Carbohydrates: Matching Fuel to the Workout

Toolbox: Carbohydrate-rich foods have gone through heaven and hell in the past decades. While the role of carbohydrates is well recognized in enhancing cycling nutrition and performance, it seems that the perfect harmony lies in eating according to the workout you are going to perform.

Training adaptations
In cycling and endurance sports, pasta is still worshiped as the goddess of carb loading. Certainly this idea may sound familiar to you.

Chronic carbohydrate restriction had its moment in the weight loss and sports performance realm. For many years (and still ongoing), endurance athletes still engage in restricting carbohydrate foods for weight loss purposes, although they recognise the importance of this macronutrient to maintain high intensities during training and competition.

However, the scientific data of the past decade seems to point that deliberately training with low muscle glycogen stores around some key training sessions may further amplify training adaptations induced by training.

Training adaptations generated by the “sleep low, train low” model. Adapted from Burke & Hawley, 2018.

What training adaptations?
Training is essentially an “aggression” from which your body responds by generating adaptations that ultimately result in improved performance.

As a cyclist, whether you’re a pro looking to compete at the highest level or an amateur looking to keep up with your weekend training buddies, you may seek to:

• Generate more power

• Sustain high intensities during long hills

• Keep up with the group

• Be able to respond to attacks

For this, it is absolutely essential that your muscle glycogen (your most precious fuel) is spared for when it is most needed. This means optimizing your fat oxidation capacity. Training already does this but manipulating carbohydrate availability further amplifies that.

Reducing carbohydrate intake before a specific low intensity workout bout (low enough to still allow for the workout to be performed with the desired intensity) may generate some additional stimuli that signals your body to set in motion some extra adaptation mechanisms (see above Burke & Hawley image).

These adaptations are essentially:

Adaptations induced by training with low carbohydrate availability

When and how to do it?
It is important to clarify this issue. Let’s not engage into chronically restricting carbohydrate intake. The point is to do a “smart carb” approach where low intensity training sessions are undertaken with low carbohydrate availability.

Let’s assume that today you’ve done a 3 h cycling workout with sets performed at high intensities and tomorrow you’re going for a low intensity 2 h ride. Since at low intensities the glycogen demand is low, it may be the right context to eat a low carbohydrate dinner and perform the morning training session in a fasted state or with a low carb-high protein type of breakfast (an omelette would work).

But let’s assume that the training varies throughout the week as in most types of cycling workout plans. Thanks to the amazing research of Samuel Impey, we sports nutritionists are able to program our cyclists’ diet according to the principles of “fuel for the work required”.

Fuel for the work required model suggested by Impey, et al (2018).

This schematic organizes meals into different categories according to the amount of carbohydrate in each meal. Red for low carbohydrate, orange for medium carbohydrate and green for high carbohydrate quantity.

Notice that carbohydrate amount per meal is adjusted according to the next day’s session, day-by-day, meal-by-meal.

The amount of carbohydrate must be considered the day before a hard/long training session takes place in the morning after. This will allow you to perform a small glycogen loading that will allow for the prescribed intensity to be performed.

The point is to ingest a sufficient amount of carbohydrate required to perform with the required training intensity, plus further amplifying training adaptions that would otherwise be blunted by an excessive amount of carbohydrate required for that said session.

In summary, carbohydrate is more than a fuel but also a training amplifier that can further enhance or blunt the normal training adaptations that occur with exercise.

Take home message
Although carbohydrate-rich foods are unquestionably essential for cyclists looking to perform high training bouts and competing, manipulating carbohydrate availability throughout the training season according to the demands of the training sessions seems to be the best approach if you seek to further maximize training adaptations that ultimately will translate in an improved performance whilst competing.

The best way of doing this is to rely on a Registered Dietitian with experience in cycling nutrition to adjust the dietary plan to your training sessions.

Impey, S. G., Hearris, M. A., Hammond, K. M., Bartlett, J. D., Louis, J., Close, G. L., & Morton, J. P. (2018). Fuel for the work required: a theoretical framework for carbohydrate periodization and the glycogen threshold hypothesis. Sports Medicine, 48(5), 1031-1048.

Burke, L. M., & Hawley, J. A. (2018). Swifter, higher, stronger: What’s on the menu? Science, 362(6416), 781 LP-787.

About Gabriel Martins:
Gabriel Martins is a Portuguese Nutritionist with a Master’s degree in Sports Nutrition. He currently lives in Spain where he works with cycling teams and integrates the research group on sports physiology at the University Camilo José Cela in Madrid. Additionally, Gabriel is the Host of Fuel the Pedal Podcast. A show where he interviews researchers, sports nutritionists and cyclists discussing topics related to nutrition and physiology.

Gabriel can be reached for comments at You can also follow him on Instagram, Twitter and Facebook.

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