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Are deep squats bad for your knees?


Are deep squats bad for your knees?


Squats are a common part of any exercise schedule. No matter how intense workout regimen you are following, squats should always be there.

In the early 1960s, Dr. Karl Klein of the University of Texas published a book titled ‘The knee in sports’.[1] According to the book and the studies carried out by Dr. Klein and his co-author Fred Allman, deep squats increased the load on the knee and exposed the knee to a greater risk of injury.

Another study done around 1993[2] concluded that squats below parallel (less than 90 degree of knee angle), the force on the knee increased drastically. This study also followed a similar methodology.

The conclusions drawn by both of these studies have propagated over the ages to become one of the most widely accepted myths in fitness circles. Yes, accepted myths!

In this article, I am going to revisit the study and try to assert why the conclusions of the study are not true.

deep squats harmful or beneficial


My love for Squats

I just love doing the squat. After 3 sets of free squats and an equal number of weighted squats, I can see a drastic change in my quadriceps muscles.

What actually is a squat? Each time you sit on a chair, you are squatting. Squat is nothing but bending your knees until you sit down, except while you are exercising, there is no chair and there are additional weights over your shoulder.

One reason why I love the squat is that they affect the entire lower body and the lower back. In fact, it also affects the core muscles including that of the chest and shoulders. The next day after I workout with squats, my legs feels much stronger, more muscular and it becomes really easier to climb stairs.

If done properly, squats can prove to be a really effective exercise. Even you should do squats at least twice a week.

Putting Klein’s study under the lens

After Klein’s study, the results have been replicated just once and have been contradicted in almost every study carried out on this topic[3][4]. Even after such a large scale contradiction, the myth that deep squats are bad for the knees refuses to die out.

Dr. Klein’s did a comparative study between 130 competitive weightlifters and about 360 college students. Competitive weightlifters formed the group that have previously done deep squats and the college students formed a group that had no experience with deep squats.

According to his study, the weightlifters had unstable ligaments around the knee and hence he concluded that deep squats are bad for the knees.

He studied his test subjects by covering the upper and lower legs with an aluminum gadget like a case. He then applied pressure around the knee and used a device similar to the blood pressure gauge to take his readings.

As I understood from various studies done later on[5], the entire study done by Dr. Klein was biased. His research methodology had the following shortfalls:

  • The methodology was highly subjective: The tester kept applying pressure on the knee of the subject till the subject started complaining about pain. This means, he never applied the same pressure on everyone.
  • Not randomized, not a blind trial: Dr. Klein used to classify each subject as a non-squatter or a squatter before applying the force. This way he built a prejudice around which he could adjust the findings he did from the test subject. While ideally this classification should have been done after the test was performed.

Honestly speaking, a researcher following the same testing methodology can actually get contradictory results if he decides to.

The advantages of deep squats

Squats basically target your quadriceps muscles, calves, hips, hamstrings and lower back. The effect on the core muscles is an added advantage.

As per studies[6][7], the major focus area of the squat till at angle of 80-90 degrees is the quadriceps muscle (thigh muscles). After you go below 90 degrees (deep squat), the focus area shifts to your behind (gluteus maximus or the hip region) and the hamstring muscles.

Doing deep squats ensures that the glutes and hamstrings receive their due attention. These studies also iterate that deep squats do not have any significant increase in effect on the quadriceps muscles. This however, also makes deep squats not very useful in case you only want to focus on your quadriceps muscles.

In such a case you should restrict yourself to parallel squats.

Just like a full circular motion of your arm impacts more muscles that a partial circular motion, deep squats also have the same impact on the lower half of the body.

The right way of doing deep squats

Before you start doing the squat on your own, read out the below procedure so that you know you are doing it right.

  1. Start with some warm up activity. Either do a one-spot slow jogging, jumping or stretching for about 5 minutes.
  2. Start with some free squats. Keep your feet about shoulder length apart, back straight and knees straightened.
  3. Stretch your arms so that they are parallel to the floor and join your hands.
  4. Now slowly bend your knees and hip in such a way that your knees do not go past your toes. Bend down till your reach a sitting position. You do not need to go deep with free squats as they act as a warm up exercise and do not have a significant impact on the gluteus.
  5. Repeat this motion for about 50-60 times divided in 3 sets.

Once you are done with free squats, you can start doing squats with additional weights.

Take a barbell without any additional weight. Hold the barbell above your head and slowly bring it just above your shoulder, behind your neck. Keep the bar there in a resting position such that your body is bearing the weight.

In case it hurts, you can put a wet towel behind your neck. Keep holding the bar with your hands, but do not use your shoulder force. You can also use light weight dumbbells instead of a bar. Now follow the same motion as you did with free squats.

Read: How To Do Barbell Squats ?

You can gradually increase the weight but make sure that you are always comfortable during the exercise.

Breathing is very important during squats. When you bend down, breathe in and when you stand up, breathe out. Breathing should be slow during the entire exercise as this way you would be able to the exercise easily.

So, ready for some deep squats?

More on Squats:


[1] Karl Kermit Klein, Fred L. Allman. The knee in sports. (Google Books). ^Back to Top^

[2] Wretenberg, P., Feng, Y., Lindberg, F. and Arboreilus, U. p. (1993), Joint moments of force and quadriceps muscle activity during squatting exercise. Scandinavian Journal of Medicine & Science in Sports, 3: 244–250. doi: 10.1111/j.1600-0838.1993.tb00389.x. ^Back to Top^

[3] Rippetoe M. Strong Enough: Thoughts from thirty years of barbell training. Pp. 66-69. The Aasgaard Company, Wichita Falls TX. 2007. ISBN: 978-0976805441. ^Back to Top^

[4] Robertson DG, Wilson JM, St Pierre TA. Lower extremity muscle functions during full squats. J Appl Biomech. 2008 Nov;24(4):333-9. PubMed PMID: 19075302. ^Back to Top^

[5] Starr B. The Strongest Shall Survive: Strength training for football. Pp 39-40. Fredericksburg, Va. ASIN: B000GK2BLU. ^Back to Top^

[6] Escamilla RF, Fleisig GS, Zheng N, Barrentine SW, Wilk KE, Andrews JR. Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises. Med Sci Sports Exerc. 1998 Apr;30(4):556-69. PubMed PMID: 9565938. ^Back to Top^

[7] Wilk KE, Escamilla RF, Fleisig GS, Barrentine SW, Andrews JR, Boyd ML. A comparison of tibiofemoral joint forces and electromyographic activity during open and closed kinetic chain exercises. Am J Sports Med. 1996 Jul-Aug;24(4):518-27. PubMed PMID: 8827313. ^Back to Top^

Last Updated: May 13, 2014

Next Scheduled Update: July 14, 2014

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