Document Detail


Guidelines for glycerol use in hyperhydration and rehydration associated with exercise.
MedLine Citation:
PMID:  20092365     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Dehydration in athletes alters cardiovascular and thermoregulatory function and may inhibit endurance exercise capacity if fluid loss exceeds 2% of bodyweight (BW). If this level of dehydration cannot be prevented when starting from a state of euhydration, then athletes may create a state of hyperhydration by consuming extra fluid prior to exercise. From this hyperhydrated situation, individuals have a greater capacity to tolerate fluid loss before becoming dehydrated. Furthermore, excess pre-exercise fluid intake enhances thermoregulatory ability, as well as increasing plasma volume to maintain cardiac output. However, hyperhydrating before exercise is difficult, because a large fluid intake is typically accompanied by diuresis. Glycerol-containing beverages create an osmotic gradient in the circulation favouring fluid retention, thereby facilitating hyperhydration and protecting against dehydration. Many studies have shown that increases in body water by 1 L or more are achievable through glycerol hyperhydration. This article analyses the evidence for glycerol use in facilitating hyperhydration and rehydration, and provides guidelines for athletes wishing to use this compound. An analysis of the studies in this area indicates that endurance athletes intending to hyperhydrate with glycerol should ingest glycerol 1.2 g/kg BW in 26 mL/kg BW of fluid over a period of 60 minutes, 30 minutes prior to exercise. The effects of glycerol on total body water when used during rehydration are less well defined, due to the limited studies conducted. However, ingesting glycerol 0.125 g/kg BW in a volume equal to 5 mL/kg BW during exercise will delay dehydration, while adding glycerol 1.0 g/kg BW to each 1.5 L of fluid consumed following exercise will accelerate the restoration of plasma volume. Side effects from glycerol ingestion are rare, but include nausea, gastrointestinal discomfort and light-headedness. In summary, glycerol ingestion before, during or following exercise is likely to improve the hydration state of the endurance athlete.
Authors:
Simon Piet van Rosendal; Mark Andrew Osborne; Robert Gordon Fassett; Jeff Scott Coombes
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Sports medicine (Auckland, N.Z.)     Volume:  40     ISSN:  1179-2035     ISO Abbreviation:  Sports Med     Publication Date:  2010 Feb 
Date Detail:
Created Date:  2010-01-22     Completed Date:  2010-03-12     Revised Date:  2013-05-16    
Medline Journal Info:
Nlm Unique ID:  8412297     Medline TA:  Sports Med     Country:  New Zealand    
Other Details:
Languages:  eng     Pagination:  113-29     Citation Subset:  IM    
Affiliation:
School of Human Movement Studies, The University of Queensland, Brisbane, Queensland, Australia. svanrosendal@hms.uq.edu.au
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MeSH Terms
Descriptor/Qualifier:
Athletes
Beverages
Body Water / physiology
Dehydration / rehabilitation*
Dizziness / chemically induced
Exercise
Fluid Therapy / methods*
Glycerol / administration & dosage*,  adverse effects
Guidelines as Topic
Humans
Hyperhidrosis / rehabilitation*
Nausea / chemically induced
Physical Endurance / physiology
Chemical
Reg. No./Substance:
56-81-5/Glycerol

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


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