GI distress

GI distress refers to digestive discomfort such as nausea, cramping, bloating, vomiting, or diarrhea that arises during or after exercise.

Why it occurs in athletes

Gastrointestinal problems are common among endurance athletes. Studies report that 30–50% of athletes experience some form of digestive complaint during events, and the prevalence can be higher in long-distance races. During intense exercise, blood flow is redirected away from the gut toward working muscles. When athletes are dehydrated, this reduction in mesenteric blood flow is even greater. Reduced perfusion limits oxygen delivery to the intestinal wall, which can compromise gut integrity and slow gastric emptying. Mechanical jostling, particularly in running, can further irritate the stomach, while nutritional choices such as high‑fiber foods, concentrated carbohydrate drinks, or excessive fructose can slow digestion and contribute to symptoms. People who do not regularly practice fueling strategies may be more susceptible. Nutritional training that promotes rapid gastric emptying and the absorption of water and nutrients, along with maintaining adequate hydration, helps reduce the risk.

Practical considerations for athletes

Runners in marathons sometimes report stomach cramps or an urgent need for a bathroom in the later stages of a race. Triathletes and cyclists who drink highly concentrated carbohydrate solutions without sufficient water may experience nausea or bloating. To minimize GI distress, athletes often choose easily digested carbohydrates and small amounts of sodium to support absorption. Consuming multiple types of carbohydrates (e.g., glucose and fructose) at moderate concentrations can improve absorption and reduce gastrointestinal upset. Practicing race‑day nutrition during training teaches the gut to handle fluids and food while moving. Avoiding large, high‑fiber meals and unfamiliar foods before events, and allowing time for digestion, can also help. Maintaining a steady hydration strategy to prevent hypohydration supports blood flow to the gut and aids in digestion.

Gastrointestinal distress can be a significant barrier to performance, but it is often manageable. Understanding why symptoms arise and adopting appropriate nutrition and hydration practices helps athletes stay comfortable and focused during competition.

Related Terms: Nausea, Vomiting, Dehydration, Electrolyte imbalance, Gastric tolerance