Before: It doesn’t matter whether you’re tackling hill repeats or a fartlek—any kind of speed work will zap your energy stores, so some pre-run chow is a must. “This is not the place to skimp on calories,” says Antonucci, who advises taking in 200 to 400 calories (depending on your size and how long before the run you’re snacking) of easily digestible carbs, such as toast with jelly. And Ryan suggests replenishing your fast-twitch muscles with a sports drink or gels between intervals. It’s been shown to improve performance up through the last rep.
After: Unlike with those easy runs, you’ve got no time to waste after speed work. “It’s absolutely crucial to eat something within 30 minutes,” says Antonucci, to supply your muscles with fluid, carbs and some protein: aim for a 4 to 1 ratio of carbs to protein (ultra-easy source: chocolate milk) to best aid recovery.