AMonod47
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chaussure nike solde femme Italy, in May, where Eliud Kipchoge notched a mind-blowing 2:00:25, albeit under non-record-eligible conditions thanks to a rotating cast of pacers blocking the wind for him. The “4%” label refers to the claimed improvement in running economy, a measure of oxygen consumption at a given pace, compared to other state-of-the-art marathon shoes. Nike hoped the shoes would help Kipchoge break the two-hour barrier—and although he didn’t quite make it, his performance launched a debate about the shoes that’s still going on. At the heart of the shoe is a foam sandwich, with thick layers of a new foam surrounding a stiffened carbon-fiber plate. Importantly, the Colorado study didn’t aim to figure out how the shoe worked; it was only designed to assess how well it worked.
chaussure nike solde femme The Vaporfly prototype they tested returned 87.0 percent of the energy, compared to just 65.5 percent from Nike’s previous state-of-the-art marathon racer, the Zoom Streak 6. Interestingly, they also tested the Adidas Adizero Adios Boost 2, which was used by Dennis Kimetto to set the current men’s marathon record of 2:02:57. It returned 75.9 percent of the input energy. The authors note that versions of these two shoes (the Streak 6 and the Boost 2) had been used for all ten of the fastest marathons in history at the time the study started, in April 2016. The other aspect of the mechanical testing was compliance: How much does the shoe squish down when you press it.
chaussure nike pas cher femme Deforming by 11.9 millimeters compared 6.1 for the Streak and 5.9 for the Boost. This is what you get from having the Vaporfly’s distinctively huge platform of foam under the shoe’s heel. This off-the-charts compliance could be one of the shoe’s key advantages. When you run, you naturally adapt your stride to get the “right” amount of shock absorption. In hard shoes on a hard surface, you bend your knees more to absorb the impact; in super-soft shoes, you keep them straighter. Outsourcing some of this shock-absorption to the shoes may save a bit of energy that you’d otherwise spend contracting the muscles around your knee joint.
chaussure nike pas cher homme Do Nike’s new shoes improve running economy by four percent on average, give or take some individual variation? Yes. Sure, it will be nice to see studies looking at much slower runners, over longer durations, and under various other circumstances. And yes, this was a Nike-funded study. But these are rigorous results from a respected laboratory. There’s something going on with these shoes. As yet unresolved are the debates over how they work, and whether the rules around shoe technology should be tightened to keep things simple and avoid a technological arms race. But the big question lingering in my mind is: Where does that four percent go when you leave the lab and race.
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