The Knee And Squat Safety
What is the ideal safe range of movement during the squat exercise when you care about your knees? A look at the different ranges of motion.
What Is A Squat?
Basically every time you sit down on a chair, you perform a squat: bending the knees until you sit down. As the picture below shows, the difference between sitting down in a chair and doing the same motion as an exercise is that during the exercise there normally is no chair and you will use additional weight in the form of dumbells or a barbell to make the movement more difficult.
What makes the squat a great exercise is that it activates all muscles in the leg, from the quadriceps, hamstrings, glutes to the calf muscles, as well as those in the lower back, which stabilize the upper body during the movement. And when when performed correctly, it won’t cause problems to your spine.
Forces On The Knee
But what about the knee? Studies in the 1950s and 1960s came to the conclusion that the squat itself, even when done correctly, causes harm to the knees, but these studies later were discredited, as they involved parachute jumpers, who, due to the nature of their trade itself, are prone to unstable knees.
The overhead squat
However, a 1993 study took experienced lifters and examined the load on the hip and knee at four different knee flexion angles: 45°, 90°, parallel and deep squats.
The researchers found no differences in the load between the 45°, 90° and parallel angles, but the deep squat showed significantly more stress for the knee.
A second study looked at the compressive force between the quadriceps tendon and the femoral intercondylar fossa (the knee notch of the thigh bone), where higher forces can mean injury to the tendon.
The force began with 6000 N at 130° knee flexion, decreased to about 1750 N at 90° and was at approximately 0 N at 60° (Nisell R, Ekholm J. Joint load during the parallel squat in powerlifting and force analysis of in vivo bilateral quadriceps tendon rupture. Scand J. Sports Sci. 8(2):63–70, 1986, found in Garret, William, and Donald Kirkendall. Exercise and Sport Science. Philadelphia: Lippincott, Williams & Wilkins, 2000. 589).
A review (PDF) from Duke University of the available literature summarizes this as follows:
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. The squat does not compromise knee stability, and can enhance stability if performed correctly. Finally, the squat can be effective in developing hip, knee, and ankle musculature, because moderate to high quadriceps, hamstrings, and gastrocnemius activity were produced during the squat.
Quadriceps Or Gluteus Maximus?
The other interesting question we have to examine is what muscle actually benefits the most from these different ranges of motion.
A study from 2002 (PDF) showed that up to parallel position, the most involved muscle in the squat is the quadriceps. After parallel, the muscle becoming most active is the gluteus maximus, which means by going below parallel, you shift activity from your quadriceps to your behind.
That the hamstrings are more active during a deep squat is therefore something you often read on many bodybuilding and fitness sites, but nothing supported by science – maximum hamstrings activity tends to occur at 10 – 70 degrees of flexion.
In Conclusion
Going below parallel (deep squat) causes the greatest risk to the knee without increased benefits to your quadriceps development. If at all, this “full squat” is only worthwhile for those that explicitly want to train their gluteus maximus and have healthy knees to begin with. The ideal trade-off between maximum effect of the exercise and least risk is the parallel squat.
Picture courtesy of Amber Karnes.
57 Comments
Why have you made this post? It will be completely disregarded by anytime who trains correctly, and will be praised by chumps who do not train correctly, much like you I anticipate.
Get a life, Bongo.
Evil your just causing trouble making this thread nobody will agree with it.
If somebody doesn’t agree with it, he has to present better arguments than “you are wrong because I say so”.
Evil dont you squat slightly below parallel? Thats what i was told anyway.
No, I tried the various positions and the full squat indeed presented less work for my quads and trouble for my knees.
Excellent stuff Evil. I downloaded Escamilla’s paper a while ago (the Duke University review paper you cite) but hadn’t read it yet. I skipped through it and AFAIK the part you quoted has solid evidence to support it, but I’ll definitely read it carefully when I have time.
Yes, I feel that presents some solid evidence in this endless discussion.
Lol, i didnt bother reading since i know its gonna be another debate. I for one am all for doing deep squat or atlest below parallel. But that girl has got some fine legs. Quite hot.
Abdul, one thing is certain: For you I need other pictures on this blog 😉
Whats her name? The powerlifters.
I have no idea; you have to ask the photographer that took the picture. The link is at the end of the article.
ah ok, well hoping for some more really hawt girls in your next blogs. 🙂
I want to add this to the debate:
http://www.exrx.net/ExInfo/Squats.html
“Squats, when performed correctly and with appropriate supervision, are not only safe, but may be a significant deterrent to knee injuries.”
http://www.exrx.net/Kinesiology/Squats.html#anchor4522492
The primary danger to the knee occurs when the tissues of the calf and thigh press together altering the center of rotation back to the contact area creating a dislocation effect. The danger of knee injury in this situation may be prevented if either of the following factor are present:
center of gravity of the body system is kept forward of the altered center of rotation
muscles of the thigh are strong enough to prevent the body from resting or bouncing on the calves.
~Danny
I disagree with this one as well.
Not going to post any reasoning (I’m sure someone will post better reasons than I ever could). But we’ve had this argument so many times already. I just don’t think this is worth it 😉
BTW the girl really has been doing her sqwats
Yes, I am of course aware of the discussion. I felt it is time to put in some solid science where so far only “it is good / bad for you because xy says so” ruled.
Nobody has to agree with me about it; I just present this as food for thought.
Ok. Then it’s fair enough 😉
Okay thats fair enough difference of opinion. 😉
The more i look at those legs the better this article gets. 😛
This is extrapolating data. Just because the load is higher beyond a larger flexation does not mean it leads to higher chance of knee injury.
Alot of studies have found that they are no correlations between deep squatting and Knee Injuries (Meyers, 1971; Steiner et al., 1986; Panariello et al., 1994). Some studies have even found that Deep Squatting leads to an increased stability of the Knee joint (Chandler, et al. 1989).
Not only that, but would’nt the larger load on the knee’s lead to a more adaptive response in the strength of the knee joint(connective tissue adapts too) which inturn reduces the chance of injury.(Buchanan & Marsh, 2002)
I think the main concern for squatting and the knees is merely pushing your self to use far too much weight too soon, your muscles adapt much faster than connective tissue as far as Im aware.
I am aware of Chandler’s study, which indeed was one of those that saw no problems.
One interesting outcome of his study was that when in part two groups were subdivided by skill, low-skilled weightlifters had significantly tighter knees than the controls for the quadriceps active drawer at 90° knee flexion.
Panariello, as far as I remember, had football players do parallel squats.
Good article. I’m gonna try parallel and 90 next time I’m at the gym.
Doing the partial squat will get more dangerous you wont be doing the full range of motion and you will be able to do more weight because of this.
Strongly disagree, I think ATG increases the risk a bit, but there’s middle ground between parallel & ATG. “At bottom of squat, crease at hips must be lower than top of knee cap” = What I think is right.
There are studies saying yes & no to many issues, as well as the squat. It’s not a simple issue, but glute vs quad involvement? It’s a compound. The safest version is the way to go, regardless of working quads or glutes more.
On the safety issue we agree. My article simply provides another perspective in a discussion that so far was dominated by “xy says do full ROM, so it must be right”.
I’m with Danny and Chilli on this one. While I respect your opinion a lot, I simply disagree on this one.
There is just as much research showing that real squats are just as(if not more) safe than partials. I think I even had a few links myself, hopefully I can dig them out before this discussion over.
That’s the thing with stuff like this, you can almost always find research to support each side of the argument. In most cases there are flaws to both sides of the argument, and in the research your presented there are flaws in the methodology, mostly concerning the weight used.
Would be glad to see those links, Owen!
Please don’t kid yourself. He has no links.
The average IQ of a fitness aficionado is low, even for a shoesize.
Just try to mention the word “smith machine” in any fitness forum and you’ll see what I mean.
Evil i was the only one online to talk to Scooby bout the CGBP and i failed miserable he banned me before i could even give him links to what i was talking about.
Is there a way around this? ps its gray fox.
OMG HER LEGS! <3
Now for squats, I can't say for I havent ever done real squats (limited to split squats at the moment)
Evil, when you’ll post a new article with a gorgeous girl like that, I beg you to get her number for me 😀
On topic:
I agree that going below parallel will not work your legs more. I’ve done both parallel and ATG and I don’t feel my legs getting more worked out from the last one.
But I always noticed that my knees hurt after doing parallel while feeling nothing when going ATG (used the same amount of weight just to be sure)
So you may call it bro-science, but in my humble opinion, ATGs are safer for the knees 🙂
“Anecdotal evidence” sounds better in this case – and going deeper did in fact help my legs grow more (both by building the hams and glutes, and the upper part of quads, which I almost don’t feel in any exercise safe for deep squats). Again, useless to draw a final conclusion (this is to be done via scientific research).
Yes, I agree, we are still far from a final conclusion.
Nickyz do you have facebook?
You been banned gray lol?
Yep, Scooby banned him.
Why do so many people think that my blog is the Court of Appeals? 😉
Where else am i supposed to go evil? 😛
yeh im stil on the forum but making a new account is a lot harder that will take a little more time.
But im watching over you all 😉
Hey, in all seriousness, Evil, I disagree with you on this point however I respect your methodology and the steps you took to come to your conclusion; however, here are my issues:
1) Only Olympic Style Squats were tested for the below parallel Squat, I speculate and strongly believe that if a legal Powerlifting Squat where the top of the leg at the hip joint just barely breaks the point of being parallel to the top of the knee; where the technique of “Sitting Back” is heavily emphasized, the results would be very different.
2) Along that same line of thought, there is no way for any of us in examining that study to know what the specifics were about the technique used by the people being examined.
3) I believe that the High Bar position puts significantly more stress on the knee based on a few things: I) personally, high bar squatting has given me sore knees regardless of what depth I used yet I’ve never had any issues with the low bar position consistently squatting below parallel, II) The High Bar Position puts significantly more stress on the quads causing th movement to be generally knee-initiated as opposed to hip-initiated like the low bar squat, and III) speaking generally, Powerlifters have very few issues knee injury and soreness.
The study that in my opinion would yield the best and most accurate results would be to take:
1) A group of Olympic-style Weightlifters (to Squat ATG High-bar)
2) A group of RAW Powerlifters (to Squat just below Parallel as I defined above)
3) A group of Powerlifters who compete in gear (to Squat just below Parallel as I defined above)
4) A second group of RAW Powerlifters (to Squat just to the point of parallel as I defined)
5) A third group of RAW Powerlifters (to squat appreciably above the point of being parallel, about half way, I’d say)
6) A group of Weightlfters to Squat High Bar to just the point of being parallel.
7) A group of Weight lifters to Squat High Bar half way above parallel.
** Groups 2-5 all Squat Low-Bar
And then run similar trials with detailed documentation about the specifics of the biomechanics of the technique used.
I have not seen a study like that done, I don’t expect you or anyone else to be convinced by this. But, within the next 10 years, if that study does not get done, I’ll find a way to get it done. I promise you and anyone who reads this post of that.
You make some valid points and further research on the subject would be interesting.
Am I missing something?:
1) What’s the difference between 90º knee flexion squats and parallel squats?
2) What’s the difference between 100º knee flexion squats and full squats?
3) What’s the problem with more stress on the knee joint during full squats?
As far as I’m concerned, there’s no difference between 90º knee flexion squats and parallel squats, as much as there’s no difference between 100º knee flexion squats and full squats. Or am I missing something?
I think the problem here is that the conclusion is based on definitions that are not the widely used. It seems to me that when people in favour of full squat refer to them as “full squats”, they do it as if they were “just more than 90º knee flexion squat”, which would be translated as “just below parallel squats” (what the woman is doing in the picture); but when the study refer to “full squats”, it refers to “full flexion of the knee”, which could be translated as “ATG squats”, which is not the kind of full squat that such people are in favour of. On the contrary, they consider it to be dangerous as most people lack flexibility and propioception skills necessary to keep the body tight during the execution of the exercise. This is, as far as I’m concerned, of course. Did that make any sense at all?
So, if it did make any sense, then the study wouldn’t be proving that full squats -as in the way I think most people understand them, which is “just below parallel squats”- are dangerous, but rather that ATG squats are dangerous. In fact, it even comes to say that 100º knee flexion squats (full squats to me) are as safe as 90º knee flexion squats (parallel squats to me).
Again, as far as I’m concerned there’s nothing wrong with stressing more the knee joint. If it’s a bearable stress it won’t do any harm to the joint at all, but instead it will strengthen it. There’re certain sports (Olympic weightlifting, for example) in which is necessary to full squat in order to accomplish certain task. It makes sense to strengthen the joint in that range of motion in order to keep it safe during the execution of the task. Again, did that make any sense?
At 90° you will be slightly above parallel, as your lower legs normal aren’t vertical to the floor at that point of the movement.
A full squat will be at the point where your behind touches or almost touches your heels.
I thought so.
Then, what about squatting just below parallel – nor above parallel, nor parallel, nor too much below parallel (i.e: touching your heels with your “behind”)? Would it be the same scenario as in “half squats” or the same scenario as in “full squats”?
This, indeed, differs from terminology most of us on the forum use – I doubt that literal ATG is in anyone’s mind when we say “full squat”, the point of breaking parallel and stopping at a more natural position is what matters (again, I’m discussing terminology here, not trying to present an argument for or against your opinion).
Personally, the only squat in which I went so deep that my behind was near my heels was while doing pistol squats (the deepest squats I do since absence of spine loading makes it safe for back rounding in the very bottom position), but I disliked it doe to knee discomfort and subsequent soreness I began stopping when my hamstring gently touched my calves), and it felt much better.
You’re discredited by your picture, go do smith machine squats, for they’re very safe for your knees! The smith machine is the most useful utility in the gym.
Discredited because you don’t like the girl or because you can’t identify an overhead squat? 😉
the picture of your face
Translation: “I just ran out of arguments” 🙂
Sorry for my poor English. I’m a 28 years old woman in South Korea.
I’ve googled about “the quadriceps tendon” and found your post.
I absolutely agree with you.
It’s not about the correct form, but about the hamstring flexibility.
My knees injured (the quadriceps tendon) doing the full squat.
It’s so hurt that I cannot ride a bicycle and run.
Before I start weight training, a weight trainer gave me advice to do the full squat on internet.
He said “The parallel squat is the false squat, so you must do the full squat, not the parallel squat. Just ignore them who say about the risk of a knee injury. It’s good for your hip joint and knees”
I trusted him and practice it for 1 month,
but my knees injured.
I think the reason I injured is that my hamstring is inflexible.
If someone who lacks hamstring flexibility do full squat, he must get injury.
I’d like to tell the full squat lovers.
Please do not suggest full squat without warning of the risk of a knee injury.
Remember that your thoughtless suggest may spoil someone’s life.
Also my prolotherapist told me that there are a risk of injury ligaments of hip joint.
So Even if you do full squat correctly, don’t overtrain it.
Now I cannot do any exercise forever because of full squat.
I feel miserable 🙁
Ahn-nyung KHJ, thank you for adding your experience. It may give some people food for thought about how important it is to have a qualified instructor with you when attempting to do squats.
I hope you will fully heal and be able to further enjoy working out!
Try stretching your legs before n after exercising, before exercise- dynamic stretching, after exercise- static stretching. it’ll improve ur flexibility and help stay away 4m injuries.
I have been lifting weights for 25 years, well not actively all the time but anyway I have been training with a lots of different methods; I started with old-school body building, but it has varied over years and nowadays is a mixture of BB, power lifting, some olympic weight lifting, and kettlebell. I have also had my share of knee pain and even injuries due to squatting so I could say I have a lot of hands-on experience on this subject. (By the way, if my language is a bit naive it is because I am not a native English speaker).
However, I haven’t had any knee pain for many years, because I finally realized how to squat: Deep squat with wide stance, and concentrating on keeping knees as straight above the ankles as possible.
The key is really to not let knees go forward from the center of gravity when going down; it is not just the angle of knee that matters.
In fact, doing deep squats causes less knee pain which is especially noticeable when doing variations of one-leg squats because in practise one-leg squats easily (I mean like unintentionally) concentrate more on quads eventhough you would concentrate on glutes and hams. This is probably because one-leg exercise requires more muscles to keep the balance. In fact, I am doing one-leg exercises so that I don’t straighten the leg, I mean not even close. The worst thing I could do for my knees is to do squats (or actually any kind of leg exercise, this applies even leg extension machine) with only a small angle. This causes the highest stress on tendions from quads to knees which soon causes knee pain. This is not even related to the amount of weights: with the same weights doing partial squat between 100 – 50 degrees does not cause any pain, but doing squat between 60 – 10 degrees starts hurting knees.
Those studies where deep squat has shown to be harmful for knees are based on squatting with narrow stance, which is the common way of squatting unless you are not a power lifter.
With narrow stance knees are forced to go forward from the center of gravity when going down. This is the reason of knee pain, not the knee angle.
Many people say they have tried wide stance and it feels even worse than narrow stance. Well, I know that: it took me half a year until wide stance started to feel good because for twenty years I had used narrow stance as it is normally instructed everywhere.
By the way, the definition of wide stance in this context is that shin is directly upward when you are in the lowest squatting position.
If somebody would have taught me this 25 years ago, I would have been saved for numerous breaks of exercising for months because of knee pain and even muscle sprains above knee.
It is really a shame that the importance of wide stance is not taken seriously in mainstream weight training. It is just thought as a peculiarity of power lifters.
Heah Malakias, thanks for sharing this! Hope everything is ok with you now!
Evil I always thought deep squats were more natural or does that not really mean anything.
Hm, “natural” can be a lot of things. I’d say keep an eye on how your body reacts to the different ROMs and choose the one you are most comfortable with.
While this might be true in the sense that you should never use a ROM that is clearly painful and/or takes you into extremes such as making a muscle enter passive insufficiency (e.g. – bringing the bar all the way down to the chest on CGBP is commonly a shoulder overkill for long-limbed trainees, especially if their upper torso (chest) girth is small as well).
On the other hand, restricted ROM is most often, especially in beginning trainees, result of poor motor patterns and flexibility. Only when these barriers have been removed, through proper teaching and practice, discuss what exactly is natural ROM and what really feels comfortable.
Restricting ROM before having considerable amount of practical experience with the particular exercise is what usually proves disastrous for joints and overall muscle balance in the long run.
Aaaaah, this is what you get when typing long sentences – you forget you had begun them with a “while”, and begin the other half in a new sentence (and paragraph, to make things worse). I apologize for this lapsus calami (and mentis, if I might add). 😛