Running Shoe Anatomy: 6 Parts That Shape Comfort and Performance

Tooling ring for the ASICS Gel Nimbus 24.

Shoes. You put them on your feet, lace up and head out for your run. It’s that simple, right? Well, yes… in theory. A quick lesson in shoe anatomy teaches us that while running shoes have the same elements, those elements are designed to function differently.

Have you ever gone for a run and felt uncomfortable aches or pains during or after? Have you worn the same pair of shoes for a run on roads as you have on trails or to the gym? For optimal comfort and performance, ideally, you’d wear different shoes for different types of runs.

Anatomy of a Running Shoe

Your average running shoe will include the same basic components. However, within those design components, there are key differences that cause a shoe to fit, feel or perform a certain way.

Upper

Road and trail-running shoes often feature an engineered- or knit-mesh upper for breathability. Knits offer extra flexibility for fit and comfort. A racing shoe generally has an even lighter engineered mesh upper to reduce the overall weight of the shoe.

Some road and trail shoes are designed with a weather-proof upper, making it easier to stay on track with your training plan in windy, wet or muddy conditions. These incorporate Gore-tex® (look for styles with “GTX” in the name) or other waterproof fabrics, and bonding or seam-sealing to prevent water from seeping in where fabrics meet.

Pro tip: It’s important to note that while these do a great job of keeping moisture out, it also means that sweat will stay trapped in the shoe. This can feel heavy and cause hot spots or blisters, so wearing weather-proof shoes is generally not recommended on dry days.

The upper of the Karhu Ikoni.

Insole

The insole is a lightweight, foam footbed that rests inside the bottom of the shoe to offer extra cushion and comfort for the foot. Insoles are a surprisingly important part of running-shoe anatomy. These can be replaced with a more cushioned or supportive option. Many people will select new insoles for additional arch support, plantar fasciitis treatment or pain relief. Popular insoles include Superfeet and Currex, whereas some people use custom orthotics created by a podiatrist.

Midsole

Positioned between the upper and the outsole, the midsole is the part of the shoe that provides comfort, shock absorption, energy return and varying levels of stability and motion control. Midsoles are primarily engineered with foam, but some feature gel or air-pod technology.

Neutral shoes keep it pretty simple with a variety of midsole designs and densities across brands and models for varying levels of comfort and energy return. Stability shoes, however, feature a medial post or dual-density foam to manage motion control for pronating and supinating. Brands manage this in different ways. Examples include:

Racing shoes often feature a carbon plate or rods, or TPU plate embedded in the midsole to propel the body forward and upward and reduce the energetic cost of running.

From neutral to stability, foam to gel, minimalist to ultra-plush, there’s a running shoe for every foot and every activity.

The midsole of the ASICS Gel Kayano Lite 2

Outsole

The outsole is the part of the shoe that touches the ground. This offers varying levels of traction depending on the surfaces you’re running on. Road running shoes are designed to perform best on paved surfaces such as roads and sidewalks, treadmills, and even packed dirt that doesn’t require an outsole with extra traction (think: rail trails).

A trail running shoe is best for varied terrain, such as dirt, gravel, mud, rocks and other non-smooth surfaces where your shoe’s outsole grips to help prevent slips and falls. These are easy to spot due to the deeper and thicker lugs and more rubber covering the bottom of the shoe. Fun fact: Adidas running shoes feature outsoles made with rubber from Continental, a popular tire brand.

The outsole of the ASICS Gel Nimbus 24

Tongue

Any shoe with laces will have a tongue. It seems like a pretty uninspiring part of running-shoe anatomy, but the tongue actually serves a pretty important purpose. The tongue prevents laces from rubbing or adding pressure to the top of the foot.

Trail running shoes often feature a gusseted tongue. This means the tongue is connected along the sides, and this design feature prevents debris from entering the shoe. Fewer stops on the trail to empty out your shoes is never a bad thing!

Laces

You’d think laces are pretty standard, but–surprise!–they’re not. Flat laces are the most common. Round laces tend to be a bit sturdier and last longer. Then there are shoes with a BOA Fit System for a precision fit that can be easily adjusted during a run. Some shoes even come with bungee cord for laces, reducing the pressure that traditional laces can put on the top of the foot. Pro tip: There are tons of ways to lace your shoes to manage comfort. Learn how to re-lace your shoes for a better fit.

Top down view of the men's HOKA Arahi 6.

Not All Shoes Are Alike

Now that you know more about the anatomy of running shoes, how they function, and reasons to select activity-specific footwear, you probably have the urge to shop. We’ve made it easy to browse the major categories to find the best shoes for each type of runner.




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