Marathon record breaker Tigst Assefa, her coach and experts on historic run

After smashing the world record in Berlin, Ethiopia's Tigst Assefa, her coach and marathon experts answer three key questions on the evolution of the event.

Related Keywords

Ethiopia ,Italy ,China ,Berlin ,Germany ,Valencia ,Carabobo ,Venezuela ,Ethiopian ,Chinese ,Sammy Wanjiru ,Alex Hutchinson ,Gemedu Dedefo ,Renato Canova ,Paula Radcliffe ,Paul Tergat ,Eliud Kipchoge ,Haile Gebrselassie ,Tigst Assefa ,Diamond League ,Valencia Half ,Adida Adizero Adios Pro Evo ,Formula One ,Marathon World Record ,Berlin Marathon ,Super Shoes ,Getty Images ,