The effect of glycemic index on plasma glucose and lactate levels during incremental exercise

Consumption of low glycemic index (GI) foods before submaximal endurance exercise may be beneficial to performance. To test whether this may also be true for high intensity exercise, 10 trained cyclists began an incremental exercise test to exhaustion 65 min after consuming equal carbohydrate portio...

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Bibliographic Details
Published in:International journal of sport nutrition 2000-03, Vol.10 (1), p.51-61
Main Authors: Stannard, S R, Constantini, N W, Miller, J C
Format: Article
Language:English
Subjects:
Adult
Analysis of Variance
Blood Glucose - analysis
Dietary Carbohydrates - administration & dosage
Digestion
Edible Grain
Exercise Test
Fatigue - physiopathology
Follow-Up Studies
Food
Glucose - administration & dosage
Humans
Hydrogen-Ion Concentration
Lactates - blood
Male
Physical Endurance - physiology
Physical Exertion - physiology
Placebos
Pulmonary Gas Exchange - physiology
Rest
Single-Blind Method
Space life sciences
Time Factors
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Summary:Consumption of low glycemic index (GI) foods before submaximal endurance exercise may be beneficial to performance. To test whether this may also be true for high intensity exercise, 10 trained cyclists began an incremental exercise test to exhaustion 65 min after consuming equal carbohydrate portions of glucose (HGI), pasta (LGI), and a noncarbohydrate control (PL). Time to fatigue did not differ significantly (p = 0.05) between treatments. Plasma glucose concentration was significantly lower after LGI vs. HGI from 15 to 45 min of rest postprandial. During exercise, plasma glucose concentration was significantly lower after HGI vs. LGI from 200 W until exhaustion. Plasma lactate concentration following HGI was significantly higher than PL from 30 min of rest postprandial through to the end of the 200-W workload. Plasma lactate concentration following LGI was significantly lower than after HGI from 45 min of rest postprandial through to the end of the 100-W workload. At higher exercise intensities, there was no significant difference in plasma lactate levels between treatments. These findings suggest that a high GI carbohydrate meal (1 g/kg body wt) 65 min prior to exercise decreases plasma glucose and increases plasma lactate levels compared to a low GI meal, but not enough to be detrimental to incremental exercise performance.
ISSN:1526-484X
1050-1606
1543-2742
DOI:10.1123/ijsnem.10.1.51