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The Right Way to Fuel During Your Long Runs

Practice your marathon hydration and nutrition plan during training to avoid race-day dehydration and carb-store exhaustion.

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As you train for a marathon and fine-tune your overall fueling plan for long runs, a certain amount of trial and error is necessary. But it is especially vital to test midrun nutrition during training.

By getting this right, you’ll avoid both dehydration and exhaustion of those precious carbohydrate stores. Since you’ll be fueling throughout the marathon itself, practice drinking and refueling during workouts that exceed one hour. While there are times when you may have to force yourself to eat and drink during a hard effort, your body will thank you on race day. There is perhaps no greater performance booster than simple calories and hydration.

Hydration will undoubtedly give you the most bang for your buck in both training and races.

Not only will fluids help maintain blood-volume levels, but sports drinks can also provide crucial calories without having to add another component to fuel your long run. Your own sweat-loss rate may vary, but on average, we lose between 2 and 4 pounds of sweat per hour. If that’s not replaced, muscles receive less oxygen, less heat is evaporated, and by-products (lactic acid) accumulate in greater amounts. Among other outcomes, the body tries to compensate by making the heart beat faster.

Indeed, for every 1 percent of body weight lost as a result of sweating, your heart rate will increase by up to 7 beats per minute. Furthermore, for every 1 percent of body weight lost through dehydration, you will slow down by about 2 percent. The marathon is already hard enough, so the last thing you need is your heart thumping faster and your legs moving slower. At an 8:00-minute pace, a 2 percent loss in pace resulting from a 1 percent loss in body weight (as little as 1–2 pounds) translates into 5 lost seconds per mile. If you slow down by 2–4 percent, which is quite common, that 8:00-minute pace slows to closer to an 8:20 pace. That is the difference between a 3:29 and a 3:38 marathon finish.

The most recent research says that when we drink solely based on thirst, somewhere between 68 and 82 percent of the lost fluid is recovered. These researchers suggest that the body compensates by basically pulling water from inside the cells to make up the difference, in addition to the natural formation of water through the combustion of fats and carbohydrates. While this undoubtedly occurs, they also discuss a major flaw in this line of thought. Their study indicated that all of the aforementioned stipulations are true up to a 3 percent reduction in body weight caused by sweat loss. The problem is that if we wait to drink until we are thirsty, we are already at about 2.3 percent (their calculation).

While their subjects had unlimited access to fluid, in reality, you won’t have the luxury of consuming 6–8 ounces whenever you feel like it. When I first read this study, I thought that perhaps everything we had been telling people was wrong. However, upon further examination, I realized that our hydration strategies remain appropriate and pertinent in terms of real-world endurance performance conditions. The following are the general rules of thumb about hydration for runners who need to a fuel a long run:

Start early.

Drink within the first 10–20 minutes of running or at the first water stop. As mentioned, thirst may be a good indicator, but in the marathon scenario, you won’t be able to drink enough soon enough to cover the deficit.

Drink 2–8 ounces of fluid every 15–20 minutes.

For training workouts, this means carrying sufficient water with you, or placing it strategically beforehand. For races, this should work well with the water and sports-drink stations. Most races provide these stations approximately every 2 miles.

  • Keep in mind that it’s easier to drink more during the early stages of a run or race. If you drink more early on and keep replacing fluids regularly, you will keep the fuel stores topped off for your long run. This creates the fastest gastric emptying, which means more rapid absorption of water, electrolytes, and carbohydrates.
  • Count the gulps. One gulp is roughly equal to 1 ounce of fluid. Try for 4–6 gulps per water stop.
  • Don’t overdo it. Downing multiple cups of water will only make you sick.
  • If you plan to use sports drinks and gels provided at the race, find out ahead of time what products will be offered and practice using them in workouts. If they cause distress, plan on bringing your own.

The guidelines for midrun nutrition are similar to those for hydration.

Gels are probably the most popular fueling product for long runs, but other options, such as chews, are quickly gaining a following. Glucose tablets, which diabetics use to raise their blood-sugar levels, are another alternative. They dissolve in your mouth and are a quick source of carbohydrates. Also, sports drinks will add precious calories to your overall intake, relieving the need to take in as many calories from solid foods. Here’s what we suggest:

Consume 30–60 grams of carbohydrate per hour of exercise.

  • The longer you’re running, the more carbs you should consume. For anything longer than 4 hours, take in 60 grams per hour.
  • An 8-ounce sports drink supplies 50–80 calories.
  • Gels provide 25 grams of carbohydrate.

Take in 200–300 total calories per hour.

  • If you were to drink 8 ounces of sports beverage every 20 minutes, you would get roughly 195 calories per hour. For most athletes, this will be sufficient for most runs that last less than 2 hours.
  • In addition to fluids and gels, some runners also find calories in other types of food. It depends on what you prefer.
  • If you use gels or something similar, chase with water, not a sports drink.
  • One gel every 30–45 minutes should provide enough calories.

A calculated fueling regimen can also play an important role in the mental marathon game. Former Olympian and Hansons-Brooks Distance Project team member Brian Sell used this strategy at the 2005 IAAF World Championships marathon in Helsinki. Since it was a humid day, he knew refueling would be instrumental to his success because he’d be sweating more than usual. During the second half of the race, Brian kept saying to himself, “just get to the next bottle.” He continued that mantra and envisioned his energy levels being boosted at each water stop every 5 kilometers.

In addition to fueling his working muscles and keeping himself hydrated, he was simultaneously feeding his motivation to continue pushing onward.

Adapted from Hansons Marathon Method, 2nd edition, by Luke Humphrey with Keith & Kevin Hanson, with permission of VeloPress.

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