Determine the ins and outs of all parts of a running shoe.

The Upper

The upper is the part of the shoe that crosses over the top of the foot and encases it and holds it in place.

Upper is made up of the following:

     • Overlay is the reinforcing strips that provide structure to the shoe. Commonly, it is stitched or bonded to the upper.

     • Heel Counter provides support and helps the upper to cover around the foot. It maintains the position of the heel while running. Heel Counter is rigid or semirigid inside part of a shoe. 

     • Collar is the material on the top line of a shoe. It supports the heel and Achilles tendon. Preventing the foot to slip inside and helps to be much stable while running. It can be padded to add more comfort. 

     • Toe Box is the front part of the shoe that protects and provides space for the toes. A wide toe box is recommended for running shoes so the toes can splay.

     • Lasts are the layer of materials that are stitched in between of midsole and insole. Each last was developed for a specific heel height, toe shape, and size. 

     Shoe lasts are categorize into three:
     • Slip - The shoe upper material is stretch over the last and then fastened to the midsole. This type of lasting is commonly used to create flexible shoes.
     • Strobel - The upper is connected to a thin sheet material which glued onto the midsole and creates a sock. Compare to Slip-lasted shoe, Strobel lasted shoes are less flexible but much lighter.
     • Combination - The heel part is attached to the bottom of a flexible board on top of the midsole and using the Slip last on the forefoot area. This method is to secure that the toe of a shoe is perfectly shaped to the last. 

The Midsole

The midsole is the thick spongy layer of technical foam or rubber between the upper and outer sole. The cushioning and stability materials are found in the midsole. It is a big factor in terms of the durability of the shoe as well as the overall experience.

     • Compression-molded EVA -  The EVA or Ethylene Vinyl Acetate is the common component of a midsole. It is a blend of two kinds of plastics. 

     • Polyurethane - This material is heavier than EVA and it is also a type of foam. Polyurethane material does not have the tendency to flatten or compress.

     • Durometer - Identify how tough the midsole by the durometer.  The higher the durometer, the denser the midsole.

     • Cushioning devices - Most cushioning is from the EVA in the midsole. However, shoe manufacturers tend to combine their own cushioning device but none of them are better to another.

     • Dual-or multi-density midsole - Using dual- or multi-density midsoles prevent overpronate. Having two different densities of materials is a dual-density midsole and using more than two is multi-density midsoles.

     • Medial Post - The medial post helps to slow down the pronation motion and lessen instability. It is a device that can be found inside the midsole.

     • Thermal Plastic Unit - It is usually used to the bottom of the midsole at the midfoot. Also, used to lessen overpronation and support the midsole material.

The Outsole

The outsole, also known as the sole, is the bottom of the shoe which has direct contact to the ground. Outsoles should have a strong grip, excellent durability and must be water resistant. Just like the other parts of the shoe, it is made from a variety of materials.

      • Carbon Rubber - Provides more stability and long-term durability, though it is stiff and heavier. 

     • Blown Rubber - A rubber compound that mixed with air while on the process to create a more flexible and lighter outsole. 

     • Shape - Outsoles differ in shape, from curve to straight. Curved shoes have less stability and recommended for a neutral runner. While straight shoes are designed for motion controls and best for overpronation.

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