The squat is, perhaps, the single best exercise for leg strength and development.
Squatting significantly strengthens the muscles responsible for knee and hip extension: quadriceps, hamstrings, and glutes, as well as the smaller stabilizing muscles such as the torso musculature. The squatting motion and position is also the foundation for many other exercises, such as deadlifts, Olympic lifts, and even every day lifting tasks.
I think it is a very worthwhile task to learn how to squat, and anyone who can get out of a chair can do it. It has benefits not just for your strength, but for balance, confidence, daily-life strength, cardiovascular capacity, and active flexibility.
Problem is, the squat is often taught incorrectly, and it’s stigmatized as difficult and dangerous.
People warn that it is bad for your knees and back, inappropriate for beginners (or anyone not a male collegiate athlete), too hard to learn, blah blah the sky is falling, etc. So, let’s go through all the scary things we’ve heard about squatting, to debunk them one by one.
myth #1: squatting must not be done with a full range of motion or you will hurt your knees.
This is probably the worst myth of all.
It’s one of those “well known facts” which is mysteriously unsupported in the research (it’s a well known fact that as soon as you say “it’s a well known fact”, you won’t be able to back it up).
According to this myth, full squats (a squat in which the knee joint is taken through a full range of motion, so that at the bottom the hamstrings make contact with the calves) are inherently dangerous, particularly to the knee joint.
While biomechanical research does support the fact that forces on the connective tissues of the knee increase with the knee angle, particularly on the posterior cruciate ligament, there is no evidence that these increased forces actually lead to injury. There is no direct evidence that full squatting causes or even exacerbates knee pain nor damage.
I do not know of a single documented case where full squatting led directly to knee injury. Not one!
Which is pretty amazing, considering that the clinical literature is positively littered with injury narratives. You’d think we’d see some evidence, but there is nothing, nada, zero.
Studies of Olympic weightlifters and powerlifters, both of whom squat with heavy loads, show no increased risk of knee damage in either population. Olympic lifters, in particular, regularly drop to full depth under hundreds of pounds, perhaps as often a hundred times a week or more, for years, and yet their knees are healthier than those of people such as skiiers, jumpers, or runners.
No study, short or long term, has ever shown an increase in knee laxity from deep squatting.
“Anyone who says that full squats are ‘bad for the knees’ has, with that statement, demonstrated conclusively that they are not entitled to an opinion about the matter. People who know nothing about a topic, especially a very technical one that requires specific training, knowledge, and experience, are not due an opinion about that topic and are better served by being quiet when it is asked about or discussed. For example, when brain surgery, or string theory, or the NFL draft, or women’s dress sizes, or white wine is being discussed, I remain quiet… But seldom is this the case when orthopedic surgeons, athletic trainers, physical therapists, or nurses are asked about full squats. Most such people have absolutely no idea what a full squat even is, and they certainly have no concept of how it affects the knees, unless they have had additional training beyond their specialties, which for the professions mentioned does not include full squats. Because if these people knew anything about squatting and the difference between a full squat and any other kind of squat and what they do to the knees, they would know that ‘full squats are bad for the knees’ is wrong and thus would not be making such a ridiculous statement.”
In fact, there is strong evidence that squatting actually improves knee stability!
The increased strength, balance, and proprioception from regular squatting can make a substantial contribution to keeping knees healthy. Progressive overload (beginning with a light load, then increasing gradually as the trainee is able) assists in strengthening connective tissues and muscles surrounding the joint.
It has been suggested that deep squats could cause an increased injury risk of the lumbar spine and the knee joints. Avoiding deep flexion has been recommended to minimize the magnitude of knee-joint forces. Unfortunately this suggestion has not taken the influence of the wrapping effect, functional adaptations and soft tissue contact between the back of thigh and calf into account…
Menisci and cartilage, ligaments and bones are susceptible to anabolic metabolic processes and functional structural adaptations in response to increased activity and mechanical influences. [Translation: When you squat, stuff gets stronger.]
Concerns about degenerative changes of the tendofemoral complex and the apparent higher risk for chondromalacia, osteoarthritis, and osteochondritis in deep squats are unfounded. [Translation: Deep squats don't hurt you.]
With the same load configuration as in the deep squat, half and quarter squat training with comparatively supra-maximal loads will favour degenerative changes in the knee joints and spinal joints in the long term. [Translation: Partial squats are not "safer" -- in fact, they're worse.]
Provided that technique is learned accurately under expert supervision and with progressive training loads, the deep squat presents an effective training exercise for protection against injuries and strengthening of the lower extremity. Contrary to commonly voiced concern, deep squats do not contribute increased risk of injury to passive tissues. [Translation: BAM!]
(Hartmann H, Wirth K, Klusemann M. “Analysis of the Load on the Knee Joint and Vertebral Column with Changes in Squatting Depth and Weight Load.” Sports Med. 2013 Jul 3.)
Most interesting to me is the problem with what is usually recommended as “safe”: squatting to parallel.
At parallel (where the thigh is parallel to the floor, higher than the depth of a full squat by about 30 degrees), the compressive forces on the patella (kneecap) are actually at their highest.
As the Sports Medicine article above points out:
“Based on biomechanical calculations and measurements of cadaver knee joints, the highest retropatellar compressive forces and stresses can be seen at 90°.”
Decelerating, stopping, and reversing direction at this angle can inspire significant knee pain in even healthy people, whereas full squats present no problem.
Another exercise which is supposedly “safer” is the leg extension, even though patellar tension and shear forces on the knee joint are demonstrably higher with such an exercise.
It is worthwhile at this point to comment on the things that do cause knee injury. The primary causes of knee injury involve:
- twisting under a load
- too much load (for example, I knew a guy who boasted that he could squat 800 lbs. He had never done it before, and couldn’t even full squat half that much, but he decided that 800 was a good round number, and he was going to attempt to quarter squat it. Long story short, knee ligaments did not agree with his assessment)
- landing unevenly from a jump, especially with straightened rather than bent legs (this is a big problem for folks like basketball and volleyball players)
- being in a situation where one part of the leg is held stationary while the other is moving (for example, stepping in a gopher hole while running: shin stays in place while the thigh keeps moving)
- impact to the knee (such as a hit from the side or front in football)
- squatting in a Smith machine which does not allow proper shifts in weight through the movement, and results in shear on knee and spine
In other words, knee injury usually results from varus or valgus force (twisting of the joint in either direction), inappropriate loading, or forcible shear across the joint.
It does not occur simply from taking the knee joint through a full range of motion, using correct technique, and using a weight which is appropriate to the abilities of the trainee.
Why are leg extensions hard on the knee joint?
To understand why this is, it is helpful to understand the concept of shear. Shear in this case just refers to a horizontal force on the joint.
Imagine two cans stacked on top of one another, and imagine that a piece of masking tape joins them. Then, imagine what happens if you hold the top can still while you push the bottom can sideways. Eventually that tape will snap.
This is a simplistic description of what happens to the knee joint in a leg extension.
- In a squat your feet are on the ground (hopefully), and the force of the load is transmitted downwards, along the length of the bones.
- In a leg extension machine, there is a pad against the front of your shin or ankle, and you press against it to move the weight. The foot swings upward in an arc. Thus, the pressure is coming across the shin bones, not along their length. This creates the problem in the knee joint as the shin is pressed backwards.
Leg extensions do have their place, usually in rehab. If the leg extension machine is used, it is wise to use a smaller range of motion, perhaps the top third of the movement (from slightly bent to fully straight leg), and light weight.
This is not to say that everyone can immediately leap into full squatting.
It is essential to learn to squat in a way that meets your individual needs, and I’ll discuss that in Part 3. It is common to have difficulty with a full range of motion in the beginning. If knee pain is felt during the squatting motion, there are a few possible reasons.
First, it is important to rule out existing pathology. Some people may indeed have knees that are so damaged that they are unable to squat, but this is rare (and these people are probably walking with a cane).
In particular, full squatting is contraindicated for someone with an acute posterior cruciate ligament (PCL) injury, but these types of injuries are uncommon and usually result from something like a car accident. Someone who has rehabilitated a PCL injury can attempt full squats with light loading, and see how it goes. With correct loading and technique, anterior cruciate ligaments (ACL) and medial cruciate ligament (MCL) injuries generally don’t present a problem. I know someone who is even missing an ACL on one knee, and has a reconstructed ACL on the other, and she squats quite happily.
Some people may have irritation in the joint due to things like patellofemoral syndrome or age-related degeneration, and the goal initially should be to squat in a pain-free range, while aiming to increase that range and strengthen the muscles around the joint.
Some people may experience pain due to poor technique, which includes allowing the knees to cave in or twisting during the ascent. In this case, the trainer should again establish probable cause and direct attention to remedial work (such as stretching and additional strengthening) in conjunction with improving pain-free range of motion and correct technique.
In Part 4 of this article, I suggest some stretches and assistance exercises to help you eliminate possible problems.
Do not do an exercise, no matter how great that exercise is, if it causes you pain. Find alternatives or modify the exercise. Full squats are great, and most folks can eventually do them, but nothing works for absolutely everyone.
myth #2: squats hurt your back.
Probably this myth grew from someone who leaped into squatting too quickly, loaded up too much weight, rounded the back during the movement, and guess what, had an owie.
In general, squats are excellent for strengthening the lower back and the rest of the torso musculature. Simply standing upright with a squat bar on the back is a good challenge for folks who are new!
In most people, the lower back will indeed be a weak link in the chain, but there are three simple solutions:
- First, squat light initially, progressing with weight only as you are able to handle it.
- Second, use good technique at all times, which includes neutral spine.
- Third, include some additional lower back strengthening work in your program.
Squatting may indeed be contraindicated for some people with particular types of spinal injuries, particularly folks in the acute phase of a herniated disk. While many people with disk herniations do continue to squat without pain (often with quite heavy loads), this is an area where it is important to figure out where your limits are.
One limit to squatting with a back injury may be that it is inappropriate to use axial loading (in other words, to squat with the bar on your back).
In this case, an excellent alternative is the Super Squats hip belt from Ironmind. It’s a nylon belt that sits around your hips with the weight hanging from it. Feels weird at first, but very comfortable. Certainly worth investigating if you love squatting and hate to give it up!
myth #3: squatting is hard to learn, and only natural athletes should do it.
Bollocks to that! I’ve taught everyone from octogenarians to teenagers to squat. Babies already know how to squat; we just forget how.
The squat is a very natural movement. Following some simple steps and cues, anyone can squat.
We may not all be able to full squat hundreds of pounds like some Olympic lifters, but everyone can perform the squatting motion and eventually improve their range of motion, balance, and technique. Check out my “Lurn to Squat Good – E-ZY!” article.
myth #4: squatting “bulks up” your legs and butt.
If you’ve been paying attention to anything on this site, you should know that this is crap and you should know why, so I won’t even waste time on it. If you don’t like the bulk on your ass, honey, try laying off the Twinkies, not the squats.
myth #5: machines are just as effective as free weight squats.
Give this little experiment a try. Let’s say you can leg press a certain amount, perhaps 200 lbs. Make sure your safety bars are set in the power cage, grab a spotter, and load up 1/4 of that amount on a squat bar.
Try a full squat.
I think you will find that leg press is to squats as dog poop is to Belgian truffles. Machines have their place, as I said, but a leg press isn’t a squat and there’s no sense pretending it is.
myth #6: squats require special equipment to perform, and you can’t do it by yourself.
All you need for a squat at first is your own body.
I generally suggest that beginners work up to a few sets of about 20 unweighted full range squats before attempting to add any weight. This helps build balance, flexibility, and good technique.
If you want some more fun, try going for higher rep sets of unweighted squats, such as 50 or 100 or even more (work up to this gradually instead of trying to do it right away… trust me). You can also try doing these unweighted squats explosively, with a rapid drive up from the bottom like a jump. A minute or so of this will really kick your butt, literally.
To add difficulty, you can hold a pair of dumbbells, wear a weighted knapsack, hug a sandbag or put it on one shoulder, put a barbell on your back, add reps or sets, or try them one-legged.
Most folks opt to use a barbell on their back for convenience, and they perform squats in a power cage. A power cage has pins or hooks to hold the bar, and safety bars to stop the bar below a certain point. So if you get stuck at the bottom, you just let go and dump the bar on to the safety bars. Sometimes it makes a crashy sound if the safety bars are exposed steel, but other than that, no harm no foul!
There’s no need to train to failure anyway, but it does happen, and in a power cage, it happens safely, if a bit embarrassingly. If you don’t have a power cage but you want to use a bar, try learning front squats, and have fun adding the clean to it!