Document Detail

Effect of pre-exercise carbohydrate feedings on endurance cycling performance.
MedLine Citation:
PMID:  3547009     Owner:  NLM     Status:  MEDLINE    
Six men were studied to compare the effects of pre-exercise carbohydrate feedings on endurance performance and muscle glycogen utilization during prolonged exercise. Trials consisted of a cycling ride to exhaustion at 75% maximal oxygen uptake preceded by the ingestion of either 75 g of glucose in 350 ml of water (GLU), 75 g of fructose in 350 ml of water (FRU), or 350 ml of an artificially sweetened and flavored placebo (CON). No differences were observed between trials for oxygen uptake, respiratory exchange ratio, heart rate, or exercise time to exhaustion (CON = 92.7 +/- 5.2 min, FRU = 90.6 +/- 12.4, and GLU = 92.8 +/- 11.3, mean +/- SE). Blood glucose was elevated as a result of the GLU feeding, but fell rapidly with the onset of exercise, reaching a low of 4.02 +/- 0.34 mmol X l-1 at 15 min of exercise. Serum insulin also increased following the GLU feeding but had returned to pre-drink levels by 30 min of exercise. No differences in blood glucose and insulin were observed between FRU and CON. Muscle glycogen utilization during the first 30 min of exercise (CON = 46.3 +/- 8.2 mmol X kg-1 wet weight, FRU = 56.3 +/- 3.0 mmol X kg-1 wet weight, GLU = 50.0 +/- 4.9 mmol X kg-1 wet weight) and total glycogen use (CON = 93.4 +/- 11.1, FRU = 118.8 +/- 10.9, and GLU = 99.5 +/- 4.3) were similar in the three trials.(ABSTRACT TRUNCATED AT 250 WORDS)
M Hargreaves; D L Costill; W J Fink; D S King; R A Fielding
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Publication Detail:
Type:  Clinical Trial; Controlled Clinical Trial; Journal Article    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  19     ISSN:  0195-9131     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  1987 Feb 
Date Detail:
Created Date:  1987-03-31     Completed Date:  1987-03-31     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  33-6     Citation Subset:  IM; S    
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MeSH Terms
Blood Glucose / metabolism
Dietary Carbohydrates / administration & dosage*
Fructose / administration & dosage
Glucose / administration & dosage
Glycogen / metabolism*
Insulin / blood
Lactates / blood
Muscles / metabolism*
Physical Endurance*
Physical Exertion*
Time Factors
Reg. No./Substance:
0/Blood Glucose; 0/Dietary Carbohydrates; 0/Lactates; 11061-68-0/Insulin; 30237-26-4/Fructose; 50-99-7/Glucose; 9005-79-2/Glycogen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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