Abstract
To examine the level of oxidation between different carbohydrate foodstuffs ingested
one hour before exercise, three experiments were conducted in men. They performed
a series of exercise tests of two hours duration at 60% V̇O2max preceded in experiment I by ingestion of one of five isocaloric (836 kJ) successive meals of bread, potatoes,
rice, spaghetti, or glucose; in experiment II, by either spaghetti or glucose, both naturally 13C enriched; in experiment III, by one of four 13C labelled meals containing starches differing in their proportion of amylose and
amylopectin and in their culinary preparation. Results show: 1) The following glucose
and insulin response from the highest to the lowest was: glucose > potatoes > bread
> rice > spaghetti and after 30 min of exercise a significantly lower blood glucose
concentration observed after glucose and potato diets compared to the rice and spaghetti
meals. The level of 13CO2 production from the food ingested in experiments II and III was expressed in terms
of Atom Percent Excess (APE). Data suggests that spaghetti is oxidized to a lesser
degree than glucose. The comparison between starches shows that gelatinized amylopectin
is metabolized to the same extent as glucose when there is a progressive decline in
the level of oxidation from gelantinized amylose and crude amylopectin to crude amylose.
Key words
Carbohydrate feeding - complex carbohydrate - starch - prolonged exercise - stable
isotope - insulin - blood glucose
