BOULDER, Colo. – Scientists at the University of Colorado Boulder say their research helped Nike name its new running shoe that reduces a runner’s energy use by an average of 4 percent.
Nike unveiled the $250 Zoom Vaporfly 4% in July and 2017 New York City Marathon winners Shalane Flanagan (a Boulder native) and Geoffrey Kamworor both wore the shoe when they ran the race earlier this month.
Prior to the shoe’s release, scientists at CU Boulder’s Locomotion Lab recruited 18 male runners to help test the shoe. All participants were in their 20s, had run a 10-kilometer race in less than 31 minutes and wore a size 10 shoe.
Over the course of three days, the runners rotated through the Nike Vaporfly 4% (which hadn’t yet been named) and two other high-performance running shoes – the Nike Zoom Streak and Adidas Adios Boost 2 – while running on a treadmill. To make sure shoe order or weight didn’t affect the results, the runners reversed the order in which they wore the shoes and researchers also put lead pellets in the Vaporfly 4% so they’d be the same weight as the others.
By measuring the runners’ oxygen consumption and determining the number of calories burned, the researchers were able to determine that the runners used between 2 percent and 6 percent less energy while wearing the Vaporfly 4% shoe, with an average energy savings of 4 percent – giving the shoe its name.
The researchers say the energy savings will allow runners to decrease their run times, bringing a 2-hour marathon within reach. The current world record, set in 2014, is 2 hours, 2 minutes and 57 seconds.
“Our extrapolations suggest that with these shoes the technology is in place to break the 2-hour marathon barrier,” said the study’s lead author, Wouter Hoogkamer, a postdoctoral researcher in the Locomotion Lab at CU Boulder. “Now, it is up to the athletes to make it happen.”
The Vaporfly 4% shoe features high-tech foam cushioning that researchers say “stores and returns twice as much energy” as the other shoes studied, as well as a carbon-fiber plate that some have argued works as a spring, giving runners an unfair advantage. Hoogkamer says the plate works more like a lever than a spring, but an ongoing study is taking a closer look at how it works with the other materials.
It should be noted that Nike funded the study and co-author Rodger Kram sits on Nike’s scientific advisory board.
The authors insist this did not affect the study’s results and they say they look forward to other scientists taking a stab at duplicating the study.
“We are extremely confident that other scientists will find similar results,” Kram said.
Nike also has made the entire study available free of charge. It’s published in the latest issue of the journal Sports Medicine and can be found online here.