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Acute Topics in Sport Nutrition

Editor(s): Lamprecht M. (Graz) 
Table of Contents
Vol. 59, 2012
Section title: Hydration and Fluid Balance
Lamprecht M (ed): Acute Topics in Sport Nutrition. Med Sport Sci. Basel, Karger, 2013, vol 59, pp 113–119
(DOI:10.1159/000341945)

Salt and Fluid Loading: Effects on Blood Volume and Exercise Performance

Mora-Rodriguez R. · Hamouti N.
University of Castilla-La Mancha, Exercise Physiology Laboratory, Toledo, Spain

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Article / Publication Details

First-Page Preview
Abstract of Hydration and Fluid Balance

Published online: 10/15/2012
Cover Date: 2013

Number of Print Pages: 7
Number of Figures: 2
Number of Tables: 0

ISBN: 978-3-8055-9992-4 (Print)
eISBN: 978-3-8055-9993-1 (Online)

Abstract

During prolonged exercise, fluid and salt losses through sweating reduce plasma volume which leads to heart rate drift in association with hyperthermia and reductions in performance. Oral rehydration with water reduces the loss of plasma volume and lessens heart rate drift and hyperthermia. Moreover, the inclusion of sodium in the rehydration solution to levels that double those in sweat (i.e., around 90 mmol/l Na+) restores plasma volume when ingested during exercise, and expands plasma volume if ingested pre-exercise. Pre-exercise salt and fluid ingestion with the intention of expanding plasma volume has received an increasing amount of attention in the literature in recent years. In four studies, pre-exercise salt and fluid ingestion improved performance, measured as time to exhaustion, either during exercise in a thermoneutral or in a hot environment. While in a hot environment, the performance improvements were linked to lowering of core temperatures and heart rate, the reasons for the improved performance in a thermoneutral environment remain unclear. However, when ingesting pre-exercise saline solutions above 0.9% (i.e., > 164 mmol/l Na+), osmolality and plasma sodium increase and core temperature remain at dehydration levels. Thus, too much salt counteracts the beneficial effects of plasma volume expansion on heat dissipation and hence in performance. In summary, the available literature suggests that pre-exercise saline ingestion with concentrations not over 164 mmol/l Na+ is an ergogenic aid for subsequent prolonged exercise in a warm or thermoneutral environment.


Article / Publication Details

First-Page Preview
Abstract of Hydration and Fluid Balance

Published online: 10/15/2012
Cover Date: 2013

Number of Print Pages: 7
Number of Figures: 2
Number of Tables: 0

ISBN: 978-3-8055-9992-4 (Print)
eISBN: 978-3-8055-9993-1 (Online)


Copyright / Drug Dosage

Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in goverment regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.

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