Eliud Kipchoge and the sub two hour marathon

Last weekend was exciting for fans of distance running. Kenyan runner Eliud Kipchoge broke the "unbreakable" two-hour marathon barrier and compatriot Brigid Kosgei smashed a 16 year old women's marathon world record by more than a minute. Kosgei's record was achieved during a standard competitive marathon race in Chicago but Kipchog's attempt involved precisely engineered non-race conditions: a wind break of a pace setting runners, a guiding laser beam, a pair of performance-enhancing Nike Vaporfly shoes, and a major commercial sponsor. We'll ask former international athlete and exercise science writer Alex Hutchinson about the uneasy mix of commerce, technology and sport.