Shoe Construction

By Rick Morris

There are five primary components of running shoes: the outer sole, the mid sole, the upper, the heel counter, and the slip lasting or board lasting. The outer sole is the bottom part of the shoe that contacts the ground. Shoes designed for road running will have a variety of patterns on the bottom. Trail running shoes will have a large waffle or knobby pattern to provide better traction on dirt, grass and mud. The most important consideration of the outer sole is wear ability and traction. Some outer soles are softer than others. A hard outer sole will wear longer. A softer outer sole will provide a small amount of additional cushioning. This could be of benefit to a heavier runner. The softer material can also provide more traction on slick surfaces.

The mid sole is the part of the shoe just above the outer sole. The main function of the mid sole is to provide cushioning, stability, and flexibility. Earlier shoes had mid soles made of rubber. Most of today’s shoes have some sort of combinations of vinyl compounds and air bladders or other lightweight shock absorbing materials. This has decreased the weight of shoes and increased their shock absorption abilities. Wear of the mid sole is the first sign that your shoes should be replaced. Most of the cushioning and shock absorption is located in the mid sole. As the mid sole wears, it becomes compressed and loses its ability to absorb the impact created when running. There is a rule of thumb that says to replace your shoes every 500 miles of running. You do not have to blindly follow this rule. Just check the cushioning of your mid soles frequently. Press on the mid sole at the heel, mid shoe and at the front of the shoe. If the mid sole feels compressed or feels like much of the cushioning is gone, you should replace the shoes.

The upper is part of the shoe that wraps around your foot. This is usually made of a nylon material. The upper is either slip lasted or board lasted. Slip lasting means the nylon upper is tucked under and glued directly to the mid sole. This type of lasting provides more flexibility and is lighter in weight. In shoes that are board lasted, a board is placed over the tucked under portion of the upper. This type of shoe provides more stability and prevents pronation, which is the tendency for the foot to roll excessively to the inside. A board lasted shoe is best for a runner that pronates or supinates excessively. A slip lasted shoe will work well for a mechanically efficient runner.

The heel counter is the stiff, molded portion of the shoe directly behind the heel. This feature will also reduce ankle pronation. The stiffer the heel counter the more protection the shoe has against pronation. Pinch the heel counter between your thumb and index finger. The harder it is to pinch the heel counter, the stronger the heel counter. A strong heel counter is better for runners that need a stable shoe.