You’ve logged the miles. Done the training. Now it’s race day. One big question remains: What should you eat before you run? Chances are, you should eat whatever you usually eat—now is not the time to introduce something new. For some insight, we called up a handful of elite trail runners to see what they eat for breakfast—what fuels them through mile after mile on both training and race days. Then we asked sports nutritionist, writer and runner Matt Fitzgerald, author of “The Endurance Diet: Discover the 5 Core Habits of the World’s Greatest Athletes to Look, Feel, and Perform Better,” for his take.