We’ve heard it time and time again “Don’t squat! It’s bad for your knees”. But where did this myth come from? Where did it start? Why has this become an acceptable statement in gyms the world over?
This training myth started in 1961 when Dr. Karl Klein looked to compare ligamentous knee laxity by measuring medial/lateral deviation of the knee (valgus/varus) between two groups (Klein, 1961). The test group was post-competition lifters who had just performed the full squat, and the control group was untrained members of the general population. Using a modified goniometer coupled with the manipulative force of the tester, Klein saw that the athletes showed more mobility through the collateral ligaments of the knee than those subjects in the control group. From this he stated that deep squatting causes knee laxity, knee laxity coincides with injury, ergo squatting causes knee injury.
When we delve further into the study there are numerous biases and generalizations that need to be considered before coming to any sort of conclusion.
1) The control group was not a control at all; if the control group squatted before the measurement was taking then the measurements would serve as an applicable comparison. That way you could adequately analyze the acute effect of squatting as it relates to ligament laxity.
2) The force applied was not standardized; it was to the discretion of the tester of how much force was applied to the subject’s knee. This instrumentation bias greatly devalues the efficacy of the study.
3) The study was contingent on the readings of a self-developed measuring device, not that there was a gold standard for measuring co-lateral ligamentous knee laxity at that time, but it still should be considered when examining the validity of the study.
4) The benefits of strengthening the muscles acting on the knee joint were not taken into consideration. The squat is a compound exercise that strengthens the flexors and extensors of the knee. The study merely looked at the acute effects of the movement did not consider long term benefits of exercise.
It’s been over 50 years since this first stone was cast, and the effects of this research article still ripples through mainstream training paradigms.
Going forward I want you to consider this article when examining research. In my first article “What we Can Learn From Research” I said that you could find research to prove just about anything you want, but this takes it a step further; this research article proves that you can interpret research to prove anything you want. So you need to approach these superlative, definite statements with caution and criticism, evaluate the methods and draw your own conclusions.