If you were to randomly survey 10 marathoners about their biggest concerns heading into a goal race, it’s a good bet that at least half of them would list bonking or dehydration as their top worries. It makes sense—26.2 miles is a long way to run and a long time for your body to be working at an elevated level.

Executing an effective fueling and hydration strategy is a crucial element in races lasting more than two hours, both because you can easily get dehydrated during that time and you will burn through your glycogen (or energy) stores if you aren’t re-
fueling. For that reason, running a marathon is much different than running a half marathon. It is very important to have a fueling strategy heading into a marathon, but putting an emphasis on specific amounts of fluid and a precise number of calories can overcomplicate things—partially because there isn’t an exact science to fueling for a marathon. Also, there are many variables that can alter your body chemistry on race day—what you ate for breakfast, how hydrated you were to start the race, along with the race-day temperature and humidity level.

Lee Troop, a three-time Australian Olympian and high-performance coach for the Boulder Track Club, says that the last thing you want to worry about on race day is whether or not you ingested a specific number of calories or amount of fluid. The most crucial thing during a race is that you are taking in fluids at every aid station.

“It’s an important consideration,” Troop says of fueling and hydration during a marathon. “But we don’t want to overcomplicate it. Throughout the race, it’s mainly just hydration and topping off the tank.”

Proper nutrition and hydration for the marathon can be confusing concepts because there’s an overwhelming amount of information available out there about things like nutrient timing, simple and complex carbohydrates, and high- and low-glycemic foods. Not to mention a myriad of complex formulas for determining how much to eat and drink, plus an endless grocery list of food suggestions and fueling strategies aimed at helping you achieve optimal energy levels. It’s a lot to digest.

The truth is, every runner has different and specific nutritional needs for optimal performance. The best ways to find out what works for you are by experimenting through trial and error, and making fueling practice a regular part of your marathon-specific workouts. Simulating race-pace scenarios in practice is the best way to do that, says Ben Rosario, head coach of the Hoka Northern Arizona Elite training group.

“What’s getting you to the finish line is being efficient at marathon pace and getting economical at that rhythm—not how many carbs you get in during the race,” Rosario says.

Over the following pages, Rosario and Troop shed some light on three tried-and-true approaches for developing an effective marathon fueling and hydration strategy. Apply them to your own training, so that when you step to the starting line of your next big race, your biggest concerns don’t revolve around how much you should eat and drink.

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Learn to burn fat more efficiently

In races lasting more than two hours—and especially for a marathon—Rosario says the ability to burn fat effectively and efficiently is a crucial skill to have in your arsenal, whether you’re a mid-2-hour marathoner or a mid-4-hour marathoner. The food you ate before the race—both the night before and for breakfast on race morning—is converted into glycogen, so, in theory, your body has a full tank of energy when you start running.

But as soon as you start moving at race pace, your body begins to burn that fuel—in other words, it starts to drain your energy tank. For shorter races up to 2 hours—no matter if it’s a mile race, a 5K, 10K or half marathon—your body should have plenty of glycogen to burn without the fear of running out before you reach the finish line. But in a marathon, you’ll need to replenish your tank throughout the race or train your body to find a secondary source of fuel.

“The marathon is different from any other distance in that way,” Rosario says of the fueling aspect of the race. “Even in a half marathon, most runners really don’t need to take much, if anything at all.”

When you ingest carbohydrates during a race, your body converts them to glycogen and begins burning it as its primary fuel. Burning fat as fuel is more efficient, but your body will only start burning fat once your glycogen stores have been depleted. And, it’s important to note, if you ingest too many carbs during a race, or too quickly, you could wind up with a gut ache as your body labors through the digestion and absorption process.

Rosario says he has his runners practice taking in fluids during marathon-specific workouts but he also assigns carb “depletion” runs every other week (on average) over the course of a 12- to 16-week training cycle. For the elite-level athletes he coaches, this culminates in a 26-mile “no carb” run four weeks out from race day. Rosario says that for most runners, though, doing medium-length long runs (ranging from 90 minutes up to 14–16 miles) every other week without taking in calories or sugars—only water—will help teach your body to burn fat more efficiently.

“You need to prepare the body to run without additional fuel,” explains Rosario, who advises runners to stay close to home and bring an emergency gel with them on these carb-free runs, just in case. “Because eventually that’s going to happen—whether you plan for it or not—or at least you’re going to get low on fuel at some point and it’s important that you’re efficient when the tank is low.


Simulate race-day conditions

Specificity in training is a key component in preparing for a marathon, and simulating race-day conditions in training is top of mind for both Rosario and Troop, particularly when it comes to dialing in an effective fueling strategy.

Over the course of a three- to four-month training cycle, Rosario and Troop emphasize the importance of practicing with the drinks, gels or blocks you plan to utilize on race day during your key marathon-specific workouts and long runs. For Troop, one of his key sessions for working on both pacing and fueling is a progressive long run three weeks out from race day. This 18-mile run, which finishes with 6 miles at goal marathon race pace, is done on a 3-mile loop so his athletes can practice taking fluids and gels at the frequency they’ll do so during the race.

The act of running fast while in a fatigued state and trending toward dehydration will create the realistic conditions that a runner will experience in a marathon.

“We use a couple different drink mixes that contain carbohydrates,” Troop says. “And the athletes will take them every 5K all the way up to 30K, trying to get down a minimum of 5 ounces every 5K or 3 miles. The first one isn’t as critical, especially with clusters of people around the aid stations, but every drink stop after that you need to try to get those fluids down.”

Rosario follows a similar approach with his athletes during their marathon-specific workouts and uses the buildup before a race to eliminate any uncertainties regarding fueling and hydration. He says that every athlete is different in terms of what and how much they need to consume, and stresses the importance of experimenting first to learn what works best for you.

“They’ll practice taking fluids every 3 miles like they do in a race,” Rosario says. “And that’s typically 4 to 8 ounces each time, so over the course of a race you can take in a lot. In training, we’ll try different things until they find what works. Over 12 weeks of marathon training, you get a lot of opportunities to figure it out.”


Don’t rush yourself

Perhaps the best tip for any marathoner is to make sure race-day aid station execution is optimal. Drinking and eating during a race can be tricky business, especially because it’s easy to fly through an aid station when you got caught up in all the energy and excitement around you.

Remembering to fuel can also present a challenge in long workouts—which is where you should be practicing the situations you’ll encounter in a race—when holding your goal pace starts to get difficult and you’re not always inclined to make the smartest decisions. Practicing during training will help you be present and alert the moment you see an aid station in a race.

“Don’t run right through the aid stations when things get tough,” Rosario cautions.

In a race or long workout, there’s often a tendency to grab water, sports drink or a gel and get it down as quickly as possible, which often results in a gag reflex or upset stomach. Don’t throw your cup or wrapper down so fast, Rosario says. Instead, hold onto it for as long as possible to lessen the likelihood of something not settling well in your stomach.

“Be comfortable holding [the cup or bottle] longer and longer,” he advises. “You can’t squeeze 4, 6 or 8 ounces down your throat in 20 meters. Spread it out and hold onto the cup or bottle a little longer and try to get in as much as you can without causing a problem in your stomach.”

Troop says that if you’re carrying a water bottle during a race, draw a line or lines on it so you know how much you’re trying to get down. If you’re grabbing a cup, squeeze the top so you don’t lose any excess fluid and take your time drinking to ensure that you’re getting what you need. Slow down and take your time to ensure you get everything down.

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“I tell my athletes to pace themselves over a mile or even a mile and a half to make sure you’re not rushing to get it in,” he says. “The last thing you need to do is panic.”