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Marathon Race Day Fueling

Amanda Wendorff

Racing a marathon means more than just preparing your body to cover the distance; it's crucial to master your fueling strategy as well. Though fueling for a marathon might seem daunting at first, it's essential for maximizing both your performance and enjoyment on race day. From the moment you wake up to the moment you triumphantly cross the finish line, making smart nutrition choices is key.

This guide will simplify the process, walking you through optimal marathon nutrition every step of the way. (For a more detailed strategy on fuel during any type of endurance race, including marathons, you can check out our book "Triathlon Nutrition Foundations", which goes in depth to help you nail your fuel for any race.)

In this blog, you will learn:

  • The critical role of carbohydrates as your primary energy source during the marathon.
  • The timing and best foods to consume before and during your race for optimal fueling.
  • How to avoid hitting the wall, ensuring a smooth and enjoyable race day experience.
  • The carbohydrate intake needed to prevent energy depletion and enhance endurance.
  • The importance of hydration and how to effectively manage it throughout the event.
  • Why it is important to practice your nutrition plan during training to ensure race day success.
MOTTIV app user and US Marine Kevin Rodrigues smiles for the camera as he runs during the marathon portion of his triathlon race.

Why You Need to Fuel During the Marathon

Although most understand the importance of proper training before trying to run a marathon, many runners overlook the importance of developing a nutrition strategy prior to the race and then practicing it diligently during training. Starting a marathon race without a proper fueling strategy is like setting out on a long car ride with minimal fuel; you might not make it to your destination in the state you hope for.

Here's a deep dive into why race-day nutrition is key to running your best marathon.

Energy Sources for Endurance Runners

Running taps into the body's energy reserves, drawing from fats, proteins, and carbohydrates, all of which are stored in the body from your day-to-day fueling in the days leading into the marathon. Fat and carbohydrates are the two primary sources of energy for runners.

When you run at a very low intensity, like during some of your long runs in training, the body is able to use both carbohydrates and fat for fuel efficiently. However, the harder and faster you run, the more the body's preference shifts towards carbohydrates because they can be converted to energy quickly and efficiently.

Fuel During the Race To Avoid the Bonk

This reliance on carbohydrates as the primary fuel highlights their importance in endurance sports. Initially, the body will use the carbohydrates stored in your muscles and the liver, known as glycogen, for energy. However, these glycogen stores are limited and can be quickly depleted when you are running hard. The dreaded "bonk" refers to the point where a runner's glycogen stores run out, leading to a significant drop in energy and performance. As any runner who has hit the wall knows, glycogen depletion can dramatically affect a runner's ability to maintain pace and finish strong.

Because a marathon is a relatively hard effort and lasts for more than three hours for most runners, the rate at which carbohydrates are burned is high. Every runner is different, and the rate at which you burn through carbohydrates is dependent on many things, including how hard you are running, your metabolism, your size, and more. Estimates show, however, that running at a relatively high intensity, such as during a marathon, could burn through 125 grams of carbohydrates per hour. That's equivalent to 500 calories of carbohydrates. At that rate, you can quickly burn through your body's stores of carbs.

To avoid the performance decline that can occur when you run out of fuel, you can take in external sources of carbohydrates, such as sports nutrition products like gels or sports drinks.

Performance Benefits of Carbs

Incorporating carbohydrates into your marathon fueling strategy offers significant performance benefits. Ensuring a continuous intake of carbs helps you to:

  • Maintain energy
  • Avoid energy crashes from low blood sugar
  • Sustain your cognitive function, which is crucial for race strategy and pacing.

The positive impact of carbohydrate consumption during races is well-documented in scientific research, with many studies showing that carbohydrates consumed during exercise will improve performance.

What to Eat Before a Marathon

The pre-race meal sets the tone for your race day, making it a crucial element of your marathon preparation.

The Race Day Breakfast

Although you have hopefully been filling your glycogen stores in the days leading up to the race through a good carb-loading plan, the pre-race breakfast provides a final opportunity to replenish before the marathon. Try to eat breakfast at least 3 hours before your race, targeting 2 to 3 grams of carbs per kilogram of body weight. The goal of this meal is to top up your glycogen stores before your race starts, so carbohydrates should take center stage in this meal.

A well-planned pre-race breakfast can significantly impact your race-day performance, providing the energy needed to tackle the miles ahead. It's not just about filling up; it's about fueling smartly with foods that will release energy steadily throughout the race, keeping you powered and focused. To avoid digestive system discomfort, choose easily digestible foods that you've previously tested as part of your marathon training, and avoid high-fiber foods.

Good pre-race breakfast options include:

  • A bagel with almond butter
  • Oats with berries
  • Toast with honey
  • An energy bar, such as an Rx Bar or Clif Bar.

These options provide a solid foundation of carbohydrates, ensuring your glycogen stores are topped up and ready to power you through 26.2 miles.

Of course, remember the golden rule: nothing new on race day! Practicing your fueling before and during your training runs allows you to refine your pre-race meal to suit your personal digestion and energy needs, making sure nothing holds you back on race day.

Pre-Race Hydration

In the hours leading up to your half, don't forget about fluids! Hydration plays a pivotal role in your pre-race preparation, especially on hot and humid days. Include plenty of fluids in your pre-race breakfast. Sports drinks are an excellent way to boost carbohydrate intake while ensuring you're starting the race fully hydrated. Remember, starting the race well-hydrated can make a significant difference in how you feel and perform.

Quick Carbohydrates Right Before the Start

Many marathon runners like to consume a quick-acting carb source, such as an energy gel, roughly 20 minutes before the race begins. This timing ensures the glucose is absorbed and ready to fuel your muscles right from the start, offering a quick energy boost that can be pivotal in setting a good pace. Limit this last snack to about 100 calories or 20-25 grams of carbs to prevent GI distress.

Marathon Fueling Strategy

What to Eat During a Marathon

Selecting the right fuel during a marathon is crucial for maintaining your energy and performance. The best choices for most runners are sports products -- primarily fast-acting carbohydrates that are in liquid or semi-solid form for quick absorption and easy digestion. Ideal options for race day fueling include:

  • Energy gels: There are dozens of brands that manufacture energy gels that are designed for runners, with different combinations of carbohydrate sources, flavors, and textures. There are even gels with caffeine that provide an additional boost of energy. Like any nutrition product, you need to practice taking these gels in and should try a few different options during training to figure out what works best for your body.
  • Sports drinks: Sports drinks are useful during races because they contain carbohydrates as well as essential electrolytes and fit within a good hydration strategy. A few ounces of sports drink at every aid station during your marathon may lead to your best race day.
  • Other high-sugar options: Although not designed specifically for runners, simple sugar products such as cola, bananas, or candy can help fuel your race or long run.

For many runners, solid foods (or "real food") can prove challenging to digest efficiently, potentially leading to gastrointestinal distress. Liquid or gel-based carbohydrates are generally easier on your digestive system and will keep you powered and focused throughout the race.

How Often To Eat During a Marathon

Every marathoner is a little different in terms of how often and how much they need fuel during a race to keep up with their energy expenditure, but you should aim to take a gel every 20 to 30 minutes. A good rule of thumb is to aim for at least 30 grams of carbs (up to 60 grams) per hour.

Generally, more frequent carbohydrate intake can enhance performance and endurance, but you want to practice your fueling throughout your training to know how well your gut will tolerate that intake. To identify what works best for you, test different fuel sources, fueling frequencies, and quantities during the training leading up to your race, ideally at the pace you plan on running.

The Logistics of Marathon Nutrition

Managing your fuel on race day requires planning on how to carry and consume your chosen products efficiently. There are a couple of options:

Carry Your Nutrition Products

If you want to make sure that you have your preferred sports nutrition and can eat and drink exactly when you want, you can carry your gels or drinks with you. There are several ways to do this:

  1. Carry them in your hands: Hold a gel or two in each hand.
  2. Wear running clothes with pockets: There are many types of running gear that have pockets specifically designed to hold nutrition products. Look for shorts that have large cargo pockets or zip pockets along the waistband.
  3. Purchase a pouch or number belt designed for carrying nutrition: Numerous companies sell pouches or belts that fit around the waist and allow you to carry a few gels comfortably
  4. Use a handheld water bottle or hydration pace: If you'd like to carry your own sports drink, consider a handheld water bottle, which is ergonomically designed to make carrying fluids easy, or a hydration pack, which is designed to allow runners to carry all the fluids they need.
You can see MOTTIV app user Laura Yamasaki's race fuel in her belt, and her hydration in a hand-held bottle as she runs a hot-weather race on the Big Island of Hawaii.

Rely on Aid Stations As a Way to Fuel

Almost all marathons will have numerous aid stations, placed every one to two miles, that will serve water and sports drinks, as well as gels or other foods like bananas or pretzels. If you'd like to avoid carrying your nutrition, you can use the aid stations to ensure that you obtain the carbohydrates you need to fuel your run.

Before planning to rely on aid stations, make sure you know what products they offer. Test these products in training to make sure they work for you. Also, make sure you know where the aid stations will be located and how many there are - plan your fueling strategy with this knowledge so that you can make sure you have adequate energy throughout.

Hydration During a Marathon

If you want to perform in your race, staying hydrated is critical. Even mild dehydration can negatively impact your performance, and dehydration of just 2% of a runner's body weight can lead to significant slowing.

So, during your marathon, don't forget to drink frequently! Sports drinks are a great option, as they are both hydration but also provide the additional carbohydrates and electrolytes needed for sustained energy and performance. However, remember that if you are also consuming energy gels, it's best to pair them with water in order to dilute the concentration of carbohydrates. This will allow for smoother digestion and absorption and help to prevent any potential gastrointestinal discomfort.

Wrap Up

This guide has covered everything you need to know about marathon fueling and hydration, providing detailed insights into the best strategies for pre-race and mid-race fueling while also explaining the crucial role of carbohydrates in running performance.

Remember, the key to a successful race day lies in planning an effective nutrition strategy and practicing it during training. This will allow you to approach the starting line with confidence, fully prepared to tackle the challenges ahead.

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Amanda Wendorff

| Author

Amanda Wendorff is a professional triathlete, focusing on the 70.3 and 140.6 Ironman distances. In the last several years she’s competed in multiple gravel bike races. Top Achievements: Top 3 Ironman Ireland and Ironman 70.3 Coquimbo, Multiple time top-5 finisher, 3rd Overall at Moran 166 Gravel Race in Michigan, Age group podium at Gravel Worlds, Big Sugar, and Ned Gravel in first year of gravel racing.

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