Finish strong by following these race-time nutrition and hydration guidelines from Matt Pahnke, Ph.D., principal scientist at the Gatorade Sports Science Institute.
If you're running a 5K/10K
These races are too short to warrant gels, chews, or sports drinks. Include carbs in your pre-race breakfast, and grab water from aid stations if you’re feeling thirsty.
If you're running a half-marathon
If your projected finish time is within one to two hours, take 30g carbs per hour; take 60g per hour if your slower pace puts you at a finish time between two and three hours. Take one to two cups of fluid at each aid station. You goal: Don’t lose more than 2–3% of your body weight during the race. To calculate your fluid loss and needs, visit gssiweb.org.
If you're running a marathon
Up your fuel intake to approximately 90g of carbs per hour if you’ll be running for 2.5 hours or longer. Follow half-marathon hydration rules, but consider a sports drink to help offset the electrolytes lost via sweat.
If you're tough-or crazy-enough to run an ultramarathon
The nutrition game gets a lot wackier when you have to push through 50 or 100 miles. On the course, pro ultramarathoner Adam Campbell gulps flat Coke—unfizzed so it won’t spray everywhere while he carries it on the run—because of the high sugar content; he calls it “rocket fuel” and says the drink gives him an immediate energy boost. These endurance athletes burn almost everything they consume by midrace, so Campbell also pops gummy bears, while fellow competitor Dean Karnazes has been known to down pizza on the trail.