Squats are Bad for your Knees?

EVERYONE seemingly has a strong opinion on squats.

"Squats are bad for your knees!" scream "squat haters".

"ARE YOU KIDDING ME? Squats are the best exercise EVER....

SQUAT OR DIE! End of discussion!" squat-o-philes (aka "squat lovers") counter.

Are the squat haters correct, or is their opinion based on myth and misinformation?

Do the squat lovers have the facts on their side, or are they ignoring real health risks of the movement?

Maybe the answer is somewhere in the middle?

This post will analyze both sides of the squat debate.  I relied on a pretty thorough 2010 review by Schoenfeld in creating this post.

We are limiting our discussion to healthy knees unless clearly specified otherwise.

Squatting Benefits

The squat simulates some basic daily activities such as rising from a chair. Certainly, many seniors have great difficulty rising from a chair. A bit of squatting would likely improve their daily functioning. Even squatting's detractors would probably concede this point.

Most athletic strength and conditioning program utilize squats.  Athletes from such varied sports as football and distance running have seen performance improvements from squatting. Squats can improve athletic performance in numerous ways including increasing strength and power.  

Squats also provide an aesthetic benefit.  There are few, if any, exercises which better improve lower-body physical shape.  Squats can increase Resting Energy Expenditure (increased daily caloric burn) as part of an overall resistance training program. In other words, squats can help shape lower-body muscle AND keep you lean. 

If we are engaging in a risk-benefit analysis, we can logically conclude squatting benefits nearly all populations. The "benefit" side of the analysis comes down strongly for the squat lovers.

POINT: SQUAT LOVERS

Efficient Exercise

Another point squat haters will have to concede is the massive efficiency of the exercise. Approximately 200 muscles are utilized during squats (Solomonow 1987).  Most of the lower body is utilized as well as abdominal and lower back stabilizing muscles.  The squat's efficiency makes it a great choice for overall strength and caloric expenditure.

POINT: SQUAT LOVERS

Yeah, but are they safe?

The squat potentially provides great benefit. Now we must consider whether squats are safe.

Not all squats are created equal.  I have seen poor squatting form in every gym I have ever been in. The squat, when done incorrectly, can be bad for the knees and many other parts of the body.  

How can the average person, who does not employ a knowledgeable exercise professional, know correct form?  

Although correct squatting form potentially can be found on the Internet, the exercise consumer does not always know what is correct form. There might be a few ;-) incorrect advice pieces on the 'net. Exercise consumers will iikely encounter some challenges finding reliable squatting direction.

My best advice is to hire someone who knows how to squat correctly and provide you personal feedback (a Certified Strength and Conditioning Specialist (NSCA) is probably your best bet). This costs money, of course. Since many people routinely perform squats incorrectly and probably unsafely without seeking appropriate guidance from an exercise professional, I give this point to the squat haters. 

POINT: SQUAT HATERS 

Ankle and Calf

Various ankle and calf-related problems (weakness and immobility are two) can lead to a variety of squat problems (Schoenfeld 2010).  

Knee

Now we move to the knee-often the center of squatting controversy.  

The knee is a complex joint with various ligaments, tendons and muscles all impacting the knee stress levels.  

And the "stress" sustained is also complex with a variety of stresses (compression, shear and muscular) coming into play.  

Knee Tendons

One important knee stress is tibiofemoral compression.  

The highest recorded TF compression levels were found with powerlifters squatting 2.5 times body weight.  If you are a 180 lb. man, that would require you squatting 450 lbs.  That is well beyond what most people squat during a training session.

Even under this extreme stress which most people will get nowhere near during exercise sessions, stress at the two primary knee tendons ( patellar and quadriceps) was below maximal sustainable stress (Schoenfeld 2010).

Knee Ligaments

The two primary ligaments stressed during a squat, the ACL and PCL, likely never approach the level of stress necessary to cause injury.  In fact, the highest ever recorded levels of PCL stress were approximately 50% of maximal stress capacity-nowhere near stressful enough to produce injury.  

Interestingly, ACL and PCL stress apparently decrease in deeper squats contrary to popular opinion (Li 2005).  The highest recorded PCL stress is approximately 50% of a healthy, young person's PCL maximal strength (Stoppani, 2006). It would appear PCL squatting stress does not threaten healthy knees.    

It should also be noted squat and squat variations are utilized in numerous physical therapy clinics to rehabilitate injured knees.  Just as in sports-related resistance training, physical therapy clinics utilize the "SAID" principle-Specific Adaptation to Imposed Demand.  SAID means the body gets stronger when exposed to a steadily increasing, APPROPRIATE level of stress.

Knee ligaments respond to appropriate resistance training the same way muscles do: the ligaments get stronger.  APPROPRIATE level resistance training increases the strength of the tendons thereby decreasing injury risk.

Certainly, squats must provide some knee health benefit if squats help rehab injured knees. This is a tough one for the squat haters to explain.  If the most compromised knees are not only not injured by squatting but actually rehabilitated, how can squatting be "bad for the knees"?

I can hear the squat lovers now: "TRUMP CARD!"

"Ha-ha...I always knew squat haters were loco, Fred!" 

POINT: SQUAT LOVERS

Risky areas

Not so fast, squat lovers....

We still have to consider the menisci, articular cartilage and two "wild cards"-the lumbar spine and the shoulder.

Menisci and articular cartilage appear to be at the greatest risk from squatting (Schoenfeld 2010). Unfortunately, there is little or no research available to even estimate maximal safe load in these area.  If pre-existing injury exists, appropriate caution and care must be taken with squats.  

The obvious problem here becomes the subjective nature of these guidelines.

What is appropriate?

What is the risk of overestimating "appropriate" levels of stress?  

And how can an average person determine these answers?

These are tough questions to answer, but it is clear those with pre-existing menisci or cartilage conditions should err on the side of caution. Perhaps they need to be avoided completely until complete rehabilitation occurs.

Low Back 

The all-important lumbar spine must be considered.  Similarly to menisci and articular cartilage, it is impossible to look into the lumbar spine and determine maximal individual stress capacity.

Here are a few thoughts to consider:

A 180 lb. man squatting from .8-1.6 times body weight (144 lbs,-288 lbs) may experience L3-L4 compressive forces 6-10 times body weight (Cappozzo 1985).  The heavier the weight lifted, the greater the spinal compressive force.  One variable difficult to quantify is lower back and abdominal musculature's ability to lessen some of this stress.  

Someone (such as a powerlifter) who lifts heavier weights will have extremely strong supporting musculature therefore allowing them to sustain seemingly impossible external loads.

Again, there is no clear or objective standard to determine how much this supporting musculature reduces compressive force at L3-L4.   But stronger muscles can reduce the amount of compressive force the lumbar spine sustains from squatting (Schoenfeld 2010).

Again, the subjective, speculative nature of how muscular strength modifies lumbar spine compression makes it difficult to provide effective guidance. However, those with pre-existing low back injuries should exercise caution and proceed cautiously if squats are utilized.  

Excessive bending of the spine can greatly increase spinal stress.  Squatters should aim for a fairly upright torso position while squatting.  

From experience, someone can squat much heavier weight with a bending torso during the squat and this might even be a "natural" movement pattern.  

Watch someone squat a very heavy weight (a powerlifter, for example) and you will generally see the torso moving forward pretty dramatically-greatly increasing the risk of developing a low back problem. However, this forward torso position is certainly riskier to the low back.

Young athletes who compete in impact sports such as football are a particularly high risk category for low back injuries and special precautions should be taken with them.  Many young athletes develop spondylosis or "spondy" from the impact of their sport.  This is a very serious low-back condition which can be further complicated by squatting.  If young athletes experience consistent low back pain, see a doctor immediately.

Since it is difficult to determine how much stress each person can handle at L3-L4 and the low back stress of squatting can be high, I am scoring this one for the squat haters.

Shoulders

The shoulders are one unexpected area where back squats can be problematic.  Due to the vulnerable shoulder position during a squat (externally rotated and abducted), heavy back squats may increase shoulder injury risk.  Those with past shoulder injuries or those high-risk athletes (football quarterbacks, baseball pitchers, etc.) must consider this risk when deciding whether to back squat.

Due to the number of high risk areas and the general absence of awareness of these risks, the argument can be made that back squats may be excessively risky for a certain percentage of the resistance training population.  It should be noted these are usually previously injured populations.

POINT: SQUAT HATERS

Here are a couple of "squatting pictures" I pulled from an online photo site:

This is a pretty good shoulders over hips position although once some weight is added, it becomes harder to maintain the position.  The foot position is good-shoulder-width or slightly wider. Knees are pointing straight ahead or even slightly out which is good.  

The only minor negative in this position is the hips should be back a bit more. I prefer a deeper hip position.  The "hips back" position has been described as "sitting in a hole".

She should look straight ahead-even a little downward glance can throw off posture.

Heels should be firmly on the ground. 

When squatting with weight, the hands would obviously be holding a bar or dumbbells.

Ideally, I would have her shoulders a little more over her hips although a light weight and strong low back musculature may lessen the risk here.

Note no excessive  spinal curve which is good.

Knees are pretty good-avoid "knock knees" and point knees straight ahead or slightly outward-never in towards each other.

Heels are firmly on the ground.

You will also generally want a wider foot position-shoulder-width or slightly wider.

She should look straight ahead and not downward. 

Squatting Alternatives

One option some coaches are moving towards is the "front squat." In the front squat, the weight is held in front of the body rather than behind the head.  The front squat is one way to minimizethe high L3-L4 stress of a back squat while still maintaining squatting's numerous benefits.

Conclusion

There you have it.  Hopefully, I have been able to contribute some objective evidence to the squatting debate which is often purely emotional or anecdotal.

Squatting offers incredible benefits to nearly every population.   The evidence does not support the claim that squatting is "bad for healthy knees" assuming proper form is utilized.

When done correctly and at an appropriate weight, squatting probably increases knee health and decreases injury risk.

Those with pre-existing menisci, cartilage, shoulder and low back problems should exercise particular caution, and the front squat is always a great alternative to the back squat.

Like most exercise science questions, the question of "whether squats are safe?" is largely an individual one. Find someone who understands the relevant issues to instruct and advise you.

References 

Cappozzo, A, Felici, F, Figura, F, and Gazzani, F. Lumbar spine loading during half-squat exercises. Med Sci Sports Exerc 17: 613–620, 1985.

Li, G, DeFrate, LE, Rubash, HE, and Gill, TJ. In vivo kinematics of the ACL during weight bearing knee flexion. J Orthop Res 23: 340– 344, 2005.

 

Schoenfeld, BJ. Squatting kinematics and kinetics and their application to exercise performance. J Strength Cond Res 24(x): 000-000, 2010 

Solomonow, M, Baratta, R, Zhou, BH, Shoji, H, Bose, W, Beck, C, and D’Ambrosia, R. The synergistic action of the anterior cruciate ligament and thigh muscles in maintaining joint stability. Am J Sports Med 15: 207–213, 1987.

 

Stoppani, J. Encyclopedia of Muscle and Strength. Champaign, IL: Human Kinetics Publishers, 2006. pp. 151.

 

 

 

 

 

 

 

Posted Jun 28, 2010 by .
This entry is filed under Los Angeles resistance training, Los Angeles exercise expert, Los Angeles weight-lifting, squatting bad for knees, and squatting bad for back.