# are deep knee bends a good exercise? **URL:** \ **Category:** Factual Questions\ **Created:** [February 13, 2003, 9:25am UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790 "2003-02-13T09:25:15Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Fuel](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@Fuel](https://boards.straightdope.com/u/Fuel)\ **Post date:** [February 14, 2003, 7:40pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/21 "2003-02-14T19:40:19Z")
Keep in mind that the true answer to this question is **very** subjective to the individual. That’s why I myself go 100 degrees, whereas I tell my skinny but athletic workout partner to go farther down. ---
**Author:** ![Rucksinator](https://avatars.discourse-cdn.com/v4/letter/r/898d66/32.png) [@Rucksinator](https://boards.straightdope.com/u/Rucksinator)\ **Post date:** [February 14, 2003, 8:09pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/22 "2003-02-14T20:09:41Z")
> [@](#): > > \*Originally posted by Hermann Cheruscan \* > \*\*… I also use a 2" by 4" board under my heels… \*\* Why the 2x4? - Guy just getting back into weight lifting, this time without the benefit of his HS football coaches’ supervision ---
**Author:** ![Fuel](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@Fuel](https://boards.straightdope.com/u/Fuel)\ **Post date:** [February 14, 2003, 9:34pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/23 "2003-02-14T21:34:44Z")
> [@](#): > > \*Originally posted by Rucksinator \* > \*\*Why the 2x4? > > - Guy just getting back into weight lifting, this time without the benefit of his HS football coaches’ supervision \*\* Consider yourself lucky that you are not under the supervision of a HS football coach. (for the most part, no offense) the 2x4 is usually suggested for taller individuals. It’s meant to keep them from having to bend the knee forward past the feet. I’m not sure of the implications of doing this, but I would assume it’s perfectly safe, especially for people who have a hard time with knees going past feet. ---
**Author:** ![Hermann\_Cheruscan](https://avatars.discourse-cdn.com/v4/letter/h/b782af/32.png) [@Hermann\_Cheruscan](https://boards.straightdope.com/u/Hermann_Cheruscan)\ **Post date:** [February 14, 2003, 11:11pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/24 "2003-02-14T23:11:29Z")
The 2x4 does help me keep my balance. It also seems to throw more of the exertion on my quads rather than my glutes. I once had a training partner who always did his squats flat footed. I did them the same way for a while, even getting rather good doing them that way. The only thing was, my glutes would be more sore than my quads. And then my ass started getting too big, so I started using a 2x4 again. ---
**Author:** ![GOM](https://avatars.discourse-cdn.com/v4/letter/g/5f9b8f/32.png) [@GOM](https://boards.straightdope.com/u/GOM)\ **Post date:** [February 14, 2003, 11:59pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/25 "2003-02-14T23:59:36Z")
:::: ponders asking a question :::: hmmm :::: decides to take the path of wisdom, this time :::: 😃 ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 15, 2003, 5:57am UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/26 "2003-02-15T05:57:00Z")
> [@](#): > > \*Originally posted by Dr\_Paprika \* > \*\*I did my honours engineering thesis on knee biomechanics under a leading expert in the field. Articles in Muscle Mag and by “Dr. Squat” have less scientific credibility than peer-reviewed journal studies… > \*\* :rolleyes: Not to discredit your thesis or the person you worked under but this is the silliest thing I have heard. I agree with you about the articles in muscle mag, though discrediting them just because the are in a bodybuilder magazine is folly. Childish as well. It is an ad hominem attack, a logical fallacy if your engineering degree taught you anything. As for Dr. Squat- sure the name sounds goofy, but look at his [credentials](http://www.drsquat.com/index.cfm?action=about). Yes, I am aware that this is the appeal to authority fallacy, but I figured since you were being fallicious I might as well also. Lets see, whom to believe. You- with a P.E I am assuming. Or a Dr. of sports science. Phd. with well, lets see what the cite says about Dr. Squat. > [@](#): > > In college, he competed in gymnastics, and was team captain in his senior year. He competed in the National (NCAA) Gymnastics Championships three consecutive years as a college gymnast, and was the SCSU charter president of the National honorary athletic fraternity, Sigma Delta Psi. He graduated with honors in 1969, earning his Bachelor of Science degree in health, physical education & recreation. > [@](#): > > Following graduation, he accepted a teaching fellowship at the University of Illinois at Champaign/Urbana, earning his Master of Science degree in the social sciences of sport. His doctoral studies at Temple University (Philadelphia) were completed during his tenure there as a teaching associate. His doctoral competency examinations were successfully completed in the social sciences of sport (psychology, sociology and motor learning). He was awarded his doctorate (Ph.D.). degree in 1973. > [@](#): > > accepted a professorship at the University of Wisconsin (Madison) in 1976, where he conducted research in sport psychology and taught undergraduate and graduate level courses > [@](#): > > In 1983, Dr. Hatfield studied for a brief time at the famous Lenin Institute of Sport in Moscow (USSR). He returned there in 1989 as co-coach of Team USA for powerlifting competitions in Moscow and Abakaan, Siberia. He has four training books translated into Russian, distinguishing him as one of the best known Western strength experts in the Soviet Union. > [@](#): > > Dr. Hatfield advanced to the position of Senior Vice President of Weider Health & Fitness, Inc. by 1989, and was director of research and development for that corporation until June, 1991. > [@](#): > > In 1991, Dr. Hatfield was awarded the prestigious Alumni Citation Award from Southern Connecticut State University “in recognition of [his] extraordinary achievements and distinguished career.” And the list goes on. Quite a long and sucessful career. A leading expert in the field, and has apparently been one for several decades. Not to mention he puts his science to practice. So, whom to believe. A guy on the internet we know nothing about that claims to have a thesis that says squating is bad on the knees, and a leading expert that says doing squats wrong is bad on your knees but doing them right helps the knees. I think I will believe the expert. He seems to have a track record that I can check up on. You don’t. Thanks for the post though. So sorry you only find peer reviewed journals credible. When I am 80 and my knees are going strong I will remember your article on how squats screw up knees. 😉 This from a guy that has a medical discharge from the military due to knee injury. Squats bad for you knees indeed. :eek: ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 15, 2003, 6:05am UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/27 "2003-02-15T06:05:34Z")
I missed the Dr. Part of your user name. Oh well, ignore the engineering part of my post. 😃 ---
**Author:** ![Fuel](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@Fuel](https://boards.straightdope.com/u/Fuel)\ **Post date:** [February 15, 2003, 6:22am UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/28 "2003-02-15T06:22:57Z")
That article I posted was not a part of Musclemagazine, it was an unrelated article posted on [musclemag.com](http://musclemag.com) by a user on the forum. I WOULD NEVER POST ANYTHING OUT OF MUSCLE MAG! ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 15, 2003, 6:36am UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/29 "2003-02-15T06:36:54Z")
[http://www.ironmagazineforums.com/showthread.php?threadid=437](http://www.ironmagazineforums.com/showthread.php?threadid=437) A good article by Lyle Mcdonald on the trend towards demanding peer reviewed studies and etc. It is funny how a strength trainer can have 30 years actual experience in training countless athletes in the top of their sport says “doing such and such has this result” and some pedant comes along and say “but there is no studies showing this to be true”. How about 30 years experience? Studies smudies. (only teneously related to the knee thing I know…) ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [February 15, 2003, 6:12pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/30 "2003-02-15T18:12:52Z")
Now don’t be an idiot, Epimetheus. You clearly did not read my post, and jumped to all sorts of silly conclusions. Quoted by Epimetheus > [@](#): > > So, whom to believe. A guy on the internet we know nothing about that claims to have a thesis that says squating is bad on the knees, and a leading expert that says doing squats wrong is bad on your knees but doing them right helps the knees. I think I will believe the expert. He seems to have a track record that I can check up on. You don’t. While I have squatted for ten years, I do not claim to be an expert in squatting, nor was my thesis on squatting. I did not say squatting was unsafe. The article I quoted did not say sqautting was unsafe. So don’t be a friggin’ moron. Dr. Squat and the article I quoted are saying the same thing. I want you to read that again, slowly, and saying all of the difficult sounds out loud. I really could care less what some self-righteous punk believes, Epimetheus, but these are the facts. The fact is that there is a lot of twaddle and pseudoscientific bullshit about weightlifting around, including many articles in magazines such as musclemag, etc. This does not mean that they cannot have good articles, but many “articles” in such magazines are clearly unscientific or shallow advertisements for dubious products, etc. Few articles in AJSM advertise Hydroxycut. The fact is, that in any field, the opinion of one or two experts adds up to a relatively low degree of credibility, regardless of credentials. Experts, even those who use phrases like “you gotta”, are often wrong. The biomechanics of the knee are far less well understood than you think, both in vivo and as mathematical models. While I agree there is a danger in requiring studies for everything, they do give a lot of useful information. In addition to clearing up ignorance, they can show cause-and-effect, and they can suggest which side of the debate is right. Perhaps you should learn more about the value of a good study. No one is denying that experience is helpful. But if a well-conducted study does exist on the relavant topic, it would be foolish to simply ignore it because it contains big words one finds “pedantic”. Twenty years ago, orthopedic surgeons with thirty years experience recommended removing the meniscus (cartilage) from arthritic knees, based on a lifetime of experience. The meniscus was thought to be relatively useless. In fact, it is now known to act as a shock absorber, and is extremely important in healthy knees. Surgeons now do everything they can to preserve the meniscii. These are the structures that may be damaged by doing deeper squats. But no one really knows. These surgeons have many impressive credentials, as does Dr. Squat. Mine are more modest - an honours gold medal winning biomechanical engineer and a medical doctor who did research with several orthopedic surgeons (with more impressive credentials, IMHO) than Dr. Squat. But none of these people fully understand the knee. Nor do I. Neither, may I say so, do you. ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [February 15, 2003, 6:23pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/31 "2003-02-15T18:23:39Z")
And thanks for finding that article. It is, indeed, “a good writing”, which lends much support to your “arguments”. Much good writing comes from ShitDisturber™. Unfortunately, as the one person who commented on his confused polemic said, the author does not understand the scientific method. Nor does he understand the basic statistical techniques he discusses. I agree it can be dangerous to rely only on studies. I agree no “ideal workout” exists. I don’t think such a workout would be the same for two different people, or the same person at different periods of time. Statistics can be manipulated, but not by the extent the author believes. Some studies can indeed show cause and effect. Good studies have ways of showing the reader that the statistics were not manipulated in an unacceptable manner, although this is not foolproof. Nor proof from you. ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 15, 2003, 6:34pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/32 "2003-02-15T18:34:26Z")
Now now, no need for insults. This is hardly for forum to be calling me an idiot and a punk. I also never claimed to be an expert on knees. Nobody can be an expert on everything so sometimes we have to rely on the statments of other experts. The only thing I can do is rely on judgement of what others that know more than me say. Bring up a contrary opinion of another expert to somebody else claiming to be an expert is not the same as claiming to be an expert themselves. Sorry you feel that way. Of course a cool headed expert tends to hold more weight to me than somebody whom childishly insults dissenting views. But I am just a self righteous punk so my opinion doesn’t matter. I am sure you feel the same way about the other people viewing this thread making their own judgements as well. After all, they don’t have near the credentials you do, so who are they to say otherwise. Pah, whatever. ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 15, 2003, 6:58pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/33 "2003-02-15T18:58:43Z")
> [@](#): > > \*Originally posted by Dr\_Paprika \* > \*\* Experts, even those who use phrases like “you gotta”, are often wrong. \*\* Obviously the guy isn’t writing for a scientific journal, he is writing for a specific audience. Use too many fancy words and “proper” pedantic babble and you lose the audience he is trying to educate. Audience targeting. Remember that the next time you feel the need to try to discredit somebody on how they write their articles. Not everybody has the luxury of being blessed with remarkable intelligence and wonderful parents that can help pay the way through 8-9 years of school so they can be called Doctor. In that case the person teaching has to find a way to teach them without the students falling asleep. ---
**Author:** ![Fuel](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@Fuel](https://boards.straightdope.com/u/Fuel)\ **Post date:** [February 15, 2003, 7:03pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/34 "2003-02-15T19:03:34Z")
> [@](#): > > \*Originally posted by Fuel \* > \*\*You know, I remember some discussions I have had on this topic and some people, including the article I posted, don’t realize that 90 degrees is almost full ROM for some people, especially people with big legs. Hear me out. > > The average person has a certain range of motion, until the hammy hits the calf _near the knee joint_. This is what I consider full ROM, which happens to be about 100-105 degrees for me. (_remember that the shape of your leg makes the angle look much steeper, the bones are at 90 degrees and the leg looks like about 100-110_). Even though my legs can move an additional 30 degrees together, the reason I say that this point is full ROM is that once you touch these areas together, it creates a lever that prys your knee joint apart. While toting 300+ lbs., this is seriously dangerous. For skinnier athletes, their point of touching is more around 120 degrees. > > So, in light of that article, I say 90 degrees squats are good, but full ROM is better and healthier in every way, assuming you are in shape and use good form. Try to go hams to calf. > > I welcome your comments on this, **Dr. Paprika** , you have done much more reading and research than I. \*\* **Dr. Paprika** , could you comment on this post? Does this line of thinking mesh well with what you have seen in your research? I would propose that the reason the pressures go up so much in the “functional” ROM is because of this lever effect. Is this true? ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [February 16, 2003, 3:55am UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/35 "2003-02-16T03:55:15Z")
I did go too far in calling you a punk. But it shopuld have been clear the article I quoted was generally agreeing with Dr. Squat. I was pretty cavalier in making fun of his use of “gotta” and his name, which I agree are irrelevant. I think some of the comments in your first post were also cavalier. I have not researched squatting specifically, although I am an avid weightlifter. My research involved angles of knee bending, but not under those sorts of loads. You are quite correct in assuming that functional pressures are high due to the lever effect. IIRC, these loads can be as high as seven times body weight when climbing stairs WITHOUT additional load. When not squatting, a lot of the force is between the kneecap and the femur. If squatting 300 lbs, obviously the tibiofemoral component is greater than if squatting body weight only, but probably lessened if the lifter does use a two by four (which changes the practical direction of the reaction force to counteract gravity). The theoretical ROM limit is, according to the excellent _Clinical Orthopedic Examination_ 135 degrees for the knee, limited when the heel touches the buttock. I agree that close to this angle (like the ones you mention), the lever would place heavy forces on the knee fibrocartilage (meniscus), damaging it in some people. But I don’t think anyone knows that it definitely leads to damage in people with healthy knees. ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [February 16, 2003, 4:02am UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/36 "2003-02-16T04:02:32Z")
Hmmm, maybe I didn’t go too far in calling you a punk, either. You called me childish, told me my reasonable comments were the silliest thing you ever heard, told me I was being fallacious (e.g. lying) and claimed I only found peer reviewed articles credible (when I merely said they were more credible than Musclemag, which I think most people would agree with). I did not make most of the claims you argue against. Incidentally, researchers often choose a topic they are interested in – the people who do this sort of research tend to be pretty avid athletes themselves. Many of their trials involve weightlifters and professional athletes. I think your citation is a little off base here. ---
**Author:** ![Fuel](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@Fuel](https://boards.straightdope.com/u/Fuel)\ **Post date:** [February 16, 2003, 6:02am UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/37 "2003-02-16T06:02:32Z")
Dr. Paprika, so what do you think is the difference, pressure-wise, between squatting until parallel and squatting until hams touch calf? At what angle does the pressure intensity spike upwards? Does this angle correspond with the angle at which the ham touches the calf for the individuals you tested? I am trying to get as close to this pressure point as possible, to take advantage of the fullest safe ROM possible for maximum fiber recruitment. Surely your research logs could answer this question… Hey, you guys drop it and let’s pump some good, useful info into this post. There is a place for technical facts and a place for experiential facts, let’s use both. ---
**Author:** ![Dr\_Paprika](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr_paprika/32/3042_2.png) [@Dr\_Paprika](https://boards.straightdope.com/u/Dr_Paprika)\ **Post date:** [February 16, 2003, 9:31pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/38 "2003-02-16T21:31:56Z")
I quite agree. The knee is a very complicated structure. Two-dimensional models of the knee (hinge models) do not usually give results all that similar as those experimental studies – the centre of gravity of the knee, the position of the kneecap, and the direction of the involved leg muscles change with flexion angle. Even how you measure the knee flexion angle differs between papers, although the best ones simply have angle sensors on both the calf and thigh. So you’re better off using sensors and simulating what you want to measure than just using free body diagrams. The research on this question is far from complete. This site summarizes the earlier article well. [http://www.sportsinjurybulletin.com/archive/1034-the-squat.htm](http://www.sportsinjurybulletin.com/archive/1034-the-squat.htm) This article [http://asme.pinetec.com/bio2001/data/pdfs/a0097172.pdf](http://asme.pinetec.com/bio2001/data/pdfs/a0097172.pdf) is more relevant to your question, but is based on a two dimensional model (which involves several simplifications), however the weights involved are realistic. It would seem to imply that the limiting factor is the force on the PCL which would shoot up sharply after 120 degrees. But again, they do not explicitly say just how they are measuring this angle (as you flex the knee, the calf moves forward, so I would say the ROM is less than 150 degrees). Even the analysis of one of Dr. Squat’s flunkies at: [http://www.drsquat.com/index.cfm?action=viewarticle&articleID=73](http://www.drsquat.com/index.cfm?action=viewarticle&articleID=73) does not address depth of squat. Dr. Squat’s research relies pretty heavily **on the same paper I earlier quoted**. Given what is out there, I would say that above 90 degrees you are increased risk of damaging your menisus due to shear forces and above 120 degrees you are at risk of damaging your PCL in a healthy knee. But no one knows for sure, and all the engineering diagrams and technical facts in the world are not going to replace experimental studies, but I never claimed this to be true. There is a lot of anecdotal evidence about squatting injuries. Nevertheless, I bleieve squatting to 90 degrees with good form is clearly safe. Going beyond ninety degrees would increase calf development (gastrocnemius and soleus muscles) and increase stress on lumbar muscle in the back. But these can also be approached with other exercises. Why take the risk of injury to go as close to the pressure point as possible, when it likely differs between two people? I just don’t see the cost-benefit paying off. ---
**Author:** ![Epimetheus](https://avatars.discourse-cdn.com/v4/letter/e/c4cdca/32.png) [@Epimetheus](https://boards.straightdope.com/u/Epimetheus)\ **Post date:** [February 16, 2003, 10:12pm UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/39 "2003-02-16T22:12:54Z")
> [@](#): > > \*Originally posted by Dr\_Paprika \* > \*\*Hmmm, maybe I didn’t go too far in calling you a punk, either. You called me childish, told me my reasonable comments were the silliest thing you ever heard, told me I was being fallacious (e.g. lying) and claimed I only found peer reviewed articles credible (when I merely said they were more credible than Musclemag, which I think most people would agree with). I did not make most of the claims you argue against. > \*\* No, fallacious (I spelled it wrong before) is not the same as lying, it is containing or based on a [fallacy](http://dictionary.reference.com/search?q=fallacy). Somebody that reasons something based off a fallacy isn’t lying, they are just following a corrupted logical path. My claim that you found only peer reviewed journals credible was a hyperbole of your statment which insinuated that Dr. Squat was not a credible authority. It was not really intended to be taken literally. I reflected on your statements that I am a self-righeous punk and I have to concurr and say that it is an unfortunate reality. I was a bit snarky as they say, and appologize. I should have been more civilized and more of a man and approached it with much more tact. I appologize for insults given and taken, intended or not, and hope that future confrontations will be much more civilized than what I haven given this time. Hopefully I will be much more educated on this subject if it comes up again, or have a bit more than indignation to fill my post up with. Untill then Doctor. ---
**Author:** ![Fuel](https://avatars.discourse-cdn.com/v4/letter/f/df705f/32.png) [@Fuel](https://boards.straightdope.com/u/Fuel)\ **Post date:** [February 17, 2003, 12:20am UTC](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790/40 "2003-02-17T00:20:13Z")
> [@](#): > > \*Originally posted by Dr\_Paprika \* > \*\*I quite agree. > > The knee is a very complicated structure. Two-dimensional models of the knee (hinge models) do not usually give results all that similar as those experimental studies – the centre of gravity of the knee, the position of the kneecap, and the direction of the involved leg muscles change with flexion angle. Even how you measure the knee flexion angle differs between papers, although the best ones simply have angle sensors on both the calf and thigh. So you’re better off using sensors and simulating what you want to measure than just using free body diagrams. > > The research on this question is far from complete. This site summarizes the earlier article well. > > [http://www.sportsinjurybulletin.com/archive/1034-the-squat.htm](http://www.sportsinjurybulletin.com/archive/1034-the-squat.htm) > > This article > > [http://asme.pinetec.com/bio2001/data/pdfs/a0097172.pdf](http://asme.pinetec.com/bio2001/data/pdfs/a0097172.pdf) > > is more relevant to your question, but is based on a two dimensional model (which involves several simplifications), however the weights involved are realistic. It would seem to imply that the limiting factor is the force on the PCL which would shoot up sharply after 120 degrees. But again, they do not explicitly say just how they are measuring this angle (as you flex the knee, the calf moves forward, so I would say the ROM is less than 150 degrees). > > Even the analysis of one of Dr. Squat’s flunkies at: > > [http://www.drsquat.com/index.cfm?action=viewarticle&articleID=73](http://www.drsquat.com/index.cfm?action=viewarticle&articleID=73) > > does not address depth of squat. Dr. Squat’s research relies pretty heavily **on the same paper I earlier quoted**. > > Given what is out there, I would say that above 90 degrees you are increased risk of damaging your menisus due to shear forces and above 120 degrees you are at risk of damaging your PCL in a healthy knee. But no one knows for sure, and all the engineering diagrams and technical facts in the world are not going to replace experimental studies, but I never claimed this to be true. > > There is a lot of anecdotal evidence about squatting injuries. Nevertheless, I bleieve squatting to 90 degrees with good form is clearly safe. Going beyond ninety degrees would increase calf development (gastrocnemius and soleus muscles) and increase stress on lumbar muscle in the back. But these can also be approached with other exercises. Why take the risk of injury to go as close to the pressure point as possible, when it likely differs between two people? I just don’t see the cost-benefit paying off. \*\* Very helpful Dr. I got a couple extra-important things out of these articles by breezing through them: 1. Fatigue causes forces and pressures to increase. 2. The Quad (supposedly) does not work any harder after 90 degrees. Very interesting to hear that. 3. The forces in the graphs in the Adobe article spike upwards at 100 degrees. Well, none of those articles addressed the issue of the hams-touching-calf-lever issue, as i figured. I wish they would address this, as it comes into play tremendously, i’m sure. The degree of the lever created no doubt has an impact on these shearing and compressing forces spiking upwards at said angles. I just wish I knew how much of an impact. Was the Adobe paper yours? Were there large deviations in test results from person to person? Were the test subjects athletes or normal folk? Any other background info on that research would be nice. It’s so odd to hear these forces increase so drastically with deep knee bends. I mean, you can’t even feel these forces. Thanks **Dr. Paprika**. I will be much more careful when decribing form to my training partners. [Previous page](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790.md?page=1) [Next page](https://boards.straightdope.com/t/are-deep-knee-bends-a-good-exercise/154790.md?page=3)