(FOX NEWS) — Runners are demanding this shoe be investigated.
Several athletes with the International Association of Athletics Federations claim the ‘Nike Zoom Vapor-Fly’ provides an unfair advantage to runners.
Specifically the use of what’s described as spring-like carbon fiber plates within the midsoles to make runners go faster.
Concerns after Eliud Kipchoge broke a world record for marathon runner by running 26.2-miles under two hours at an unofficial event in Vienna Austria while wearing the shoes.
They were also worn by Brigid Kosgie who set a record at the Chicago marathon.
The shoes cost $250.
Nike has not responded to the controversy.