Great Running Shoes.
Running shoes have become more complicated over the years, but still consist of some basic components:
The outsole: This is the treaded layer on the undersurface of the shoe, usually made from carbon rubber or similar material. It resists wears and provides traction. It may also have a studded or waffle design to enhance traction on softer surfaces.
The midsole: This is considered the most important part of running shoes as it is the cushioning and stability layer between the upper and the outsole. The most common materials for the midsole of running shoes is ethylene vinyl acetate (EVA), polyurethane (PU) or a combination of the two. Often there is a dual-density midsole that has a firmer material on the inner side (medial side) to help limit pronation (rolling in) of the foot. A lot of proprietary technologies developed by different manufacturers go into the midsoles of running shoes (eg air, gel and high-tech plastics materials).
The upper: This is the part of the shoe that wraps around and over the top of the foot. It may be made of leather or a synthetic material that is lighter and breathable (to reduce heat from inside the running shoe). The tongue of the upper should be padded to cushion the top of the foot against the pressure from the laces. Often, at the back of the running shoe, the upper is padded to prevent rubbing and irritation against the achilles tendon.