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?

The Science of Trail Shoes: How to Pick a Trail Shoe

Martyn Shorten

As noted in the first part of this series, trail shoes are as individual as the runners using them and the conditions trail racers face.  Part II of the series deals to some tips on how to pick a trail shoe based on the  research of Martyn Shorten, PhD, a shoe scientist and head of Biomechanica LLC, a Portland, Oregon company that helps design and test athletic shoes.

"I'd divide them into three classes," says Shorten of the trail shoes.  The first is the "urban trail shoe," which is for mostly runners "running on groomed trails,"  and/or want a trail shoe to run through the snow in the winter.  "A regular shoe will do most of the job, most of the time," says Shorten.  A shoe similar to the one they would normally wear for running on the roads or wet grass.  Many of the shoe companies make trail versions of their road shoes.  The difference being that the trail versions will have a more rugged outsole, a little more traction, water proofing, toe bumper, and a sturdy upper.

These shoes use treatment, material, and/or construction strategies to manage moisture.  For example, a GoreTex upper or treatment with ion masking to keep water out, perhaps gussets to drain water.  "Water always goes in," Shorten notes, and the trail adapted shoe has a way to let it get out.  Though, he notes, water is going to get in, so the best strategy of water management is often a good pair of socks that doesn't retain that water and, in cold conditions keeps your feet relatively dry and warm.

The second category of trail shoes are what Shorten calls "Off Road trail shoes."  These are designed for ungroomed terrain that is uneven, often has sections with rocks and/or forest debris, tree roots, etc.  These are "real trail shoes," rather than adapted road shoes.  More rugged, more luggy(more studs on the bottom to help with traction on soft, muddy, and or loose surfaces).  They have more abrasion resistant mesh on the upper.  They have a "full sole," not one with an arch cut out, for a more stable base so that side to side motion is minimized.

Pronation control is not the major issue for trail runners, Shortyn adds, it's helping to minimize the risk of "rolling," spraining your ankle.  "Total ground contact , a bigger base of support" helps achieve this.  These trail shoes will also have a "plate" in the sole to protect your feet from rocks or other hard, sharp hazards from bruising the bottom of the feet.  And a lacing system with big eyelets, often molded to allow for a smoother movement of the laces as your foot copes with the uneven surfaces, even when the shoe gets wet and/or muddy.

Finally, there is the "Hard Core Mountain Shoe" for extreme terrain.  As these are primarily worn for racing on the mountain running circuit, the shoes should be a "lightweight, flexible, low to the ground package," says Shorten.  Tighter weave in mesh uppers, a rock plate made of lightweight thermoplastic, more rubber on the toe area and possibly around side of shoe as well.  These shoes can weigh as light as from 12 to 8 ounces, yet provide all the toughness necessary for navigating the often sharp, rocky trails.

They have a more abrasion-resistant mesh and a tough rubber outsole.  Some of these specialty shoes may also have "posts" in the midsole to control pronation, the cushioning(usually molded rubber) is firmer, and there is a "substantial structure" around the foot, helping keep the foot stable along with the flat base of the sole.

The flexibility of the shoe is largely a matter of preference, Shorten says.  Usually the top racers want a more flexible shoe as flexibility is more of an issue for speed.  The faster you run, the more flexibility is preferred, but Shorten notes, the great majority of trail runners are not moving at high speed, they may average nine or ten minute mile pace, so flexibility is not a big issue. "Having super flexibility isn't an issue," he says.

"If it feels comfortable," says Shorten, that is more important than flexibility.  Part of that comfort is a non chafing upper.  "So many of the shoes have seamless construction," says Shorten.  Peal Izumi created the first seam-free uppers and now most of the companies produce seam free constructed uppers where the only sewing may be for the tongue of the shoe.  This freedom from ridges and seams helps minimize friction and the potential for blisters.

Running biomechanics is pretty much the same for trail and road running, says Shorten, so the decision on what shoe to wear comes down to the variables of course location, course condition, racing speed, and personal preference.  There is no magic formula or "one size fits all" for trail shoes.  Like running training it can be more "trial and error," figuring out what works for you.

Trail Shoes – Who Needs Them?

This is the first of a two-part look at Trail Running shoes.  The second part will deal with the science that goes into developing these products.

By Alex Kurt
Trail running is growing. Races as famous as the Leadville 100 and as local as the Superior 25K filled in record time this year. Why? Part of the reason is the growth in popularity of ultra-distance races, many of which are run on trails. Though often synonymous, ultrarunning and trail running are not one in the same! 

Ultra runs are often just longer road races, trail running takes participants on journeys over seldom run terrain.  The category of trail shoes has grown along with the sport. Like spikes or racing flats, trail shoes are designed and made to help the trail racer go faster on rugged terrain--rocks, tree roots, mud, and streams. 

What they do

First, no two trail shoes are alike, as no two trails are exactly the same (nor are any two athletes). Shoes like the Salomon Speedcross (http://www.salomon.com/us/product/speedcross-3-fw2013.html) are aggressively lugged for rugged, technical, and/or slippery terrain; they work very well but in a more limited number of scenarios. Meanwhile the Brooks Cascadia (http://www.brooksrunning.com/Cascadia-9/1201531B545.050,default,pd.html#start=4) has a more subtle outsole that allows a broader range of use – from fairly rugged to very runnable terrain, and even pavement – but won’t perform as well at either extreme.

Some trail shoes come from brands familiar to road runners (New Balance, Mizuno, Nike, Brooks) and will feel similar to road shoes; products from other brands (Salomon, Pearl Izumi) reflect little to no preexisting bias for how a “running shoe” should look or feel, often with great, innovative results.

Like road shoes, some are more highly structured while some reflect minimalist principles; some are more stable and some are more neutral; some are more protective and some are lighter. Some are waterproof. The point is that, as with road shoes, there is no “best” trail shoe, only different shoes that work to different degrees for different athletes on different terrain.

That said, there are three primary features in most trail shoes:

1      Increased outsole traction. In other words, cleats. They provide more traction on soft ground, especially climbing and descending. Outsole lugs range from being very aggressive for technical and soft terrain to being more subdued for those runners who don’t live at the trailhead and have to cover a mile or three on pavement to even get to the trail.

2      Increased underfoot protection. This can be a fiberglass rock plate under the ball of the foot, more built-up rubber on the outsole, and/or a hard bumper to protect the toes; whatever form it takes, it is meant to prevent sharp rocks from coming through the bottom of your shoe and rocks of all forms from making direct contact with your foot. The Born to Run crowd might disagree here, but I consider direct foot-to-rock contact a real bummer on any run.

3      Lower profile/decreased stack height. This is not a universal feature
    http://www.hokaoneone.com/men/mafate-3/30109029.html#start=1&cgid=men 
), but many trail shoes allow your feet to sit lower to the ground – regardless of their heel-to-toe differential – so you can better dance over the myriad rocks and roots you’ll encounter off-road. Running on higher platforms offers less lateral control, which can be problematic on the trails, where there’s simply more stuff to avoid.

Who needs them?

Does anyone who ever runs off-road need trail shoes? No. The truth is that most of the trails in the Twin Cities are quite runnable. (The very technical Superior Hiking Trail, near and north of Duluth, is the one trail I can think of in Minnesota that comes close to requiring trail shoes under any circumstances.) If you have only one pair of running shoes at a time and run on a combination of trails and roads each week, the downsides of using a road shoe on dirt will probably be more bearable than the pains of wearing a trail shoe on the roads.

That said, provided you have the down payment for a second (or third or fourth) pair of shoes, having a few different shoes in your quiver can be very beneficial – and not just because both pairs will last a bit longer. Having a pair of shoes designated and designed specifically for your days off-road will simply help you run better on trails; it can also make the experience more enjoyable.

Some other considerations for whether a trail shoe is worth the investment include:

-Are you training for a race that is on trails? If racing well is your priority, consider which shoes will be best for your goal race and train in those. If your aim is to run the Superior 50k and run it fast, you’ll want to grow accustomed to a fairly protective trail shoe by training in them.

-Do you run on the roads in the winter? I work at TC Running Company, and most of the trail shoes we sell between November and March are for road runners who want more traction on snowy and icy sidewalks. Even running around the lakes and along the river in Minneapolis, I’ve found my less-aggressive trail shoes a great fit for the layer of snow that’s become well-packed down by the plows.

-Do you run more than half of your runs on trails? Even if you only have one pair of shoes, the downsides of a road shoe on trails might outweigh the cons of a trail shoe on roads if more than half your miles are on trails.

Ultimately, the shoes you wear are a matter of personal preference. Take Rob Krar, a North Face-sponsored runner who last year took the ultra world by storm, winning two of the year’s most competitive races and placing second at the Western States 100; he was recently named the 2013 Male Ultrarunner of the Year by Ultrarunning Magazine. And he ran every mile, from the fire roads of northern California to mountain passes in Colorado, in Nike road racing flats. Could anyone cover the UROC 100k course in Nike Lunar Racers comfortably? No. But he could, so he did.

Happy trails.

News Bits

MIAC indoor track previews are HERE(women) and HERE(men)

NSIC weekly roundup is HERE

Results from past meets and info on this year's Super indoor track meet in Bemidji are HERE.

USTFCCCA preseason NCAA DI indoor track rankings are HERE. DII rankings are HERE. DII rankings are HERE.

Results from beginning of long-term study on ultrarunners is HERE.

Road Race Management article on the selection process for the 2016 US Olympic Marathon Trials is HERE. Toni Reavis writes on the USATF decision making process HERE.

Running Times winter trail shoe guide is HERE.

USATF Track & Field Clinic and Meet info is HERE.

More pictures and quotes from Garrett Heath's win at the Bupa 4K XC race are HERE.

Pioneer Press on vendors bidding to take over city golf courses at Como and Phalen.  If approved would it impact cross country races, such as MIAC XC championships, cross country skiing in the winter? Article is HERE.

Video from the Meet of Miles is HERE.