Nice invention, huh. Almost a decade ago some Nike engineers came up with the idea of placing a carbon fiber plate in the middle of a pair of shoes and they revolutionized something as natural, so human, as simple as running.. Suddenly everyone was running faster. Specifically, according to the first studies and the first announcements, 4% faster. Marathon records plummeted, popular races were filled with fans wearing those shoes, brands rushed to create their carbon fiber plate models, and running was changed forever.. Today it is impossible to see a race, from the Berlin marathon to the San Esteban de Litera Popular Race -one of the many that are held this June in Spain-, where you do not see those very high mattresses so fashionable. Nice invention, huh. But… What if it wasn't so wonderful?

After the first analyses, promoted by the brands -especially Nike-, various groups are studying the 'magic' shoes and their effects are no longer so clear. Or if. It's hard to come to a single conclusion.. “Right now there is a lot of fuss, the scientific literature is in constant review. There are articles that indicate that the benefit of these shoes can reach 12%, but there are others that indicate that runners can lose performance with them. There are also other factors that are not at all clear, such as the long-term effect of this shoe on the runner”, says Borja Muñiz, a researcher at the University of Zaragoza and a member of the Sub2hrs group, one of the most prolific in the world in the study of invention of the century in athletics.

In one such analysis, they invited top runners and popular runners to wear the shoes and measured their benefits.. The results were so bizarre that they were forced to repeat the experiment.. “These types of shoes are quite unstable, they need adaptation and perhaps that's where the failure came from, but we have also verified that the variability is still very large. The pioneering studies were very clear about it, they said that the improvement was 4%, but that is not the case.. Its not that easy. There are runners who benefit a lot, perhaps more than that 4% and others who do not benefit at all. What we want to study now is why this happens.. We do not know if it is due to the type of footprint of the runner, because of their weight or due to many other variables.. That is very relevant information for the future,” says Muñiz, stressing that, in any case, “normal” is for a runner to benefit in some way from these shoes.

possible injuries

Another thing is that you can do damage with them. Beyond the instability due to its height – let's say it's like walking in heels – a recent study published in Sports Medicine by researchers from the universities of Harvard, Palo Alto and Hamburg warned of the dangers of its 'magic'. Due to the 'rebound effect' they cause, shoes with a carbon fiber plate reduce muscle crushing and help recovery, but they also soften. If they are used in all training sessions, the stride changes, the muscles and tendons lose strength and all of this ends up affecting the bones.. In their study, these researchers presented several cases of stress fractures of the scaphoid of the foot – a very difficult injury to heal – that they related to the prolonged use of 'magic slippers'. In their conclusions they accepted that there is not enough evidence to indicate them as a risk, but they called for more studies on their relationship with certain pains.

“I haven't seen these shoes directly cause injury, but they do change the stride. If you go from not using them to doing it every day there may be problems. There are elite athletes who already limit their training with a carbon fiber plate so that their soleus muscles and Achilles tendons are not weakened,” analyzes Muñiz, who does not believe that the recently discovered defects in the 'springs' are going to make them runners stop using them. Neither the professionals nor the amateurs.

“Although there is a lot of variability in their effect on performance and although their long-term effects have to be studied, for the most part these shoes reduce oxygen consumption for those who wear them and that means they can run faster and recover better. Either way They continue to be a help for the runner”, he concludes. Nice invention, huh.