Why do we shim in the case of a femoral length discrepancy? (I apologise)

[Pericles]

Why do we shim the shorter leg in the case of a femur discrepancy? If we stagger the stance by the same length as the discrepancy, without shimming, wont the hips be even at the top and bottom of the squat? What am I missing?

I am a noob and a moron, obviously. I assume this is a stupid question but I couldn't find or figure out the answer.

If anyone with knowledge could help me out, that would be much appreciated.

FYI I'm doing it just like it says to do in the article, works great!

[Szymon]

Staggered stance rotate your hips and rotated hips do not provide symetrical base for your spine. That is the way I see it.

[Pericles]

First up, thanks for replying I do appreciate it.. Surely a staggered stance (when staggered the same distance as the discrepancy) would not result in any rotation? Basic maths no? Besides, a staggered stance is called for in the article.

I’m just confused about the reason for the shim.. Wouldn’t shimming AND staggering the stance result in uneven hips?

I’ve been racking my brains, can’t for the life of me think of the reason. Dare I even suggest this could be a mistake in the article? As I said, I’m a noob, so feel free to crucify me.

[Pericles]

With an LLD of 20mm, maths dictates that if you stagger the stance by 20mm the pelvis will become level. Alternatively, if you shim by 20mm then the hips will be level. Therefore if you do both by 20mm (which is what is called for in the article), the hips cannot be level.

It will result in the hip on the side of the shorter leg being lower by 20mm.

Take someone with an LLD, shim their foot, now they have level hips right? Now, stagger the stance. Whats happens to the hips? One side is now lower than the other.

Im not trying to be annoying here.

[Mark Rippetoe]

Think about the frontal plane, and the top of the squat.

[Pericles]

I'm thinking about the frontal plane, and I'm still having trouble! I will continue to think about it.

If someone could please spell it out for me though, that would be great.

Also was meant to say in my previous post: surely it would result in the hip of the longer leg (not the shorter leg) now being lower than the other.

Rip, I came to the site for the articles that completely changed my view on strength and conditioning. I stayed for your political and social commentary. I love it. Thanks for the great work.

[RElliott]

Take all this with a grain of salt, I’m a novice also.

I don’t know about femoral discrepancy, but for me personally when I shim my squat the set up is even. When I pull a deadlift without the shim, it is staggered with the longer leg more externally rotated and forward of the short leg. Unshimmed squat set up is similar. As mentioned in a previous post, if I squat without a shim (lld is 3/4”) I collapse on the short side and helicopter out of it. If you think about it, the short side has to travel through a larger range of motion all other things being equal relative to the long side-so the long side will reach depth before the short side and the slack has to be made up somewhere, in my case by rotating forward while the short leg catches up. This has to place the hips in an uneven loading, at least in my experience, and all kinds of bad for knees hips and back. Strangely enough I’ve found the effect is less pronounced in a high bar position, but it’s still there.

My sense is that if you’re dealing with a short femur on one side (I have a total leg length discrepancy so it’s different) your leverages will be unequal as you power out of the hole. Not only are you exerting force over different length like I am, but with a short femur the leverages should result in force discrepancy as well, generating unwanted torque at the bottom and twist as you go up. To counter the torque issue, feet would logically need to be staggered, while to counter the issues I laid out earlier, foot would need to be shimmed.

Or maybe I’m just full of crap. I don’t know.