Ingesting Different Types of a Single Carbohydrate

1 KEY POINTS • During prolonged exercise, the performance benefits of carbohydrate ingestion may be achieved by maintaining plasma glucose concentration and high rates of carbohydrate oxidation. • Limitations to exogenous carbohydrate oxidation appear to be in the absorptive process most likely because of a saturation of carbohydrate transporters. By using a combination of carbohydrates that use different intestinal transporters for absorption (multiple transportable carbohydrates), carbohydrate delivery and oxidation can be increased. • Studies demonstrated up to 65% higher exogenous carbohydrate oxidation rates of multiple transportable carbohydrates (glucose:fructose) during exercise compared with a single carbohydrate (e.g., glucose only). • Exogenous carbohydrate oxidation rates reach values of 1.75 g/min with multiple transportable carbohydrates whereas previously it was thought that 1 g/min was the absolute maximum. • The increased carbohydrate oxidation with multiple transportable carbohydrates was accompanied by increased fluid delivery and improved oxidation efficiency and thus the likelihood of gastrointestinal distress may be diminished. • Studies also demonstrated reduced fatigue and improved exercise performance with multiple transportable carbohydrates compared with a single carbohydrate. • Multiple transportable carbohydrates, ingested at high rates, can be beneficial during endurance sports where the duration of exercise is 2.5 h or more. • The advice for prolonged endurance events (2.5 h or longer) is an intake of 90 g of multiple transportable carbohydrates per hour. This advice is not expressed relative to body mass because body size/mass appears to play no major role in exogenous carbohydrate oxidation.