Accession Number:

ADA455935

Title:

Human Water and Electrolyte Balance

Descriptive Note:

Book Chapter-Present knowledge in Nutrition

Corporate Author:

ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA THERMAL AND MOUNTAIN MEDICINE DIVISION

Report Date:

2006-04-01

Pagination or Media Count:

9.0

Abstract:

Humans demonstrate a remarkable ability to regulate daily body water and electrolyte balance so long as food and fluid are readily available. The imposition of exercise and environmental stress can, however, challenge this ability. Most circumstances involving physical exercise require the formation and vaporization of sweat as the principle means of heat removal in man. Sweat losses, if not replaced, reduce body water volume and electrolyte content. Excessive body water or electrolyte losses can disrupt physiological homeostasis and threaten both health and performance. Persons often dehydrate during physical activity or exposure to hot weather because of fluid non-availability or a mismatch between thirst and body water losses. In these instances, the person begins the task with normal total body water and dehydrates over a prolonged period. This scenario is common for most athletic and occupational settings, however, in some situations the person might begin exercise with a body water deficit. For example, in several sports e.g., boxing, power lifting, wrestling athletes frequently dehydrate to compete in lower weight classes. Also, persons medicated with diuretics may be dehydrated prior to initiating exercise. If sodium chloride deficits occur then the extracellular fluid volume will contract and cause salt depletion dehydration. A sodium chloride deficit usually occurs due to sweat sodium losses combined with excessive water consumption, but a sodium deficit can also occur without excessive water intake owing to high sweat sodium losses. Both of these scenarios produce sodium dilution more commonly known as hyponatremia or water intoxication. This chapter reviews the physiology, needs, and assessment of human water and electrolyte balance. The extent to which water and electrolyte imbalances affect temperature regulation and exercise performance are also considered.

Subject Categories:

  • Medicine and Medical Research
  • Stress Physiology
  • Hydrology, Limnology and Potamology

Distribution Statement:

APPROVED FOR PUBLIC RELEASE