Exercising in the heat increases the likelihood of gastrointestinal (GI) distress because blood flow is redirected away from the digestive system toward the working muscles and skin, slowing digestion and nutrient absorption. Heat stress, dehydration, and consuming unfamiliar or excessive amounts of carbohydrate can further increase the risk of symptoms such as nausea, bloating, stomach cramps, and vomiting, all of which can impair performance. Athletes can reduce GI issues by staying hydrated, matching carbohydrate intake to their individual tolerance, practicing their race-day fueling strategy during training, and progressively gut training to improve carbohydrate absorption. Ultimately, preventing GI distress in hot conditions requires a personalized approach that integrates heat acclimation, hydration, and well-rehearsed fueling strategies to maximize endurance performance.
Read more of Aaron's own words from the Carbs Fuel Website: https://carbsfuel.com/blogs/news/the-heat-gi-distress-and-fueling