With some recent research I have conducted and carefully examining the work of Dr. Stuart McGill, I feel it is my obligation to share and discuss some information I came across.
I am currently working a physiotherapy student and am an assistant a a clinic at the moment. I have been a highly active individual who has lifted weights and has played a wide variety of sports.
Stuart McGill is a Professor at the University of Waterloo and is the foremost expert in biomechanics in dealing with back health. What I found from his research was rather interesting.
There is the notion of the "Neutral Spine". This refers to the fact that our 24 interlocking "blocks" are properly aligned. If it is not properly aligned we are going to get muscle imbalances and other complications. Muscle imbalances are primarily caused by shortening of certain muscles while others lengthens. One thing that is extremely devastating to our spine health is SPINE FLEXION. During flexion we are putting massive amounts of force (usually shearing) on our disks and vertebrae.
Now, here is where we can discuss Squat and Deadlifts. Many people have gained amazing results from these two highly demanding exercises. However, there has been some controversy, as they have been associated with the most injuries in the fitness profession.
The reason being is that many people simply do not have the motor patterns necessary to preform these exercises properly. It has nothing to do with will power or desire to be stronger than others, it is simply because these exercises cause them pain. If continued, serious injury can become very real. Now the problem lies in spine flexion. Everyone knows you must not round the back, and that a straight back in the most important. Although a straight back is part of the proper technique, you must make sure to overly hinge with the hips and make sure the lower back is not rounding (especially seen in most individuals past parallel).
According to Dr. McGill, the majority of people will have a point of break where they come into spine flexion sometime throughout a squat. It is during this point of break where injuries will occur. In order to help train and prevent this, one must forget the spine extension notion, and concentrate on firing and pinching with the PSOAS. This PINCH causes a slight realignment and will aid in preventing the flexion.
This has me concerned with the notion of Squatting ATG. It is something that only a hand full of people can achieve without spine flexion. However, it is preached as though this is the ONLY way to perform such an exercise. Unfortunately , many individuals heath the advice, but end up seriously injuring their backs on such exercises due to the lack of knowledge.
I believe that anyone (I have tried this myself) who squats or deadlifts, should attempt a zero weight bearing squat in the mirror and simply look for any moment of spine flexion. It can be very slight. If you do not see the slightest "BREAK" in posture you may be ok. However, for myself (Most I've squatted was 345lbs) There is a breaking point just after parallel. I was unaware of this and believed I had excellent form, and was even told by trainers of such. This was NOT the case.
Whether you are performing deadlift, Squats, or the controversial ATG squats, make sure to examine carefully for even the slightest spine flexion as this is what seriously injures individuals and can cause a lifetime of pain and troubles.