Runners crest “Heartbreak Hill” in Newton, Massachusetts, during the running of the Boston Marathon. (Photographer: Neal Hamberg/Bloomberg News)

Want to Run a Fast Marathon? Pay a Top Athlete to Run It With You

(Bloomberg) -- Adam Donahue was feeling pretty good eight miles into a half-marathon last March and was ready to speed up. But his coach, Andre Laboy, who was trotting alongside him, said it was to...