Document Detail


Carbohydrate ingestion immediately before exercise does not improve 20 km time trial performance in well trained cyclists.
MedLine Citation:
PMID:  9774209     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study examined the effects of carbohydrate ingestion on 20 km cycle time-trial (TT) performance in 14 well-trained cyclists (11 males, 3 females; peak oxygen uptake [VO2peak] 4.52 +/- 0.60 l/min; values are mean +/- SD). All subjects performed two experimental trials on their own bicycles mounted on an air-braked ergometry system (Kingcycle). Subjects were instructed to maintain the same training and dietary regimens before trials, which were conducted in a random order, 3-7 days apart, and at the same time of day for each subject. On the day of a trial, subjects reported to the laboratory and ingested an 8 ml/kg body mass bolus of either a 6.8 g/100 ml commercial carbohydrate-electrolyte (CHO) beverage (39 +/- 4 g of CHO), or a coloured, flavoured placebo. Ten min after finishing the drink, subjects commenced a 5 min warm-up at 150 W, before commencing the 20 km TT. The average power output (312 +/- 40 vs 311 +/- 38 W) and heart-rate (171 +/- 6 vs 171 +/- 5 beats/min for CHO and placebo, respectively) during the two rides did not differ between treatments. Accordingly, the performance times for the two TT's were the same (27:41 +/- 1:39 min:sec, for both CHO and placebo). We conclude that the ingestion of approximately 40 g of carbohydrate does not improve maximal cycling performance lasting approximately 30 min, and that carbohydrate availability, in the form of circulating blood glucose, does not limit high-intensity exercise of this duration.
Authors:
G S Palmer; M C Clancy; J A Hawley; I M Rodger; L M Burke; T D Noakes
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Publication Detail:
Type:  Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  International journal of sports medicine     Volume:  19     ISSN:  0172-4622     ISO Abbreviation:  Int J Sports Med     Publication Date:  1998 Aug 
Date Detail:
Created Date:  1998-12-17     Completed Date:  1998-12-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8008349     Medline TA:  Int J Sports Med     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  415-8     Citation Subset:  IM    
Affiliation:
School of Life Science, Kingston University, Kingston Upon Thames, Surrey, England.
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MeSH Terms
Descriptor/Qualifier:
Adolescent
Adult
Beverages
Bicycling / education,  physiology*
Biological Availability
Blood Glucose / analysis
Diet
Dietary Carbohydrates / administration & dosage*,  pharmacokinetics
Electrolytes / administration & dosage
Ergometry
Female
Heart Rate / physiology
Humans
Male
Oxygen Consumption / physiology
Physical Endurance / physiology
Placebos
Psychomotor Performance / physiology
Time Factors
Chemical
Reg. No./Substance:
0/Blood Glucose; 0/Dietary Carbohydrates; 0/Electrolytes; 0/Placebos

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


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