The Anatomy of a Running Shoe
Editor’s Note: This post is written by Indriyas Wahyuni from runningshoesguru.com and has been edited for length and clarity. The opinions expressed in this article are the author’s own and do not necessarily reflect the views of Minneapolis Running.
Knowing the anatomy of a running shoe will help determine the right shoe for you. Once you have the right shoe, the run will more be comfortable and the risk of injuries will be reduced. While there are a number of brands on the market, the shoes all have the similar anatomy. After reading the article, you will better understand the parts that make up a shoe and what those different parts do.
The Anatomy of a Running Shoe
Upper and Sole Unit
The upper part of the shoe is usually made of engineered mesh, fabric, or leather. It is the top part of the shoe that aids in securing it to the feet, along with the laces. The upper keeps debris, such as rocks and dirt, away from your feet for a more comfortable run. It also aids in the stability of the shoe.
The tongue is also part of the upper and designed to protect your feet from the laces. It helps you put the shoes on and take them off. A well-designed tongue is well-padded and does not rub against your feet.
The toe box holds the widest part of your feet and is where your toes are located in the shoe. A good fitting shoe allows the toes to spread out comfortably without being smashed together. Keep in mind there should be about the width of your thumb between the longest toe and the front of the toe box.
Medial Post and Shank
The midsole is located between the outsole and the upper. Most midsoles are made of a foam called ethyl vinyl acetate or EVA. The cushioning of the midsole does differ between manufacturers as some use gel while other use encapsulated air as well. The midsole provides stability and cushioning devices, which are an important part of the shoe.
Another important part of the midsole are stability devices. Thermoplastic urethane is usually located in the post-medial aspect of the rearfoot. Dual-density EVA foam runs from the rearfoot to the arch. Some shoes have a combination of both EVA and TPU.
The shape and size of the medial post determines how much stability the shoe provides. Stability from the midsole helps to control pronation and stabilize the arch. While it does help control pronation, it does add weight to the shoe.
The shank part of the shoe is located under the arch and controls flexion and torsion. It helps the feet bend at the toes instead of under the arch while assisting with weight transfers. The shanks usually has a “V” shape and is made of TPU.
The heel drop is the drop from the heel of the shoe to the toe. Take the forefoot height and subtract it from the heel height and you have the heel drop. For example, a forefoot height of 5mm and a heel height of 15mm gives a 10mm heel drop.
The heel of the shoe also has a heel counter for an internal support feature, such as an exoskeleton that wraps around the heel, and a wedge for cushioning. The wedge adds height to the heel to reduce strain on your feet and absorb shock. Keep in mind that a thicker heel makes your heel hit the ground first. A flatter shoe makes your whole foot hit the ground at the same time.
The outsole is the part of the shoe that hits the ground when you run. It provides durability and traction while protecting the shoe from wear and tear. The outsole normally has a design to it, such as ripples — which are better for road or asphalt, or stud/waffles — which are better for grass or dirt. Flex grooves are also located on the outsole to aid in flexibility.
When it comes to trail shoes, the outsole is more important. There are a few materials the outsole can be made from, which include blown rubber, carbon rubber, or a combination of the two. Carbon is the sturdiest but is also stiffer than blown rubber. However, blown rubber is more flexible and provides a softer feel.
The last is the shape of the shoe and describes the way the upper is attached to the midsole.
The shape of the last can be curved, straight, or semi-curved. A straight last tends to be heavier but offers more arch support. A curved last is lighter but less supportive. A semi-curved last is a combination of the two.
The curved lasts are “C” shaped from the heel to toe. They are typically racing flats, competition shoes, cushioning/neutral shoes, and lightweight. Straight lasts are straight from heel to toe and tend to be more clunky. Semi-curved are the shape of most running shoes.
Strobel lasted is the most common lasts and is usually made of EVA. It is glued to the midsole and the upper is stitched around the footbed. The strobel last is less flexible than slip but not as rigid as a board last. Other lasts can be made of cardboard or plastic, although these are less common, most stable, and have a rigid platform. Slip lasted wrap the fabric from the upper under the foot and is the most flexible last. Combination lasted is a combination between slip and board lasted. It allows for some control and some flexibility.
The anatomy of a running shoe is important to know because when you are shopping for the perfect shoe, you will be able to find a more comfortable fit. These terms are used across the board, no matter what brand you are thinking of purchasing.