How Can Cyclists Train The Gut To Fuel Better & Perform Optimally at Races?

The motto of performance nutrition is to fuel for the work required.

To ensure a cyclist can maintain work capacity throughout a hard ride or race, it's important that we fuel the ride.

The fuel needed during the ride depends on duration and intensity, where the amount of carbohydrate needed increases as both factors increase.

Cyclists may need higher carbohydrate intakes of 90-120g/hour for more demanding rides and races to optimise performance and reduce the recovery burden.

Consuming high amounts of carbohydrates is only beneficial if the gut tolerates this amount of carbohydrates during the ride.

It's been very well established that high carbohydrate and fluid intakes during exercise can cause gastrointestinal distress (GI) and subsequently ruin performance.

The good news is that the GI tract is highly adaptable through changes in the diet and can, therefore, be trained to tolerate higher-carb intakes – meaning that GI symptoms (bloating, cramping, diarrhoea, and vomiting) decrease.

Carbohydrates are absorbed via two transporters in the gut (SGLT1 and GLUT5) – see these as doors that allow the passage of carbs from the gut into circulation.

If too many carbohydrates are consumed hourly, these transporters (doors) become saturated, and you get a bottleneck in the gut. The carbohydrates and the associated water will begin to pool, and you feel fullness and additional discomfort.

For example, SGLT1 allows the passage of glucose from the gut and into the circulatory system. Glucose saturates this transporter at 1g per minute or 60g per hour. Therefore, if more than 60g of glucose is consumed each hour of riding, there'll be a backlog of glucose in the gut, which can cause gastrointestinal upset.

Side note: When higher carbohydrates are needed, composite carbohydrates containing glucose and fructose are recommended to meet the fuelling demands, as fructose is absorbed by the gut transported, GLUT5, and therefore another door becomes available for carbohydrates to pass from the gastrointestinal tract and into the circulatory system. The ratio of fructose to glucose in composite carbohydrate drinks is typically 0.5-1.0:1-ratio fructose: glucose (30-60g fructose: 60g glucose).

Although sports nutrition products such as carbohydrate powders, gels, chews and bars make hitting higher carbohydrate intakes easier, most cyclists need to familiarise themselves with the fuelling process to ensure they can tolerate the fuel they consume.

The good news is that we can increase the number of gut transporters on a high carbohydrate diet within 1-2 weeks because the gut is highly adaptable to the nutrition stimulus.

The goal of 'training the gut' is to improve gastric emptying rates, perception of fullness (bloating), tolerance to larger volumes and increased speed of absorption.

Training the gut is achieved in the following ways (Jeukendrup, 2017):

• Training with relatively large fluid volumes to 'train the stomach'.⠀
• Training immediately after a meal.⠀
• Train with a relatively high carb intake.⠀
• Simulate a race day plan in training.⠀
• Increase the carbohydrate content of the diet.

These strategies may cause some discomfort initially, i.e. who wants to train straight after a big meal? This strategy differs from what the FTR team would recommend before important races and key training sessions, as it may be detrimental to performance.

Therefore, these strategies must be viewed as part of the training process to improve adaptation and better prepare you for a key race or race season.

Long story short, if you need to consume higher amounts of carbohydrates and fluid during competition – It'll be wise to start training under these conditions so your gut can adapt to the nutritional stimuli.

It's essential to be methodical with your approach. Like training, you won't start from zero and then attempt to set a new world record on the Tour divide straight out the front door. You'd build up duration and time spent in the saddle slowly over time.

Training the gut follows the same methodology: If you're only familiar with consuming one gel or 25g of carbohydrate per hour on a ride, don't jump straight to 120g/hour. Focus on building the tolerable amounts weekly until you've achieved your target race strategy.

In return, it increases your capacity to deliver more carbohydrates to the liver and muscle, reducing gastrointestinal issues and, most importantly, improving performance.

- Coach Chris