Myth Debunking Monday: Knees over toes blows

I've kind of touched on this topic before but I plan on diving head first in on this specifically. How often in the gym [or in highschool] have you  been told, "don't let your knees come over your toes," on things like squats and lunges? The logic behind this is that it puts too much pressure on the knee cavity and can lead to stress injuries.

The myth comes from a deep squat in which improper hip rotation producing extra force on the knee and causing strains and possible damage.  A proper squat has the hips abducting [external rotation] and forcing the knees out. Consider how we walk, run, or even climb stairs. To do any of these things our knee protrudes past our toes, so why would a coach take this away from working out. Its like a swimming coach training his athlete by keeping them out of the water [that's a leap but you get the point].

Andrew @ Texas State meet squatting with knees over toes and hips abducted. Team Endunamoo

A study was conducted to examine joint kinetics during back squats under two conditions. The first condition placed a board in front of the participants' shins, which restricted forwards displacement of the knee. In the second condition, movement wasn't restricted at all. They squatted normally and the knees were allowed to pass the toes.

The researchers found that restricting the forward excursion of the knees during the squat [preventing the knees from going over the toes] increased the anterior lean of the trunk and promoted an internal angle at the knees and ankles [adduction].

The knee received roughly 27% decrease in torque, however the hip recieved a 1070% increase in torque.
[Fry AC, Smith JC, Schilling BK. Effect of knee position on hip and knee torques during the barbell squat. J Strength Cond Res. 2003 Nov;17(4):629-33.]

Below is the modeled front squat, high bar and low bar squat. In each instance the toes are called to go over the knees. This reduces the torque on the hip so that they have the ability to create a stretch reflex in the adductors and give you the bounce in the end. Going knees over toes keeps the hip healthy and knees strong.