with zero supporting evidence is hardly any basis for providing any legitimate rules about squatting.

There was one study conducted in 2003 that essentially recreated this scenario by having experienced weight lifters squat under two conditions. First they squatted normally, allowing their knees to travel forward past their toes. Then, they repeated the movement while restricting forward movement of the knees beyond the toes. This reduced torque at the knee by about 22%, and it also increased torque at the hips by over 1000%. (What appears to be a disproportionate redistribution of forces can be explained by a change in torso angle.) This shows that you can reduce torque at the knee by preventing them from going past the toes, but it doesn’t prove that this is necessary. Interestingly, it appears that letting the knees travel past the toes was part of the “normal” method of squatting for those experienced lifters, and the prevention of forward movement of the knees was accomplished by artificial means. In either case, the volunteers in the study seemed to be fully capable of handling the load without incident or injury.

Front Squat

Go ahead, tell him he’s doing it wrong and see what he says

This shouldn’t be surprising, because your knees go past your toes all the time when you run, jump, walk, sit down, and stand up. This is made possible in part by the natural dorsiflexion range of motion at the ankle. Furthermore, when your knee is flexed, some tension is removed from the gastrocnemius muscle at the knee joint. This allows the ankle to dorsiflex through a greater range of motion than when the knee is fully extended, and permits movement of the knee over and past the toes. Why, all of a sudden, will your knees get blown out if they go past your toes during a squat? It’s amazing how our bodies work but it’s a shame that some people remain so unaware of its capabilities.

The actual distance your knees will travel is dependent upon which type of squat you’re doing, as well as your body proportions. Are you doing front squats? Your knees are definitely going over your toes, no matter what. If they don’t, you’re doing them wrong. Do you have long femurs? Your knees will go further over your toes than an individual with shorter femurs, regardless of which type of squat you do. Are you doing split squats? In that case, your front knee may not go beyond the toes at all, but your back knee will travel well past the toes on that respective leg. Are you doing a back squat? As long as you push your hips back into the squat appropriately, and stay balanced on your midfoot throughout the movement, it doesn’t matter where your knees end up. Let them travel as far forward as they need to.

Myth #3: Squats are bad for your back

This is like saying food makes you fat. The idea that squats will hurt your back gets perpetuated by people who perform squats incorrectly, and sometimes by woefully misinformed professionals who claim to know what they are talking about. A recent article posted on Journal Sentinal Online titled, in part, “Squat lifts likely cause of stress fractures in young athletes” claims that performing squats with good form puts the spine at risk of injury, based on a new study. The main problem with the study they reference is that the researchers don’t know how to properly perform a squat. The pars fracture cited as the predominant injury risk is typically an overuse injury involving hyperextension of the spine, and the increase in “sacral slope” they measured is another indication of hyperextension.

By contrast, the goal in any squat should be to maintain a neutral spine. If there is hyperextension of the spine, then the squat is not being performed correctly. Furthermore, as the weight gets heavy in a squat, the challenge is to resist excessive spinal flexion, not extension. It’s much more common to observe a lifter who is rounding their back when squatting, even when lighter loads are being used. This error can easily be corrected by learning proper form and using a manageable resistance. That study and related article fail on such a massive scale, yet the faulty arguments still have the potential to exert undue influence on the general public for many years to come.

Other concerns focus on spinal compression in the squat, and again with the back squat usually being singled out. Some individuals will assert that placing a load on the back is an unnatural movement that should be avoided. The truth is, the human spine is very capable of handling compressive forces. The trick is to load the spine without creating excessive shear, which can be accomplished by keeping the torso as upright as possible (and practical, considering which squatting variation is being used), as well as by keeping the spine in neutral. The ability to maintain an erect torso with a neutral spine will be the limiting factor in the squat for most people. This need not be interpreted as a reason to avoid the squat, though. It simply requires that more attention be given to proper form instead of the amount of weight being lifted. If squats hurt your back and you haven’t had a recent injury or chronic pain issue, then you need to fix your squat. My suggestion is to seek advice from someone who knows how to squat!

Safe squatting and mythbusting basics

Can I promise that no one will ever get hurt doing squats? Well, no, there are no absolute guarantees, and freak accidents do happen. Even the idea that you won’t get hurt if you’re bigger and stronger sounds nice in theory, but in reality it’s impossible to predict and/or protect against all injuries. You can be sure, however, that when you squat correctly, your chance of injury will be very, very slim. Properly supervised weight training has been shown to have an extremely low risk of injury, lower than soccer, rugby, basketball, football, gymnastics, tennis, and even badminton. This may seem surprising or even hard to believe, especially if you’ve gotten hurt while lifting weights, but it makes sense if you understand that weight training can and should be performed in a much more controlled environment, absent the chaos and unpredictability inherent to many sports. Weight lifting injuries can be avoided 99.99% of the time.

There are two basic tips that will help you squat safely and I’ve already referred to them in this article. The first is to squat with proper form, simple as that. Admittedly, the squat can be a tricky movement to master, especially the back squat. How do you know if your form is good? The video in my previous post about Hip Drive should give you a good idea of how a squat should look, comparing three different squat variations. If anything hurts when you squat or the movement feels awkward or imbalanced, those are good indications that you’re doing something wrong or using too much weight. And very importantly, if your lower back is rounding at the bottom of your squat, that is an issue that needs to be addressed before you start adding more weight. I explain how to do this in my post about maintaining a neutral spine in the squat. Take whatever time is necessary to learn proper form.

Goblet Squat

Whichever squat variation you use, start light and make gradual progress

The second tip is to squat within your limits, adding resistance conservatively. This will allow your body to recover and adapt, a concept that is completely ignored when you read or hear about the supposed dangers of squatting. Amazingly, your body will adapt to the demands placed upon it, as long as you don’t exceed its current ability or its capacity for recovery. Usually, this is more of an issue with men, for whom its tempting to add 50, 75, or 100 lbs. at a time to the bar in an attempt to force progress or prove their masculinity. (Women typically go in the opposite direction, hesitating to add much weight at all out of an irrational fear of getting big and bulky and losing their femininity, another stubborn myth that has no basis in reality.) A good way to avoid this mentality is to approach each squatting session as an opportunity to practice the squat, rather than a chance to show off how much weight you can lift. That’s a bonus tip: keep your ego in check.

Squats are a skill like any other movement, and many of us have been out of practice for a long time. It can be difficult to learn (or re-learn) how to squat and labeling them as dangerous provides a convenient excuse for omitting them from a workout program. You don’t have to be that person who always looks for the easy way out! As long as you’re willing to make the effort required to learn how to squat correctly and patiently allow your body to adapt, you’ll be rewarded by making consistent progress with minimal injury risk. On a personal note, I’ve had numerous people over the years warn me that I was going to destroy my knees from deep squatting. Well, I’ve been squatting well below parallel for the last ten years and I’ve never had an injury. I’ve also never had a client who I couldn’t train to perform some variation of a deep squat, even those with previous back or knee injuries, or both. They squat with skill and confidence, undeterred by unsubstantiated myths, and you can too.


1. Schoenfeld, BJ. Squatting kinematics and kinetics and their application to exercise performance. J. Strength Cond. Res. 24(12): 3497-3506. 2010.
2. Fry, A.C., J.C. Smith, and B.K. Schilling. Effect of hip position on hip and knee torques during the barbell squat. J. Strength Cond. Res. 17(4): 629-633. 2003.
3. Caterisano, A., Moss, R.F., Pellinger, T.K., Woodruff, K., Lewis, V.C., Booth, W., and Khadra, T. The Effect of Back Squat Depth on the EMG Activity of 4 Superficial Hip and Thigh Muscles. J. Strength Cond. Res. 16(3): 428–432. 2002.
4. H. Orloff, G. Veil, R. Askins. (1997). Forces on the lumbar spine during the parallel squat. Conference Proceedings Archive, 15 International Symposium on Biomechanics in Sports. http://w4.ub.uni-konstanz.de/cpa/article/view/3648.
5. Shea, J. Deep Squats. http://www.apec-s.com/wp-content/uploads/2011/12/Deep-Squats.pdf
6. Fauber, J. (Nov. 2, 2011). Squat lifts likely cause of stress fractures in young athletes, study finds. http://www.jsonline.com/blogs/news/133028228.html
7. Rippetoe, M. & Kilgore, L. (2007). Starting Strength Basic Barbell Training 2nd Edition. The Aasgaard Company.
8. Calais-Germain, B. (1993). Anatomy of Movement. Eastland Press.

Image Credits: CrossFit North Atlanta, Fashionablefit, Ultimate Aussie Training

93 comments to 3 Squatting Myths That Refuse To Die

  • Great read. I’ve seen too many people refuse to squat (properly) because they think it’ll break their knees or injure their spine somehow. If done correctly, and that can be a big if, there’s nothing to worry about.

  • DUMB Question (but I don’t know the answer)

    You said of “Myth #2: Your knees should never go past your toes” that “This one is a true myth,” implying that it is preferable that your knees don’t go past your toes.

    Furthermore, to support this claim, you pointed out that researchers have found that restricting forward movement of the knees beyond the toes reduces torque at the knee by about 22%, BUT! ALSO increases torque at the hips by over 1000%, strongly implying that it’s a “bad tradeoff” where you lose in leverage at the hips.

    However (and here is why I am confused & asking for clarification), you conclude with this statement:

    “As long as you push your hips back into the squat appropriately, and stay balanced on your midfoot throughout the movement, it doesn’t matter where your knees end up. Let them travel as far forward as they need to.”

    QUESTION: If it’s a true myth, due to the bad tradeoff in leverages (where you lose MUCH more leverage at the hips than you gain at the knees), then why is it a good thing?


  • Biomechanics Fitness and Performance

    Hi Seth,

    Yes, it really is that simple. Unfortunately, many people are unwilling to admit they’ve been wrong, or too impatient to allow their body to adapt at a realistic rate.

  • In my prior post to your page (which I don’t see you’ve reviewed & approved yet), I think I mis-read one of your statements: The restriction of movement was to keep toes behind knees, which produced better overall torque for the person squatting & thus supported your conclusion that “it doesn’t matter where your knees end up,” but I’m still confused because you said it was true myth & yet seem to have given arguments against it.

    I apologize for what looks like a reading error on my part.

    Thx in advance for not getting annoyed at my reading Faux Pas here.!

    I think I’ll also post this follow-up & own up to & admit my reading mistake here.

  • Biomechanics Fitness and Performance

    Hi Gordon,

    I really wasn’t commenting on which type of squat is “better”, and I think that’s a different issue. What I took from that study was just one piece of evidence that you’re not substantially reducing forces at the knee by preventing them from moving past the toes. Even if those researchers observed a more dramatic reduction, that wouldn’t prove that the knee joint is unable to adapt to the imposed load.

    So, if you want to emphasize the hips in your squat, go ahead, but don’t do it because you think you need to protect your knees.

  • Oh, I think I see what you’re saying:

    That is the change in position of the knees relative to the toes might affect one angle in a helpful way, and another just the opposite, but that doesn’t quite completely answer my question:

    In my prior post to your page, I think I mis-read your claim: The restriction of movement was to keep toes behind knees, which produced better overall torque for the person squatting & thus supported your conclusion that “it doesn’t matter where your knees end up,” but I’m still confused because you said it was true myth & yet seems to have given arguments against it.

    I apologize for what looks like a reading error on my part.

  • Tom

    Hi Gordon, in your first post, you seemed to be concerned by the statement “This one is a true myth,”, I think you will find that what is meant by this, is that Myth #2 is a real myth by the definition of the word myth, as there is no evidence at all to support it, and its origins are unclear. It is not intended to mean that the myth is in fact true though. I hope that clarifies.

    Great article, I thought that I was squatting correctly, I have been squatting for over a year now, but this article has shown how I could improve my squat to be safer, and removed some irrational fears. I always focused on keeping my knees behind my toes. Very grateful for the info.
    I watched the video linked from your Hip Drive Article, it is the most informative squatting video I have seen yet. Thank you.


  • Biomechanics Fitness and Performance

    Hi Tom,

    Thank you for your comment, and I’m really glad if I was able to help with your squat. I think I’ve made all the same squatting mistakes as everyone else, including trying to prevent my knees from going past my toes, so I’m happy to share what I’ve learned.

    @ Gordon – Before I address your comment any further, was Tom’s analysis correct? That’s exactly what I meant by using the term “true myth”, that it’s an actual myth, not that it’s true. Maybe that wasn’t the best choice of wording.

  • Dan

    So how do u prevent rounding at the bottom? Hammy stretching?

  • @ Ben & Tom: — Yes, Ben, you are correct:

    Tom’s analysis was correct, and it was simply the choice of words that threw me.

    no big deal — “true myth” could kind of sound like it’s really just a myth –or that it’s true.

    The context of the other things where you uniformly argue that it’s a myth, should have clued me in.

    New Question: Why can I deadlift way more than I can squat? I know part of the reason is that I am somewhat tall, and at almost 5’10”, I have long femur bones, which make the lever-angle more difficult when trying to go to parallel, but that can not fully account for why I have done a 285-lb deadlift at a BW of 120-lbs from the floor, and a 350-lbs deadlift when the weight it elevated on a 4″ wooden block set, but I struggle with a 205-lb squat — even when I fall a few inches short of parallel, I am often buried.

  • Biomechanics Fitness and Performance

    Hi Dan,

    It’s possible that hamstring tightness can limit your mobility, but just having flexible hammies doesn’t guarantee that you won’t round your lower back. It’s hard (impossible?) to give specific advice in this setting, but in general these 3 guidelines should help:

    1) The bar should travel in a vertical path centered over the mid-foot. The common mistake is to let the bar drift forward which places additional torque on the low back.

    2) Keep your back tight – traps, lats, everything. If you’re using a high-bar position, literally pull the bar into your back, even on the way up.

    3) Maintain tightness in the front of your hips, as if you’re “pulling” yourself into the bottom of the squat. The hip flexors are powerful lumbar extensors, and help buttress the anterior spine, IF they’re contracted. You’re not going to place much of a stretch on the hamstrings when flexing both the hip and knee, and I think what gets interpreted as a lack of hamstring flexibility in the squat is often just the result of relaxing the hip flexors.

  • Biomechanics Fitness and Performance

    @ Gordon:

    Well, it’s pretty normal to have a bigger number in the deadlift than the squat. Your ratio may not be the so-called perfect “ideal” but it’s not that far off, either. Do you have a particular goal in mind?

    Your anthropometry and other genetic traits will definitely play a vital role, but the one thing that stands out to me is your weight. Is that right, 120 lbs? Assuming that there’s nothing amiss with your lifting form or your training program, at some point I would expect you to have to put on some weight in order to get stronger. That’s about the best I can offer from the info you provided.

  • “Do you have a particular goal in mind?”

    — Just the standard goals, to get stronger in general and in the specific lifts, and also health, self-esteem, and having fun.

    “Your anthropometry and other genetic traits will definitely play a vital role…”

    — I have long arms, at least 68″ and possibly 70.5″ (depending on who much I stretch when measuring reach), which helps in the deadlift, and somewhat long legs also, which helps if I use sumo, since longer legs can spread further apart and get lower better.

    “…but the one thing that stands out to me is your weight. Is that right, 120 lbs?”

    — Yep — I weigh only one-hundred and nineteen pounds at last check, and I eat almost every time I’m hungry –only once every few years do I fast (to cleanse my body and for religious purposes), but that’s not very often at all.

    “Assuming that there’s nothing amiss with your lifting form or your training program, at some point I would expect you to have to put on some weight in order to get stronger.”

    — I would agree, but I wrestled in the 114-lb class in high school, and once was able to wrestle in the 105-class, but I think the standard had been allowed to “creep up” to like 110 or so, as the season progressed, due to the rules. But, as I’m forty-six (46) years old, and I rarely vary in weight, no matter how much I eat or exercise, I think that my bone structure & metabolism are restraining factors.

    Thx 4 your best attempt to help me here. Maybe I am just not trying hard enough in the gym, as sometimes personal projects are ‘time vampires’ and either cause me to miss a workout, or drain me physically and/or cause me to lose focus.

  • Awesome post…I wonder if the knee myth might have come from people misconstruing what it means to “keep your knees over your feet.” they think it means not passing toes when really what matters is side to side movement.

  • Ben — I’m currently writing a series of articles on injury prevention in youth soccer players. One of the topics coming up is weight training and since I’m a huge advocate of using squats, I found the Fauber article you cited a little disconcerting. Any thoughts specifically on that article and its relatively strong caution regarding the use of squats in a program for young teenagers?

    We do a lot of plyometrics in my program but I will be working this summer with several 14-15 year olds who, quite frankly, are going to need some serious strength training to be able to compete with their old high school counterparts. Squats seemed a natural part of that!



  • Biomechanics Fitness and Performance

    Hi Jim,

    I would never minimize the need to reduce injury risk, but the main thing that article says to me is that if you perform squats incorrectly, you might get hurt. The conclusion was that “even good form puts the spine at risk”, but the method described in the paper was an example of POOR form. Bad science, but good advertising for the North American Spine Society.

    Having said that, there’s definitely reason to be cautious, and it would be wise to avoid any high-intensity, low-rep programs at that age. Depending on the athlete’s development, it’s also possible that jumping into a barbell program would be premature. I have some youth training articles in my files from much more authoritative sources than me. If you give me a little time, I can dig them up and email them to you.

  • Anoop

    Hi Ben,

    Nice post.

    There is one problem with citing powerlifters and olympic lifters as evidence. It just could be that these lifters had genetically strong knees and hence had no problem going deep. The powerlifters who had knee pain stopped lifting or going deep and hence we never hear about them.

  • Biomechanics Fitness and Performance

    Hi Anoop,

    I won’t claim to be free from any confirmation bias, but I do hope I was careful with the way I interpreted those studies. While I agree that a successful powerlifter is probably blessed with certain genetic traits, I would expect the reduction in shear forces at the knee joint as the knee flexes beyond 90 degrees to be observed in unexperienced subjects as well.

  • Katie

    Hi great article!

    I’ve been around Olympic lifting all my life and I completely agree with your article, I really enjoyed it. People should know that it doesn’t matter what age you start lifting at, as long as you maintain correct technique. I have been lifting and doing full squats since I was 8 (I’m now almost 20) and if anything it has prevented my knees from injuries that other girls my age have had.

    Thank you for sharing this topic with the public!


  • Anoop

    Hi Ben,

    Just saying that is the problem when you do observational studies. Just too many confounding variables to come to a conclusion with high certainty.

    And ACL and PCL are forces are not the concern here. It is the patellofemoral compressive stress that can stress the articular cartilage. Ligaments get stronger, but cartilage just wears away.

    And if you go by the specificity argument, should athletes do deep squat?

    There is a recent paper in NSCA which looks at the issue. You might be interested Ben.

  • Biomechanics Fitness and Performance


    Sure, I’m always interested. Do you have a link, or at least a title?

    The forces that an athlete will experience on the field, track, etc. participating in their sport are greater than for any strength training movement, due to the much higher rate of acceleration. If squats are so destructive to the human body, then wouldn’t we also want to avoid any running or jumping?

  • Anoop

    Hi Ben,

    Are Deep Squats a Safe and Viable Exercise?: http://journals.lww.com/nsca-scj/Fulltext/2012/04000/Are_Deep_Squats_a_Safe_and_Viable_Exercise_.6.aspx

    Just one of the questions raised in the article and it is a good point about specificity. Most athletes rarely go down to deep squat position so there may not arise a need to do deep squats. Probably depends on the sport I guess. I do deep squats but I do mainly for bodybuilding purposes.

    I am not sure why you think I said squats are destructive. I am just throwing out some points for discussion.

  • Biomechanics Fitness and Performance


    You made a comment about cartilage wearing away, maybe I misunderstood where you were going with that?

    Thanks for the article link, I will look at it.

  • Anoop

    Hey Ben,

    I was talking about deep squats or full squats. There is always greater risk with deep squats (135 degrees) compared to parallel or below parallel squats. Will these show up as injury or osteoarthritis? Nobody knows.Depends on a lot of other factors I would guess.

  • Biomechanics Fitness and Performance

    Seems like we are in mutual disagreement, Anoop. The risk is introduced with the individual and how they perform the squat, how much weight they use, etc., not with the full-depth squat movement itself. Specificity is another topic altogether and I’m fully aware of the possibility that an elite athlete can perform at a championship level without ever having done a barbell back squat.

  • Anoop

    Hi Ben,

    Why do we have to disagree? We know all the forces (pattellofemoral & tibiofemoral compressive forces are high are maximum knee flexion than at 90 degree. This s true whatever technique you use or whatever weight you use.

    And this may show up as pain or something depending on the genetics, how old they are, how much weight they use, how often they do it and so forth. So here is where the uncertainty lies.

    I am agreeing with you for most of what you wrote and understand the big picture. I get a lot of these questions from my group fitness instructors.

  • Biomechanics Fitness and Performance


    It’s a good point that patellofemoral compression forces increase with knee flexion, but doesn’t PF surface contact area also progressively increase, distributing those forces over a greater area? Is compression at the PF joint necessarily a bad thing, or does it contribute to knee stability?

    From Escamilla (2001):

    “Unfortunately, it is currently unknown how much patellofemoral compressive force and stress is detrimental to the patellofemoral joint… Beyond 90–100 degrees knee flexion, compressive force has been shown to remain relatively constant. Hence, stress may decrease at larger knee flexion angles, because patellofemoral contact area continues to increase.”

    “…Compressive forces have been demonstrated to be an important factor in knee stabilization by resisting shear forces and minimizing tibia translation relative to the femur.”

    Granted, that was 11 years ago. Has anything changed?

  • Biomechanics Fitness and Performance

    @ Dan (and anyone else who is interested):

    To follow up on the comment about avoiding lower back rounding…

    I attended a strength coach seminar with Jim Smith last weekend, and he emphasized maintaining total body tension and intra-thoracic pressure for the squat and other main barbell lifts. So, while there are isolated areas where you can lose tightness (back, hips, hands, etc.), if I’m sharing general advice for maintaining proper form, it’s probably more accurate to just say… maintain total body tension!

  • Anoop

    Hi Ben,

    It is true that patellofemoral forces & tibioefemoral shows relatively little change with greater knee flexion. But all these forces are increasing with greater knee flexion. It is just that there weren’t statistically significant.

    Here is the conclusion from the very same review paper you quoted: “For athletes with healthy knees, performing the parallel squat is recommended over the deep squat, because injury potential to the menisci and cruciate and collateral ligaments may increase with the deep squat”

    And I think that’s the reason why he had the conclusion that way though the forces weren’t significant. Do you have the Meyers or the Chandlers paper, Ben?

  • Biomechanics Fitness and Performance


    That’s why it’s important to read beyond the abstract of any paper. The data presented in that paper does not support the author’s conclusion.

    I think I’ve sufficiently explained my position and I’m done with this circular discussion.

  • Ze

    “Why do we have to disagree? We know all the forces (pattellofemoral & tibiofemoral compressive forces are high are maximum knee flexion than at 90 degree. This s true whatever technique you use or whatever weight you use.”

    patellofemoral forces are higher at increasing knee flexion ASSUMING constant activiation of the quadriceps. In reality, quadriceps force decreases at higher knee flexion angles. So the combination leaves ambiguity as to if PF force is increasing, decreasing, or constant in the lower range.

    However, it is important to note that if you do full squats, you are going to be using LESS WEIGHT than if you did a parallel squat. That in itself should reduce overall PF forces seen.

  • charlie

    great article

  • Chris

    Thanks for this article. Very helpful.

    I’m a beginner to lifting, and I’m working on low bar back squats, out of the book Starting Strength. There are several annoying PT’s in my gym that insist that going below parallel will hurt my hips. I think they’re concerned about hip abductor impingement or something like that. What should I say to get them off my back?

  • Biomechanics Fitness and Performance

    Hi Chris,

    I’m not sure exactly what those trainers are referring to or what they’re basing their opinion on, so it’s hard to provide a direct response. Did they give you a reference? If I was to guess, they might be talking about femoroacetabular impingement, which is associated with structural abnormalities at the hip joint. Obviously, they aren’t qualified to determine whether you are at risk for that type of injury or not.

  • Chris

    Yeah, they didn’t describe an exact physiological mechanics issue, rather cited the NASM or the NSCA or something like that.

  • Biomechanics Fitness and Performance

    How can they be so sure you will get injured if they don’t understand the mechanism involved? If they insist on “advising” you, you could just keep asking them questions and requesting evidence to back up what they’re saying. Eventually, they will leave you alone and maybe, just maybe, one of them might realize that they don’t actually have a good explanation for it.

    Not everyone is open to holding a rational discussion, though, so you might find it easier to just ignore them :)

  • Rickie Siggins

    Hi Ben

    I totally agree, I am a Personal Trainer and Lecturer for an English Fitness Training company,One thing I find very frustrating is that almost harldly anyone of the Trainers that I know in the gym use deep squats or even know how to do them(mostly they do butt poking out type moves it is hard to tell if they are just breaking wind or squatting),one of the things that is happening even with many of those guys training to become Personal Trainers or Fitness Coaches is that they are not learning to challenge ideas which they are taught, they do not question but merely accept and because of this are in many ways short changing their clients and themselves from which for the most part should be common sense, anyone who is in contact with their body and able to find true mind to muscle connection in order to properly activate and contract the muscles of the body will know that unless there is an injury or genetic limitation that deep squats are both functional and highly productive as a movement, it may well be argued that it is unnatural for the human body to go so low with a heavy load, as why or when would this ever be required in nature(sorry Charles Atlas), but I have to say I take great pride in being able to do this within my own training. I fully support and enjoy deep squatting, my genetics are by no means superior but the one thing that helps to set us apart is our intuition and our ability to learn through watchin, listening,questioning and then doing that which may not sit right within our own minds, deep squats are without a doubt one of the best exercises that I have ever personally performed and more people should learn to peform them and perform them properly, one thing which often prevents this is or can prevent this is often the male and sometimes not so easily influenced but rarely seen female ego, trying to get a guy to suddenly take almost half the load off the bar in order to do a deep knee bend, but at the same time convince them that this will be more effective for them is a hard one to pull off, even as a Trainer, I call it the bullet proof syndrome, anyway thank you for this article and your Pearls of wisdom, this is another tool in my armoury of how to convince people that deep squats are not only very safe if done correctly, but are in fact to coin the once used but often long time not heard phrase; The king of all exercises.. and I for one will continue to sit down into the deep dark and not so scary hole that is the full squat.Thank you Ben.


  • Biomechanics Fitness and Performance

    Hi Rick,

    It’s unfortunate, but it seems like most people will do anything to avoid the cognitive dissonance that results from challenging their beliefs and ideas. They’re committed to one idea or method for life, and anyone who disagrees with them or their favorite “guru” is wrong by default.

    Advocates for squatting can go too far the other direction, as well, for example by claiming that anyone who can’t back squat a certain percentage of their bodyweight is somehow undeserving of life.

    I’ve recently revisited Supertraining and Mel Siff wrote about this flawed “thinking model based on the concept that everything may be polarised into categories of… all or none… either-or thinking. However, “events, training and research invariably take place between well defined numerical limits… Everything is a matter of degree.”

    The situation you described with new trainers is very similar in the U.S. The willingness to learn while retaining the capacity to think for yourself is a rare combination.

    Thanks for your comment.

  • Craig

    From another article by Schoenfeld, we have this:

    “The greatest risk for injury during deep squatting would theoretically be to the menisci and articular cartilage (5, 10). Tibio- femoral compressive forces have been shown to peak at 130 degrees of knee flexion where the menisci and articular cartilage bear significant amounts of stress (14). Deep squats may also increase susceptibility to patellofemoral degeneration given the high amount of patellofemoral stress that arises from contact of the underside of the patella with the articulating aspect of the femur during high flexion (6). However, there is little evidence to show a cause-effect relationship implicating an increased squat depth with injury to these structures in healthy subjects.”


    This doesn’t seem scary until you think about what he means by “healthy subjects”, and then ask how many people past the age of 40 have “healthy” knees.

    I learned the hard way that my knees were not healthy enough to sustain the stress of deep squatting. By way of background, from an early age, I always did squats Ass to Grass (ATG). I always had plenty of mobility, and it felt good to go deep, stretch out the hamstrings. Then, in my early 50’s, I hurt my knee doing something pretty unremarkable: a set of unweighted ATG squats. I was just doing them to stretch and warm up. But it caused some damage to my 50 something meniscus. From that point forward, I was never ever able to go ass to grass. Eight years later, I can just get to parallel, if I am very careful about keeping my feet in line with my knees, and keep my shins fairly vertical. If I try to go deeper, the knee tightens up and starts to hurt in a way that says ‘stop right now’. If I do push it a little too far on depth, I will be rewarded with some pain and swelling in the following days.

    I don’t think my experience is all that unusual. If I look at medical web sites dealing with knee pain, most suggest that for people past the age of 35-40, simply squatting without any added weight may be enough to trigger meniscal tears. By that age, lots of people have worn those buggers to the point where they tear pretty easily. Hard to imagine that putting a heavy barbell on your shoulders and going ATG doesn’t make tears more likely, given Schoenfeld’s description of how the stresses rise as the depth increases.

  • Biomechanics Fitness and Performance

    Hi Craig,

    I’d agree that it’s not unusual to have a bad experience with the squat, but personal experience isn’t proof of anything and that was the whole reason for this post. Besides, tissues heal. So if you’re still experiencing pain years later, then you don’t have a squat problem, you have a chronic pain issue.

    The idea that your body is shot once you hit 40 and low-intensity bodyweight movements are only going to result in injury and pain is completely out of touch with current pain science, and the medical establishment has done an incredible disservice by contributing to this irrational fear of movement.

    If you’re interested in what pain science is all about, I can suggest that you watch the video of Lorimer Moseley’s TEDx talk entitled, “Why Things Hurt”. You may find the information very useful in relation to your knee.

  • john

    Good article but I have to make a comment. I have 50 year old knees, and if I go beyond 90 degrees when I work out then my knees hurt and ‘pop’ sometimes just walking around.

    When I was a young man I did deep squats. No problem and in fact I know they were great for me. I also know most people reading this article are younger men. But not all of them.

  • Biomechanics Fitness and Performance

    Hi John,

    I appreciate your concern, but again I have to caution against using personal experience as the basis for an explanatory model.

    What about the 20 year old whose knees pop and hurt, yet imaging tests reveal no structural damage? How about the 70 year old who can perform deep squats just fine, even though their joints have considerable degeneration? Or the 40 year old who had knee problems for years until they started doing deep squats?

    This is beyond the scope of this post, but there’s a wide variety of responses and experiences that can’t be explained by biomechanics alone. See my earlier comment on 12/20… I’m not suggesting that everyone should perform heavy back squats, but if you perpetuate a belief that a movement will hurt, then it probably will.

  • Craig

    “Besides, tissues heal”.

    Muscles, tendons, ligaments will heal. Damaged meniscal and articular cartllage may not, particularly past the age or 30 or 35. Once this kind of tissue is damaged beyond the point of healing, joint function may never be entirely normal. No amount of pain management can restore normal function to a damaged joint. I think that is what happened to me: I no longer have a normal ROM because of degenerative tears to the meniscus. This is something very common in older people.

    My point isn’t that all movement past a certain age is risky. My point was that deep squats (ass to grass) with a lot of weight put high stresses on the cartilage in the knee, and that as you get older, these structures become more vulnerable to injury from such stresses. That doesn’t mean no one should ever squat. But I do think that past a certain age, there could be increased (and unnecessary) risk to going well below parallel, particularly if you are using a lot of weight.

    “but personal experience isn’t proof of anything, and that was the point of the post.”

    Then why do you conclude with this comment:

    “Well, I’ve been squatting well below parallel for the last ten years and I’ve never had an injury. I’ve also never had a client who I couldn’t train to perform some variation of a deep squat, even those with previous back or knee injuries, or both. They squat with skill and confidence, undeterred by unsubstantiated myths, and you can too.”

    So because you’ve never seen it or experiened it, it never happens?

  • Biomechanics Fitness and Performance

    My personal experience wasn’t included as proof of anything, but I do believe there are good reasons why I’m able to keep myself and my clients uninjured, regardless of age or the type of squat being performed: I give priority to form over the amount of weight being lifted, and I don’t pursue new 1RM’s every week… I make conservative increases in resistance, only adding 5 or 10 pounds at a time… if something ever hurts or just doesn’t feel right, then I back off instead of pushing through it… and I include regular deloading periods for recovery.

    “So because you’ve never seen it or experiened it, it never happens?”

    Actually, I’ve met many people who have experienced pain and injury when squatting… And then I watch them squat, with the bar too far forward, weight on their toes, back bent over, too much weight on the bar, divebombing into the hole, etc… and training like that week after week, year after year, with no break ever… and it’s no surprise that it hurts. I don’t know exactly what happened in your case, but I do know that our knees aren’t ticking time bombs just waiting to blow up the next time we perform a bodyweight squat. There is no “certain age” at which our bodies simply fall apart from basic body movements, without some history of trauma, disease or overuse.

    You can’t just throw out words like “stress”, “compression”, or “force” as being bad in and of themselves, because that’s simply not true. Our bodies require all of these in order to function and adapt, no matter what age we are. How much stress is actually damaging to the cartilage? You don’t know, because no one does!

    I’d agree that you won’t be able to squat as much at 50 as you could at 20, no objection there. Our bodies definitely slow down as we age, including our healing capacities. But our tissues still heal as well as they’re going to within a certain time frame, after which point any persistent pain is not necessarily a reflection of the state of those tissues. Everyone experiences joint degeneration as they get older, there’s nothing you can do about it and it will happen whether you squat deep or not. That absolutely does not mean you have to give up basic body movement and function. In fact, complete avoidance of any particular movement is a guaranteed way to lose it.

    This isn’t to minimize your experience, but i’m trying to explain that there’s more to it. Damage does not equal pain and pain does not equal damage. We all understand that concept when we stub our toe really hard, but somehow when it comes to internal structures like our joints, we tend to catastrophize any pain we feel. I’m not attempting to diagnose you either, but if it was possible to regain the full squat movement, wouldn’t you like to know how?

    Here are a couple posts I would recommend reading, both of which reference current scientific literature and they also link to that Lorimer Moseley video I mentioned before. Did you get a chance to look that up?


  • Craig

    I did look at the Tedx talk, and have to say that I didn’t find it all that useful. So pain is an illusion that sometimes doesn’t indicate the extent of danger or damage to tissue. But sometimes it is an output from the brain that protects you from impending danger or further damage. It would seem very important to distinguish between the two situations, yet that wasn’t really addressed.

    The first paper expresses a similar idea: You can have a lot of pain and little damage, or no pain and a lot of damage. You can also (obviously) have a lot of pain with a lot of damage. So ignoring pain could either be a great idea, or a very foolish one.

    As for the last paper – I am well aware that pain and/or radiological imaging is a poor basis for recommending surgery. I think good orthopedic surgeons need to see evidence of disfunction or instability before they consider a surgical repair to a joint or back.

    Regarding MRI studies on general populations: I think many of these do demonstrate that the incidence of joint damage does increase with age, even if the damage is not associated with pain. And, as your linked articles indicate, the absence of pain doesn’t mean that these injuries are inconsequential.

  • Biomechanics Fitness and Performance

    “…sometimes it is an output from the brain that protects you from impending danger…”

    Pain is always an output from the brain that protects you from actual or perceived danger. Big difference.

    “So ignoring pain could either be a great idea, or a very foolish one.”

    I never implied that ignoring pain is ever a smart thing to do, and that idea is not expressed in any of the links I shared.

    “…the absence of pain doesn’t mean that these injuries are inconsequential.”

    So, how would you determine the relevance of injury or degeneration as it relates to basic body movement and function? Once you feel any pain in a deep squat, that’s it? You’re done? I haven’t even gotten into how to potentially resolve a persistent pain pattern, but so far you don’t seem too interested in that.

  • Yo, Squatin’ will snap ALL YOUR STUFF UP! if done incorrectly. They feel quite natural to me, and I enjoy doing them. One function of the hamstrings is actually to protect the knee joint once one goes below parallel. However, one should take the time to learn how to do squats properly, and to actually check the credibility of the one teaching them.

  • Biomechanics Fitness and Performance

    Agreed, Santino. Do the squat properly, and you shouldn’t snap anything.

  • J.R.

    Great article, thanks for sharing. I’ve been doing deep squats with my wife for about 18 months and somewhere in that time frame she started having hip flexor pain during the deeper parts of the movement. Her form looked good. The pain started small but got worse over time (and as we went up in weight gradually) with the pain being experienced even when she wasn’t squatting. She’d sometime experience some pain sitting down or even laying down. Needless to say, we’ve taken lots of time off and looked at rebalancing her body. We have been trying everything from stretching the hamstrings and hip flexors to strengthning her core and gluteal activation work. The pain she was experiencing while not squatting has gone away.

    We have started over since with deep squats with no weight as we continue the rehab work above. Last time we worked out she said she felt a “tinge” of pain (a “.5” on the 1 to 10 pain scale) during the deep portion of body weight deep squats. Any thoughts on what might be happening? I don’t expect a diagnosis since I know that’s not possible via a post like this, however, I’m curious on whether anything jumps out as you as a possibility. I appreciate your thoughts. I certainly don’t want her doing anything that leads to pain or injury.

  • Biomechanics Fitness and Performance


    From what you’ve said, there’s no way to tell if your wife is doing anything wrong, and it sounds like you’re taking reasonable steps to resolve the painful issue. I’d be hesitant about blaming the pain on muscle imbalances, though. Pain can actually be the cause of any apparent muscle weakness or tightness, and trying to determine which came first isn’t such a clear cut task. I’d encourage you to think of those rehab exercises as providing positive input to the brain, instead of addressing muscle imbalances. By performing a variety of simple, undemanding movements that aren’t associated with pain, you may be down-regulating the pain response in the squat.

    You’re not limited to strict, repetitive, choreographed movements either. Many stretching and strengthening exercises promote movement in a single plane of motion, but it may be more beneficial to explore all planes of motion, including movements that allow the pelvis to tilt and swivel. Your wife can also try less demanding versions of the squat when warming up, for example by supporting some of her weight with her arms. Or start out by doing slow, partial depth, bodyweight squats in a pain-free range of motion, then gradually increase the range of motion and see if that helps.

  • Abhinav

    Great article. I started Stronglifts and started squatting 3 times a week about a year ago. I went up pretty heavy progressively and faced a lot of injuries because of bad form, muscle imbalances and prior injuries. I used to squat in running shoes. Recently I started the program again and bought myself a pair of flat soled chuck taylors. I am very close to squatting my max and I have no pain or injury in my legs (knees or anywhere else). My form is better than ever and I feel so much stronger.

  • Biomechanics Fitness and Performance

    Hello Abhinav,

    Thanks for reading… I’m glad you were able to resolve your squatting issues. There’s not much point to getting strong if it hurts!

  • Thomas

    Thank’s for this article, I’m a big fan of the Poliquin education (very similar to your approach), I’m living in Australia, and actually learning Biomechanics, you can’t even imagine how much restriction there is in Australia concerning Fitness, when you’re doing you’re Cert III and IV they tell you to never go past 90 degrees because it increases risk of injuries, I’m trying in vain convince some people, but there very stubborn in this country. In general fitness, deep front squat is a crime, can you believe that !!!, as a fitness trainer you should recommend any of these movement. I’ll not give an “ass to grass” squat to a beginner in training, but I’ll teach him in time, And you can’t even do that because if anything hapens you can be in a lot of trouble with insurance and all this crap. It’s like when you doing 120 kilo front squat for 5 reps, an a trainer comes to you and telling you that you go over your toes and that you going to low, you just want to shut him down.

    Anyway thanks for this article, deeps squats are the key to the best core balance, and core strength.

  • Biomechanics Fitness and Performance

    Hi Thomas,

    That’s an unfortunate situation. When trainers and regulators in suits (or khakis) claim that no one should ever squat below parallel, you can be sure they don’t know how to do it themselves and they certainly have no idea how to coach it.

    I won’t attempt to provide advice on the legalities in your country, but perhaps you can present a case to your certifying body using available research as well as corroborating statements from actual athletes and sports coaches.

    Would partnering with the Australian Weightlifting Federation or a similar organization give you more freedom to train the way you would like?

  • Toes pointing outwards reduces any chance of knee injury and doing an almost sumo squat reduces the pressure placed on the knees.

    I do regular heavy squats, without knee straps, just a lifting/squatting belt and go for broke with “balls to the floor” movements.

    Like people who do 1/4 rep bench presses and complain they don’t grow…

  • gint0036

    I wish I had more empirical evidence to report with but….
    -I’m not going to say that going to a 1-5 rep max all the time is the way to go
    -I’m not going to say that 100% of research says full squats is the way to go
    -I’m not even going to say that if you do a squat 100% (by the book) correctly there is no CHANCE of injury to the knee or spine

    What I will say is this…..
    Western society has a severe “sitting bias”. A chair seems like a common thing but in all actuality it hurts us. Much of the world does WITHOUT chairs and literally sits in a full squatting position. Don’t even get me started on people who use chairs and benches to do 90-ish-degree squats and literally soften there core when they sit on the chair for a second before reascending. Ok, off my soapbox.

    I love this website….http://iliftthereforeiam.blogspot.com/2011/11/squats-injury-risk-or-natural-human.html
    Do we see a lot of babies and young children hurting their knees when they are in the full squat position? Oh that’s right, health care costs keep rising because of those darn 3 year olds tearing up their knees while sitting in full squat positions. I’m sure all their parents TAUGHT them to sit in a full squat position; no, this is a natural movement….a functional movement.

    Even though the movement may not APPEAR to have a purpose, it certainly did serve a purpose (and was very functional) a thousand years ago. And fortunately or unfortunately we have the same body structure (for the most part) as humans did then. I’m not saying to go out and act like a caveman….I am saying we have similar bodies.

    PS: the other funny part about people who don’t like full squats is that they suck at them and/or they like to wear little tank tops, carry a gallon jug of water, and grunt loudly as they do 400# leg presses with twig legs while in the gym. Good luck with your fake bake….I’m out.

  • Biomechanics Fitness and Performance


    I agree, people in general spend way too much time sitting in our part of the world. And deep squatting doesn’t require exceptional flexibility or mobility anyway, so there are very few excuses for not being able to perform a deep bodyweight squat short of deformity or disfigurement. Disuse is no excuse.

    According to a recent study, if you can’t squat down and sit on the floor, then return to a standing position, without using your hands and knees, then you can probably expect to live a shorter life:

    Ability to sit and rise from the floor as a predictor of all-cause mortality

  • Rob

    The problem is not shear forces on the ligaments – it is compression. Patellofemoral compression, specifically.

    In lay terms, the rear of the knee cap is pressed against the end of the thigh bone as it slides over it. This is due to pulling forces on the patellar tendon. As the force increases, it can damage the articulating cartilage of the patella. When that goes, it goes – there is no easy fix, not even surgery.

    Compression increases with flexion, weight, and widening stance (especially on descent).

    It is a misnomer to call squats “dangerous” or “safe” – any exercise can be done to excess, or incorrectly. The fact is, no one can tell just how much compression will cause damage (or how that correlates to weight on a bar), and likely every individual has slightly different tolerances.

    Improper tracking increases the risk of damage to the articulating cartilage (imagine grinding something at an angle – it wears faster). Well developed musculature about the knee will assist with proper tracking, but will not relieve compression.

    The cartilage is there for a reason, so the patella glides smoothly during flexion. Clearly it is meant to withstand some compression. But as you increase the force and repeated flexion, you will eventually damage it. As you get older, the risk goes up.

    Bottom line, be informed and, most importantly, listen to your body. Pain at or beside your knee cap from squats is usually a sign to back off.

  • Jon

    Hey there, this is a pretty good read in making me aware of the benefits and misconceptions of squatting. But there is still one question on my mind though – Does squatting stunt a person’s growth? Or even make one shorter? I’ve looked this up and asked many people but there always some who say yes and no. Is it possible for me to get a definite answer which is accurate?

  • Biomechanics Fitness and Performance

    Hi Jon,

    As far as I know, resistance training has been shown to result in some spinal shrinkage. But so has running, and the effect is temporary. There’s no evidence I’m aware of to indicate that either activity can lead to any permanent loss of height.

    There’s no evidence that squatting stunts growth either, and of course that doesn’t mean that young kids should be doing heavy back squats or anything. But running, sprinting, jumping, etc., all place considerable compression on the spine, and does anyone ever claim that those activities will make you shorter? Does anyone ever recommend that children/teenagers shouldn’t run or jump to ensure proper growth?

  • Aaron Andronyk

    We live in a sit-centric society and therefore rarely flex our hips and knees beyond 90 degrees. Hip flexors are sucked up tight, hams are shortened and femur and knee arthrokinematics are altered and reduced.

    Deep squatting when done properly increases flexibility and I believe restores proper arthrokinematics. For those who do not know, arthrokinematics are the shifting,sliding and rolling that the bones of your joints make to get through full range of motion.

    For those concerned with squats wearing out cartilage, think of it like this, rub your finger on the wall, how long does it take to get through the paint, not very long . Use your whole hand, takes a very long time. Thing of your hip with tight hip flexors and reduced arthrokinematics, the head of the femur is now pivoting on a very small area of cartilage and eventually wear through. The flexible peson with nice free movement in the joint has no problems because the head of the femur is gliding over the entire surface of the cartilage and therefore does not wear through.

    I believe squats prevent joint injury by giving proper range of motion and proper joint movement and i also believe because of our culture is so sit-centric that is why hip and knee replacements are so common today.

  • freddyfro

    I enjoyed this article. My only concern is that individuals with knee problems (particularly patellofemoral dysfunction of any kind) will come here and come away with the idea that deep squats are preferable. Deeper squats can put increased pressure through the patella and articular surfaces of the knee, and are not recommended if you have previous knee injury. I dont think the author was reaching out to individuals with knee injury, but those same people could end up here seeking advice and come away with an unsafe idea regarding the subject. just my 2 cents

  • Biomechanics Fitness and Performance

    “Deeper squats can put increased pressure through the patella and articular surfaces of the knee, and are not recommended if you have previous knee injury.”

    What kind of injury? How much pressure is too much? Yes, compressive force on the patella increases with squat depth, but so does patellar surface area, so how do you determine which position is “worse”? An individual may certainly need to reduce their ROM and intensity after an injury, but why would they no longer be able to adapt to a carefully imposed stress on their body?

    There are too many variables involved to make generalized statements on which movements should be avoided. My advice to anyone with a previous injury is to work within their current ability, but to try and regain as much range of motion as possible.

  • ziggy

    Nice article. I have come across this information before and I personally agree with all that you say. I used to (deep) squat a lot when I was younger and with some decent weight, and never had a single problem.
    Now, at age 52, I am about 3 weeks into the Starting Strength program and have added 60 pounds to my starting weight on back squat. Lately I have been experiencing stiffness across the front of my knees; I assumed this had something to do with 25 years of sitting at a desk and being somewhat sedentary, and then being maybe a little overly-enthusiastic when picking up weight lifting again.
    Today I saw my Chiropractor (whose opinion I respect) and I must say he has made me a little nervous. He told me that:
    1) Deep squats are extremely dangerous for my knees and I should not squat below parallel.
    2) I should do at least 10-15 reps per set (as opposed to the 5 rep sets I have been doing).
    3) At my age I should not use weights at all and should only do bodyweight squats.
    4) If I insist on using weights in my training then they must be very light and I should never feel like I have exerted myself during an exercise. None of the sets should ever feel challenging.

    I noticed that the articles online are usually geared towards younger people. Is there any truth to what my Chiro told me about training at my (advanced?) age. Could I do permanent injury to myself if I try to increase my strength at my age? I was secretly hoping that I could get my squat weight back up to about 225 for reps…

  • Biomechanics Fitness and Performance

    Hi Ziggy,

    I’m sure your chiropractor has good intentions, but the claim that deep squats are dangerous for the knees is based on outdated, faulty research as I’ve highlighted in my post. Yes, our rate of adaptation and physical potential declines as we age, but we don’t lose the ability to adapt to an imposed stimulus, and no progress will ever be made if you don’t challenge yourself. However, after a 25-year layoff, it’s certainly possible that you need to make a more gradual return to training.

    Programs can always be modified for age by decreasing workout frequency or intensity (maybe 2 “hard” days/week instead of 3) and planning for more frequent recovery weeks. Ultimately, it’s your decision but my suggestion is to expect your progress to be a little slower, allow more time for recovery and of course never push through any pain.

  • Matt EP

    Great read, however I find section II a little vague. In my experience from strength and conditioning and working as an exercise physiologist the whole “knees not going beyond your toes” is more of a coaching que. It encourages the athlete to put more weight in their heels rather than coming up onto the toes. For lighter weights this would not be a problem, but encouraging good technique is essential for those who are aiming to increase strength of the lower chain.. 60kg squats, no problem but as you increase the resistance more to say 150, 180, 200kg etc the amount of strain on the toned, smaller connective tissues supporting the sole of the foot (long plantar ligament, plantar calcaneonavicular ligament etc) resulting in inflammatory, degenerative and painful conditions such as Plantar Fascitis. This in no way is a criticism of your article, I find it to be quite an informative read. I was just hoping to get your thoughts on this? (also the photo that you have displayed in this section is a hang clean (or a poorly performed front squat)

  • Biomechanics Fitness and Performance

    Hi Matt,

    Thanks for your comment. I don’t really like that as a cue because it reinforces the widely held misconception that the knees cannot go past the toes. If the weight is shifting toward the toes, that’s because the bar is shifting forward, and the torso is getting pushed forward. Cueing a lifter to keep their knees back and heels down might help with keeping the bar balanced over the mid-foot, but it doesn’t correct the torso angle. If anything, I prefer the “knees out” cue (which does keep the knees back in the sagittal plane) because that will help keep the torso in a more vertical position.

  • ziggy

    Thanks for the quick reply!
    Glad to hear that I can still challenge myself and adapt to progressive resistance, as I am not yet ready sit around and collect dust (as my chiro seemed to advise).
    I will use your suggestion about fewer ‘hard’ days per week. here is what I envision…

    – Deload 30% on squats from previous working weight and resume progression
    – Do light squatting on deadlift days
    – (possibly) make smaller jumps -> 2.5 lb increments vs the 5 – 10 lb I was using (my fractional plates have arrived)
    – I will be taking about 8 planned recovery weeks per year, more if required

    Does the above sound reasonable? Would 85% of previous day’s working set weight be appropriate for the light squat days?

    Thank you

  • Matt EP

    Thank you for your quick response Biomechanics Fitness and Performance

    In your respond I feel as if you have only addressed one part, my coaching que. Although you find this particular cue to be a ‘misconception’ (purely because you say that you have not found any articles suggesting otherwise), I don’t think that you have considered the potential for injury that can result from incorrect weight distribution throughout the foot. My response to your article wasn’t really to discuss positioning of the torso, it was to point out potential injury that can result from poor technique.


  • Biomechanics Fitness and Performance


    That sounds very reasonable. 85% for your light days may be fine right now, since you’ve recently started your program. As the resistance gets relatively harder, though, you may need to drop that to 60, 50 or even 40%, just enough to “groove” the movement and provide active recovery. And you may want to squat lighter on a non-deadlift day, so that you’re actually getting an easier workout in each week.

  • Biomechanics Fitness and Performance

    Hi Matt,

    I’m definitely concerned with avoiding injury, and keeping the heels down is actually my first priority with new clients. I just choose a different way to achieve that, and torso angle isn’t a completely unrelated issue. If you pull the knees back, the hips have to go back, and you will create a less vertical torso.

  • Noah

    I’m only 26 and I’ve dealt with chronic lower back pain, but have rehabbed it through the expertise and wisdom of Professor Stuart McGill.

    Now I’m trying to overcome my chronic anterior knee pain.

    I feel that focusing on gluteus medius strengthening has been helpful. (clams with bands, lateral leg raises with bands, banded monster walks.

    Recently I’ve gotten back into barbell back squatting. I find the barbell front squat hard to manage; I can’t get the grip right. My knees are feeling good right now and I want to continue to squat, but I know I’m walking on thin ice potentially.

    My question is: Given that I have some mobility constraints and some back and knee issues, how should I limit my squatting? I’m in no hurry to pile on the weight, and as a matter of fact I never want to struggle to do less than five or six reps in a set. So far I’ve just been squatting with 135 lbs. total and it’s feeling pretty good.

    I’m just trying to figure out how to to maximize performance and minimize injury. I feel like squats can help me become more resilient to injury, at least as far as me knees go.

    I can hit parallel, not much, if any, lower than that. I don’t keep a super up-right torso when I back squat.

    Thank you for your help!

  • Biomechanics Fitness and Performance

    Hi Noah,

    It sounds like you’re already taking practical steps for making progress while avoiding injury. If you do want to squat deeper, you can use each deloading period as an opportunity to increase your depth little by little. Or use your initial warmup sets to squat a little lower than you would with more challenging resistance.

    Regardless of your goals with squat depth in your working sets, you might benefit from including bodyweight exercises in your warmup or cooldown, or both, that provide a full range of motion for the knees. For example, groin prying, strider and crawling variations, etc… Start with less weight bearing movements and move up to more weight bearing ones as your knees feel better.

  • Noah

    Thanks a lot Ben!

    Is there anywhere I can find more information on good bodyweight exercises like the ones you mentioned (groin prying, strider, crawling)?

    And, can you please define what a “deloading period” is? Just f.y.i., I’m not really trying to squat max weight, more just trying to have great form while still doing a good amount of weight and reps.



  • Biomechanics Fitness and Performance

    That’s a good question Noah, and I’m using exercises that typically fall under “hip mobility” as a way to gradually load the knee through a full range of motion. I really like Smitty’s approach to warmups, you could check out his YouTube channel (Diesel Strength & Conditioning) for some more ideas.

    If your knees are ever really bothering you, you can try some Edgework for the Knee, Sitting and Standing, from physical therapist Cory Blickenstaff.

    There are different ways to deload but you can simply look at it as using less resistance for recovery. This doesn’t have to be after a max effort type of cycle, it can also be when your form deteriorates at a certain perceived intensity level (for example: 80% of max effort) or when your workouts start feeling a lot harder than you think they should.

  • benn

    a year a go i did squats (heavy weigts)(well at least for me they were heavy weights :) ) with bad form (knees in front of toes)now i still have pains when i try to squat, i’m now getting physical therapy but i dont think its realy working.. my physical therapist says its probably not my meniscus but the problem lies behind the the kneecap, maybe a little scratch of some kind.. it’s a annoying little sharp pain enough to prevent me from squatting down. any ideas and suggestions are welcome. thanks guys..

  • annie

    I have been diagnosed with very little remaining cartilage in my left knee (arthritis) and I am a 52 year old woman. I have been lifting for approx 15 years now, and have been doing barbell back squats (not smith) for about 2 years. I do experience some pain in my left knee if I don’t allow for a long enough rest period, although I like to have two leg days a week. I squat about 2 inches below parallel because that’s what feels natural for me, If I go shorter I have pain. I am usually pain free during the act of squatting and while warmed up. It is the next day that I struggle with. Do you know of any new improvements or therapies for lost cartilage that are available or on the horizon? I have been told I’m too young for a knee replacement, and frankly the thought of surgery is not appetizing to me. Isn’t the wearing away of cartilage an age related condition?

  • Biomechanics Fitness and Performance

    Hi Annie,

    Yes, our joints degenerate as we age, to a greater or lesser degree for each individual. While I don’t attempt to provide medical advice, there is something you can try that is much simpler than surgery, it just requires a little patience: If you can squat once/week without pain, just do that for a couple of weeks. Then work your 2nd squat day back in, but go very light (possibly just the bar, or even bodyweight) with very low volume and see how you feel the next day. Then very gradually try to work back up to a regular workout. If you ever cross that pain threshold again, simply back off your 2nd squat workout for a week or so and repeat the process.

  • CoachJ

    Just a suggestion, you might have pre-empted a lot of the challenges to you article if you had cited studies to support you opinion in the article. For each of the “myths” you took the time to back them up with known studies. For your side, no studies were mentioned by name to even reach a balanced position as presented by you. It is a good discussion, but it makes the reader aware of research backing up the myth and none to support the debunking.

  • Mia Riccio

    I’m really interested to read the original study that Karl Klein did, but can not seem to find it anywhere on the internet. Do you have access to this and share it with me? Or could you point me in the right direction?

  • Biomechanics Fitness and Performance

    Hi Mia,

    No, unfortunately I was never able to obtain it myself. My comments in this post were based on a summary and review of others. This is the citation for the actual study:

    Klein K. The deep squat exercise as utilized in weight training for athletes and its effects on the ligaments of the knee. J Assoc Phys Ment Rehabil 15: 6–11, 1961.

  • Donal


    Just my two cents on this:

    I broke my pars articularis at 17 during a squat. At the time I was part of the high end rugby factory train ( private rugby school, province etc ) in Ireland. We received pretty all round training on lifting etc.Subsequently it turned out I had 2 degen disks at l5s1 upwards too.

    After about 4 years the pain was under control, mostly by doing body weight exercises and lots of stretching in my mid/upper back ( seems to cause the most trouble for me: mid/upper tight = lower doing more flexion and usually pain then ).

    I can squat now, not too big a deal, just have to keep perfect form, which is good. As such, being tall and relatively inflexible, that means low weight, but that works fine with some body weigh Bulgarian split squats or similar.


  • Daniel

    As someone who suffers from chronic back pain due to sitting too much because of my job I’m wondering if I can do squats. I have always avoided doing squats because of how much pressure it appears to put on your spine. While looking for a better workout I’ve decided squats and deadlift are something I have to start doing to get stronger, and from what I’ve read it sounds like they can actually help back pain. Deadlift seems to be fine but squats is something I’m concerned about. While doing military press on a machine or with free weights it actually seems to hurt my spine because of the weight I’m lifting, the last time I stopped and realized it was putting to much pressure on my spine…if this is the case then is barbell squats something I can do, I’m looking into 5×5 stronglifts but obviously want to know if it is safe for my situation.

  • Noah


    If you have back problems and a painful back like I do, it will take the utmost diligence to overcome. This means not irritating your back, which is something squats and deadlifts are very likely to do! DO NOT SQUAT OR DEADLIFT. Work on your core endurance and research the work of Stuart McGill, PhD of Spine Biomeechanics at the University of Waterloo – he is a fitness and rehab expert of the highest caliber for back disorders. Treat yor back right and you will be rewarded. This means great posture, movement patterns, and not beating up your back. Its a,24/7 plan of attack! It takes the utmost discipline and it is a,long process to rehab a bad back. Be smart, be careful, listen to your body, and read up on the science of rehabilitating back pain!

    Best of luck,

  • Andy

    I’m a 100m track sprinter. I’ve been doing full squats for the off season, yet it’s has come to my attention that it is in best of “intrest” to only do 90 degree. I back up this information from Justin Gatlin’s post on Instagram (100m sprinter) in which he does “degree squats. It’s also listed in the comment section that speinters will never be in that position and “supposedly” makes your body stiffer. Can anyone clear this up.

    Here’s the link, notice how he doesn’t full squat.
    Is that why he is so fast?
    p.s. Thanks!

  • Biomechanics Fitness and Performance


    In the best interest for what? And for who? You have to take into account the entire adaptation process. Deep squats are very good for general development because they not only build leg strength, but they involve the rest of the body by training the transfer of force from the legs through the core and back through the most difficult part of the movement. At some point in this process, you are going to approach your genetic limits and you will enter the realm of diminishing returns, putting more and more effort into smaller and smaller gains.

    An elite athlete is already at this point, and it’s not advantageous to train for more and more strength at the expense of time and energy that should be spent training for the sport. General adaptation is typically not needed at this level of performance, and any training in the gym needs to be carefully considered in terms of potential carryover to the actual sport without unnecessarily affecting recovery times.

    There is certainly a place for partial range squats, and with time and energy constraints, there may not be a need for full depth squats. This should be determined for the individual athlete, and that may be the case for you but I would be cautious about copying training from another athlete without understanding how it might apply to yourself or not.

  • Andy

    Thank you for putting this into perspective! I’m personally trying to get the most out of my squats for explosiveness of the start of the line.

  • Andy

    P.s. I’m in high school track and it is my best interest for getting a fast time for season. Also would you recommend training just as hard in season as I did off season.

  • Biomechanics Fitness and Performance

    Hi Andy,

    I don’t know what your program looks like obviously, but in general you wouldn’t want to lift as hard and heavy in-season, which could negatively impact your track training and events. If you’re doing 40-100m sprints and/or acceleration drills every week, the maximal muscle fiber recruitment you’ll get from that should preserve much of your strength gains from the off-season. This doesn’t mean you can’t ever go heavy or gain strength during the season, but it would be wise to avoid grinding out any reps, and you’d want to work any harder gym workouts around important training or competition dates. Best wishes for your upcoming season!

  • Andy

    Thank you! I appreciate it!

  • Colby

    Hello, I am a exercise science student and I had a slight bulging disc (l5-s1) last year which I had gone to pt for. Back squats and deadlift were my favorite exercises and I have been progressively trying to get back to these exercises…but have yet to attempt any…given my previous injury is it unwise to load the spine with back squats?
    Thank you

  • Anastasia

    I have been squatting for quite a long time allowing my knees go past my toes and Ive suffered a lot of pain on my knees and quads whereas I wouldn’t feel it in my buttocks at all. Once I’ve started doing them keeping my knees behind my toes all the pain was gone and I’ve noticed some great results. Moreover I have heard from the majority of instructors that the latter is the best way to squat and I think it’s right (I’m a ballet dancer myself).So could you tell me if doing squats this way is harmful to my knees? Thank you! (Apologizing for my English)

  • Biomechanics Fitness and Performance


    Keeping your knees behind your toes isn’t bad for the knees. However, this probably means you’re pushing your hips back to initiate the squat, which means you won’t be able to squat below parallel without rounding your lower back. Just keep that in mind.

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