Gastric Emptying

Gastric emptying refers to the speed at which food and drink leave the stomach. High-fat, high-protein meals take longer to digest and require more processing time in the stomach. Therefore, precompetition or pretraining meals should be consumed with gastric emptying time in mind. With the goal of exercising with no solid food in the stomach, higher-protein and higher-fat meals should be eaten a minimum of 2.5 hours before physical activity, while low-fiber, starchy carbohydrate meals should be eaten a minimum of 1.5 hours before physical activity. Exercising with food in the stomach may lead to nausea and vomiting. Furthermore, the sensation of fullness may inhibit adequate fluid consumption, which could lead to dehydration and heat stress. Cyclists may better tolerate solid foods in the stomach while exercising, but in general, all athletes should be wary of eating meals too close to the time of exercise. The following known factors affect gastric emptying:^2,3

• Ingested volume (higher volumes result in faster gastric emptying)
• Energy concentration (higher concentrations result in slower gastric emptying)
• Type of carbohydrate (glucose results in slower gastric emptying than other mono- and disaccharides)
• Osmolality (higher osmolar solutions result in slower gastric emptying)
• pH (deviations from neutral pH slow gastric emptying)
• Exercise intensity (higher intensities result in slower gastric emptying)
• Stress (severe psychological stress slows gastric emptying)