are deep knee bends a good exercise?

I vaguely recall something about deep knee bends being too stressful on the knees. Is this true?

You are fortunate, Morpheus. This is something many of us did not learn until after we wrecked our knees. It’s useful to fully bend the knee during stretches, but not under load. Do half knee bends.

No cite, but yes: the advice these days is when doing load-bearing knee-bend exercises, never let your knees bend tighter than 90 degrees (and some versions even say 110 degrees).

This question comes up quite a bit and I always see the “bad on the knees” folks spouting their answers without much of any explination or evidence.

Bending your knees repeadedly is bad on your knees(like for a job or something). Proper form, good rest and nutrition deep knee bends, or weighted knee bends (squats) strengthen the muscles and tendons that support the knee. It is bad technique and abuse that cause injuries. It only stands to reason that if the muscle that supports the knee is stronger, the knee is stronger. Duh.

I have been doing Olympic style squats for quite some time now. Previously I could not even run for 100+ feet because of my knee problems that I got in the Marines. (Torn meniscus, Ligament tears) Now I can run for as long as my lungs hold out due to my new stronger and better knees.

No, deep squats do not cause your knees to go bad. It is a myth and I daresay that nobody will ever cite a study to back it up. Stronger knees are better knees and putting the muscles through the full range of motion makes them stronger than going half ass.

With proper form, squats are good for your knees. See this article for a full explanation.

I have had a couple discussions about this over the years. It depends on a couple of things:

  1. How are you built? The distance between the different bones and cartilage make a huge difference. Do you have any muscle asymmetry?
  2. How in shape are you? Are you flexible? Are your tendons and ligaments strong but supple? Are you proportionally strong in all muscles involved?
  3. Will you use perfect form on every rep of every set of deep squats, every workout for the rest of your life?
  4. Will you give your connective tissue enough time to adapt to the new loads? muscle adapts much quicker than does tendons.

Since these things can never be perfectly ascertained, the answer is it’s basically not safe. However, if you know what to feel for (pain), have some x-rays and MRI’s done, are in shape and know good form and are risk averse, you can do them.

Summary: Most people that injure themselves doing deep squats did something wrong. For me, i went too heavy too early and used my knee too much outside the weight room (mountain biking). I also wasn’t flexible enough and did ignore a small pain too. i say try them out… it’s worth it, but be responsible. THere is no replacement for full ROM.

whoops, i meant to say in the 3rd paragraph that it is safe.

My experience is that your muscles need to be strong before you do deep bends with weights. The idea is that you want your muscles to be doing all the work in supporting your weight, not to relax and let the other things (ligaments etc) take more than they can handle.

I agree that damage comes from using too much weight, too early in training. My belief is that it takes time to strengthen all the little muscles that contribute to the overall balance and support. As well, it takes time for the brain and peripheral nerves to build up good proprioceptive control, so that your brain is able to marshall all the relevant muscles in a coordinated movement.

You aren’t just building muscle, but learning to coordinate muscles to work together.


proprioception = the ability of the brain to sense limb position and muscles, and to control them.

It sums up as: if your basic physical nature is to be a macho side of beef (or you have the application to become one) you’ll be fine. For the rest of us, deep knee bends should be treated with caution. I can’t be be arsed to look for cites, because you’ll always get egotistical beefboys claiming “o its garbage because ive done a million squats since i was rambo”. Just try a Google search on [“deep knee bends” damage] and you’ll find plenty of sports and medical websites warning of the risk for the rest of us mortals.

I’ve been lifting weights off and on for over 20 years now. The squat is my favorite exercise, and I always go below parallel. I’ve never had a problem with my knees, but thats probably because I squat only after my knees are fully warmed up. I also use a 2" by 4" board under my heels. I think the trick to avoiding knee injury is to only go as low as you feel comfortable.

Important to keep in mind: when doing deep squats, one will typically have to lower the weight in order to do the movement. This can be thought of as MORE safe. The way I look at it is if you are not using full ROM, you will be using too much weight than what your joint should handle. It can be argued that only going partially down is more dangerous than full ROM.

I think form, rep speed and weight choice are much more important than anything else, for joint health.

And if you google on “magnetic insoles”, you’ll find plenty of websites that tout the benefits of those things. They’re still junk.

Squats are safe, and they’re good for your knees, if you do them right. You fuck up, you fuck up your knees.

See the article I linked to earlier as well as this page.

raygirvan, we are all humans and have the same risk of getting a knee injury whether you are a beefboy or a mortal.

As for the search you suggest, you will find all the sites who are just too cautious, because whenever you get health advice from an official source, it will always be too cautious. If you get advice from guys like ultrfilter and I, it will be more realistic and unbiased. Talk to the big guys in your gym, they’ll tell you about going what we call ATF. (ass to the floor… not to be taken literally, that will get you a cast.) Just be responsible.

  1. When you say “lower the weight” do you mean hold the weight in a different position, or reduce the amount of weight you are lifting.

  2. Got any stats to back up that argument?

Deep knee bends, like many other things in life, are not always bad but they are not always good either. What kind of condition are you in now Morpheus?

Sheesh. Make that a question mark after my first question…

By “lower the weight” Fuel means “use less weight”.

Here’s an article posted by someone on… it’s too bad there was no cite, but it will help get a point across better than i could:

"Squatting to parallel (legs bent 90 degrees) not only makes the exercise less effective but, additionally, it increases the risk of injury. First of all, by not squatting the full range of motion, one doesn’t maintain proper lumbosacral bodymechanics. When performing the squat movement, the sacrum undergoes a process known as nutation (it tilts forward, relative to the two ilia on either side of it). At approximately 90 degrees of knee bend, the sacrum tilts back (a process known as counternutation) and sets the lifter up for lower back pain.

In order to perform a full squat, flexibility and range of motion must be maintained in the lumbar spine and SI joint, as well as in such muscles as the iliopsoas and hip external rotators—piriformis, gemelli, etc. If the lifter can’t squat past 90 degrees of knee bend without the heels raising or the body bending excessively forward at the waist, but can squat all the way to the floor while holding onto something, we know that there are some muscle imbalances in regard to the pelvis/lumbosacral region (iliopsoas, external hip rotators, erector spinae) as opposed to a knee or foot/ankle dysfunction.

Additionally, since the hip joint is considered by many authors as the “steering mechanism for the leg,” improper pelvis, hip, and lumbosacral mechanics could manifest down the kinetic chain as chronic or recurring knee/ankle problems. Thus, regular performance of the full squat offers a “screen” for the athlete of his or her lumbosacral/pelvic flexibility, which may prevent injury or muscle imbalances long before they become chronic.

Parallel squats also may be potentially damaging to the knee joint. The original data on full squats causing ligament laxity was obtained in an uncontrolled manner. Recent attempts to replicate these studies haven’t shown any increased laxity or knee pain/dysfunction from doing full squats as opposed to parallel squats.

Furthermore, ask any orthopedic surgeon at what degree of knee bend does one perform the Drawer test—90 degrees. Why? Because in this position, the knee joint is the most unstable, and if you were trying to assess the integrity of the cruciate ligaments, you’d want the least amount of interference from other structures as possible. Bend the knee to full flexion. How much does the tibia move on the femur anteriorly or posteriorly? Very little. However, do the same test at 90 degrees of flexion, and you’ll get considerably more movement.

Therefore, you can imagine how much force is on the knee ligaments if the athlete is descending with a weight on their shoulders, and then at 90 degrees—the most unstable point—reversing the momentum and accelerating in the exact opposite direction. Couple this with the fact that most, if not everyone, are capable of squatting considerably more weight to the parallel position than the full squat position, and you’ve set your body up for muscular imbalances, yet again."

Summary: working any movement in partial ROM while approaching failure is dangerous.

The author of that article sounds a lot like Fred Hatfield, the guy who wrote the first article I linked to.

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…

In English? Doing any squat will put stresses on your knee ligaments, but healthy knees can stand this. Doing deep squats will put comparitively more force on the back of your kneecap (PFJR) and between the bones in the top and bottom of your leg (tibiofemoral force). If you have knee problems, a bigger bending angle is bad. The benefits of going below 90 degrees may be outweighed by risk of injury if the weights involved are large.

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.