Voluntary dehydration and alliesthesia for water

Abstract

The purpose of this experiment was to explore the complex relationship between fluid consumption and consumption factors (thirst, voluntary dehydration, water alliesthesia, palatability, work-rest cycle) during a simulated 14.5-km desert walk (treadmill, 1.34 m X s-1, 5% grade, 40 degrees C dry bulb/26 degrees C wet bulb, and wind speed of approximately 1.2 m X s-1). Twenty-nine subjects were tested (30 min X h-1, 6 h) on each of two nonconsecutive days. The subjects were randomly assigned to one of three groups: tap water (n = 8), iodine-treated tap water (n = 11), or iodine-treated flavored tap water (n = 10). The temperature of the water was 40 degrees C during one trial and 15 degrees C on the other. Mean sweat losses (6 h) varied between 1.4 kg (warm iodine-treated; 232 +/- 44 g X h-1) and 3.0 kg (cool iodine-treated flavored; 509 +/- 50 g X h-1). Warm drinks were consumed at a lower rate than cool drinks (negative and positive alliesthesia). This decreased consumption resulted in the highest percent body weight losses (2.8 and 3.2%). Cooling and flavoring effects on consumption were additive and increased the rate of intake by 120%. The apparent paradox between reduced consumption concomitant with severe dehydration and hyperthermia is attributed to negative alliesthesia for warm water rather than an apparent inadequacy of the thirst mechanism. The reluctance to drink warm iodine-treated water resulted in significant hyperthermia, dehydration, hypovolemia, and, in two cases, heat illness.

High prevalence and associated risk factors of dehydration among college students: implications for health and academic performance

“…21,65,66 The consumption of sugar-sweetened beverages (SSB), physical inactively, intake of alcohol, nightclubbing habits and poor dietary habits among students should be discouraged because of their significant associations with poor hydration status. Hydration status determination should constitute a component of the preadmission medical examination to identify the high vulnerable groups and those already dehydrated for proper health education and counselling.…”

Hydration Knowledge, Behaviours and Status of Staff at the Residential Camp of a Fly-in/Fly-out Minerals Extraction and Processing Operation in Tropical North-Eastern Australia

“…These results in combination provide highly confirmatory evidence of the unpalatability of unfiltered tap water at camp. As the availability of fluids with taste appeal has previously been demonstrated to significantly increase hydration rates and contribute to voluntary hydration 22,23) , enhancing the palatability of unfiltered tap water represents the most promising solution to address the observed imbalance between the fluid loss and intake rates.…”

Fluid and fuel intake during exercise

“…A person's physiological drive for fluid intake during exercise is perceived through 'thirst mechanisms' and it has long been known that when given ad libitum access to fluid, and thus drink voluntarily, that these mechanisms compel people to drink at a rate that replaces approximately one-half of their fluid losses and at best two-thirds (Pitts and Consolazio, 1944;Hubbard et al, 1984). The concept that thirst during exercise does not drive people to take in fluid at the rate of fluid loss is termed 'voluntary dehydration'.…”