How to Master Marathon Hydration

Updated OnOctober 19, 2016
Written by
Matt Fitzgerald

By the same token, if your stomach tells you drinking anything at the moment isn't a good idea, then don't drink even if you are thirsty. Runners commonly find themselves in this situation in the last few miles of a marathon. If you can get through 20 miles before your stomach says "no more," you're doing OK.

Choose Sports Drink


As for what to drink, it's almost always preferable to choose the sports drink offered at aid stations instead of water. The reason: Sports drinks contain carbohydrate, and carbohydrate enhances marathon performance more than water. One study reported that runners completed a marathon 4 minutes faster, on average, when they consumed water and carbs together than they did when they drank plain water.

More: What Makes a Good Sports Drink?

To get the maximum benefit from carbohydrate intake during a marathon you need to take in at least 60 grams per hour. Most runners aren't able to drink enough sports drink to get this much carbohydrate. You'd have to drink 33 ounces of a typical sports drink per hour to get 60 grams of carbs. Fortunately, you can still get a significant performance benefit from 30 grams of carbs per hour, which requires a more manageable 16 ounces of sports drink.

More: The Role of Carbohydrates in Recovery

If you have a strong stomach and can tolerate a fairly high level of nutrition intake while running, you can achieve the optimal rate of 60 grams of carbohydrate intake per hour by supplementing the sports drink offered along the course with energy gels. A typical energy gel contains 25 grams of carbs per packet. If you consume one gel packet per hour in addition to drinking the sports drink by thirst, you'll likely reach the magical 60 grams-per-hour threshold.

If you have a weaker stomach and can take in only modest amounts of water and carbs without GI discomfort, don't panic. Just do what you can and remind yourself that Amby Burfoot won the 1968 Boston Marathon without drinking anything.

More: What to Drink, How Much and How Often

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About the Author

Matt Fitzgerald is a certified sports nutritionist, endurance coach, and author. His many books include Racing Weight and The New Rules of Marathon and Half-Marathon Nutrition. Matt's writing also appears regularly on competitor.com, in Women's Running, and elsewhere. He has served as a consultant to several sports nutrition companies, as a peer reviewer for scientific journals, and as a nutrition advisor to professional runners and triathletes. Matt also provides nutrition counseling services to athletes of all experience and ability levels through racingweight.com. A lifelong athlete himself, he speaks frequently at events throughout the United States and internationally. Learn more at mattfitzgerald.org.