Journal ArticleDOI
Errors in the estimation of hydration status from changes in body mass.
TLDR
Hydration status is not easily measured, but acute changes in hydration status are often estimated from body mass change, and substantial loss of mass may occur without an effective net negative fluid balance.Abstract:
Hydration status is not easily measured, but acute changes in hydration status are often estimated from body mass change. Changes in body mass are also often used as a proxy measure for sweat losses. There are, however, several sources of error that may give rise to misleading results, and our aim in this paper is to quantify these potential errors. Respiratory water losses can be substantial during hard work in dry environments. Mass loss also results from substrate oxidation, but this generates water of oxidation which is added to the body water pool, thus dissociating changes in body mass and hydration status: fat oxidation actually results in a net gain in body mass as the mass of carbon dioxide generated is less than the mass of oxygen consumed. Water stored with muscle glycogen is presumed to be made available as endogenous carbohydrate stores are oxidized. Fluid ingestion and sweat loss complicate the picture by altering body water distribution. Loss of hypotonic sweat results in increased osmolality of body fluids. Urine and faecal losses can be measured easily, but changes in the water content of the bladder and the gastrointestinal tract cannot. Body mass change is not always a reliable measure of changes in hydration status and substantial loss of mass may occur without an effective net negative fluid balance.read more
Citations
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Journal ArticleDOI
National Athletic Trainers' Association Position Statement: Fluid Replacement for the Physically Active
Brendon P. McDermott,Scott A. Anderson,Lawrence E. Armstrong,Douglas J. Casa,Samuel N. Cheuvront,Larry Cooper,W. Larry Kenney,Francis G. O'Connor,William O. Roberts +8 more
TL;DR: This statement updates practical recommendations regarding fluid-replacement strategies for physically active individuals and educates physically active people regarding the benefits of fluid replacement to promote performance and safety and the potential risks of both hypohydration and hyperhydration on health and physical performance.
Journal ArticleDOI
Statement of the Second International Exercise-Associated Hyponatremia Consensus Development Conference, New Zealand, 2007.
Tamara Hew-Butler,J Carlos Ayus,Courtney Kipps,Ronald J. Maughan,Samuel Mettler,Willem H. Meeuwisse,Anthony J Page,Stephen A Reid,Nancy J. Rehrer,William O. Roberts,Ian R. Rogers,Mitchell H. Rosner,Arthur J. Siegel,Dale B Speedy,Kristin J Stuempfle,Joseph G. Verbalis,Louise B. Weschler,Paul C Wharam +17 more
TL;DR: This research presents a state-of-the-art virtual reality system that automates the very labor-intensive and therefore time-consuming and expensive and therefore expensive and time-heavy and expensive process of designing and implementing virtual reality systems.
Journal ArticleDOI
Sweating Rate and Sweat Sodium Concentration in Athletes: A Review of Methodology and Intra/Interindividual Variability.
TL;DR: A review of the literature regarding the effect of laboratory and field sweat-testing methodological variations on sweating rate (SR) and sweat composition (primarily sodium concentration [Na+]) can be found in this paper.
Journal ArticleDOI
Hydration for recreational sport and physical activity
TL;DR: Fluid needs predicted for running 5-42 km at recreational paces show that fluid losses are <2% body mass; thus, aggressive fluid replacement may not be necessary, and spot measures of urine color or urine-specific gravity to assess hydration status have limitations.
References
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Journal ArticleDOI
Regulation of endogenous fat and carbohydrate metabolism in relation to exercise intensity and duration.
Johannes A. Romijn,Edward F. Coyle,Labros S. Sidossis,Amalia Gastaldelli,Jeffrey F. Horowitz,E. Endert,Robert R. Wolfe +6 more
TL;DR: It is concluded that, whereas carbohydrate availability is regulated directly in relation to exercise intensity, the regulation of lipid metabolism seems to be more complex.
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Energy cost of running.
TL;DR: In this article, indirect calorimetric measurements were made on two athletes running at different speeds up to 22 km/hr at grades from -20 to +15; the function was found to be linearly related to speed.
Journal ArticleDOI
Fluid and fuel intake during exercise
TL;DR: The amounts of water, carbohydrate and salt that athletes are advised to ingest during exercise are based upon their effectiveness in attenuating both fatigue as well as illness due to hyperthermia, dehydration or hyperhydration.