Stanley asked last week:
What I am asking is does the increased stride length from a valgus fore
> foot post result from:
> 1. An increase in firing of the gastrocnemius (as Kevin suggests).
> 2. Or an increase in midtarsal pronation so there compensation for the
> ankle joints sagittal plane motion, and hence a longer stride length.
You have answered that with a shorter midstance, there is less MTJ
> compensation, more foot stability and a longer stride as a result of hip
> extension (and 1st MPJ dorsiflexion).
> So you are saying that MTJ pronation limits hip extension. Can I assume
> this is because external rotation of the femur allows for more hip
> extension? If this is correct, then forefoot valgus posts would have to
> work by causing more external rotation of the femur. Is this what you see?

I would have to agree with Stanley here.  There is no doubt in my mind that
MTJ pronation limits hip extension. Since extension of the 1st mpj allows
STJ supination, when timed properly, this will match the intenal rotation of
the swing limb and cause external rotation of the lower extremity, including
the femur, causing external rotation and a longer stride length.  In my
mind, this action facilitates the function of the GS complex, not the other
way around.
I hope this clarifies things.
Sorry for the delay.
Sincerely;
Bruce Williams

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