Components & Technology That Make Up a Modern Running Shoe
Article by: Adam Bible
Illustrated by: Allie Surdovel
The components and technology that make up a modern running shoe
Man's urge to run more comfortably has lead him from running barefoot across grassy savannas to crafting thin leather sandals to glide through rocky desert canyons to designing running shoes inspired by a waffle iron. In 1971, in his Eugene, Oregon, kitchen, Nike co-founder Bill Bowerman created a sole modeled after the knobby pattern on the waffle maker that would grip all sorts of terrain. This innovation became one of the earliest iterations of the modern running shoe.
Advancements in running shoe technology have come a long way since that morning in the kitchen, and now every part of the shoe has come under scientific scrutiny. Companies are tweaking and twisting rubber, foam, textile, and plastic compounds to create shoes that will last longer, perform better, and provide more comfort. From toe to heel, they continue to make important advances in materials and techniques to build running shoes that are not only lighter, but more durable and supportive than ever before.
To understand how a modern running shoe is made—and the innovations that abound—here's a breakdown of the major components of an advanced running shoe.
This is the ridged part on the bottom of a running shoe that strikes the surface when you run. The tread pattern—now evolved far beyond the waffle iron—is designed to match whichever terrain you choose to tackle—dirt, road, gravel, track, or even a mix. The outsole is usually made with a mix of carbon rubber (for durability) or blown rubber (for cushioning) to provide stability and comfort while gripping the ground. Companies like Michelin and Vibram have contributed to outsole technology in recent years by coming up with new compounds that are durable, sticky, and long-lasting to give you enhanced traction and road feel.
The next portion in the sole sandwich (the layers of shoe below your foot that's comprised of the exterior outsole, midsole, and interior insole) is often made from either ethylene vinyl acetate (EVA), a closed-cell foam, or polyurethane, a type of plastic. It is placed in the middle of the shoe to add stability and cushioning that will last over repeated pounding as you run. This is the part of the shoe that most affects how it feels while you run and the most recent advancements have involved coming up with new foam combinations to increase "bounce" or how the midsole returns energy back to you as you run.
The midsole is also where any heel-to-toe drop will come in. Drop, also called offset, is the change in elevation in the sole from the height of the heel to the toe box. Zero drop, or very low offset, is what barefoot and minimal shoes try to achieve. Traditional running shoes have about 12mm of drop, allowing for much more cushioning.
Within the midsole, companies are now experimenting with special cushioning cells that attempt to provide extra comfort or more stability such as with Nike Air technology or ASICS GEL cushioning. Like the names suggest, these additional components use materials such as air pockets, gel-like goo, or liquid silicone encased in polyurethane to alter and enhance feel when running. They may provide additional lateral support in a trail shoe or amp up the cushioning for a long-distance runner.
The insole is the inner part of the bottom of the shoe where your sock-covered feet rest. They are typically made from a slim layer of EVA and don't offer much in the way of cushioning or performance. An insole is usually topped with a thin piece of microfiber for a bit of moisture wicking and comfort, and may have holes strategically placed for more airflow. To get enhanced performance from your insole, you may have to step up to an aftermarket insole insert company like Superfeet11 or currexSole12. These inserts include technology like heel cups for absorbing shock, special foam/rubber blends that offer cushioning and enhanced arch support to make running more comfortable.
An upper is what covers the top of your foot. These have changed a lot in the last few years as manufacturers are now able to knit yarns and fabrics into almost-seamless, lightweight, breathable, and form-fitting uppers. Before this innovation—which Nike catalyzed after more than 10 years of research—uppers were crafted from multiple panels of material that made for a heavier and less-comfortable shoe.14 Now versions of the technology, which Nike dubbed Flyknit, appear on shoes across the industry. Inspired by the abuse that some customers mete out on their shoes, some companies now offer products with more durable coverings that still provide sufficient air flow but can also stand up to rougher treatment (think: Rope climbs and the like).
The toe box, or the area around the mid and forefoot, is one part of the shoe which has lately seen some significant expansion. Newer brands like Altra have taken the advice of podiatrists and widened the toe box considerably so toes can splay out when hitting the ground to more closely mimic the natural way an unshod foot performs when running. This more-natural position is linked to fewer foot problems, more stability, and better performance. Most running shoe brands still hew to a tighter toe box that can squeeze the forefoot, but companies have taken note and are slowly expanding the size of their toe box areas on some models.
Tongues are the flap of fabric that comes up from the toe box to give the top of your foot some protection from the laces. They weren't an area of much innovation until recently. Now some companies are experimenting with different designs, like double-folded tongue or a “burrito"-style tongue that is integrated into the upper and more closely wraps around your foot, eliminating slippage and discomfort.
Another component of the running shoe that hasn't always seen much innovation, laces are now made thinner, stronger, and last longer than your typical cotton or polyester shoelace. Some brands now offer shoes that have a speed lacing system made with super-thin and extremely durable nylon laces that don't tie but have a plastic locking mechanism. The newest lacing shoe tech comes from the Boa system, which has thin and tough laces made from plastic-coated, stainless-steel wire. It has a dial that lets you tighten with a few quick turns or loosen with a snap.