Friday, February 21, 2014

The Science of Shoes: What Will the Future Bring?

The final installment of the Trail Shoe series deals with the science involved in shoe design and materials.  Since the majority of people purchasing running shoes don't run--they either want to look like an athlete or be able to walk in a comfortable shoe--it's easy to see why marketing concerns on design, color, etc. play a big role in running shoes.  Without the science, however, they wouldn't be as comfortable nor as functional for runners.40 years ago, the only real running shoes were track spikes.  Today the variety in the running shoe market is staggering.

Arguably, no category of running shoes puts a premium on science more than the trail shoes.  While many African athletes have run barefoot and the Tarahumara tribe of Mexico seem to do fine in the most rugged of wilderness conditions with mere sandals, the rest of the world seems to want footwear with the most modern technology and design backed by science to help them go faster, avoid injury, and keep their feet comfortable.

To design and build trail shoes, the creatorss wanted three things: durability, traction, and water and mud resistance.   They had models to follow, said Rob Lyden, a Minnesota coach and inventor who now lives in Oregon.  The tire industry did extensive research to develop types of rubber that could grip the road or trail in all sorts of conditions whether these tires were for bicycles, or race cars, or all terrain vehicles.  The army did research to develop the Panama sole for army boots that gripped in the soft, muddy jungle terrain, but repelled the mud, didn't allow it to stick to the sole.

Clothing manuafacturers came up with Gore Tex and later ion masking agents that basically repelled water from the surface of the fabric.  In developing cleated soccer shoes, Lyden developed a non sticking outsole that was flexible enough, but repelled mud the same way the ion mask treated fabrics repelled water.  For trail shoes, says Martyn Shorten, head of Biomechanica LLC, you want a tread pattern that grips the ground, but doesn't allow mud to stick to the bottom of the shoes.

So, a combination of  well placed "lugs"(think differently designed cleats placed at different ankles on the sole of the shoe), the researchers found when placed in a cantalevered fashion, as on the Panama sole did the trick.  Spacing and angling of the cleats have very elaborate criteria, said Ned Frederick of Exeter Research, to allow them to perform the desired function of grip and mud repulsion.  Shoe designers call it the "dog shit" factor, says Frederick, noting that the pooch excrement is even tougher to keep off a sole than mud as it seems to have a natural adhesion that pastes it to non repelling surfaces.

Dupont and 3M have developed treated fabrics that deal with the water issue.  Mesh fabrics with tiny pores are used to keep water out.  Using such fabrics with high top shoes, if one is comfortable in that type of footwear, can minimize the water that gets in or is retained by the shoe.  If you're on a course that has you wading through streams, there are shoes designed much like track spikes for steeplechasers that has discharge valves in the arch area of the foot, so each footstrike acts as a pump to spew the water from the shoe.

Socks, says, Shorten are important in water management, maybe even more important than the other measures, as a pair of cotton socks will hold that moisture from both sweat and stream creating a "lead weight" on your feet.  A "wicking fabric" is just as important inside the shoe, in the socks, as it is for the base layer of clothing that keeps you dry and warm during winter runs.  Another key area of water management has been the use of injected, molded midsoles that have a closed pore construction.

If you had blown foam midsoles in the past you'll rmember how light they felt when you put them on out of the box, but the first time you ran with them on a rainy day or through puddles their weight increased.  Not unlike cotton where the fibers soak up moisture and trap it, open pored mid soles would retain some of the moisture they absorbed creating the increased weight.

Looking toward the future in shoe design Shorten says that the new innovations will probably come in new materials that are either lighter, more durable, use a tighter mesh, are water proof or a combination of pieces that do many or all of these things.  Lyden has patented designs for a modular shoe--a shoe that could be customized according to individual conditions, sort of like race car or bike tires that have specific materials and or design to perform maximally at certain temperatures, under wet conditions, or on a soft or hard surface and can be changed during the course of a race to allow the car to perform maximally under the new environmental conditions.

40 years ago these were the "hot"training flats for
runners.  What will tomorrow bring?
While many of us can remember the day when the shoe's we trained and ran in were more like basketball or tennis shoes than designed specifically for running.  The future could well mirror the specially designed and fitted shoes top elite athletes make available to their top runners.  Some day mass market shoes that individuals can order that are created to meet their specific needs may make what we have today look like relics.  If we can have shoes for trail, roads, and track, why not for an individual?  And if the barefoot model for locomotion is one day proved to be the best, then shoes may become like a "second skin," wrapping the foot in a coating that has protection where needed as well as allowing full articulation of the human foot.

In as short a span as 40 years athletic footwear has become a major industry producing a huge variety of products.  Who knows what the future will bring?

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