If you ask the big shoe brands how often you should replace your running kicks, they’re going to give you a mileage estimate. Brooks, for example, comes right out and suggests every 250 to 500 miles, depending on the shoe. The problem is, there’s little in the way of hard evidence to back the need for such frequent replacement, and running coaches’ recommendations to clients vary dramatically.
“I don’t follow the guidelines you typically see from the shoe companies,” says Kyle Kranz, a competitive runner and coach. “My rules are easier to follow and much more economical: If the shoes fall apart or you wear through the bottom, it’s time for a new pair.” Kranz practices what he preaches, usually racking up between 800 and 1,500 miles per pair.
The Myth of Mileage
If a shoe’s expected mileage lies somewhere between Brooks Running’s suggested 250 miles and Kranz’s 1,500 miles, it becomes evident pretty quickly that a shoe’s lifespan really just depends on the runner. Debbie Woodruff, a running coach based in California, points out that bigger men generally go through shoes faster than smaller men, since extra poundage compresses the shoes’ internal EVA foam more quickly. Likewise, dudes with less-efficient form who pound the pavement with each step tend to wear out shoes faster than those who are light on their feet. And of course, environment makes a difference: Rough terrain or loose asphalt tears up shoes faster than grass or well-kempt trails.
While actual research on this subject is limited, a 2011 study published in Footwear Science found that high-quality shoes maintained good functional stability and cushioning after 1,000 kilometers (about 621 miles), concluding that “the lifetime for a high-quality running shoe is expected to be much higher than 1,000km.” Good news if you’re a runner on a budget.
And for those who argue that older shoes lead to running injuries, evidence is pretty sparse there, too. A 2003 article published in the British Journal of Sports Medicine acknowledges a correlation between shoe age and running injury, but points out that there’s no clear causation, since possible contributing factors like previous injury and running experience weren’t accounted for. Kranz cites a 2013 study that he bases his own training after. “I wear different shoes throughout the week when running,” he says. “Running in different shoes, at different paces, at different distances, on different terrain, all give the legs a greater deal of variation in how and where they’re loaded.” The study (and Kranz’s own anecdotal evidence), suggests this type of regular change in loading reduces the risk of running-related injury, regardless of how many miles you put on any one pair of shoes.
It Comes Down to Comfort
Of course, that doesn’t mean you can buy one pair of shoes and wear them forever. Just like tires eventually wear down on your car, shoes wear down and give out over time. And it’s often the unseen, internal cushioning that loses its “fluff” before the external features, like tread, give way.
So as unscientific as it sounds, you should replace your shoes when they stop feeling good. In fact, kinesiology researchers from the University of Calgary proposed in a 2015 review study that a runner’s personal “comfort filter” is the best means of selecting shoes that support the preferred movement path and reduce the likelihood of injury. So perhaps instead of stressing over how many miles you’ve racked up, or how old your shoes are, you should take a moment every time you slip on your kicks to ask, “Do these still feel comfortable?” If the answer is no longer a resounding “yes,” or if you’re just not sure, it’s probably time to head to the sporting goods store to pick up a new pair.