The efficacy of saliva osmolality as an index of hydration state: is it worth the spit?

Authors

Nigel A.S Taylor, University of WollongongFollow
Anne M. J van den Heuvel, University of WollongongFollow
Pete Kerry, University of WollongongFollow
Christiano A. Machado-Moreira, University of WollongongFollow
Sheena McGhee, University of WollongongFollow
Marc A. Brown, University of WollongongFollow
Mark J. Patterson, Defence Science and Technology OrganisationFollow
Gregory E. Peoples, University of WollongongFollow

RIS ID

28644

Publication Details

Taylor, N. A.S., van den Heuvel, A. M. J., Kerry, P., McGhee, S., Machado-Moreira, C. A., Brown, M. A., Patterson, M. J. & Peoples, G. E. The efficacy of saliva osmolality as an index of hydration state: is it worth the spit?. Thirteenth International Conference on Environmental Ergonomics; Wollongong, Australia: University of Wollongong; 2009. 279-282.

Abstract

Water represents ~60% of the body mass, ranging from 40-80% across individuals. In sedentary people, about 5-10% of this water is turned over daily, with urine flows averaging ~1.5 L.day-1 for normally hydrated individuals. However, when working in stressful environments for extended durations, particularly when wearing personal protective equipment, fluid losses via sweat secretion are dramatically elevated, and can approach 8-16 L.day-1. Indeed, during a moderate exercise-heat stress, whole-body sweat rates typically range between 1-1.5 L.h-1, and sustained and undefended fluid loss at this rate significantly impacts upon body water content, resulting in a 1% body-water loss for every 30-40 min of steady-state sweating without fluid replacement.