Shoepaedia: Key Running Shoe Terms Explained

In-depth explanations and diagrams to help you understand more about how running shoes are constructed


Posted: 4 August 2009

Collar

Ever notice how the collar, or the part of the shoe that fits around your ankle, is lower on one side? This is because the bone on the outside of your ankle is lower than the one on the inside. Because the collar's job is to fit snugly under the ankle bones, it's always asymmetrical. No two ankles are the same, so a collar's fit isn't always perfect. This is why you should look for a collar made of a soft material, like memory foam, without any stitching or seams that can irritate the skin. Also, lacing your shoes differently can help lock a loose collar around your ankle. Here are five lacing techniques to improve your shoe's fit.

Decoupled Heel

This split design in the heel works like a car's independent suspension to isolate the initial strike zone at the back of the shoe from the rest of the sole unit. This design improves a shoe's shock-absorption capabilities by reducing the impact forces travelling from the heel to the rest of the outsole and midsole. The latest running shoes achieve this function by using column-like pods in the heel to act as individual shock absorbers. Since 80 per cent of runners land on their heels first, decoupled heels have become a popular way to enhance a shoe's cushioning.

 

 


Footbridge

A reinforced platform under the arch between the heel and the sole that prevents the shoe from bending in the middle. The footbridge, or shank, supports the foot between the heel of the shoe and the forefoot and supplies torsional rigidity to prevent the shoe from twisting easily under landing pressure (excessive twisting can lead to runner's knee and other joint alignment injuries). To test the torsional rigidity of a running shoe, hold it at the heel and toe with both hands and try to twist the sole from side to side in opposite directions. The harder it is to twist the shoe in the middle, the more stable its foundation and the better the torsional rigidity.


Gait pattern cycle

Heelstrike
The moment the heel first makes contact with the ground is also the moment it experiences the most impact force. A well-cushioned shoe will help the foot absorb this impact as it moves to

Footstrike
The instant when the foot lies flat on the ground. Your foot doesn't start to pronate until both the heel and forefoot connect with the ground.

Toe-off
The propulsion phase of the gait pattern starts when the heel lifts and the body begins to move forward. Efficient runners spend as much time absorbing the impact of each footfall as they do propelling themselves forward.


Heel Counter

As the part of the shoe that aligns the foot as it strikes the ground, the heel counter should cradle the heel but not be so stiff that it irritates the lower ankle. Its primary job is to support the heel and keep it secure in the shoe, which is particularly important since 80 per cent of runners strike the ground on the outside of the heel, with the foot twisted slightly outward. If the heel counter doesn't do its job, this angled footstrike can cause the foot to move and compromise the shoe's support. In motion-control and stability shoes, the heel counter commonly reaches further down the inside of the shoe to help control overpronation.

Impact Force

When your foot hits the ground, the force that travels through the leg is about 2.5 times your body weight. To absorb this shock, the body reacts in several ways, including pronating and flexing at the hip and knee. In runners with a normal footstrike, the force of impact is concentrated on the outside of the heel. The foot rolls inward (pronates) toward the arch to absorb the impact. Then it rolls outward, and the force travels forward toward the ball of the foot as the runner toes off. Shoes often utilise shock-absorbing foams and design features, such as independent heel lugs, to absorb, isolate and disperse impact force.


Laces

Laces are what most people older than eight and younger than 80 use to secure the upper of a shoe around their feet. Velcro is a distant second. Laces come in different lengths, according to the size and design of the eyestay and eyelet pattern. They are the only component of the upper that gives you direct control of a shoe's fit, so experimenting with different lacing techniques can often improve the overall comfort. Previously made from cotton, today's shoelace is constructed from long-lasting polyester thread, giving manufacturers more lace-construction options. Laces shaped like sausage links, for example, are less likely to come undone.

Last

A last is the foot form that a shoe's upper is built around, giving the shoe its shape. It's the single biggest factor that determines how a shoe fits, so knowing what goes into the design of these dense plastic moulds will give you a better idea of how your next pair should feel on your feet.

Heel to Toe
This is the aspect of fit most people are familiar with. If your shoe doesn't offer a bit of extra length, your toes will jam into the front of the toebox, which can result in black toenails. This is because your arch flattens and your foot lengthens as you move through your gait cycle.
Fit tip Tap your heel on the ground so it rests firmly in the back of the shoe. Then press on the toebox. You should be able to lay your thumbnail on the upper between the tip of your shoe and your longest toe.

Heel to ball
If the length from the heel to the first big-toe joint (the widest part of the foot) is off, the foot may move inside the shoe. This can compromise stability and cause blisters by not keeping the heel snug and not holding the arch effectively.
Fit tip The ball of the foot should fit in the widest area of the shoe. The easiest way to find this spot is to pick up the shoe and flex it. The area where the shoe bends is the widest.

Ball girth
The measurement around the widest part of the foot impacts the arch fit. If it's off, the shoe might not offer the support a runner needs because it doesn't properly wrap and support the foot. Improper fit can even lead to plantar fasciitis.
Fit tip Not only does your foot slightly lengthen as it hits the ground with each stride, it also spreads out, so you need a bit of extra room in the toebox to accommodate this. You should be able to pinch a quarter of an inch of upper material along the widest part of the forefoot.

Top-line length
This measurement affects the way the shoe fits the heel and supports the arch. If the collar height and top-line length are off, the shoe doesn't lock around the ankle, which will cause the arch to slip.
Fit tip Top-line length is off when you feel a lump ahead or behind your instep, which is the highest point of your arch. The “lump” you feel is your foot not sitting properly in the shoe, which could mean that the shoe isn't right for you. To find out, go down or up half a size.

Collar height
The height of the shoe as it dips around your anklebones is different on both sides because the two bones that form the base of your ankle end at different points. The tibia (the inside bone) is higher than the fibula (the outside bone).
Fit tip Make sure the eyestays are parallel when your feet are in the shoe. If you feel pinching along the top of your foot when you step forward, your collar heights are too high, your laces are too tight, or you are using an extra eyelet you don't need.


Outsole

As the shoe's bottommost surface, the outsole supplies traction and durability. Outsole designs vary greatly, but they are commonly constructed from carbon rubber, the same material used in car tyres. Shoemakers also commonly use blown rubber (rubber that contains more air) in the forefoot of outsoles because it provides better cushioning at the expense of some durability. Since it's the initial point of impact, the outsole often includes features like decoupled heels and footbridges that assist in the overall cushioning and support. Every running-shoe outsole functions in a similar way, yet looks a little different because most manufacturers have a signature tread pattern in each line of shoes.


Overlay

Pretty much anything that is stitched or bonded to the upper, though the term most commonly refers to the reinforcing strips that provide structure to the shoe. The famous adidas stripes were adapted from the three leather overlays that wrapped around the company's early athletic shoes. Overlays can be used to decorate running shoes in the same way and are often made from reflective materials to increase a runner's visibility at night. Most of the time they are stitched to the upper but can be welded on to reduce the amount of thread that can irritate the skin. This is the reason stitched overlays are often backed with fabric over common blistering and chafing hot spots on the foot.

Sockliner

Since shoes are mass-produced to fit a wide variety of foot shapes, manufacturers use these removable foam footbeds to cover the seams and gaps in a shoe's construction, conforming it more comfortably to the bottom of your foot. There isn't much to most sockliners, so if you're looking for ways to improve your shoe's fit, you might consider replacing them with a more substantial footbed. Before you do this, however, make sure your shoe provides the essential support, cushioning and fit you need, since no other element is going to add what isn't there to begin with.

Improved fit
Some narrow feet can benefit from an additional cushioned insole under the sockliner that raises the foot to provide a more snug fit. Conversely, a flatter footbed from another pair of running shoes can provide wide feet with a little more room.

More cushioning
If you've found a great fit but you're looking for a softer feel, try a pair of flexible insoles, such as Sorbothane's Ultrasole or Spenco's Cross Trainer. Make sure the shop assistant checks the fit to make sure it won't affect your stride in any way.

Corrective aid
Doctor-prescribed footbeds, or orthotics, don't always extend all the way to the toes, so that they can be used in a variety of shoes. Cutting a sockliner so that it fits flush against the front of an orthotic can improve the fit and reduce the chance of blisters.

More stability
Replacing the sockliner with a supportive footbed will reduce the collapsing of the arch that leads to muscle fatigue and running inefficiency.


Tread

Tread is the part of the outsole that comes in direct contact with the ground. On road-running shoes, treads supply cushioning while giving the shoe a bit of added traction. Runners often refer to these small raised treads as waffles (left), in reference to the first popular Nike outsole created by Bill Bowerman with the help of his wife's waffle iron. On trail shoes, where traction is more important than cushioning, the raised treads are called lugs (right). Lugs are often deeper, with straight edges rather than the more rounded edges found on road shoes. These may be moulded as an integral part of the outsole or encapsulated in another material to form a separate unit.


Upper

In the most basic terms, the upper is the top part of a shoe that encases the foot. It's made from a soft, breathable mesh that gets stretched around a foot form – or last – to mould it into shape. This mesh is reinforced with more durable material and moulded plastic that holds the foot in place. Here's how all the individual pieces of the upper determine how your running shoes feel on your feet.

1. Laces
Used to pull the upper around the arch. If you can feel your laces, either they're too thin or the tongue isn't thick enough.

2. Tongue
The tongue should be pulled up tight and line up straight between the eyestays (which anchor the eyelets). You should use a tongue's lace keeper to hold it in place.

3. Overlays
These strips work with the laces and eyestays to make the shoe conform to the shape of the foot.

4. Collar
Made out of a soft material, the collar should wrap just below the ankle and supply a snug, gap-free fit.

5. Vamp
A part of the upper that surrounds the toebox. If you can pinch a quarter inch, the vamp is too baggy. If you can't wiggle your toes, it's too tight.

6. Saddle
A reinforced mesh that tightly wraps the midfoot and supports the arch. If it's not snug, the foot will move inside the shoe, causing blisters.

7. Eyelets
The laces run through these to tighten the shoe. If you feel pressure under a pair of eyelets, you don't have to use those ones to tie your shoe.

8. Heel counter
The fit of the shoe isn't perfect unless the heel sits flush against this stiff backing. Tapping the foot back into the heel will lock it into position.


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