Are Nike’s Vaporfly Running Shoes Too Good?

Last month, elite marathoner Eliud Kipchoge ran 26.2 miles in less than two hours, breaking a barrier some thought impossible. The following day, fellow Kenyan Brigid Kosgei shattered the women’s marathon record. The common thread for both performances: the shoes on their feet. Kipchoge was running in a prototype featuring Nike Inc.’s latest Vaporfly technology. Kosgei was wearing an earlier version of the same shoe, which retails for $250.

Their runs reignited a debate that’s simmered since Nike unveiled this class of shoes in 2017. The sneakers have a carbon fiber plate, lightweight foam, and a stiff forefoot that rocks you forward. Nike says they’re proven to decrease effort by at least 4%, helping you run faster on the road and recover quicker afterward. “Out of the box, you are 4% better,” says Matt Nurse, vice president of the Nike Explore Team Sport Research Lab. “No question. We tested that across ranges of speed and ability.”