Medicine and science in sports and exercise
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Independently living older adults (over the age of 65 yr) consume adequate volumes of fluids on a daily basis. However, when challenged by fluid deprivation, a hyperosmotic stimulus, or exercise in a warm environment (all of which combine hypovolemia and hyperosmolality), older adults exhibit decreased thirst sensation and reduced fluid intake. Full fluid restoration eventually occurs, but full restoration of fluid balance is slowed. ⋯ Compared with the elderly, there are scant data associated with homeostatic control of thirst in children. Nonhomeostatic control of thirst and drinking behavior may likewise be different for children (as it is for the elderly), as compared with young adults; however, little empirical data exist on this topic. Children rarely exhibit voluntary dehydration for activities lasting 45 min or less; however, drink flavoring and sodium chloride are important promoters of drinking in active children.