Short answer every 6 months. Here is why…
Runners are told to replace their shoes every 300-500 miles. This is because the EVA foams used in 99% of running shoes wear down and no longer provide proper cushioning. The same goes for you nurses out there!
The Math
On a low estimate, you are probably getting about 8000-10000 steps every shift. 2000 steps = 1 mile means you are getting 4-5 miles in every 12 hour shift. For this example, let’s use 4 miles/shift as our benchmark, you would need to replace your shoes every 75-125 shifts.
To put this into perspective, if you followed the 500 mile rule at 8000 steps/shift, the foam in your running shoes is wearing out after 75 shifts or 6 months at 3 shifts/week.
Set a reminder on your calendar, 6 months after you purchase a new pair of shoes. I bet you will find the exact moment that your feet start getting fatigued and heels hurting again is pretty close to this calendar reminder. Comment below on what you notice, I’d love to know.
Why?
Let’s talk about those foams that are breaking down so quickly. There were huge innovation leaps in athletic shoes in the late 90’s early 2000’s. Before EVA foam was introduced to mainstream athletic footwear, you might remember Shox, Air and different iterations of those shock absorbing technologies. These shock absorbing technologies had their own performance drawbacks, but either way they existed. After this huge trend, the athletic industry started aiming for how to make footwear more lightweight. Speed was the goal then, not necessarily cushion. The idea was the lighter your feet, the faster and longer you run.
What the industry discovered was EVA foam. It is an ultra lightweight low density foam. It achieved the most lightweight shoes but it also provided great out of the box cushioning. There are so many different ways companies engineer their EVA and mix and match different densities of foam to provide different support and comfort benefits.
What this foam does not provide is longevity. Take a look at your athletic shoes and you will notice they compress easily, you will see wrinkles in the most weight-bearing parts of your shoe. We call this bottoming out, meaning that nice cushiony foam you used to love is worn out and you are basically just walking on the hard flat ground now.
Now what?
You will be hard-pressed to find shoes that are not made with EVA foam these days. So how can you get a little more wear out of your shoes? This is where insoles play a HUGE role. If you do know about insoles, read more here. The foams used in your insoles along with proper contouring can actually work in a beautiful combination with your EVA shoes. Try it for yourself, at that 6-month mark, if you notice your shoes wearing out, just swap your insoles and see if that gives them new life.
While we are on the subject of foam. First I want to clear up the misconception about memory foam. I’ve said this before and I will say it again…stay away from memory foam. Second, I want to talk about Polyurethane foam. Sounds horrible for the environment, right? Well to define environmentally friendly/sustainability and what it means in footwear. In the meantime, the benefits that polyurethane foam has for your comfort and longevity. It takes years for polyurethane to compress or bottom out. Polyurethane is used mostly in orthopedic shoes, which means all the more reason to trust its comfort capabilities.
It will take a few tries to find the right comfort package for you, but we are here to answer your questions. You deserve all the information so you can make confident decisions about maintaining your foot health and body alignment. Shoot us your questions and comments below!