Biomaterial Database

Voluntary dehydration and electrolyte losses during prolonged exercise in the heat. 1985

L E Armstrong, and R W Hubbard, and P C Szlyk, and W T Matthew, and I V Sils

The effects of water temperature (6 degrees, 22 degrees, 46 degrees C) and chlorination on voluntary dehydration (D), sweat electrolyte losses (SEL), and total body electrolyte losses (BEL) were studied in 12 healthy males during 6 h of intermittent treadmill exercise (1.34 m X s-1, 5% grade) in a climatic chamber (40.6 degrees C DB, 25.5 degrees C WB). Body weight (BW), rectal temperature (Tre), mean weighted skin temperature (Tsk), heart rate (HR), plasma osmolality (PO), sweat rate (SR), sweat sodium (Na+), chloride (Cl-), potassium (K+), and magnesium (MG++), urine volume, Na+, and K+ were measured. No differences were found between chlorinated and non-chlorinated treatments except SEL of Mg++. Subjects (Ss) who drank 46 degrees C (-2.1% BW) consumed approximately 50% less water (p less than 0.001), and had D which was 1.050 kg larger (p less than 0.001) than subjects who consumed 6 degrees C (-0.5 %BW). There were no significant between-group PO differences, but Tre and Tsk differed between 46 degrees and 6 degrees C (p less than 0.01), and the HR of 22 degrees and 46 degrees C were both different from 6 degrees C (p less than 0.05). SR of all groups were essentially equal, although differences in total sweat Na+ (p less than 0.02) and Cl- (p less than 0.04) losses were observed between 46 degrees and 6 degrees C. SEL of sweat K+ and Mg++ were not affected by the experimental design. Based on 24 h projections of BEL, it was concluded that K+ depletion is more likely than Na+ depletion because food is often supplemented with sodium chloride.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D008297	Male		Males
D002713	Chlorine	An element with atomic symbol Cl, atomic number 17, and atomic weight 35, and member of the halogen family.	Chlorine Gas,Chlorine-35,Cl2 Gas,Chlorine 35,Gas, Chlorine,Gas, Cl2
D004326	Drinking	The consumption of liquids.	Water Consumption,Water Intake,Drinkings
D004573	Electrolytes	Substances that dissociate into two or more ions, to some extent, in water. Solutions of electrolytes thus conduct an electric current and can be decomposed by it (ELECTROLYSIS). (Grant & Hackh's Chemical Dictionary, 5th ed)	Electrolyte
D005082	Physical Exertion	Expenditure of energy during PHYSICAL ACTIVITY. Intensity of exertion may be measured by rate of OXYGEN CONSUMPTION; HEAT produced, or HEART RATE. Perceived exertion, a psychological measure of exertion, is included.	Physical Effort,Effort, Physical,Efforts, Physical,Exertion, Physical,Exertions, Physical,Physical Efforts,Physical Exertions
D006359	Heat Exhaustion	A clinical syndrome caused by heat stress, such as over-exertion in a hot environment or excessive exposure to sun. It is characterized by SWEATING, water (volume) depletion, salt depletion, cool clammy skin, NAUSEA, and HEADACHE.	Heat Collapse,Heat Prostration,Collapse, Heat,Exhaustion, Heat,Prostration, Heat
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000328	Adult	A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.	Adults
D012881	Skin Temperature	The TEMPERATURE at the outer surface of the body.	Skin Temperatures,Temperature, Skin,Temperatures, Skin
D013546	Sweating	The process of exocrine secretion of the SWEAT GLANDS, including the aqueous sweat from the ECCRINE GLANDS and the complex viscous fluids of the APOCRINE GLANDS.