The part of the shoe between the outsole and upper. This part of the shoe is the focal point for designs that cushion the athlete's body from the forces generated in their sport. The midsole's contribution to stability must also be taken into account when designing a shoe. For example, a shoe that is very soft might be very unstable if the foot sinks to fast into the midsole.
The area of the shoe between the upper and outsole that's primarily responsible for the shoe's cushioning. Most midsoles are made of foams: either EVA (ethylene vinyl acetate) or polyurethane. EVA is lighter and more flexible than polyurethane, but it also breaks down more quickly. Many midsoles also have additional cushioning elements such as air, gel and various embedded plastic units.
The portion of the shoe between the upper and the outersole that provides cushioning.
The part of the running shoe between the upper and outsole that provides cushioning and support. Most midsoles are made of either EVA (ethylene vinyl acetate) or polyurethane foam. EVA is lighter and more flexible than polyurethane, but it is not as durable. It can come in various densities with gray-colored EVA being denser than white. The denser, gray EVA is usually placed along the medial side of the shoe to provide stability and motion control and is often referred to as a "medial post." Some midsoles have additional cushioning technology such as air, gel, grids, etc.
