Jargon-buster - Shoes

Blown rubber The lightest, most cushioned and least durable form of rubber used on a shoe’s outsole. It is made by injecting air into the rubber compound.

Carbon rubber A harder, more durable outsole, made from solid rubber with carbon additives.

Cushioned shoe Our term for a shoe without added stability features, for biomechanically neutral runners.

Cushioning The ability of a shoe to absorb the extreme forces of footstrike. Softness varies between shoes. Except at the extremes, there’s no right or wrong, though heavier runners tend to do best with firmer shoes.

Efficient See biomechanically efficient

Flex grooves Indentations moulded into the midsole and outsole to make a shoe more flexible, usually under the ball of the foot.

Flexibility The ability of a shoe’s forefoot to bend under the ball of the foot. If the shoe does not flex easily under your weight, your foot and leg muscles have to work harder, which saps energy and can cause injuries such as shin splints.

Forefoot The broad, front section of the shoe or foot. This is the point from which you propel yourself forward, so the shoe should be protective yet responsive. Some runners land on the fronts of their feet, and need maximum cushioning in the forefoot of their shoes. They’re called, appropriately, forefoot strikers.

Gait cycle The natural movement of the foot against the ground when you walk or run. The rear, outer part of the heel hits the ground first: the foot then rolls forwards and inwards (pronates) as the arch collapses to absorb shock; then it moves onto the inner and front part of the forefoot as the foot stiffens and pushes away from the ground (toe-off).

Heel counter A firm, usually plastic cup that is encased in the upper and surrounds the heel. It helps to provide a good fit and control excessive rearfoot motion.

Heel tab The back of the heel collar, which provides a secure fit and nearly always has a notch cut in the top to prevent irritation of the Achilles tendon.

Insole The foot-shaped insert, usually removable, which sits between your foot and the shoe. Now sometimes called a sockliner.

Last The foot-shaped mould on which the shoe is constructed, the shape of which strongly influences the function of the shoe. The straighter the last, the more stable the shoe. The more curved it is, the faster but more unstable the shoe.

Lateral The outside (little-toe) edge of the shoe.

Lugs Deep rubber tread on the underside of the shoe to provide grip in off-road conditions.

Medial The inside (big-toe and arch) edge of the shoe.

Medial post A firmer density of foam, sometimes with an additional plastic device, inserted into the rear, arch-side section of the midsole to add support to the foot or to control excessive rearfoot motion.

Midfoot The section of the shoe around the arch. Plastic shanks are often built into the midfoot of the shoe under the foot to provide added stability.

Midsole The foam cushioning layer of the shoe between the upper and the outsole. It’s the technical heart of the shoe and contains its primary cushioning and stability features.

Motion control shoe Our term for a shoe with added heavy-duty stability features, for big runners or runners with severe stability problems.

Neutral See biomechanically efficient

Outsole The outer rubber section of the shoe which comes into contact with the ground.

Overpronation Excessive inward rolling of the foot, which prevents normal toe-off and exposes you to a host of injury problems, particularly in the knee.

Over-supination An extremely rare condition in which the foot fails to roll inwards as you run. Instead, it strikes on the outer edge of the foot and continues to roll outwards.

Performance trainer Our term for a light shoe with enough cushioning and stability for some everyday training.

Pronation The inward rolling of the foot which is a natural part of the gait cycle.

Rearfoot The back section of the foot immediately behind the arch which takes the primary force of footstrike.

Responsiveness The ability of your forefoot to feel the ground as you push away from it.

Ride The overall feel of the shoe through the complete gait cycle. In a smooth-riding shoe, the gait feels like one continuous movement rather than impact then forward rolling then push-off.

Stability The ability of a shoe to reduce excessive foot and ankle movement, which can lead to injury throughout the body. Overpronation is the key danger. Simple design elements such as a straight shape, firmer cushioning or a thinner midsole help stability, as do added features such as a medial post (pxx) and midfoot shank (pxx). A runner’s stability needs depend on how unstable their natural running style is.

Stability shoe Our term for a shoe specifically designed to help runners with an unstable gait. Not as extreme as a motion-control shoe, though.

Supination A natural outward rolling of the foot, which is a small part of the gait cycle just before the foot starts to leave the ground.

Toe-box The front part of the fabric upper which surrounds the toes.

Toe-off The final stage of the gait cycle which propels you forward as your foot pushed off from the ground

Upper The fabric section of the shoe that surround the top of the foot and holds the laces.

...And the technologies

3D Ultralyte Reebok’s combined midsole and outsole foam. Light, durable and flexible.

Abzorb New Balance’s rubber cushioning insert.

Adiprene Adidas’s viscous EVA rearfoot cushioning insert. Adiprene+ is springier foam-based forefoot cushioning.

Air Nike’s pressurised cushioning units, in various sizes. Zoom Air is a thinner, more flexible version. Tuned Air contains pairs of plastic hemispheres for stability.

Cantilever Avia’s concave heel unit, designed for cushioning and stability.

Cell Puma’s honeycomb-shaped cushioning technology. E+ Cell replaces most of the midsole;
I-Cell is a smaller insert.

DMX Reebok’s unit of interlinked air-filled pods. The movement of the foot pushes air from pod to pod for cushioning and stability.

DUOCELL Puma's durable cushioning insert made of hexagonal material. Usually positioned under the heel.

Gel Asics’ pads of silicone (or silicone-based) cushioning gel. Comes in various sizes.

GRID Saucony’s cushioning and stability cassette made of Hytrel strands, which are strung like a tennis racquet. 3D and 4D GRID have added stability.

Hexalite Reebok’s most basic cushioning insert. Soft, honeycomb cells.

HRC Saucony’s cushioning foam insert in the forefoot.

HydroFlow Brooks’ cushioning pads, containing silicone oil. HydroFlow ST adds stability.

SKYDEX Pearl Izumi's cushioning insert found in the SyncroGuide and SyncroPace.

Substance 257 Brooks’s high-durability cushioning foam insert.

Wave Mizuno’s large, flexible fan-shaped midsole insert. Different configurations for stability and cushioning. X-Wave has a flat centre ‘sweet spot’.

V1 Mizuno’s forefoot cushioning pad.