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Running shoe soles | Sole technologies | Running brands
September 2014

ABC of

running shoe soles

Every top running brand has developed sole technologies to enhance the performance of its running shoes. JOHANN DU TOIT explains how these unique shoe sole technologies work

Since the 1970’s, running shoe companies have been on a podiatric arms race to produce the ultimate shoe sole. Major running shoe brands have worked closely with podiatrists to produce soles that provide the best possible support, cushioning and performance.

As a result of this collaboration, many different shoe sole technologies have been developed by various brands.

Adidas

Adidas’ revolutionary Boost cushioning sole technology provides “the highest energy return in the industry,” they say.

Unlike other foam technologies, Boost’s midsole is comprised of small plastic energy capsules that are compressed together.

Their unique cell structure enables these spheres to store and unleash energy more efficiently in every stride, adidas explains.

“This cushioning material also maintains its performance in almost any conditions, at unparalleled levels and over hundreds of kilometres. As a result, Boost combines the previously contradicting performance benefits of soft cushioning and responsiveness.”

Because Boost regains its shape very quickly after impact, it has excellent rebound properties.

Boost was first introduced in South Africa in February 2013.

Asics

Asics was one of the first shoe companies to develop unique shoe sole technologies. “The sculpted outer sole is one of the key features that made Asics stand out since the company was established in 1949,” says Ilana Truter, technical manager at Jordan & Co, suppliers of Asics shoes. “Asics sculpt the outer sole in a particular pattern, so that it can deform to absorb shock during the landing phase in your running or walking gait.”

“Most of Asics’ running shoes make use of blown rubber,” she explains. Air is blown into the rubber during the moulding process to give it a softer, more cushioned feel. Blown rubber is also very light, although it can prove to be less durable than other materials.

To increase durability, the blown rubber outer sole is reinforced: “Asics also developed AHAR (Asics High Abrasive Rubber) that is put in strategic points on the outer sole to decrease outer sole wear,” says Truter. This results in a “more cushioned, harder wearing, outer sole.”

Most Asics shoes make use of GEL material in their soles, which is able to absorb energy, while still being responsive. While GEL is often used in the heel and forefoot, SpEVA is used in the midsole of most Asics shoes. SpEVA is a lightweight polymer that is designed to provide rebound characteristics, while still being lightweight and durable.

Brooks

The Brooks DNA midsole technology provides custom cushioning and support for runners of all types and sizes, because it adapts to the specific runner’s size and stride. This results in the midsole offering either excellent comfort or firm support, when and where it is needed.

They explain that this is made possible by the non-Newtonian liquid that forms part of their midsole technology. Normally, the flow behaviour of liquids only change with a change in temperature or pressure and take on the shape of the container — when they don’t follow these Newtonian rules, liquids are called non-Newtonian. When incorporated into the Brooks midsole, it responds to the amount of force placed on the foot and disperses the pressure, providing just the right amount of resiliency, or cushioning.

Their midsole technology offers 30% better cushioning than standard gel or EVA materials, and two times the energy return with maximum impact, say Brooks.

Brooks DNA was first introduced in 2010 with the launch of the Glycerin 8. Since the introduction of the PureProject series in 2011, Brooks have been offering a BioMoGo/DNA blend.

This results in the DNA dynamic cushioning in a lighter shoe because the drop-in DNA pods have been removed. It offers more consistent cushioning, irrespective of the foot strike, because the DNA works across the entire midsole, not just over the pods as in other models.

It is also a more eco-friendly form of manufacturing as it requires less energy and less waste is created. BioMoGo midsoles include a non-toxic, natural additive that increases the rate of biodegradation by encouraging microbes to break down nutrients into reusable byproducts. While traditional EVA midsoles can last up to 1 000 years in an enclosed landfill, tests have shown that BioMoGo can biodegrade in roughly 20 years when placed in the same environment. BioMoGo can save nearly 30-m pounds of waste over a 20-year period.

Brooks is distributed in South Africa by SBR Agencies.

Inov-8

Inov-8 uses different densities of rubber in their outsoles in two ways, says Donovan van Gelder of local distributor Rebel Elite Fitness.

One use depends on the intended application of the shoe. “For example, in a high mileage shoe intended for rugged conditions and long distance running, Inov-8 will use an endurance rubber in the outsole, which resists damage from sharp rocks and other trail debris, protecting the foot and the shoe and giving the shoe a longer lifespan.”

In shoes intended for shorter, faster running, where traction is more important, Inov-8 uses a sticky rubber compound, borrowed from rock climbing shoes, which gives exceptional grip, without adding any unnecessary weight, he says.

The second way that Inov-8 utilises different densities of rubber is by using different rubbers on the same shoe in areas that have different priorities or demands. “In areas of the sole where grip is the most important factor, Inov-8 will use a soft, sticky rubber,” says Van Gelder. “In areas of high wear, a harder rubber will be used, thus optimising the performance of the sole of the shoe.”

Inov-8 also designs the lug, or tread pattern, of the different models depending on the application and demands placed on each model. “Shoes that are intended for softer, loose, terrain will have more widely spaced, deeper lugs, which will sink into the terrain and provide sure, confident contact with the ground.

“For harder-packed, rockier terrain, Inov-8 use smaller, shallower lugs that are more closely spaced to provide traction on these surfaces.”

Inov-8 road shoes have almost smooth soles with only very shallow grooves cut into the rubber to provide superior grip on tar and smooth surfaces, and to channel away water when it is raining.

“One of Inov-8's main design criteria is to provide the best grip with the running surface to give the runner complete confidence on any terrain,” he adds. “These design features have therefore been a part of the Inov-8 DNA since the first shoe was launched in 2004.”

Mizuno

Mizuno running shoes have their signature Wave technology, with a wave-shaped midsole to dissipate energy away from the foot as it touches the ground.

“The Mizuno Wave is a unique technology that combines the two most important elements that make a great running shoe, cushioning and stability,” says Paul Copson of local distributor, Brand ID.

Mizuno have created a Wave to suit every type of runner.

Running places stress on the body. “The unique Mizuno Wave Technology provides the right amount of cushioning and stability your body needs and blends these elements, creating a smooth and easy running experience,” says Copson.

The Mizuno Wave Plate is constructed from PEBAX Rnew, made from plant-based oil, which is sustainable and produces less carbon. The modern moulded version of the Mizuno wave was first introduced in 1997.

The latest Mizuno midsole technology is the U4ic, an abbreviation for Euphoric.

“It allows the athlete to feel light, smooth and euphoric at the same time,” says Copson. It is 30% lighter and has 5% smoother cushioning than their previous AP+ technology.

“It certainly helps the athlete to feel 100% more energised to run faster, go further and release the endorphins that leave you feeling euphoric.”

New Balance

New Balance uses four main technologies in their midsoles: Abzorb, N2, REVlite and Fresh Foam.

Abzorb was the first midsole technology that New Balance developed. It is designed to neutralise the impact of a running stride. “The force from a foot hitting the ground is roughly seven times your body weight. Abzorb is designed to take away this force,” says John Andrew, product line manager at New Balance SA.

N2 is a nitrogen-based cushioning system designed for a quick return. “The advantage for the runner is a speedier feeling and more response from the sole”, says Andrew. N2 was first introduced in 2011.

REVlite is a technology that’s all about weight. “These days, most people are looking for the lightest possible running shoe, and REVlite is our lightest material,” he says. It’s not only light, but also durable. “REVlite is so durable that it can also be used in training shoes.”

New Balance’s newest technology, Fresh Foam, was introduced in January 2014. “Fresh Foam is our softest and safest material, while still being durable,” says Andrew. The result is a very soft and comfortable sole.

Nike

Nike’s latest sole technology is called Lunarlon, which is used in their Lunar range of running shoes. First introduced in 2008, it is the softest and lightest foam compound developed by Nike, designed to conserve energy as you run or walk. The Lunarlon foam is reinforced with a harder foam, called Phylon, to provide structure, where needed.

The Nike Free series was developed in 2005 with an extremely flexible sole, allowing the foot to move more naturally. The series features soles with different levels of flexibility, ranked on a scale from one to ten, one being the most flexible, and 10 being the least.

Nike’s most famous technology, Nike Air, was first introduced in 1987. The Air range uses Cushlon foam in their soles, which is soft and durable, but quite heavy and rigid. In order to decrease weight and add some bounce, the sole is filled with numerous small bags of Air, which is a secret gas mixture.

Olympic

The Olympic range of running shoes are sturdy, lightweight shoes, combined with matching midsoles, suitable for men, ladies and teens,” says Jordan & Co technical manager Ilana Truter.

Olympic shoe soles are based on existing technology, which makes their shoes affordable, while remaining up to date with the latest shoe sole technologies.

“We do not classify the technology used in our running shoes as unique, but rather as suitable for the average, entry level runner, looking for good value for money. Olympic soles provide benefits that we all search for when training, and that is foot support, foot comfort and foot cushioning.”

The South African brand was founded in 1973, and is part of the Jordan shoe group.

Puma

Puma has developed a new material for midsoles in running shoes, says Colin Allin, head of performance at Puma SA.

“Puma’s midsole is made of Faasfoam+, Puma’s new proprietary blend of foam and rubber that is more resilient, springy and 25% lighter.

“The outsole is made of high resistant carbon-rubber for durability.” Carbon-rubber is more resilient than blown rubber, therefore the sole lasts longer. “We mix EVA (Ethylene vinyl acetate, a polymer usually used in foams) and rubber to give a softer and smoother feel when a consumer walks or runs in the product.”

The result is a softer feeling sole, with good shock absorbing qualities, which minimises running fatigue. Faasfoam+ was introduced in June 2014.

Reebok

The Reebok One series running shoe has a sole that is divided into different sections, each fulfilling a different function during a stride. “The One series basically has three contact zones designed for cushioning throughout the stride,” says Gareth Harington, fitness and media manager at Reebok SA.

The heel zone is disconnected from the sole in order to isolate the shock from a heel strike. The mid foot zone is designed to provide support and stability, while the release zone (front of the foot) prohibits pronation (when a foot rolls inwardly after a stride).

The midsole has three foam layers: a soft layer for absorbing shock, a lightweight layer that guides the foot, and a layer designed to provide bounce for quick forward propulsion. The three foams are made from a single mould.

The technology used in the One series sole was first introduced in 2013.

Saucony

Saucony’s latest sole technology is called Powergrid, says Mia Goslett of local distributor Omni-Sport. “With its roots in Saucony’s Grid technology, which has been used since the 1990’s, Powergrid aims to be responsive, while spreading cushioning evenly throughout the sole.”

The Powergrid material is evenly distributed throughout the sole, from heel to toe, which centres the foot, absorbs the impact, and evenly distributes the impact force.

“It is 15% lighter than traditional EVA, which means that the whole surface of the foot can be cushioned, unlike heavier materials that can only be used in small areas of the sole,” she says. “The Powergrid foam is also 30% more durable than traditional EVA, which allows the sole to last much longer.”


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