top of page

Rethinking Carbohydrates for Endurance Athletes

We live in a time where we're constantly bombarded by information - especially about nutrition. The problem for endurance athletes is the majority of what we see, hear and read is aimed at sedentary people, not us. Also, much of what is broadcast to athletes is being put out there by someone trying to make a buck by selling you their diet, book or next wonder-product. Let's break through the noise and create some actionable steps you can take to improve your health and performance.

Separate everyday nutrition from training nutrition.

This is one of the most important mental shifts an athlete can make. It's convenient to think we're 'fueling' our exercise even when we aren't exercising, but the body is amazingly good at down-shifting when we are at rest. When we're not working out, we should eat healthy, whole foods - minimizing simple sugars and maximizing a balance of protein, healthy fats and complex carbohydrates. By sticking to complex carbohydrates, we minimize blood sugar spikes and maximize the time they take to digest. During training, those rules go out the window, as we need quick-acting fuel in the form of simple carbs. Protein and fat digest too slowly to be useful fuels during exercise with any appreciable amount of intensity.

Earn your carbs.

This principle of timing the intake of carbohydrates I learned from the late, great Charles Poliquin. Put simply, if you aren't burning (or haven't just burned) carbs, limit their intake. By the time we get a few hours past a meal, the boost it created is gone and it's been processed into protein, glycogen, fat or waste. What this looks like for an athlete who's training later in the day would be a breakfast focused on healthy fats and protein, adding some complex carbs at lunch, probably a pre-workout snack with some quicker-burning carbs, and then a post-training dinner heavy on carbs to replenish what was burned in training.

Basically, don't think that a giant pancake breakfast is going to be productive fuel for an evening training session. After that session, however, our carbohydrate stores are depleted and need to be replenished. This is especially important if we are planning a hard training session the following day. This is best accomplished with a recovery drink (see below) and a meal within 2.5 hours with sufficient carbs to replace what was burned.

So wait, is sugar bad or good?

It depends on what we're doing. We definitely want to avoid simple sugars when we are not exercising. This is high-octane fuel and our bodies have nowhere to put it besides fat stores and stressful blood sugar spikes (with the ensuing stressful crash). However, that rule reverses when we are training and racing. Our slow-twitch muscle fibers can run on both fat and carbohydrates. Our fast-twitch fibers, which become increasingly active at higher intensities, can only run on carbs. If we are not fueling with some amount of sugar during exercise, we are depleting our glycogen stores - potentially hurting the quality of a training session and/or the following one. This is the time to be taking in simple sugars, as we want them easily and quickly absorbed.

How much do we need?

The generally agreed upon number is 60-90 grams of carbohydrates per hour during training and races that are intense and/or longer than one hour. Notice I'm saying a lower intensity session longer than an hour still requires carb fueling. The longer or more intense the effort, the more important this becomes. For athletes who haven't been fueling during workouts, it won't be easy to get into this range right away. Don't feel like you have to jump right to the max. In fact, your body probably won't be able to process that much right away. Start slow and gradually increase the amount. I often set goals with my athletes to consume a target number during specific workouts. By doing so, we have a well-tested nutrition plan before we get to goal events.

What to eat for training/racing?

There are many good options here. I generally prefer to keep fueling nice and steady, so I like to recommend having a portion of carbohydrates come from the bottle and the rest from small bites eaten every 10-15 minutes. Drink mixes like GU Hydration have high electrolyte concentrations (watch for an article on this soon) and 15-20 grams of carbohydrates per bottle. That allows the remaining carbs to come from solid food options. During high-intensity races, I generally prefer blocks over gels, as they allow small portions to be consumed steadily - not to mention without making a mess. I generally put loose blocks into my jersey pocket so they're easy to grab one at a time. For everything else, we generally aim for whole-food options like homemade date- and fig-based energy bites. When we run out those, we like Larabars because they're date-based and contain simple, whole-food ingredients.

Think about a pre-workout snack.

We don't want to go into higher-intensity sessions in a low-carb state. To avoid this, a pre-workout snack within 1-3 hours of a training session can help create a beneficial blood sugar boost. The closer to the start of the workout, the simpler the carbs should be to promote quick digestion. I like oats or muesli for the 2-3 hour range; bread or a bagel for 1-2 hours out; and fruit like a banana or dates if go-time is less than an hour away. The closer to training time, the less fiber we want, as it slows digestion.

Rethink recovery drinks.

There's a lot of outdated information out there around recovery drinks. What we have learned in the past few years is that we need more protein and fewer carbohydrates immediately after a training session. A good target is 20-30 grams or protein and 10-15 grams of simple carbs. We want simple carbs here because we want them absorbed as quickly as possible. Many commercially available drinks still stick to the old 4:1 carbs to protein ratio and don't provide the best recovery.

Know your refueling window.

Did you know that men and women have different refueling windows? It's true. For men, the window when nutrients can most easily be absorbed actually extends out close to two hours post-exercise. For women, the window is much shorter and closes abruptly after 30 minutes. This means that female athletes need to be more vigilant about getting in their post-workout nutrition. If that doesn't happen, recovery will be slower and stress on the body will be unnecessarily higher. The best bet here is to plan ahead and make sure we have what we need available so it's quick and easy to have immediately after training/racing. Is it an extra logistic to plan ahead? Yes, but it's worth it to maximize gains and minimize residual stress on the body.

Keto doesn't work for high-intensity.

This one will be sure to get some people fired up. I'm not against some of the principles of ketogenic diets, but they are not a recipe to go fast. While we can run for almost endless periods burning fat at low intensity, the vast majority of racing disciplines are not performed at low intensity. Therefore, training for those events isn't done there either. Even full IRONMAN's are a high enough level of output that significant amounts of carbs will be burned. The risk with a strict ketogenic approach is that an athlete's body will lose some of its ability to process and burn carbohydrates, limiting their speed. By following an earn-your-carbs approach, as mentioned above, we can teach the body to burn fats more effectively without risking a loss of higher-intensity power production, and therefore speed.

I hope this has broken through some of the myths and misleading information out there around carbohydrate nutrition. Please feel free to reach out with questions and feedback.


Featured Posts
Recent Posts
Search By Tags
bottom of page