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Glossary of Running shoes

Structures, Components, Functions, Interactions, Construction Terms, and some brief Brand Histories

adidas

The eponymous sports brand after founder Adolph "Adi" Dassler. During his lifetime Adi Dassler received more than 700 athletic footwear patents, a staggering number by any measure. The preeminent athletic shoe brand for most of the 20th century (currently #2). Their stable of professional track & field and running athletes is only rivaled by Nike.

Aglet

The plastic tip at the end of the shoelace.

Air mesh

Generic term for wide open mesh, used to increase air flow and cool the foot.

Air Sole

The invention of M. Frank Rudy, which was licensed to Nike as a cushioning system, and set a trend toward more engineered athletic shoes.

Altra

Brand introduced during the Natural Running heyday on the premise of a Foot Shaped toe box and Zero Drop, but with generous cushioning. Co-founder Golden Harper cut his teeth on adapting shoes for runners' needs, with modifying skill and a toaster oven, at his family's run specialty store in Orem, Utah.

ASICS

Name of the hallmark Japanese running brand founded by Kihachiro Onitsuka, taken from the Latin phrase: Anime Sana in Corpore Sano, meaning a sound mind in a sound body. Their headquarters is in Kobe, Japan, where they have impressive resources for design, testing, and development.

Atreyu

Founded in 2020 and based in Austin, Texas. Like some other small running focused brands, they use a direct to consumer model with roots in social media. Originally they had sought to use a subscription based marketing plan of one style with a well discounted price, versus single purchase consumers. It has been rethought in practice. The design of a second shoe, a carbon plated, tall stack racer, seems to have altered their focus. Stay tuned.

Barefoot Inspired Shoe

A shoe that mimics the shape of the foot and allows the unhindered function of its natural motion. It sometimes features just a thin layer of material between the foot and the ground. See Minimalist Shoe

Biomechanics

The science which applies the principles of physics to the study of human motion.

Blown Rubber

Rubber compound that has gas bubbles forced into it, to give it a softer feel, though it is less durable. Used in the lower wear regions of the outersole for lighter weight and added cushioning. With new midsole foams, it is becoming less frequent.

Brooks Running

Footwear brand founded in 1914 in Philadelphia, Pennsylvania, by John Goldenberg. The name came from the anglicized version of his mother's maiden name: Bruchs, as Brooks was easy to say and remember. The overall leader in running shoes sold by Run Specialty, they have focused solely on the running business for more than 50 years of their century-long existence.

CM-EVA

Compression-molded ethylene vinyl acetate foam. Provides the cushioning of most running shoes.

Carbon Rubber

Rubber compound that contains carbon to increase the durability and abrasion resistance of the rubber. It is used primarily in the heel, though sometimes over the entire outersole of lower priced shoes.

Combination Lasted

The use of a fibrous, stabilizing board, glued into the heel when the shoe is being constructed. The combination of the slip lasted forefoot (for flexibility) with the stabilizing board in the heel gives the shoe more stability and versatility.

Compression Set

The manufactured shape of the midsole when it is not under the pressure of the foot. The "set" allows the various moldings and grooves pressed into the midsole during manufacturing, to compress and direct the foot's motion at impact and towards the toe-off of the running gait.

Cushioning System

The combination of a polymer pad, filled polymer bag (with gas, liquid, or a semi-solid) or elastomer encapsulated into a foam midsole. It can also be the engineering of only a polymer foam to absorb some of the shock from the foot impacting the ground during physical exercise.

Dri-Lex

A fabric lining material developed by Faytex Company® that combines a soft, abrasion resistant polyester face fiber with a backing of Allied Signal’s ® Hydrofil TM nylon fiber.

Drop

The difference in the height of the shoe's midsole between the heel and the ball of the foot.

Dual Density Midsole

A configuration used for resisting overpronation, where a denser piece of foam is bonded along the medial (inside) edge of the midsole between the arch and the heel. This design prevents the midsole from breaking down before the other components of the shoe are worn out.

Eyestay

The row of eyelets that boarders the shoe's tongue where the laces cross, allowing the tightening of the shoe.

Flex Grooves

Molded grooves that allow the midsole to bend with the foot, while still providing cushioning, where the thickness of the foam might resist bending and make the ride too stiff.

Geometry

The shape of the shoe’s sole and cushioning layer, including grooves, clefts and siping. Variations can limit or enhance motion by shaping the sole in different ways.

Heel Counter

A cup shaped form which restricts heel motion and supports the rearfoot of the shoe, securing the heel.

High-Frequency (HF) Welding

Use of superheated polymers molded to the vamp or heel to add support and structure to the upper, replacing synthetic suede and synthetic leather overlays.

Hoka One One

Launched at the height of the minimalist footwear trend, Hoka One One stood out like a light in a dark room. Co-founded by industry veterans Nicolas Mermoud and Jean-Luc Diard, the shoes became a solution for all runners, from the injured to the ultra inclined because of their cushioned design. They now have models from plated racers to daily trainers, even extreme mountain running. Their influence is evident by similar models from every major brand (as well as some minor brands).

Implus

Quality polyurethane innersole, from Implus Corporation.

Injection Molded Foam

A process where a polymer is liquified and injected into the midsole mold. It often results in lighter weight foam because of , and potentially more durable because of its uniform density.

Insole

See Sockliner

Last

Foot-shaped model around which a shoe is made, then utilized in a lasting machine to bond the upper (by pressure) to the midsole/ outersole assembly.

Lasting Board

A piece of fabric or fabric-backed foam, shaped like the shoe’s upper that is perimeter stitched to close the bottom of the upper. This layer has the purpose of providing a good surface for the attachment of the midsole. The fabric backed foam version offers a bit more cushioning and an adaptable surface for the sockliner/innersole, as the material conforms a bit to the shape of the insole.

Last Shapes

Variety of shapes used to accommodate different foot types. Related to the height of the arch; high arched feet - curved last, low arched feet - straight last. These fall into relative categories of: straight, semi-straight, slightly curved, semi-curved, and curved, though there is no defined parameter for the distinction between shapes.

Medial Post

Denser (molded or injected) foam, TPU device, or combinations of the two, on the inside edge of the shoe's heel to curb pronation and maintain the shoes integrity.

Memory Foam

A soft polyurethane foam that conforms to the shape of the foot when warmed. Used in ankle collars and insoles.

Midsole

The foam material layer that is found between the upper of the shoe and the outersole.

Minimalist Shoe

A shoe that has as much of the layers, overlays, and excess material removed and simplified as possible, to reduce weight and structure.

Mizuno

Founded in 1906 by brothers Rihachi and Rizo Mizuno, as a manufacturer of quality sporting goods. The brand expanded into running footwear in 1949 with a range of track spikes. The company set its running technology apart from other brands in 1996, with the Mizuno Waveplate, a corrugated thermoplastic plate embedded in the sole, and the introduction of the Waverider running shoe, now in its 25th iteration.

Motion Control Shoe

A shoe with components for curbing overpronation, often designed with a straight last for low arched to flat feet with hypermobile tendencies.

Natural Motion

A description of the motion of the foot as it goes through the running gait cycle, unique to each person because of the complex variables and differences involved with their height, weight, strength, speed, leg length, foot size, fitness, etc. It also describes a shoe that does not hinder this motion.

Nike

The quintessential success story: boy travels the world, makes a gentleman's agreement to sell running shoes - making up a company name on the spot (after a beer brand), invests effort and his own money, and gets startup investment from his track coach/partner. Coach develops new footwear technology and they found a new sports company. Now the world's largest athletic footwear and apparel brand, currently led by an executive with roots in tech.

No-Sew

A technique which uses welded overlays instead of sewn, reducing the likelihood of irritating seams in the shoe's upper, while lightening the weight of the shoe without compromising the support.

Neutral Shoe

A description of the biomechanical properties of a shoe. Most commonly it describes a shoe with no stabilizing technologies, just a layer of cushioning under the foot. It may also describe a zero drop shoe, as it does nothing more to balance the foot or accommodate additional cushioning.

OrthoLite

Innersole material of polyurethane that resists compression, often coupled with elastomer pads; registered trademark of a division of ATP Manufacturing.

Outersole

The tough material that contacts the ground at the bottom of the shoe. Usually made from a rubber compound, its thickness adds to the Stack Height of the shoe.

Overlays

Supports, whether welded or sewn, that lend structure to the shoe, used in the heel, midfoot, and toe to secure the foot to the shoe and line it up over the midsole.

Overpronation

The slightly subjective measurement of eversion of the foot as it transitions from the heel touchdown to the toe-off during the gait cycle (see Pronation).

Phylon

Lightweight CM-EVA, originally licensed from Mattel Toys. (Nike)

Poron®

PU-based cushioning pad; registered trademark of Rogers Inc.

Pronation

The natural motion of the foot to absorb shock, transitioning from the heel while lining up the big toe to push off toward the next stride.

PU

Polyurethane, usually used in midsoles, insoles, and ankle collars.

Puma

One of two brands founded in Herzogenaurach, Germany, by the Dassler brothers. Puma is linked to Rudolph Dassler. A successful marketer, Rudy introduced footwear marketing strategies which are commonplace with athlete endorsers to this day. While not as inventive as his brother Adi, he had his own footwear craftsmen who produced an impressive array of running and track and field products. 

Quarter

The rear portion of the shoe that includes the heel. It connects to the vamp, and in running shoes is not a separate piece. It often features a piece of stiffer material called a counter (see heel counter) to keep the heel from moving from side to side. 

Ramp Angle

Related to the shoe’s drop, it is the angle that the shoe pitches forward from heel to toe. It varies with each size and is more acute in smaller sizes, when there is any amount of drop to the shoe, for instance in a shoe with the same drop (approximately 10-12 millimeters in a typical shoe) a size 13 is going to have a smaller ramp angle than a size 7. A zero drop shoe would have no ramp angle.

Saddle

The portion of the upper adjacent to the laces on each side to support the midfoot and keep it lined up over the midsole.

Saucony

Footwear brand founded in 1898 by four businessmen in Kutztown, Pennsylvania. The factory was powered by the flowing water of Saucony creek, the origin of its name and logo. In the late 1960's the brand was acquired by Hyde Athletic Industries, and moved to Cambridge, Massachusetts. Success of two of their running shoes strengthened the brand's influence and by the 1980's, Hyde became known as Saucony. Acquired again, in recent years, Saucony is presently a subsidiary of Wolverine Worldwide. 

Shank

The portion of the shoe under the arch that is often supported by a TPU or nylon device to prevent the torsion of the foot from twisting the shoe and impairing its function. Most brands have a specific name for their version of the shank support, i.e. Torsion (adidas), Trusstic (ASICS), etc. 

Siping

Vertical cuts in the sole of the shoe creating a grid-like pattern, freeing the flexibility of the sole and its effect on the foot’s natural motion, allowing for a fuller range of motion for the foot.

Slip Last

Shoe construction method which stitches the upper of the shoe that is slipped onto a last, closing the upper with stitches down the center, under the foot, before being adhered to the midsole.

Sockliner

The industry name for an OEM insole, and a term used interchangeably with “insole” to describe the layer that is directly beneath the foot in the shoe. Usually removable in a technical running shoe, it sits on top of the lasting board and provides a thin extra layer of cushioning to the shoe, but also adds extra thickness to the shoe’s stack height (see Stack Height).

Stability Shoe

A shoe which has a more supportive sidewall on the medial side of the shoe, splitting the difference between a Neutral shoe's cushioning and a Motion Control shoe's components for curbing pronation. The term motion stabilizing may be more accurate, as a shoe at rest is stable.

Stack Height

The height from the bottom of the shoe’s sole to the bottom of the foot in the shoe. This includes the outersole, midsole foam, lasting board and insole. The higher the stack height, the less proprioceptive feedback is received by the nerves in the foot. The thickness of the midsole adds what usually amounts to the largest portion of material in the shoe’s stack height.

Sticky Rubber

Lower density rubber compound that has improved grip in wet or rocky conditions, but less abrasion resistance than harder rubber compounds. 

Stretch Mesh

A woven fabric which stretches a given amount to move with the foot, while still providing the necessary support and securing the foot over the midsole.

Strobel Slip Last

Shoe construction method which stitches a sole shaped fabric board to the upper of the shoe that is slipped onto a last, closing the upper with stitches around the perimeter of the sole. The board may be varied from thin flexible materials, thicker stable materials, or a combination of the two stitched together, to improve stability or flexibility.

Supercritical Foam

A process which forces supercritical liquid nitrogen into a mold with a block of ethylene vinyl acetate. The pressure and nature of the liquid fills the spaces of the plastic and when the nitrogen gas escapes, its bubbles create foam with very stable walls within the plastic block which are both longer lasting and more lively than traditional EVA foam. 

Topo Athletic

Running brand founded by athletic footwear executive Tony Post, with the name deriving from his college track team nickname To Po. The company was founded in 2013, launching a line of running and recovery footwear choices in succeeding seasons, arriving at their current 17 styles for running, walking, hiking, and recovery. 

TPR

Thermoplastic rubber, used in some outersoles, as well as some cushioning systems.

TPU

Thermoplastic urethane, often used in devices to prevent overpronation, as a lightweight outersole, for welded overlays, and for almost a decade as a durable palletized foam midsole.

Toebox

The portion of the vamp of the shoe that contains the toes, both in width as well as the height. 

Toe Splay

The natural spreading of the toes and forefoot when the bare foot contacts the ground. In a shoe this is restricted unless the toebox is wide enough to accommodate the width of the splayed toes, often described as a foot shaped forefoot.

Tongue

The piece of fabric, and often times foam, that covers the instep of the foot under the shoes laces.

Transitional Shoe

A shoe with a drop that is lower than a traditional shoe (usually less than 10 millimeters) but not as low as a zero drop shoe. They allow a runner to transition to an even lower Minimalist or Barefoot Inspired shoe, without over stressing muscle, tendon, ligament, or bone in the process.

Torsion

The natural twisting forces of the foot as it transitions through the gait cycle.

Urethane

A transitional compound between plastic and rubber. Frequently used as a poured midsole, as well as molded midsole processes, or for a variety of upper support thermoplastic applications. Often seen in pelletized form, compressed together to form the midsole.

Vamp

The forward portion of the shoe's upper that wraps from the arch around the toes to the cuboid bone. It surrounds the instep but does not include the tongue of the shoe.

Vibram® compound

A wide variety of specific rubber outersoles, each to manufacturer specifications, by the Vibram Corporation.

Waffle sole

Outersole design, inspired by Nike co-founder Bill Bowerman's attempt to pour polyurethane into a waffle iron to make the running shoe sole. The experiment ruined the waffle iron, and would have been indented instead of protruding, but ultimately resulted in an effective design featured on many millions of Nike shoes. 

Zero Drop Shoe

A shoe with the same stack height under both heel and toe.