Ask the Expert: How Often Should I Replace My Running Shoes?

Running shoes image via Shutterstock.

How do you know that it’s time to replace your running shoes? Do you measure it by miles logged? Holes created? Fraying laces? Too many stains? We asked Greg Zuckerman, a footwear buyer at City Sports and a guy who runs 20 miles per week when he isn’t running ultramarathons, when you should replace your sneakers.

Is there really a rule for how long my running shoes will last?

In general, most experts will suggest changing your running shoes every 300 to 400 miles. That’s a pretty good gage for the most part, but as footwear has become more versatile and more specific for different types of running, there are different materials being used for different types of shoes. That changes the length and the life cycle of the shoe because there might be more or less foam in certain kinds of shoes.

Why does foam make a difference in the length of time my shoes will last?

Minimal shoes like Vibrams use less foam. There’s less cushion between your foot and the ground, which is what gives you a more “natural” running feel. With less cushioning, the overall shoe and the shock absorption of that shoe runs out more quickly. So generally, I suggest that people who run with minimal shoes replace them every 200 to 300 miles instead.

Can you give us a quick lesson on shoe anatomy?

You’ll find that there is a general foam and also a gel cushioning system that is specific to the shoe brand in the mid-sole of most shoes. The foam surrounds the cushioning system. So Asics has a special gel system, but the foam around that gel is less durable than the gel. If you think about it, foam compresses. It takes time for foam to rejuvenate, and it can break down eventually.

Is there a way to make my shoes last longer?

Because foam needs to rejuvenate, one thing you can do is switch pairs every time you run. If you run on Monday, wear pair number one. On Wednesday, wear pair number two. On Friday, switch back to pair number one. You need to give the foam time to move back and rejuvenate, and if you switch shoes, it helps to extend the life span of your shoes. If you switch between running in a pair of minimalist shoes and a pair of more cushioned shoes, that’s better from a training perspective, too. It helps your body get used to different kinds of running and helps you perfect your stride. You should run longer with cushioned shoes and shorter in minimalist shoes.

Do certain people go through shoes faster than others?

Yes. It all depends on how heavy of a runner you are. If you weigh more, you’re going to be putting more pressure on your shoes. It’s averaged that a runner puts seven to eight times more pressure on their shoes when they are running than when they are walking. That’s because of the pounding of running. So the heavier you are and the harder you run, the faster you will break down the shoe and the foam. Sprinting means you’ll go through shoes faster, too.

Another thing that plays into how long your shoes will last is your cadence and how your feet strike the ground. The more you run on your forefoot, the less pressure you put on your shoes. This is because your knee is bent when you run that way, so the shock absorbtion goes up through your calf instead of directly into the shoe.

So how can we tell if our shoes are done?

Look at bottom of the shoe and look at the rubber. If the tread is gone— if it’s basically flat along bottom of the shoe and the tread is worn out— it’s time. That’s when you know. A lot of people might see that only one side is worn out, maybe just the outside but not inside, but the truth is that you do need to replace them even if only one area is worn out. You probably just run heavier on that side.