Why flat arches are less stable when you run

I recently got a great question from a runner...

Why are flat feet less stable when you run?

Pronation of the foot happens as your arch collapses and the foot elongates. You do that every time you land as you run. You need pronation to absorb impact and decrease forces.

Supination is the opposite of pronation. Supination transforms your foot from a flexible, force-absorbing adapter to a rigid lever to propel you forward as you run and push off.  

Today on the Doc On The Run Podcast, we’re talking about why flat feet are less stable.