Our study: Is fructose an essential ingredient in sports drinks?
Carbohydrates are the main fuel source during moderate- to high-intensity exercise (infographic, van Loon, 2001). Ingesting carbohydrates such as glucose during prolonged exercise has been shown to increase performance.
However, there appears to be a limit to how much carbohydrates you can ingest and burn as fuel (called oxidation). Glucose has a maximal absorption rate of ~1.1 gram/minute. Therefore, exogenous glucose oxidation (burning ingested glucose as fuel) is also limited at ~1.1 gram/minute.
However, fructose and glucose are absorbed differently in the gut. Therefore, total carbohydrate absorption is higher when a combination of glucose and fructose is ingested. Sucrose is a disaccharide that contains one part glucose and one part fructose. Does a combination of glucose and fructose allow for a higher exogenous carbohydrate oxidation during exercise?
We investigated whether different combinations of glucose and fructose would allow for a higher exogeneous carbohydrates oxidation during exercise. Ten trained cyclists performed 4 trials during which they cycled for 180 minutes at 50% of their maximal workload (Wmax).
The cylists ingested:
- glucose (1.8 g/min)
- glucose + fructose (1.2 and 0.6 g/min, respectively)
- glucose + sucrose (0.6 and 1.2 g/min, respectively)
- placebo
Peak exogenous carbohydrate oxidation rates did not differ between GLU + FRU and GLU + SUC (1.40 ± 0.06 vs. 1.29 ± 0.07 gram/min, respectively), but were 46% ± 8% higher when compared to GLU (0.96 ± 0.06 gram/min).
In addition, the glucose+fructose and glucose+sucrose treatments resulted in less gastrointestinal complaints compared to the glucose only drink.
See more details in our video:
Go to the next infographic in the carbohydrate series:
Fructose does not further improve muscle glycogen?
Speak Your Mind