Are Deep Squats Safe: How Low Can You Go!

Posted: Monday, 14 May 2012 by Strength&Nutrition24/7 in Labels: , ,

Are deep squats safe
Written By Vincent St. Pierre

When you think weight training, power lifting, or hardcore meat heads, someone squatting with hundreds of pounds on their back probably comes to mind.

Squats in there variety of styles (back, front, dumbbell, goblet, jump, split) are commonly used in every gym as a viable form of training. I myself view this as one of the big 6 exercises (great idea for a future post). The squat is used from your athletic to your everyday meat head, to the general public and the elderly to build strength, balance, functionality, hypertrophy, and bone density. However, in the training community there is a great deal of debate on how low you should go.

This topic is so controversial due to people wondering if performing a deep squat would increase the risk on the knee joint. This debate has been traced back all the way to 1961 when Klein performed a study looking at squatting and high knee flexion angles. They had determined that there was an increase in laxity in the collateral and ACL ligaments in Olympic weight lifters who regularly perform deep squats compared to a control group. Klein believed that this increase in laxity could result in an increase in instability of the knee.

 This lead Klein to believe that when performing squats one should not go below parallel (please don’t make any conclusions yet this is one study from 1961 with many assumptions made).  This study caused a massive shockwave throughout the USA. First the US military quickly eliminated squat jumps from their training regimen. Next the New York school board forbade the practice of full squats in gym class. Even beyond this, the American Medical Association adopted the position that going beyond parallel would create a severe risk of soft tissue damage of the knee joint.

It is pretty amazing what a single study could do to the practice of squats. Great deals of assumptions were made in this conclusion. On top of that, he had not considered the tension of the muscles in the creation of stability.

Interestingly, current studies have disproved his assumptions and have found no correlation between deep squats and injury risk. In fact, Meyers, who attempted to recreate the experiment using the same testing material was unable to find a difference in ligament stability from deep and non deep squats.
A study by chandlers 1989 actually found the opposite of Klein. He found that male power lifters and weightlifters had a significant increase in joint capsule tightness and on top of that at 90 degree knee bend they were found to have a significantly tighter on the quadriceps anterior drawer test in comparison to the control group.

When we look at the research as a whole they far from agree that deep squats can increase the likely hood of knee injury.

In reality, studies have demonstrated that the risk of injury to the knee is significantly lower in the deepest part of the squat. The ACL and PCL forces have been demonstrated to diminish in high flexion angles. The forces being placed on the ACL peak between 15 and 30 degrees of flexion, they decrease rapidly until 60 degrees then level off. The greatest amount of force being placed on the PCL are found at 90 degrees (also known as parallel, meaning this is the time of greatest risk for your PCL). The forces rapidly decrease as you pass 90 degrees. Once you have passed 120 degrees, the forces on your PCL are minimal.

As you can see from the previous studies outlined, deep squats may act as a protective effect on the ligamentous structures. Part of this is due to the fact that compression of the posterior soft tissue between the distal femur and proximal tibia. In English, this means that it constrains the knee joint, essentially it allows for less movement in the tibial translation and thus allows for an enhanced load tolerance.

Deep squatting may only be a problem for those who already have pre existing knee problems (chondomalacia, osteoarthritis, osteochondritis) or if someone has had postsurgical interventions (meniscectomy, PCL, reconstruction) would make deep squatting possibly counter indicated.
Research does not support the belief of stopping at parallel. Rather, it supports that deep squats may be essential as preventative measure for knee injury. On top of this, deep squatting produces a greater amount of muscle activation and development, improved functional ability, and athletic performance. There is nearly no reason to avoid deep squats unless a medical contraindication exists.

Further consideration IMPORTANT

  • I am 100% for using squats. They are so vital in your training but please also consider the following:
  • I would argue that at 90 degrees (parallel to the floor) is the time of greatest risk to your knee joint. Your hamstrings play a significant role in maintaining knee stability and are basically taken out of the equation at 90 degrees.
  • In my opinion, the risk with deep squatting is not the knee joint but rather the individual’s flexibility. If one is not flexible enough, the following issues may occur at what we call tail tuck or rounded back (this significantly increases your risk of herniating a disk). 
  • Rounded back is something you commonly see when people don’t push their chest up and also have tail tuck. 
As you can see in this video, the person is so unflexible he can’t even reach 90 degrees before he begins to tail tuck.

The purpose of this post is not to teach you how to squat but here is a video of a squat performed properly. This is not perfect and still has a very slight tail tuck.


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  1. Unknown says:

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  1. Anonymous says:

    Thank you for sharing this. Since I'm a beginner in our team, I'm looking for a squat exercise because our coach advise us to do more squat workouts with the pro bar to develop our flexibility.