Let us clear up something for the start - squats are no more dangerous then sitting down to eat at the family table.  Or getting on the bathroom throne every morning, for that matter.  From a biomechanics point of view, these movements are almost exactly the same.  So inherently squatting is no more dangerous than a number of everyday activities, even if you do have hip, back or lower limb dysfunction like sacroiliac joint pain.  Then why do people hurt themselves squatting?

The biggest issue is using improper loads (i.e. too heavy a weight for the trainee), a constant axial load (i.e. the trainee never varies the bar placement on the back) and most importantly, a whole heap of  fitness industry myths about squat technique.  Correctly, a squat should be performed through a full range of motion at the knee with the trainee finishing in a deep squat (or ‘ass to grass’) position. Now I know you are going through the first stage of shock right now – especially if you have been a regular aerobic or pump class participant.

Coyne athlete & world champion Melissa Howard demonstrates correct squat technique

In the weightlifting community, this is the accepted way to squat and is commonplace throughout thousands of training halls worldwide.  However in the health and fitness industry where partial range squatting and restricting forward knee movement is gospel, this is viewed as pretty much a quick way to busted knees and a bad back.  There are three reasons behind this false gospel. 

One is that initially most people (at least in Western countries) do not posses the required flexibility and strength to perform the squat through a full range of motion.  Instead of developing this flexibility and strength (which is quite easy by the way if you know how), they simply carry on with the half squat.  Experts like Canadian strength coach Charles Poliquin actually consider all trainees that cannot assume this full squat position to be still in a rehabilitation phase.  Plus they should NOT squat until they are able reach the full squat position. 

The second reason is that the people developing the teaching content in the fitness industry (be they physiotherapists, medical doctors or personal trainers) have never been shown how to develop a full squat.  Or they have not had the required experience within the weight room, which can often be the case.

The last reason is the whole ‘do not let the knees travel past the toes, or it will hurt your knee’ myth.  Unfortunately there is no convincing scientific evidence that actually supports this in individuals performing any version of squatting¹⁸. Salem & Powers (2001) noted no difference between patellofemoral joint stress at squat depths of 70^o, 90^o  and 110^o19.  This was also conclusion of Comfort & Kasim²⁰ with their review on squat technique.  In fact, stopping at parallel and restricting forward knee movement may be the most dangerous of all.  According to research my good friend and Australian strength coach Tony Boutagy put me onto, the leading squat researcher in the world Rafeal Escamilla found that patellofemoral forces increased up until around 75^o of knee flexion and the forces ACTUALLY decreased as the squat depth increased²¹.  Plus it harms your back more when you do not let your knees go past your toes.  Andrew Fry and his colleagues demonstrated this when they found that restricting forward knee movement while squatting actually increased low back joint loading ten times as much as when forward knee movement was allowed²². 

The other thing that happens if you do not perform a full squatting range of motion (i.e. below parallel) is that you do not get sufficient recruitment of the gluteus maximus, hamstrings and vastus medilias muscles²³.  Why is this important?  Any physiotherapist will tell you that a strong gluteus maximus is one of the most important factors for preventing chronic back pain.  At the point of their attachment to the spinal erector muscles, strong hamstrings also help reinforce the back against injury.  At the other end where attach below the knee, they provide the best protection against dangerous medio-lateral rotation of the knee which cause ACL, MCL, LCL and meniscus tears.  Lastly the vastus medialis muscle is crucial for knee health as it prevents what physical therapists call lateral deviation of the patella, which causes all sorts of problems.  Especially in athletes that are required to do a lot of sharp changes of direction and jumping e.g. track athletes, tennis & basketball players.

Unfortunately pump classes will not improve your knee health.  In fact long term, it will probably place both your knees and spine more at risk.

The last thing that should be realized is that if full squats were bad, then weightlifters would have an enormous amount of knee injuries.  Especially considering that almost all their lifting movements are performed in a ballistic fashion (this is actually another myth but it will have to wait…).  Epidemiological studies show us that statistically serious knee injuries are actually rarer in weightlifting than other sports^24/25.  Not only this but this next point is bigger than Oprah was in the 1990s (no pun intended).  As a population, they actually have the best knee stability of all athletes and non athletes²⁶!

Weightlifters have the best knee stability out of any athletes.  The predominant reason is that they full squat.

So as you can see, it is actually far safer for you to full squat with your knees traveling past your toes. Just make sure you get a qualified strength coach or Olympic weightlifting coach to guide you through the technique.  They should be able to address any flexibility or strength limitations that would prevent you performing a full squat safely.  Let me know what you think! 

References

1. Escamila RF, Zheng N, Macleod TD, Edwards WB, Imamura R, Hreljac A, Fleisig GS, Wilk KE, Moorman CT, Andrews JR. Patellofemoral joint force and stress during the wall squat and one-leg squat. Med Sci Sports Exerc. 2009;41(4):879-888.

2. Salem GL, Powers CM. Patellofemoral Joint Kinetics During Squatting in Collegiate Women Athletes. Clinical Biomech. 2001;16:424-430.

3. Comfort P, Kasim P. Optimizing squat technique. J Strength Cond Res 2007; 29(6):10-13

4. Escamilla, R. F., Fleisig, G. S. et al. (1998). Biomechanics of the knee during closed kinetic chain and open kinetic chain exercises. Medicine & Science in Sports Exercise, 30(4), 556-69.

5. Fry AC, Smith JC, Shilling BK. Effect of knee position on hip and knee torques the barbell squat. J Strength Cond Res. 2003;17(4): 629-633.

6. Caterisano, A., et al. The effect of back squat depth on the EMG activity of 4 superficial hip and thigh muscles. Journal of Strength and Conditioning Research 16(3):428-432, 2002.

7. DeHaven K.E., Lintner D.M. Athletic injuries: comparison by age, sport, and gender. American Journal of Sports Medicine. 1986 May–Jun;14(3):218–224

8. Calhoon, G., Fry, A. Injury Rates and Profiles of Elite Competitive Weightlifters J Athl Train. 1999 Jul–Sep; 34(3): 232–238.

9. Chandler, T. J., Wilson, G.D., Stone, M.H. The effect of the squat exercise on knee stability. Med. Sci. Sports Exerc, Vol. 21, No. 3, pp. 299-303, 1989