Are full squats bad for the knees?
“Anyone who knows anything about lifting” would know that Arnold, Dave Draper and everyone else who learned to train before the mid 1960’s regularly performed full squats. Your friends essentially believe an urban legend that has some basis in terrible research from the University of Texas by Dr. Karl Klein who published “The deep squat exercise as utilized in weight training for athletes and its effects on the ligaments of the knee” in 1961. He compared those who performed full squats (all of the lifters) to people who did not lift weights and found the weightlifters to have more laxity in the ligaments of the knee. He then seemingly arbitrarily recommended limiting the depth of squats to parallel. Meyers tried to reproduce his results in 1971 by testing the laxity of medial collateral ligament and found both types of squats
Squats below parallel can be bad for your knees if you use bad form. But if you read Starting Strength by Rippetoe and Kilgore as other people have mentioned, you will learn good form and you won’t have any problems. The basic idea is that you take a wide stance and point your feet out at an angle, so that as you squat below parallel, your groin muscles support you and store elastic energy. Then as you come up, your groin muscles release that elastic energy and you bounce up out of the squat. But you should really read the book to get a full explanation. Also, you might want to check out the Starting Strength wiki.
I have grown tired of debating the formal education of a handful of the advocates of full squatting, and the cherry picking of studies to illustrate concepts that are common knowledge in discussions of squatting, such as knee forces increase with squat depth and lack of ankle flexibility causes excess stress on the hips/low back. Limiting range of motion in injured individuals is common practice, squatting is no exception, but the goal is always to restore full range of motion when possible. Using ACL reconstruction as an example, a single leg full squat is considered the gold standard of rehab by many therapists. There is an overwhelming consensus among leading strength coaches and researchers to the merits of full squatting vs partial range of motion squatting. No one considers full squats dangerous to the healthy knee, whether you are talking about elite powerlifting champions, such as Dr. Mario DiPasquae, Dr. Fred Hatfield, Ed Coan and Louie Simmons or researchers such as Dr. Paavo
