Figure 2.

Putative limitations in carbohydrate delivery to skeletal muscle during exercise with glucose–fructose (or sucrose) co-ingestion. When large amounts of glucose (>1.5 g·min⁻¹) and fructose (>0.8 g·min⁻¹) are ingested during prolonged, moderate- to high-intensity (50%–70% VO₂ peak) exercise, the rate of gastric emptying is unlikely to be limiting, since gastric emptying rates of glucose are in the region of 1.7 g·min⁻¹ [67]. Rates of intestinal glucose absorption are ~1.3 g·min⁻¹ [68]. Rates of glucose appearance into the peripheral circulation and subsequently oxidised are ~1.2 g·min⁻¹ [58,70]. Rates of fructose (and sucrose) gastric emptying and intestinal absorption must be at least 0.5 g·min⁻¹ since the appearance rate into the peripheral circulation of fructose derived carbohydrate is ~0.5 g·min⁻¹ [71], with ~50% in the form of glucose and 50% in the form of lactate, that are subsequently oxidised by skeletal muscle at a rate of ~0.5 g·min⁻¹ [71].