Reduce Your Injuries by First Understanding Footwear Cushioning

Looks can be decieving

Many patients with common foot injuries will tell us they decided to start excersizing again for fitness or to lose wight, so instead of purchasing a new pair of shoes they will drag out an old pair from the garage.

Justy because your footwear is clean and still looks good, doesn't mean that they are still functioning and supporting your feet the way they once did. Also, some footwear matertials breakdown over time when not used.

In simple terms, an athletic shoe is broken down into three parts. The upper, the midsole (cushioning) and the hard outsole.

Focusing on the Midsole

Footwear manufacters like to use cool terms to describe their point of difference in footwear features, such as "air" "gel" Energy return systems, MoGo and Stability cradles, yet most athletic shboes share a common denominator, which is a rubber type of material called EVA. This is used in the midsole of the shoe. The make up and composition of this material is like the "colonel sanders secret recipe", It is often blended with other materials. Giving maximal energy return, cushion and durability.

Eva is made in varying densities and use a numbering system to indicate its softness or firmness. For example, EVA 120 is quite soft, whereas EVA 350 is quite firm. So, when purchasing shoes, it is a good idea to ask about the density of the EVA used in the shoe. Remember commonly density is the shorter the lifespan, the heavier you are, the firmer, the density will last longer.

What makes a shoe cheap?

Less-technical, and cheaper footwear tend to use segmented rubber throughout the mid-sole of the shoe. whereas better quality and more expensive footwear will tend to use a combination of EVA densities in the same mid-sole.

Warning, some very cheap athletic shoes do not use any EVA and instead use hollowed out hard rubber. The reason they use rubber is because its extremely cheap and they hallow it out because it's quite heavy material so hollowing it out reduces the weight and means they use less material. But it is unstable, weak and not durable. The problem is it looks like EVA, but has as much function as an ashtray on a motorbike.

Design Purpose

We have seen increased attention given to rocker profiles recently. The shape hardness of the EVA and where it is placed in the shoe design will be determined by the purpose of the shoe.

Most shoe uppers will look good if they are cleaned on a regular basis and the outsole of the shoe will wear depending on the surface it was used upon.

Shoes used to run on the road will normally show significant outsole wear after a period of time,  or number of kilometers, whereas shoes used to complete an aerobics class, may show little outsole wear due to carpeted surface, but the EVA may be completely buggered.

Therefore, a good looking upper and minimal outsole wear can give you a false sense of security, making you think the shoe is still in good working order.

Your Activity

It is important when purchasing your shoes to let the sales person know what you're going to use the shoe for and there's nothing wrong with asking them when they think the shoe should be replaced but remember whatever they tell you will be a guideline. I avoid arbitrary km guides, eg 700km as i dont think this is relevant to most people.

If you're not sure whether its time to change your footwear, I suggest trying on a new pair, in a similar style and possibly the same brand, and you will probably feel the difference immediately.

Where to help

At Waikato Podiatry we've been treating runners, casual athletes, and weekend warriors for years, so when it comes to understanding footwear, the good, the bad and the ugly, we have a better understanding than most. We also work closely with the shoe service-based shops like the shoe clinic toi ensure that you get what you need. One variable in retail in retail is the experience and knowledge of the staff person.

We are here to help you however we can and when you make your next appointment, please make sure you bring your athletic shoes with you.

We can quickly tell you if the shoe is still in good working order and if it is the right shoe for your foot.