Energy gels are one of the most commonly used strategies by endurance athletes to maintain carbohydrate availability during training sessions and competitions. However, many athletes report that, especially toward the final part of a race, they begin to feel nauseous or have difficulty continuing to consume gels.
This phenomenon is relatively common and can have different physiological, sensory, and strategic explanations.
Gastrointestinal fatigue during prolonged exercise
During long duration exercise, blood flow is directed mainly to the working muscles. As a consequence, there is a reduction in blood flow to the gastrointestinal system.
This shift can reduce the efficiency of digestion and nutrient absorption, increasing the likelihood of discomfort such as nausea, a feeling of fullness, reflux, and difficulty consuming foods or supplements.
The longer and more intense the race, the greater this gastrointestinal stress tends to be.
Carbohydrate overload in the intestine
Another important factor is the amount of carbohydrate consumed throughout the race. When intake exceeds the intestine’s absorption capacity, part of these carbohydrates remains in the gastrointestinal tract, increasing osmolarity and favoring gastrointestinal symptoms.
Strategies that combine different types of carbohydrates, such as maltodextrin together with fructose, help increase intestinal absorption rates because they use different transporters in the intestine.
This approach allows greater energy availability with a lower risk of gastrointestinal discomfort.
Sensory fatigue and sweet taste saturation
In addition to physiological factors, there is also a sensory component. During long races, athletes may experience taste saturation.
This phenomenon occurs because repeated exposure to the same flavor reduces the palatability of the food. Over time, the gel may start to feel difficult to consume.
For this reason, some athletes prefer to alternate flavors or include other forms of carbohydrate intake during the race.
Dehydration and inadequate fluid intake
Consuming gels without adequate water intake may increase the risk of gastrointestinal discomfort.
Gels contain a high concentration of carbohydrates. When consumed without sufficient fluids, they can increase the concentration of solutes in the stomach, delaying gastric emptying and increasing the likelihood of nausea.
Strategies that help reduce nausea
Some strategies can help reduce the chance of nausea during a race:
• test the nutrition strategy during training
• distribute carbohydrate intake throughout the race
• use multiple carbohydrate sources
• consume gels together with water
• vary flavors when possible
Another important approach is intestinal training, known as gut training, which consists of adapting the gastrointestinal system to better tolerate carbohydrate intake during exercise.
Conclusion
Feeling nauseous when consuming gels near the end of a race is a multifactorial phenomenon. It may be related to gastrointestinal fatigue, the amount of carbohydrates consumed, dehydration, or sweet taste saturation.
For this reason, the nutrition strategy should always be tested and adjusted during training. Individualizing carbohydrate intake is essential to ensure energy availability without compromising gastrointestinal comfort and athletic performance.
Reference
Martinez IG, Mika AS, Biesiekierski JR, Costa RJS. Gut training and feeding challenges during endurance exercise, effects on gastrointestinal symptoms and nutrient tolerance. Sports Medicine. 2023. https://doi.org/10.1007/s40279-023-01841-0
