Increase Your Carb Intake During Training | Training The Gut #1

Endurance races often demand a high hourly carbohydrate intake per hour, with very trained amateurs and professional cyclists targeting up to 120 g carbs per hour. However, reaching this level of intake requires preparation. You can’t just jump into race day and expect your body to efficiently consume such a high amount of carbs if you’ve never done it before. 

The ability to absorb and use high quantities of carbohydrates relies on proper gut training. If you don’t train your gut, you’re likely to run into gastrointestinal problems on race day, one of the most common reasons for a DNF (did not finish) result among endurance athletes.

Ways to train your gut

Without sufficient carbohydrate intake during endurance events, athletes can experience fatigue, known as “hitting the wall” or “bonking.” This is when glycogen stores become severely depleted, leading to reduced physical performance and inability to continue the activity. Therefore, endurance athletes must focus on consuming enough carbohydrates during exercise to maintain energy levels and delay fatigue.

Gastrointestinal problems might be prevented by adapting the gut to the specific conditions it will be exposed to during training and competition. Nutritional training can improve gastric emptying, absorption, perception of fullness and thereby reducing the risks of gastrointestinal problems such as bloating, diarrhea, cramping and even vomiting. Here is how to train your gut so stomach issues don’t stand a chance on race day.

1. Train with relatively high carbohydrate intake during exercise
2. Train immediately after a meal
3. Increase your daily carbohydrate intake
4. Train with relatively large volumes of fluids to ‘’train the stomach’’
5. In case of competition/racing: simulate your nutrition race plan during training

These methods should not all be applied within the same week of training or training itself. You can imagine that if you would train straight after breakfast, followed by a double amount of food during training then you’re used to, in combination with double the amount of fluid consumption, that you might need a sanitary stop or are forced to slow down training. For this blog, we’ll focus on the first principle: train with relatively high carbohydrate intake during exercise.

Gut training takes time

Optimal gut training might take several weeks, depending on how ‘’trained’’ your gut system is when you start. If you’re inexperienced in consuming food and fluids during exercise, starting your gut training 6-10 weeks before race day is best. To begin gut training, you need to ask yourself a few questions:

• How many carbs per hour do I need for this race?
• What time does my race start? When will I eat breakfast?
• What temperature is expected for my race? How much will I need to hydrate?

These considerations are key to your overall nutrition plan and will guide your gut training process. EatMyRide can assist your gut training by allowing you to simulate and practice your race day fueling and hydration strategy on the bike. It’ll help you gain insights into your current carbohydrate intake, and from there you can begin gradually building up. In the EatMyRide app you can fill in your actual nutrition intake during trainings and evaluate your progress via Profile > Progress.

Tip: to track your carbohydrate intake you can use the Carbohydrate Burn / Intake Balancer app for Garmin.

Dedicate one day a week as a “gut training day” where you practice race-day nutrition during your training session. Start building up from your comfortable starting level. If your goal is to build up to 90 g/hour, you might have to start at 30 g/hour. Perform a minimum of one training session with an amount that feels comfortable before building up. Aim for small steps, such as an increase of 10 g/hour the next week. You might also consider doing some training with slightly higher intakes than you’ll aim for during your race.

Example: let’s say your race starts in 10 weeks from now, and you’re aiming to ingest a minimum of 100 g carbohydrates per hour, while your average current intake is around 30 gram / hour. Increasing 10 g / hour per week meaning you’d need a minimum of 7 weeks of gut training. And you might want to consider some spare weeks in case your build-up needs to be more gentle or needs more practice. A 10-week window seems to fit just right.

How much?

As a very general rule of thumb, trainings or races above 3 hours require multiple transportable carbohydrates (glucose and fructose) ingested in a 2:1 or 1:0.8 ratio. An important note should be made that intake for carbohydrates during exercise are dependent on the training goal, duration, and intensity. 120 g/hour might be of benefit for professional cyclists undertaking races. In order to do so, you gradually need to build up as described above.

Although this is a very general rule of thumb, trainings up till 75 minutes usually require no extra carbohydrates, you’ll use your glycogen stores and you are fine consuming water ad libitum. If your training duration is extended up till 2 hours, you do want to increase your intake up till 30 g / hour. These amounts are sufficient to provide your body with enough fuel to maximize the training quality. A carb intake of 60 g / hour seems to be necessary when training up till 3 hours. Durations longer than that, seem to benefit from multiple transportable carbohydrates aiming 60-90 g carbs hour.

Upcoming

As you are aware now; training your gut takes time like any other system in your body. It might take several weeks and might feel a little uncomfortable at first, but this is normal as your gut system adapts. Remember these key takeaways before you start your gut training journey:

1. Begin with the end in mind. Design a nutrition and hydration plan for your race day minimum 6-10 weeks in advance.
2. Take one ‘gut training’ day a week that simulates race situations best.

Gut training makes you feel less bloated, increases gastric emptying, increases your capacity to absorb carbohydrates, and ultimately helps you race to the best of your ability. The EatMyRide app can help by displaying your carbohydrate expenditure and intake needs for each workout. It also allows you to create detailed nutrition plans before, during, and after each workout and race.

In part II of the Training The Gut series we’ll dive deeper into the other aspects of training the gut.

Resources

• Costa, R. J., Miall, A., Khoo, A., Rauch, C., Snipe, R., Camões-Costa, V., & Gibson, P. (2017). Gut-training: The impact of two weeks repetitive gut-challenge during exercise on gastrointestinal status, glucose availability, fuel kinetics, and running performance. Applied Physiology, Nutrition, and Metabolism, 42(5), 547-557.
• Jeukendrup, A. (2010). Sports Nutrition-From lab to Kitchen. Meyer & Meyer Sport.
• Jeukendrup, A. E. (2017). Training the gut for athletes. Sports Medicine, 47(Suppl 1), 101-110.
• Viribay, A. et al. (2020). Effects of 120 g/h of carbohydrates intake during a mountain marathon on exercise-induced muscle damage in elite runners. Nutrients, 12(5), 1367.