hey star61 when you do box squats do you try and keep your shins perpendicular to the floor? becuase i find it very ackward to do it thatway… plus its alot harder to move the weight up that way…
Funny you should ask. I just read a fairly recent article by Lou Simmons which mentions shin angle.
https://www.elitefts.com/documents/box_squatting.htm
In it he says…
"It is generally accepted that you should keep your shins perpendicular to the floor when squatting. With box squatting, you can go past this point (that is, an imaginary line drawn from your ankle to your knee will point toward your body), which places all the stress on the major squatting muscles- hips, glutes, lower back, and hamstrings. "
I actually think he is saying that they sit back so far that the knees are not only not over the toes, they are behind the heels. I could be mistaken, his writing style leaves a lot to be desired. Although we do try to sit back on the box (or bench) we try not to rock. I don't see how you could keep your knees behind your ankle unless you rocked forward off the bottom, which we don't do.
We do try to stay as perpendicular as possible, but none of us actually stay perfectly perpendicular. As far as which muscles you hit, it also depends on depth of squat and width of stance.