Patterns of Human Drinking: Effects of Exercise, Water Temperature and Food Consumption
Final rept. Feb 1988-Feb 1989
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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The effects of exercise, water temperature and food consumption on patterns of ad libitum drinking were studied in 33 men during 6 consecutive cycles of 30 min walking 4.8 km.h-1, 5 grade and 30 min rest in a climatic chamber 40 C, 40 relative humidity. On two nonconsecutive days, subjects consumed 15 C cool water during one trial and 40 C warm water during the other. We previously reported that two groups of drinkers can be identified during work in the heat by the criterion of body weight BW loss during the trial. Thus, avid drinkers D drank sufficiently such that they lost less than 2 of their initial Bw when consuming cool water ad libitum, while reluctant drinkers RD lost more than 2 of their BW. When warm water was provided, fluid consumption was reduced by 29 and 54 in D and RD, respectively and BW deficits were comparably increased. Intake of cool water elicited cyclic drinking patterns with higher rates during walking than during rest periods in both D and RD, whereas consumption of warm water produced this cyclic pattern only after food ingestion during the third rest. Food consumption stimulated fluid intake and reduced BW losses in both trials. Compared to pre-prandial hours 1-2.5 rates, average post-lunch drinking rates during the last 3h increased 14 in D and 19 in RD when consuming cool water, and by 46 and 74, respectively with warm water. While food consumption has been encouraged to replace electrolytes lost in sweat when working in hot climates, our results indicate that food ingestion also enhances fluid consumption.
- Anatomy and Physiology