Document Detail


Effect of repeated caffeine ingestion on repeated exhaustive exercise endurance.
MedLine Citation:
PMID:  12900689     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: The purpose of this study was to examine the effect of repeated doses of caffeine on repeated exercise endurance. METHODS Nine male caffeine users performed exercise rides (ER) to exhaustion at 80% VO(2max) after ingesting a placebo, 5 mg x kg-1 of caffeine, or 2.5 mg x kg-1 of caffeine 1 h before the ER. Two ER were performed weekly on the same day once in the morning (AM) and 5 h later in the afternoon (PM). There were four treatments containing either caffeine or placebo, i.e., trial A representing 5-mg x kg-1 caffeine in the AM and 2.5-mg x kg-1 caffeine in the PM; trial B, which was placebo in both AM and PM; trial C representing 5-mg x kg-1 caffeine in the AM and placebo in the PM; and trial D representing a placebo in the AM and 5-mg x kg-1 caffeine in the PM. The order of the treatment trials was double blind and randomized. RESULTS: Caffeine ingestion significantly increased exercise time to exhaustion in the AM (trial A 24.9 +/- 10.2 min and trial C 21.8 +/- 4.9 vs trial B 18.0 +/- 6.4 min and D 17.7 +/- 4.3 min). This effect was maintained in the PM and greater than placebo (B 18.3 +/- 4.8 min) regardless of whether redosing (trial A 21.5 +/- 8.6 min) or placebo (trial C 21.0 +/- 6.8) followed the initial morning dose. Caffeine dosing in the PM (trial D 22.4 +/- 7.2 min) also increased ER after placebo trial D in the AM. CONCLUSIONS: It was concluded that redosing with caffeine after exhaustive exercise in the AM was not necessary to maintain the ergogenic effect of the drug during subsequent exercise 6 h later.
Authors:
Douglas G Bell; Tom M McLellan
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article; Randomized Controlled Trial    
Journal Detail:
Title:  Medicine and science in sports and exercise     Volume:  35     ISSN:  0195-9131     ISO Abbreviation:  Med Sci Sports Exerc     Publication Date:  2003 Aug 
Date Detail:
Created Date:  2003-08-05     Completed Date:  2003-12-11     Revised Date:  2009-11-03    
Medline Journal Info:
Nlm Unique ID:  8005433     Medline TA:  Med Sci Sports Exerc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1348-54     Citation Subset:  IM; S    
Affiliation:
Operational Medicine Section, Defence R&D Canada-Toronto, Ontario, Canada. doug.bell@drdc-rddc.gc.ca
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MeSH Terms
Descriptor/Qualifier:
Administration, Oral
Adult
Blood Glucose / analysis,  drug effects
Caffeine / administration & dosage*,  blood
Central Nervous System Stimulants / administration & dosage*
Double-Blind Method
Exercise / physiology*
Fatty Acids, Nonesterified / blood
Heart Rate / drug effects
Humans
Lactic Acid / blood
Male
Oxygen Consumption / drug effects
Physical Endurance / drug effects*
Physical Exertion / drug effects
Pulmonary Gas Exchange / drug effects
Time Factors
Chemical
Reg. No./Substance:
0/Blood Glucose; 0/Central Nervous System Stimulants; 0/Fatty Acids, Nonesterified; 50-21-5/Lactic Acid; 58-08-2/Caffeine

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


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