Optimal Knee Position in the bottom of the Squat

[Tom Narvaez]

Hey Rip, I have some questions about knee position in the bottom of the squat that I haven't been able to reason through on my own. I figured I'd see what your thoughts were.

In BBT3, reference is made to the fact that the knees should be just past the toes in a properly performed squat. In a front squat, they'll necessarily be driven forward to maintain the upright back angle which is required to keep the bar from falling off the shoulders. In a low bar back squat, a person isn't really in danger of losing the bar.

Unweighted, or at light weights, the body represents enough of the system's mass that some degree of knee travel is necessary to keep the CoM over the mid-foot. However, if the bar is heavy enough, it essentially represents the system's CoM itself. Theoretically, this could allow for nearly infinite permutations in the bottom position. It would just depend on exactly what the degree of forward knee travel was. The system's CoM could remain over mid-foot regardless.

For example, theoretically, this could allow the lifter to perform a squat with most, or nearly all, of his mass behind the bar (as in a heavy pull from the floor). This has some interesting mechanical considerations. For one, the lever arm as seen between the bar and the knee might be completely eliminated. Of course, the lever arm as seen between the bar and the hips increases as a result but that isnt necessarily a terrible thing. This might also eliminate the lever arm between the knee and the ankle.

This all said, I have never seen a lifter elect such a position voluntarily. I have seen the exact opposite quite frequently, though (too much knee travel for a LBBS). Obviously, in the BBT3 model, we want an appropriate amount of knee travel because we want to involve the mass of the quads in order to get them strong. But we are not shooting for a particular position besides the general recommendation of put the knees just past the toes. Yet, we know this varies due to anthropometry. For me, this begs the question, what is the optimal position for a given individual? And how do we know?

The best answer I've come up with is whichever knee position best facilitates a strong, vertical hip drive. That seems unsatisfactory, though.

I'd appreciate any input. Thanks in advance.

[Mark Rippetoe]

I don't know that it's possible to precisely quantify perfect knee position in a squat like it is in a deadlift, since knees are not constrained by bar path in a squat like they are in a pull. As you have correctly observed,

1. Anthropometry dictates many aspects of the diagnostic angle geometry
2. We don't want to completely eliminate any one moment arm, since we are using them all to move the load
3. The correct knee position -- the one that maximizes muscle mass involvement in all the moment arms -- is learned, and this is what makes the squat a technically complicated movement.

This is why the squat gets so much time devoted to it -- at the seminar, in the gym, and on internet discussion boards.

[David Kirkham]

This board never ceases to amaze me with people who really think deeply about things, all in an effort to improve themselves and those around them. Shingo said, "We must ask why five times." I really enjoy the conversations here. Rip, you should be proud of the community you have created.