#154 How often should I replace my running shoes? | DOC

#154 How often should I replace my running shoes?

Today on the Doc On the Run Podcast, we’re talking about how often you should replace worn out running shoes.

How often should you get new running shoes? That depends on how quickly they wear out! Some runners get new running shoes every few months. Some running coaches tell runners to replace running shoes every 200 to 500 miles. If you keep running in worn out shoes, you may be putting yourself at risk of an over training injury.

But a lot of different variables can affect how quickly your running shoes wear out. If you understand the variables that can affect how long your running shoes last, you can make much better decisions about how frequently you need to replace your running shoes.

How often should you actually get new running shoes? 

This is a great question. And this is a question I get over and over when I see patients. When I look at a runner and I realize that some slight overtraining injury they got, whether it’s the beginning of a stress fracture, or peroneal tendinitis, or posterior tibial tendinitis, or plantar fasciitis, or any one of these common overtraining injuries, it often has a lot to do with running in shoes that are just frankly worn out. 

Running shoes wear out over time, they are like any other wear item. We all know this. But most of us truthfully are probably running just a little bit too long and a little bit too much time in those running shoes before we replace them. Well, all of us runners would like to know exactly how many miles we should run before we replace our running shoes. 

Unfortunately, it depends on several factors. A good analogy to this is changing the oil in your car, you know, these oil change places, oil change providers, they will often recommend drivers of automobiles change the oil in the car every 2000 miles. But not every car needs new oil every 2000 miles. It depends on several different factors.

If you use synthetic oil instead of conventional oil it can last many thousands of miles, and it doesn’t have to be changed every 2000 miles. If you drive in an area that has relatively clean air, doesn’t have lots of dust in the air, you can also drive a lot longer before your oil has to be changed. And, the condition of your car’s engine also has a lot to do with how often you should really change the oil in your car.

Now granted, it may be safe and reasonable to change your oil every 2000 miles or so, but it could also be unnecessarily costly and time consuming to get your oil changed that frequently. Now, by the same token, if you change your running shoes too often you could be wasting time and money. 

 

How many miles?

One of the common recommendations I hear is that people should get their shoes replaced every 200 to 500 miles. It depends on who you are, and how you run. 

Obviously, 200 miles is a whole lot less than 500 miles. And the funny thing is I often see runners, and they will say, “Well, you know, I knew I needed to replace my running shoes because the tread was starting to get worn out.” 

The tread on the outsole on the bottom of your shoe is absolutely not a reliable indicator of when you should replace those running shoes. 

If you see the tread on the sole of your running shoes is actually worn out, yes, you need to replace your shoes. But that is sort of like waiting until you see the cords or the steel belts in your tires actually showing through when you have worn the tread completely off of your tires. You’re not going to wait that long to replace the tires on your car, because you could have a blow out. And that is sort of the equivalent of waiting until the tread pattern on the bottom of your shoes is worn. 

You are definitely waiting way too long if you’re waiting for the tread to wear out before you replace your running shoes.

So, this is the thing…you have to figure out what is actually right for you, and that depends on a lot of different factors. 

Again, it might be a conservative way to replace your shoes every 200 miles. You probably will not get into any trouble or get an overtraining injuries if you replace your running shoes every 200 miles. 

But for most of us that is really when our running shoes just start to feel like the new shoes have started to get broken in. That is when we start to get comfortable in them. 

Variables affecting wear rate

Some of the variables which can affect how often you need to replace your shoes has a lot to do with how much you pound on the shoes when you run. And it’s not really that complicated. 

When we talk about running shoes “wearing out”, what we’re really talking about is the midsole cushioning material, which is EVA or ethyl vinyl acetate.  

The shoes are worn out when that EVA material starts to get compressed in areas of high pressure, where you’re pounding on the shoes. The foam cushioning material, ethyl vinyl acetate (or EVA), starts to get compressed. When it gets compressed, it’s not providing the same level of cushioning nor absorbing as much force as it was before. That is when they need to be replaced. So, not surprisingly that has to do with a few different factors. 

Runner weight

One of them is how much you weigh. If you weigh more, you’re going to pound on the shoes more. If you land as a heel striker, if you run with really long strides, that type of running form tends to pound on the shoes and will wear out the shoes a little bit faster than if you’re really sort of a soft-footed mid-foot or forefoot striker. 

Vertical oscillation

The rate of wear also has a lot to do with how much vertical oscillation you have when you run. If you bounce up and down a whole lot, that actually does pound the shoes more, because you’re actually falling further every foot strike when you have a lot of vertical oscillation. 

Women who run, and you can see a ponytail really swinging violently behind them, it’s usually because there is a lot of vertical oscillation in her running form. That could beat up the shoes even more. 

If you run on stairs, or you are doing lots of hill repeats, well that can also pound the shoes because you’re running downhill. That beats the running shoes up and crushed the midsole cushioning material.

If you are running on hard surfaces like concrete, it generally makes the shoes wear out faster than if you land on a softer surface like crushed granite, or a dirt trail, or some obviously softer surface.  Softer surfaces doesn’t pound on the shoes as much as hard concrete so the running shoes can last a bit longer. 

Hard surfaces

It also depends on how you run. When you land, if your foot is supinated or pronated and you are landing basically one side of the foot, which, you would definitely see a wear pattern where it shaves off one area of the tread faster.

Landing pronated or supinated, you won’t land symmetrically and the shoes will definitely wear out way faster. When you land flat you are spreading those forces over the entire bottom of the shoe. But when you land on the edge of the shoe it’s really just that little section of the shoe where it’s pounding, and then your foot comes down, and it tends to abrade or wear off the tread in that one area. 

Landing asymmetrical

Landing asymmetrically places a whole lot more peak force under that section of the shoe and it can them wear out a whole lot faster. Anything that basically pounds on the shoes increases the wear, wears out the EVA faster, and then you are going to have to replace them sooner. 

The thing that I tell runners when I see runners and look at the shoes, there are a couple of ways to tell if they are worn out. 

Check the Feel

The first thing is that if you wear the shoes and you can tell that they feel different than they do when they are new, you probably need to replace them. Unfortunately, because we get the shoes, we start to run in them, and we wear them out gradually, most people don’t notice much difference in the feel of the shoes. 

When the running shoes get really worn out you can usually tell that they feel squishy or unstable. At that point, you know you need to replace them. But when they feel different you should probably replace them.

Another way to tell is to get two pairs of shoes and compare. If you buy two pairs of the exact same kind of shoe, because you like them, they are on sale, or whatever, and you run in one pair, and then maybe a month later you run in the brand new pair and it feels totally different, then obviously the older shoes are already really worn.

But they may not feel like they are really worn, so it’s a good experiment to try that once or twice. Track your miles, and see how far you can go in them before they start to feel worn out to you. 

Look for Wrinkles

The other way that is a surefire way to tell, which is the most reliable thing, and the thing I’m usually pointing out to patients, to runners when I see them in person, when I look at their shoes, is to look at the sidewall of the shoe, not the sole on the bottom, but side of the shoe, and actually look for wrinkles.

What I do is I grab the shoe and I basically push it together, and then I look for wrinkles in the outsole on the side of the shoe. When you have those wrinkles, what that means is that the EVA on the inside of shoe is collapsed, and it’s squishy, and it’s sandwiched, because it’s giving way very easily, and you see that as the wrinkling on the outside of the heel, or the outside of the forefoot. When you see that wrinkling in those areas it means you have deformed the EVA midsole cushioning material in the running shoe, and that is when you definitely need to replace them.

But, again, there are several variables. It can vary from shoe to shoe, from type of shoe, type of surface, the way that you run, your running form, your weight, all these things have an impact on how much you wear out the shoes. But it’s a good exercise to go through it at least once, where you get, maybe two pairs of the exact same kind of shoe, track your mileage, run in them for a month. Then, run in the other pair that you haven’t run in yet and wear them back-to-back on the same day to see what it feels like, and see if they feel the same, or if they already feel different. That’ll give you a better idea and way to gauge how quickly you should actually replace your running shoes. 

If you have a question that you would like answered as a future edition the Doc On The Run Podcast, send it to me, and then make sure you join me in the next edition of the Doc On The Run Podcast. Thanks again for listening!