The Role of Type and Structure of Complex Carbohydrates Response to Physical Exercise

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