![Too much spring in their step? Nike running shoe under scrutiny after record marathon times – GeekWire Too much spring in their step? Nike running shoe under scrutiny after record marathon times – GeekWire](https://cdn.geekwire.com/wp-content/uploads/2019/10/Screen-Shot-2019-10-18-at-9.16.56-AM-630x352.png)
Too much spring in their step? Nike running shoe under scrutiny after record marathon times – GeekWire
![Photo taken during a qualifier of the Tokyo Olympics marathon in Tokyo on Sept. 15, 2019, shows runners wearing controversial Nike shows. World Athletics, the sport's international federation, said on Jan. 31, Photo taken during a qualifier of the Tokyo Olympics marathon in Tokyo on Sept. 15, 2019, shows runners wearing controversial Nike shows. World Athletics, the sport's international federation, said on Jan. 31,](https://c8.alamy.com/comp/2ATAEJE/photo-taken-during-a-qualifier-of-the-tokyo-olympics-marathon-in-tokyo-on-sept-15-2019-shows-runners-wearing-controversial-nike-shows-world-athletics-the-sports-international-federation-said-on-jan-31-2020-that-nikes-vaporfly-available-on-the-open-market-will-be-allowed-at-the-2020-olympics-but-customized-version-worn-by-kenyan-star-eliud-kipchoge-during-his-sub-2-hour-marathon-in-the-fall-of-2019-will-be-banned-kyodo==kyodo-photo-via-newscom-2ATAEJE.jpg)
Photo taken during a qualifier of the Tokyo Olympics marathon in Tokyo on Sept. 15, 2019, shows runners wearing controversial Nike shows. World Athletics, the sport's international federation, said on Jan. 31,
![Alphafly Next % Volt Green / Hyper Orange Nike When Eliud Kipchoge ran a marathon in 1:59:40 in 2019, he did so in a prototype of the Nike Air Zoom Alphafly NEXT%. Alphafly Next % Volt Green / Hyper Orange Nike When Eliud Kipchoge ran a marathon in 1:59:40 in 2019, he did so in a prototype of the Nike Air Zoom Alphafly NEXT%.](https://www.theshoelibrary.com/productimages/1200/nike-alphafly-2_477399.jpg)
Alphafly Next % Volt Green / Hyper Orange Nike When Eliud Kipchoge ran a marathon in 1:59:40 in 2019, he did so in a prototype of the Nike Air Zoom Alphafly NEXT%.
![Technological doping: The science of why Nike Alphaflys were banned from the Tokyo Olympics - BBC Science Focus Magazine Technological doping: The science of why Nike Alphaflys were banned from the Tokyo Olympics - BBC Science Focus Magazine](https://c02.purpledshub.com/uploads/sites/41/2021/08/Alamy_2F3Y8J0-crop-ff47efc.jpg)