Voluntary Dehydration and Alliesthesia for Water,

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 9 mile, desert walk treadmill, 1.34 msec 3.0 mph, 5 grade, 40 C d.b.26 C w.b. and wind speed of 2.5 mph. Twenty-nine Ss were tested 30 minh, 6 h on each of two nonconsecutive days. Ss were randomly assigned to 1 of 3 groups tap water n8, iodine-treated tap water n11 or iodine-treated, flavored tap water n10. The temperature of the water was 40 C during one trial and 15 C on the other. Mean sweat losses 6 h were similar and averaged 3.9 or - 0.06 kg. Fluid consumption 6 h varied between 1.4 kg warm, iodine-treated 232 or - 44 gh and 3.0 kg cool, iodine-treated, flavored 509 or - 50 gh. 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 o 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.