I was told at the gym i go to that when doing squats to never cross the invisible line w/ your knees that runs up from your toes. I was told this is bad and i should stick my butt out further. Is this true? Ive tryed it and dont seem to get anything out of this form? I was at a few websites looking and reading about squats but i havent seen anythng about this. Also how is it easyest to tell when you have come to a 90 degree angle w/ at your knees?