What i meant to say is: Is there a correlation between the angles at which the forces increase and the angles at which the hams/calf lever comes into play? This is a question for anyone out there, not necessarily for just paprika.
Maybe it seems like I am making too big a deal out of this lever thing, but it would be helpful to know because you could just look at someone’s legs and tell them what angles they should be bending to.
I apologize to Epimetheus if my earlier replies seemed pompous.
I have never written a paper on squatting. The Adobe paper was not mine.
I do believe there is a correlation involving the hams/calf lever arm, like you suggest. I suspect it is not the limiting factor in picking the maximum angle of knee flexion, though. Depending how you measure the knee angle, this lever arm might be approximately proportional to the (positive number) difference between the sine and cosine of the knee flexion angle. But a difference of, say, ten degrees between 110 and 120 would probably be smaller than other changes on the knee due to the new direction of muscle forces because of the change in angle, forces on the meniscus and ligaments, etc.