Fueling for Marathon Performance

By Chris Newport, RDN, LDN, CISSN and Elisabetta Ballaben, DTR, dietetic intern

Whether your preparing to run your first marathon or your fiftieth, here’s some general information that may help your performance and make your training and racing experience more fulfilling.

Carbs to Compete

Maintaining muscle glycogen (aka stored carbohydrates to help avoid the dreaded bonk) allows for optimal endurance during marathon training. Carbohydrates are a quick source of fuel for your muscles, so it is a priority to maintain their supply in the diet. While carbohydrate needs vary on an individual basis, it’s important to choose nutrient-dense sources like fruit, vegetables, quinoa, brown rice, and sweet potatoes.

In the literature, it is suggested to consume between 8 to 12 grams per kilogram of bodyweight on a daily basis for exercise longer than 4-5 hours (like many marathoners). If you do some quick math, you may find that’s more than you can eat. For example, for 150lb person, that’s 545g of carbohdyrates alone (over 2100 calories), without even considering fat and protein needs. For any dietary adjustments, they take time to get used to so be sure to experiment during training or seek help from our dietitians to get your ideal needs.

Should You Carb Load?

A technique for building muscle glycogen stores quickly is called carbohydrate loading or glycogen supercompensation. It may benefit marathoners, since it’s ideal for endurance events longer than 90 minutes. There are several specific techniques, including the 7 day method, 3 day method and 1 day method. This is NOT something that you should try before race day, but experiment with during training for you 15+ mile training runs.

1 Day Carb Loading Method

Carb loading is NOT just eating a giant bowl of pasta the day before race day. Instead, the 1 day method is a specific technique of “topping off” and maintaining your glycogen stores 3 days before your event (or training run). It’s the easiest (and least “painful”) technique where you complete a “hard” workout (much be glycogen depleting, so zone 3-5), followed by eating 10-12 grams of carbohydrates per kilogram of bodyweight over the rest of the day (think of this as eating pretty much all high quality carbs all day long). The next 2 days should be rest days while eating your normal diet. The 3rd day is race day. Keep in mind that some potential side effects include weight gain, bloating, muscle soreness and fatigue. Again, experiment during your 15+ mile training runs before executing this on race day to see if this works for you.

What about During a Marathon? 

During a marathon, hydration is key as the most common issue with marathoners is dehydration. General recommendations are to drink on a consistent basis with a sports drink that best matches your sweat losses and paces. Get in the habit of weighing yourself before and after your long runs to ensure you’re not gaining weight while minimizing your losses to less than 2% of your bodyweight. Check out our related blog on how sweat and metabolic testing can help you run your best marathon.

Carbohydrates are just as important during a marathon as they are in preparation for one. In the literature, we’ve seen subjects consume up to 90 grams per hour, but that is generally in cyclists. Most runners can consume up to 60g of carbs per hour for men and 40g of carbs for women. The best way to know your needs is to do our Fueling Formula (metabolic testing) that measures substrate use (aka carbs and fat burned) at the paces you’ll be doing for training and racing.

Carbs can come in the form of sports drinks, energy gels, gummies, energy bars, dried fruit, candy, cookies or other portable foods that are quickly digested. Opportunities to fuel may be different for every individual and event, so planning ahead and experimenting is crucial. Marathon athletes should identify and practice a fueling regime that suits their individual hydration needs, goals, dietary habits and comfort levels. Doing metabolic and sweat testing in combination with professional nutrition counseling is the best investment to make your marathon training and racing the best experience possible. Contact us to learn more!

Post Marathon Recovery

After a marathon is complete, celebrate! Next, focus on rehydrating and cooling down. Whether it’s hot or cold outside, you’ll need to regulate your core temperature (in other words, cool off if it’s hot out and get warm if it’s cold out). About 30 minutes later, consider restoring muscle glycogen and recovery with carbs, like chocolate milk, hot cocoa, smoothies, sports drinks and salty snacks like pretzels, pizza or hot soup. Listen to your body (and what you may be craving) and take it slow as your digestive system starts “working again.” After about 2 hours, you should hopefully be feeling well enough to have a mixed, usual meal. 

Marathon Fueling Cheat Sheet

 

Need help fueling for your marathon? We can help!

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Thanks to Elisabetta Ballaben, DTR, our dietetic intern with Be Well Solutions. Her professional interests include plant-based nutrition, nutritional psychology, and women’s health.

 

References: 

Thomas, D. T., Erdman, K. A., & Burke, L. M. (2016, March). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: Nutrition and Athletic Performance. Retrieved August 28, 2019, from https://jandonline.org/article/S2212-2672(15)01802-X/fulltext

 

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