Fueling for Endurance Events, by Ashley Reaver, MS, RD, CSSD

Fueling for Endurance Events, by Ashley Reaver, MS, RD, CSSD

Fueling for endurance events is just as important as the months of training you’ve invested getting to the starting line. If you’re an endurance athlete, you’ve likely had at least one race experience where you performed below your expectations. Three months of training isn’t enough to power most of us through 2+ hour events. 

We need fuel to support our efforts.

Our muscles heavily depend on fueling from carbohydrates during moderate- to high-intensity activities, like endurance events. To ensure you don’t bonk due to under-fueling in your next event, follow these fueling strategies.

Pre-event: Days before

We are all familiar with the concept of “carbo-loading”, but do you know why you’re doing it, and are you eating enough? Strategically increasing your carbohydrate intake will help to stock your muscle glycogen stores.

Typically, our muscles can store around 45-60 minutes of fuel. Through training and timely intake of carbohydrates, glycogen storage capacity can increase.

For events that are less than 90 minutes, eat 7-10 grams of carbohydrates per kilogram of body weight the day before. For a 150 lb person, this is 475-675 grams of carbs.

For events that are over 90 minutes, eat 10-12 grams of carbohydrates per kilogram of body weight for 2-4 days before. For longer endurance events, this higher intake of carbs may achieve super-compensation of glycogen stores. For a 150 lb person, this is roughly 700-800 grams of carbs per day.

These carbs should be low in fiber for two reasons. Primarily, you’re aiming for “low residue” foods that will not leave a large amount of matter in your GI tract (and make for an unpleasant experience). Second, these carbs should be digestible carbs that your body can convert into glycogen. While fiber is a carbohydrate, it is indigestible. Fiber in = fiber out. For this reason, carbohydrates in most vegetables aren’t good choices for pre-race fueling.

Good options: white rice, white pasta, bread, baked goods, low-fiber fruits like melon and grapes, and sweetened beverages. Fat and protein should also be limited. Lastly, consuming your carbohydrates in small snacks and meals is ideal rather than three large meals over the days before. 

 Pre-event: Morning of

You should eat before any activity that will last over 60 minutes. Remember, we have about 45-60 minutes worth of glycogen. Outside of that, we need to rely on exogenous fuel sources, meaning that they come from outside of the body. Particularly in long-course endurance events lasting over 90 minutes, you want to make sure that you don’t tap into and deplete your glycogen stores prematurely since you won’t be building them back up during the race.

 The morning of the race, eat 1-4 grams of carbohydrates per kilogram of body weight 1-4 hours before the event. For a 150 lb person, this is about 70-270 grams of carbohydrates.

Your pre-event meal should contain a small amount of protein to help prevent a sharp insulin response. A pre-event meal without protein can cause a spike in insulin, which will lower the blood glucose level and may make you feel fatigued.

 Another pre-event tip is to include some high-intensity efforts in your warm-up. This can stimulate hepatic gluconeogenesis, or your body’s production of glucose in the liver, which will also provide a fuel source.

Cocoa Elite makes a complete compliment of products based on high-quality ingredients. These products range from same-day fueling to overnight recovery options. All can be found by visiting their Website: Cocoaelite.com

During event

Any activity over 60 minutes should include fueling since the muscles are essentially running on empty by around 45 minutes. You never want to feel hunger during training or a race, so eating on a schedule and not by feel is important. Ideally, take in fuel every 15-30 minutes when exercising for over 60 minutes. How much fuel will you need?

For activities from 1-2.5 hours, eat 30-60 grams of carbohydrates per hour.

For activities over 2.5 hours, eat 90 grams of carbohydrates per hour.

Additionally, you want to diversify your sources of fuel at this level. Fuel should be a mixture of fructose and glucose. You can achieve this by eating a variety of foods or purchasing specialty endurance products, such as Cocoa Elite products. This is a lot fuel and may be difficult to ingest. For events longer than 2.5 hours, your water bottle should also contain fuel. Drinking just water is a missed opportunity for necessary carbohydrates and sodium.

 A few other tips: Don’t neglect sodium. You are losing sodium in your sweat and, especially on hot days, you need to replenish it. Consider utilizing caffeine for efforts over 2.5 hours. Finally, branched chain amino acids (BCAAs) can be helpful additions in efforts over 2.5 hours. They can be used as a fuel source and can prevent some muscle breakdown during long efforts. Many products include them.

What about low carbohydrate diets?

The muscle’s primary and preferred fuel source is carbohydrates. Fats can be used as fuel, but only for low- or moderate-intensity activities, which typically doesn’t include race day. Low carb diets can impair the body’s ability to utilize carbohydrates. An ideal situation is to practice “train low, race high” sparingly. Incorporate one lower carbohydrate-fueled workout every few weeks. This will help to train your body to utilize fuel as a fat source. It should not be employed frequently, though, as it can impact your ability to utilize carbohydrates and perform your best.

These strategies should also be employed for training. You need to train your GI tract, glycogen storage capacity, and fuel utilization systems just as you train your muscles for events. Introducing these strategies on race day is not ideal. Your body should be comfortable with the fueling routine you employ in your events.


Ashley Reaver is the founder of Ashley Reaver Nutrition, a private practice that offers nutritional services. She is also the creator of the Lower Cholesterol Longer Life Method, a self-paced course that helps people with high cholesterol lower their cholesterol so that they can live a longer, healthier life. 
Ashley’s knowledge areas and counseling specialties include sports nutrition, weight loss, cooking classes, meal planning, and intuitive eating principles. She holds a Bachelor of Science in Nutritional Science from Cornell University. In addition, she completed her dietetic internship at California Polytechnic University. Afterwards, she earned her Master of Science in Nutrition Science and Policy from Tufts University.
Ashley is also a Certified Sports Specialist Dietitian.

All bloggers receive a small compensation for their contributions.

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