Shoes

by Patti and Warren Finke, Team Oregon
One of the most important aspects of a running program is a pair of proper fitting or functioning shoes. Many injuries in runners are the result of improper fitting shoes or the unsuitability of the shoe characteristics for the biomechanical needs.

Tremendous stresses are generated at the foot during running. Shock forces up to three times the runner's body weight are generated at foot strike. In addition, normal biomechanics require the foot, while loaded, to roll from the rear outer edge supinated to the inner edge pronated. The foot then returns to a supinated position at toe off. This creates additional angular and lateral forces that must somehow be absorbed by the body. Shoes can either damp these forces and/or amplify them depending on how well they match the needs of a particular runner.

The running body is a closed kinetic system. The forces and motions, which occur at the foot and the ankle, are transmitted up the legs to the knees, hips, lower back and shoulders. These forces and motions can cause a myriad of different running injuries that may simply be the result of running in the wrong shoes.

KNOWING YOUR FOOT

Take off your shoes and socks. Feet can be divided into three basic shapes illustrated below. How can you tell which shape is yours. Get a piece of colored paper, wet the bottom of your foot and step on the paper. Draw around the wet shape with a pencil and compare to the drawings below.


  1. The high arched rigid foot - This foot holds its shape when force is applied making it less likely to create excessive motion (e.g. pronation). However, the lack of movement means that it does not absorb shock well.
  2. The flat flexible foot - This foot has little or no arch and it flattens like a big suction cup rolling to the inside (pronating) as it is stepped on. This foot does not hold its shape and creates extra motion, but absorbs shock well.
  3. The in between foot - If this is your foot, you are lucky. This foot is fairly stable and absorbs shock fairly well.

SHOE FIT

Shoes come in different shapes or lasts to match these foot shapes. They are called curved, straight and semi-curved lasts. Choose the shoe shapes which best matches your foot with the curved matching the high arched and the straight matching the low arched.


Matching the width of the foot to the shoes is important in two major places - the heel and the forefoot or metatarsal area. If the shoe is too wide in the heel, the heel slips, and the stability or lateral support function of the shoe will be negated. The shoe needs to be wide enough in the forefoot area to allow for the spreading of this area that occurs during the foot strike. Shoes that are too narrow here contribute to toe joint stress creating callouses, bunions and inflammations of the nerves between the metatarsals known as neuromas.

Weighting flattens and elongates the foot. Any arch support in the shoe must allow for flattening by only being large enough to fit the arch when the foot is weighed. The shoe needs to be long enough to allow for foot elongation. Moreover, extra space is needed when running downhill and to allow for shoe shrinkage from getting wet. You should be able to put your thumb between the end of your toes and the end of your shoe when standing. Many of you will recognize this as the way children's shoes are fitted. Forget about the size marked in the shoe, different brands and models from the same company can vary widely.

The last word about fit is that shoe must feel comfortable in the store. You should walk around in both shoes for 5 - 10 minutes and evaluate the feel. You should run in the shoes and see how they feel. Shoes do not break in but should fit and function from the beginning.

SHOE FUNCTION

Shoes can perform several different functions, some of which are in opposition. For instance, a shoe with lots of cushioning will generally not have a high degree of stability. Fortunately, there are ranges of shoes with different properties designed to match various runner's functional needs.

Cushioning

Shock absorption in the foot takes place in two ways, 1) The foot flattens when it is weighted and 2) the ankle rolls (pronates) to the inside. The high arched rigid foot is a poor shock absorber. It does not flatten and is kept from pronating by the stiffness of the forefoot when the big toe hits the ground. To compensate for these attributes, shoes are designed with softer and possibly thicker midsoles that squash down under the foot for cushioning and with curved lasts and flexible uppers which encourage pronation.

Stability

The flat flexible foot absorbs shock well and pronates well. In fact, it often pronates too well. To compensate for these traits, shoes can be designed for stability. These shoes have rigid uppers ( stiff heel counters and extra reinforcing pieces) and straight lasts to discourage pronation. They may use denser, stiffer midsoles which are more stable with less cushioning. Since it absorbs shock well, the flexible foot does not need as much cushioning.

Flexibility

A certain amount of front to back flexibility is needed in the forefoot of the shoe to allow efficient toe off. Unfortunately it is difficult to incorporate this flexibility without making the forefoot too flexible laterally. Too much lateral flexibility in the forefoot causes shoes to be unstable in the later phases of weighting and, in our opinion, has resulted in many lateral support tendon overuse injuries in runners (e.g. posterior tibial and perineal tendinitis).

WHEN DO YOU NEED NEW SHOES?

If you are like most runners, you need them right now. This is because you are either running in the wrong shoe for your needs or you are wearing shoes that are worn out.

Three ways to tell if your shoes are worn out:

  • Mileage: A good sturdy pair of training shoes may last you 600 miles. Any shoe called a "lite" trainer, a "racer/trainer" or "racing" shoe may be good for 300 miles. Cross training, aerobics, walking or court shoes are good for 0 (zero) miles of running. They are great for beer drinking and other things they were designed for.
  • Wear: Most people think wear applies to the outsole. However, modern running shoe outsoles are extremely durable and may the last part of the shoe to wear out. Normal sole wear is from the outside rear corner of the shoe to the toe off point underneath the big and second toes. If your sole wear is radically different, you might want to talk to a sports medicine biomechanical specialist. Most of the wear in a shoe takes place in the midsole that crushes down and in the upper that stretches, rips, breaks or deforms. Any of these problems will cause a loss of function in the shoe. Check for obvious compression of the midsole at its greatest load points of heel strike and toe off. Put one hand inside your shoe and the other on the sole. Compare the thickness, compressibility and cushioning under the big toe joint to other less stressed areas. Check the heel counter by flexing it side to side with your hands. If it makes a clicking sound, it may be broken. Look at the uppers to see if they are coming apart or are badly stretched out of shape.
  • Looks: No matter what kind of shoes you have picked, if you wear them long enough, they will look just like your feet and have the same bad habits. The stability shoes can become pronating shoes and the cushioning shoes develop rigid midsoles. Put you shoes on a table so that you can look at them at eye level from the rear. Are they pronating? Try putting your hand in your shoe so that your thumb is at the outside back of the heel and your first finger is where your first toe joint sits. Now, rock the shoe forward and back as if you were running. Is there excessive roll to either side?

BUYING NEW SHOES

First know your foot and your needs. Do you need stability? Cushioning? A durable training shoe? Racing flats? When you go to the store you should have some idea of what to ask for. If you have shoes that either do or do not work for you now, consider taking them to the store or at least remember what model they are.

Go to a reputable running shoe store where the employees understand running shoes and how to select and fit the most appropriate pair for you. Ask around. The store should allow you to walk and, most important, run in the shoes and, possibly, observe you running in them for proper motion. Just because a shoe is advertised as a motion control shoe doesn't mean it will control YOUR motion.

Make certain the shoes fit correctly as mentioned above. Buy a quality shoe. You usually get what you pay for and shoes are cheaper than doctors.

Phase in new shoes. Start by alternating use with your old ones. If the shoes are working well for you after a couple of weeks use, consider buying a second pair of the same kind to alternate running in. This will make your shoes last over a longer period of time and their running characteristics will change more slowly.

Another good strategy is buying a new pair of shoes when your other pair is half worn out. In this way, you can alternate use between the new and old pair and minimize the risks of the old shoes creating problems.


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