Throat. The throat is the opening where your foot enters the shoe. Make sure that the rim of the throat, known as the collar, is well padded and low enough that it does not rub your anklebones.
Heel counter. This part of the shoe cups the heel. Because it needs to be stiff to control motion at the back of the foot, manufacturers often embed rigid materials here as well. However, there should also be adequate padding in this area to keep hard materials from rubbing against the foot.
The higher the heel counter, the more control it will provide. This is generally a good thing, as long as it does not dig into or rub against the back of the foot, anklebone, or Achilles tendon (the tendon that joins the calf muscles to the heel bone). Shoes with a high heel counter usually have a notch for the Achilles tendon so this does not occur.
Sock liner (insole). The foot sits directly on the sock liner which, in off-the-shelf shoes, is generally made of a single layer of foam. Buying shoes with a removable sock liner makes it possible to replace the liner with one that is custom-made to fit your foot or an off-the-shelf product that provides more cushioning or a better fit. A custom insert should have at least three layers — a soft layer of foam on top and two stiffer layers on the bottom to provide some resilience.
Midsole. The midsole is the middle portion of the sole, which serves to cushion the foot. It can be difficult for the average shopper to evaluate the quality of a shoe’s midsole, but a knowledgeable shoe fitter should have information about the types of midsoles that come with various shoe styles and their relative merits.
Several years ago, a trend started where manufacturers began removing foam from the arch area of the midsole to reduce the weight and cost of the shoe. The logic was that since people don’t walk on their arches, they shouldn’t need support in this area. The problem with this thinking, however, is that the shoe becomes weaker, and therefore more flexible, when material is removed. The more flexible the center of a shoe, the more stresses it produces across the middle of the arch because the shoe bends in a place the foot does not. Manufacturers quickly became aware of this problem and began reinforcing the arch area with stiffer plastics.
To make sure that you choose a shoe with an arch that is strong enough, hold the shoe by the heel and push the toe box slightly up and toward the back of the shoe. The shoe should bend at the joint of the toes the way a foot does when pushing off. If it instead bends at the arch, don’t buy it.
Outsole. This part of the shoe, usually made from carbon rubber, comes in direct contact with the ground, so it needs to be resilient and flexible.
Rocker bottom. A rocker-bottom shoe has the sole angled up from the ground at the heel and toe. This type of sole can help reduce pressure on the feet in a number of ways. It is a particularly helpful feature for people who have limited joint mobility (a condition in which the tissue around the joints becomes stiff and inflexible) because the rocker replicates the normal rolling motion of the foot, sparing the stiff joints from moving as much as they otherwise would have to. This also reduces the stress across the skin of the feet. Rocker bottoms additionally keep the feet continually moving forward, facilitating the normal heel-to-toe rolling motion and reducing the amount of time that pressure is applied to the bottom of each foot.
To check whether the shoe you have selected has a rocker bottom, place it on a flat surface and push down on the heel. If there is a rocker in the heel, it will make the toe rise off the ground. Likewise, push down on the top of the shoe in the toe area. If there is a rocker in the toe, it will make the heel rise off the ground.
The amount and angle of the rocker changes from shoe to shoe, so the best way to test the one on the shoes you are looking at is to try the pair on and walk around the store. If the rocker is in the correct place for your foot, you will feel as if the shoe is pushing you in the direction you are walking. Because of this sensation, it may take some time to get used to walking in shoes with rockers. Also, because rocker soles have less contact area with the ground than regular soles, it is important to be cautious on uneven terrain.