I’m a biomechanics teacher and now is the time to change my sneakers.

runnerswhether amateurs or professionals, know very well the importance of using good sneakers. If they are made from unsuitable materials or do not have good shock absorptionfor example, are more likely to cause discomfort, impair performance, and increase the likelihood of injury. Once we receive them, we can be confident, but we must also remember that they do not last forever. As we run with them, the shoes wear out, and there comes a point when all their benefits are negated. When should we change them?

This is not a simple answer. Of course, we can’t answer in time, since not all runners use running shoes with the same frequency. Ideally, talk in kilometers. Traditionally we usually talk about from 500 to 800 km. However, in an article recently published in Talksports science researchers John Arnold and Joel Fuller They note that this is not something that is easy to calculate.

This data is usually obtained in two ways. On the one hand, the use cars which simulates the friction of sneakers on the ground during a race. And, on the other hand, watching some runners in their actual performance. In this way, some figures were obtained that led to the approximation mentioned above. But there is much more data to consider.

Three factors that sneakers must meet

If you ask runners, they will all agree that running shoes should fit three requirements.

First of all, running shoes can be a key factor in performance corridor. Amateur runners do not attach much importance to this. However, professionals often use certain materials and designs to maximize performance.

On the other hand, bad sneakers can contribute to injuries. If they are not well supported, for example, sprains may increase. But that’s not all. In general, many runners, especially professional runners, associate shoe wear and tear with injury.

And finally, we must not forget the most obvious requirement. sneakers They should be comfortable.

If there comes a time when a runner feels that their performance has slowed down, they are getting injured more often, or are feeling uncomfortable, it may be time to change their running shoes.

When will this moment come?

In their article, Arnold and Fuller detail some of the research into the relationship between wear and tear and these three running shoe requirements.

When it comes to performance, professional athletes typically look to optimize it with shoes with soles made from a material known as Pebaxconsisting of polyamide blocks. In addition, they contain internal plates made of carbon fiber.

It has been observed that running shoes made from these materials help reduce energy absorption during movement. metatarsophalangeal joint. This significantly improves running performance. Therefore, if materials wear out, it makes sense that productivity will also decrease.

Unfortunately, not much research has been done on this issue. Arnold and Fuller mention in their article only a master’s thesis from the University of Connecticut, which analyzed the performance of 8 university runners over 643 km in shoes. Nike Pegasus.

These shoes are very common among recreational runners, but not so common among professional athletes. Their soles are filled with foam and They do not contain carbon fiber. Therefore, the data could not be safely extrapolated to these performance running shoes. Leaving that aside, in this university work there was a significant drop in performance over the 240km distance, and that it was statistically very significant. from 320 km. At 160 km there were no differences. Thus, the shoe’s lifespan will be between 160 and 320 km, depending on the use and footprint of the runner.

When it comes to injuries, there are no reliable studies demonstrating a link between wear and tear and these conditions. However, it has been observed that athletes who alternative sneakers they are less injured. They don’t cause them much trouble.

Finally, of course comfort is important. However, runners do not feel any discomfort once wear begins. Since most runners land on their heels, this is the area that gets worse first. According to the study cited by Arnold and Fuller, the material around the heels hardens after 160 km of travel. However, runners do not notice this. With a range of 640 km, comfort decreases by only 3%. It is from 10% that everything becomes much more uncomfortable. And this happens over many kilometers.

So when should we change our running shoes?

By now we have already imagined that there is no such thing as a golden number. If we want to improve our time, perhaps after 240 km we should consider change sneakers. However, if we run just for fun, the main thing is to be attentive to how we feel as we walk. Although these studies also show the importance of alternating between two pairs of shoes. It doesn’t matter whether you run for a profession or for a hobby. Give your sneakers a break.