Various weightlifting and exercise resources either claim that ATG squats (a**-to-ground, i.e. as low as you can) are perfectly fine or claim they will destroy your knees in two sessions.
I was wondering if anyone has any insight as to what is going on here. Will a properly performed (weighted) squat that brings legs below parallel to the ground have any greater negative impact on the knees or other joints compared to parallel squats?
Lets assume for a moment we aren't talking about competitive weightlifting weights, so with squat weight <1.5x your body mass.
Personally I side with the "it won't do anything wrong" side, considering that 1. With bar weight at approxmately your body mass you could exchange the bar with squating on one leg, i.e. this is strain your body is "designed" to be able to withstand. 2. If you assume that there is the possibility of excess joint strain, you would be seeing epidemic levels of knee injuries among competitive weightlifters, who routinely go below parallel in the clean&jerk, with much greater weight, and while weightlifters can get various joint injuries, I haven't seen anything demonstrating that injuries are more biased towards the knee.