Luca Bruno / AP
The distance runner Eliud Kipchoge completed the quickest marathon ever Saturday in two hours, 25 seconds under tightly-controlled conditions on a Formula One racetrack in Italy.
Nike project: Kipchoge's remarkable run was the showcase of Nike's big Breaking2 initiative, a multi-year, science-driven project to break the two-hour marathon barrier. (Getting under two hours would require a runner to average 4 minutes, 34 seconds per mile for the 26.2 mile distance.)
One level deeper: The athletes wore customized Nike shoes with a carbon-fiber plate that have attracted some controversy, per NYT, even though shoe design rules for standard marathons are vague.
Why it matters: Breaking2 has been a major effort by Nike to push the boundaries of running performance, while interest in the project and Nike's careful rollout has been a significant marketing opportunity for the retail giant.
One big question: Whether and when the otherworldly Kipchoge can break the world record under sanctioned conditions, and how fast he can go while still in his prime (he's 32). September's Berlin marathon, where the last several men's world records have been set, would be a logical place.
What they're saying: Sports scientist Ross Tucker predicts that Kipchoge could run around two hours and two minutes or slightly slower in a race like Berlin.
Why it's not a world record: Kipchoge ran 2 minutes and 32 seconds faster than the current world record, set by fellow Kenyan Dennis Kimetto in Berlin in 2014. But the sophisticated use of a rotating squad of pacemakers and mobile delivery of drink bottles during the event were outside the rules for record-sanctioned events.
Corporate battle: Nike is releasing a retail version of its Vaporfly shoe in June, while rival Adidas has a competing project called Sub2 and a competing shoe. Bloomberg breaks down the corporate rivalry here.