Anatomy of a Running Shoe

Do you know what a heel collar is? What about the offset? And where is the medial side? Shoe reviewers and sellers often use shoe terminology that I guess almost everyone knows what they are talking about, but I am also sure that there are a few of you that don’t know what those technical names refer to.

Fear not, I’ll try to cover all the major shoe components that you should know about.

Introduction

A shoe is not only a shoe. It’s a sum of several well-studied, tested, and assembled components that work together to give us the best running experience possible.

As you can see in the image above, there are several components in a “simple” running shoe.

So, let’s start from the top to the bottom and I’ll explain them to you. For the explanation, I’ll divide the shoe into two sections: the upper and the sole unit.

Upper

The upper is where we find the shoe fabric and a lot is going on in the upper.

Heel counter

The heel counter is what wraps the heel of your foot. In the majority of running shoes the heel counter is rigid (some more than others) and that rigidity will contribute to a more secure lockdown, will give you more support in your landing, and will also contribute to a more comfortable fit in the heel area.

But not all heel counters are rigid. Some minimalist or racing shoes have a soft heel counter to keep the weight at a minimum and, depending on your foot strike and pronation degree, for example, that could mean that you are losing comfort and stability.

Hell tab

The heel tab is a piece of fabric, with or without cushioning, that sits above the heel counter and is there to lock the shoe while protecting your Achilles from blisters.

There are different formats of heel tabs, some work better than others and some don’t work at all, especially when they rub your Achilles and leave you with blisters.

Pull tab

Some running shoes, perhaps the majority, have a pull tab in the heel tab. The purpose of the pull tab is to help you to put the shoe on without having to unlace all the laces and lose the secure fit that you got from the last run.

Heel collar

The heel collar or heel cuff is what is surrounding your ankle at the top of the foot. Again, this component will contribute to a secure lockdown and normally it has some padding (or a lot) for comfort but the padding is also used as a locking mechanism.

Tongue

The tongue is well known, even to non-runners, and it has two main purposes:

• Protect your foot from the pressure of the laces;
• Help you to put your shoes on and take them off.

The tongue can be gusseted, semi-gusseted, or non-gusseted. A gusseted tongue is connected to the shoe from both sides, the semi-gusseted only from one side, and the non-gusseted is not connected from any side.

For a road running shoe, the gusseted tongue is essential to prevent the tongue from sliding to one side or another. Usually, the tongue is connected by a simple strip.

For trail shoes, the gusseted tongue is usually fully connected from the bottom until the top and that will prevent debris from entering the shoe. It will also protect the foot from rain or puddles if it’s a rainproof shoe.

Laces

The shoe laces can be flat, rounded, simple, or with patterns, and the laces' purpose is to adjust the shoe to your foot making sure that everything is tight and snug, but without causing too much pressure on the foot. The laces are already placed in the shoe when you bought it, but you can change the lacing to achieve greater lockdown and comfort. There are several possible ways to lace your shoes.

Eyelet

That's the small hole where the shoe laces pass through. Running shoes have an extra eyelet on the top of the shoe that is there in case you need to improve the shoe lock using the runners' knot.

Toe box

This is the area where your toes rest. You need to pay attention to the toe box because you don’t want to have too much room for your toes because that means that your foot is not properly locked and can move inside the shoe while running, but you also don’t want your toes cramped because that will lead to blisters and, of course, discomfort.

Overlays

Overlays are pieces of fabric, usually branding or other design elements that can be reflective or not. They are glued to the upper fabric, and they will provide structure to the shoe upper. Usually, racing shoes don’t have overlays to reduce weight and that’s one of the reasons why the uppers have less structure.

Insole

The insole or sock liner is a removable piece of foam that is inside of the shoe, where your foot rests. The purpose of the insole is to add an extra layer of comfort and to protect your foot from the seams that connect the upper to the sole unit.
The insole can be changed by a custom one according to your specified needs.

Sole Unit

The sole unit is more than the midsole and outsole. Depending on the type of running shoe, the sole unit can have more or fewer components to it.

This is where most of the shoe magic happens. The midsole is the foam between the upper and the outsole and it’s most responsible for the shoe ride, cushioning, energy return, guidance, and stability.

Nowadays we are seeing a lot of innovation in the midsole where shoe companies try to give us more cushioning, stability, and responsiveness in a lighter package.

Each shoe’s midsole is different. Different in construction and in materials. It can be made from a simple EVA foam or it can be made from a more advanced PEBAX foam.

Plate

In the midsole, sandwiched between layers of foam, you can find a plate. The plate can be made from TPU or nylon, for example, or can be made from carbon fiber. The last ones you’ll find in more expensive performance shoes.

The plate has a major role in the level of energy return that we get from running shoes. When we land, the midsole foam will compress and, depending on the foam, it can recover its initial form slowly or quickly, giving us more or less energy return. When we have a plate in a running shoe, that plate will push our feet from the ground, forcing a greater energy return and by doing that, we have a quicker gate cycle.

Sidewall

Also known as guide rails, a sidewall is an extension of the foam in the lateral and medial side of the shoe and its purpose is to offer resistance and some guidance to our foot. It’s much appreciated by those who pronate and need a little bit of support.

Outsole

The bottom part of the shoe is the outsole. It’s usually made from rubber, but some shoes opt for a rubberized foam in order to save weight and give us a smoother heel-to-toe transition, but this foam’s durability will be inferior.

You should take a careful look at the outsole if you need extra grip for rainy days or bigger lugs for trail running.

Crash Pad

This is the piece of foam that running shoes have in the back of the heel. It’s there to provide cushioning and a smooth heel-to-toe transition, especially for heel strikers.

Heel bevel

This is a slight bevel that some running shoes have in the crash pad and, once again, the idea is to provide a smooth heel-to-toe transition, especially for heel strikers.

Stack Height and Drop

The stack height is the total height of the sole unit. Almost all shoe companies include the insole in the measurement but there are some that don’t include them, so if the stack height is important for you, pay close attention to that detail.

The stack height has two measurements: the heel stack and the forefoot stack. The difference between the two is the drop, also known as offset.

Usually, the drop goes from 0 mm up to 12 mm. Different drops serve different needs and different runners' anatomies. If you’re a beginner, start with something from 5mm up to 10mm because these are the most common offsets.

Rocker

The rocker is a pronounced curvature in the sole unit (midsole and outsole). When it’s present, you can feel a smoother heel-to-toe transition and a better toe-off. The rocker will allow not only a smoother transition, but also a more efficient ride, meaning that you should feel less fatigue with a rockered shoe, especially if we are referring to racing or long runs shoes. Combined with the heel bevel, the rocker will also contribute to better sock absorption because as soon as you hit the ground, the shoe rolls more quickly distributing the impact to other sections of the foot.

Some running shoes have more aggressive rockers, meaning that the curvature is more pronounced and starts early in the forefoot.

Medial post

The medial post or flare is a different density foam, firmer, that you’ll find on the heel section of some running shoes. Usually, the flare is only found on the medial side (internal side) of the shoe and is there to provide stability and support to runners that need it.

There are a few more components and names to know about, but these ones are enough to cover the major components and terms that shoe reviewers use.

I hope that this post was elucidative and helped you better understand what the reviewers are talking about.

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