Running Shoe Midsole
Midsole is the most important part of the shoe, mostly made from spongy material, like Ethyl Vinyl Acetate or Poyurethane foam, binds between outsole and upper.
The purpose of midsole protects your feet from impact, other shoe brands are doing a lot of cool things like ASICS, Brooks and Mizuno. All of them are designed to absorb shock away from your foot.
Running shoe medial post
Located on the inside part of the shoe, this is placed to help you reduce over-pronation. Medial post are made from EVA, that is denser material than the midsole. It also helps you with stability.