Cushioning is not the only crucial element in shoe selection. The type of shoe that you run in needs to fit your biomechanical needs. Anyone who has stood before a shoe wall at a running specialty store recognizes the sheer number of choices presented to the runner in this technological age. This choice can be daunting if you do not have an experienced, informed shoe technician to guide you through your selection process. So what is the shoe tech looking for when they ask you to take off your shoes & walk or run for them? Basically they are looking to see how your foot moves & how this movement affects the rest of your legs, from your ankle through your hips. You may hear the shoe tech use some unfamiliar words when describing your form so I will provide a short glossary before we continue.
Shoe Tech Talk
Biomechanics – Biomechanics refers to the line your body takes across the ground & through the air. Biomechanics can be divided into three basic areas: the feet & lower limbs, the core (hips to abdominals, including the lower back) & the upper body (including the head.) Our concern here is with the biomechanics of the feet & lower limbs.
Medial - to the inside of the shoe.
Lateral - to the outside of the shoe.
Pronation - the foot rolling medially, usually causing the knee to rotate inwardly.
Supination - the foot rolling laterally, usually causing the knee to rotate outwardly.
Last –A shaped piece of wood on which the shoe is built. The shape of the last determines the shape of the shoe. Shoes are made in three basic shapes: straight, curved and semi-curved, but all three shapes vary from company to company as each company has its own lasts.
Midsole – The midsole is the part of the shoe that is responsible for cushioning & support. Midsoles are made of two basic materials: EVA & PU. In recent years many manufacturers have been adding new pronation controlling & cushioning devices in the midsoles of shoes, from the Nike Footbridge to the Mizuno Wave technologies.
EVA – Ethylene-vinyl-acetate. The majority of shoes today are made with EVA. This is the softest, most cushioning midsole material & very light but is less durable. EVA is highly compressible & engineered in different durometers, which affect the levels of cushioning & support. Nike’s version of EVA is termed Phylon.
Polyurethane (PU) – This is a firmer, more durable midsole material that is not used as frequently as EVA. It is a heavier material. There are few shoes made out of PU today, though there are a sizable number of manufacturers who are using PU in the rear foot & EVA in the forefoot.
Density/Durometer – EVA is engineered in different durometers or densities, which affect the levels of cushioning & support. A higher the durometer indicates a firmer midsole. Different densities are used to control the foot’s medial rotation. A firmer or dual density section on the medial side has become the most frequently used method of controlling pronation.
Outsole – The outsole is the material used on the bottom of the shoe that grips the running surface. It is very much like the tread of a tire. There are two basic rubbers that are used on outsoles: carbon & blown rubber.
Carbon Rubber – Carbon rubber is the more durable of the two but it is heavier. Each company has their own special chemical recipe for their rubber. Carbon rubber is very long lasting & most shoe companies now combine both carbon & blown rubbers in their outsoles.
Blown Rubber – Blown rubber is significantly less durable than carbon but much lighter.
Upper – The upper of the shoe has the most to do with the fit & comfort of a shoe. After you have determined the right kind of shoe for your biomechanics, the selection of your shoe is almost completely a question of what feels best on your particular foot. The largest difference between the different shoe manufacturers can be seen in the fit of the uppers: some companies run narrower, others wider.
Ride - The ability of a shoe to provide a smooth transfer of a runner's weight from heel-strike to toe-off. Ride is a largely subjective quality, but shoe wearers know it when a shoe has or lacks a good ride.
When you go to purchase a pair of shoes you should always try to bring the current pair of shoes you are running in. If you are not running, bring a pair of shoes that you use for athletics or walking. These shoes will speak volumes to a quality shoe technician. They are looking at wear patterns that you exhibit: which areas of the outsole show the most wear, is it the heel or the forefoot (the majority of the human population strikes on their heel, especially people in first world countries where people are accustomed to wearing shoe most of their waking hours); how is the midsole compressed, does it indicate a tendency to pronate or supinate; is there anything unusual about the wear of the upper that will indicate bunions or an extremely wide or narrow foot? Before the shoe tech even sees your feet (provided you brought your current shoes), he or she should be able to determine your general biomechanical propensities.
Now the shoe tech is ready to see your feet & watch you walk. When they look at your feet, the shoe tech is principally determining the flexibility & length of your arch. The flexibility of the arch will indicate the runners biomechanical tendency: a highly flexible arch usually will indicate a heavy pronator, this is because the arch does not fall directly down, it collapses in, or medially; a rigid arch will indicate an even foot striker or a supinator. The level of flexibility will determine the amount & type of support you need in your shoe. The shoe tech should also look at the length of your arch to see what brands of shoes will work best with your arch type. The width of your foot, narrowness of your heel, length of your second toe (Morton’s toe is a second toe that is longer than the big toe) & any other unusual attributes of your foot will also be taken into consideration when the shoe tech determines which shoes will mostly likely work for you. The shoe tech should also ask to see you walk barefoot, in order to see if you splay your feet out as you walk, or if you walk pigeon-toed. Any amount of toe in or out will have an impact on your knees & needs to be take into consideration when selecting a shoe.
You can see that there is a lot of information that the shoe tech is taking processing before choosing shoe options for you. This is why it is so important to go to a running specialty store that knows what to look for in your particular gait. It can be the difference between health & injury, between comfort & pain. The staff at RunTex is highly trained & very experienced. There are a few other considerations you should be aware of in regard to your shoes:
· You should expect to move up a half or full size from your dress shoe when purchasing running shoes. There are two reasons for this. First, the sizing standard is flexible in the running shoe industry, each factory has subtle variations & as the uppers are glued to the midsole, the sizing is affected. Secondly, your foot will swell inside the shoe as you run & if you purchase a shoe that is too small it will cause blisters or black toe.
· The life of a shoe is completely dependent upon the compression of the midsole. For this reason a shoe may look like it has many more miles left in it when actually it is completely broken down. A runner’s weight, the frequency of use, the time of year & other factors will determine how long your shoe will last. Most midsoles can be expected to last between 350-450 miles. We recommend you write the date you start running in your shoes inside the shoe or in your running log so you will have a better idea of when they will break down & be prepared to replace them.
· If you do not have any idea of how many miles you have on your shoes, you can usually tell if they are broken down by new aches & pains in your knees, Achilles, lower back or hips. As you become more familiar with your body & its pain thresholds & indicators, you will have a heightened sensitivity to when your shoes are ready to be replaced.