How often are you at the gym and hear someone coaching the squat, spouting coaching cues like 'sit back as far as you can', 'keep a vertical shin', don’t let your knees pass the toes etc. all promoting the common misconception that if your knees track over your toes during a loaded squat they will spontaneously combust.
It's almost funny how often this advice gets given out' if it wasn’t so sad.
I say sad because the ankles should have the mobility to allow the tibia (shin bone in layman's terms) to move beyond the toes. It wants to pass over the toes. This movement is required to walk, run and jump, safely and efficiently, and is seen during simple movements that occur in everyday life, such as picking something off the floor or walking up a flight of stairs.
Now obviously squatting under load is slightly different to jogging or walking up stairs, but despite that, that range of motion at the knee is essential to safely perform a loaded squat.
A study published by the NSCA (Fry, 2003) looked at joint kinematics during a normal barbell back squat, in which the knees passed over the toes, and a restricted barbell back squat, in which the knees did not pass over the toes.
They found that during the restricted back squat there was significantly greater anterior lean of the trunk, which resulted in a 22% decrease in knee torque compared the normal back squat, but a 1070% (that is not a typo!) increase in hip torque.
By reducing the load on the knees, via a vertical shin whilst squatting, the load is increased through the lower back and hips x10. This increased load through the lower back is not ideal, and can even increase risk of injury of the lower back.
Not to mention that the squat is a knee dominant exercise! And by sitting back with a vertical shin we reduce the load placed on the quads, which, from a hypertrophy perspective, is what we are trying to load when squatting in the first place.
Now i don't want to get into an argument with anyone about low bar vs high bar squatting, and i am well aware that particularly from a powerlifting perspective, using a more hip dominant squat (think sitting back and down) can allow them to squat more weight, which for their particular sport, is the goal.
All i wanted to do was highlight the fact that there is no issue with knees tracking over the toes during a squat (assuming they do not have any knee issues to begin with), and the stigma surrounding it is nonsense.