Fluid homeostasis requires adequate water intake, regulated by an intact thirst mechanism and appropriate free water excretion by the kidneys, mediated by appropriate secretion of arginine vasopressin (AVP, also known as antidiuretic hormone). AVP exerts its antidiuretic action by binding to the X chromosome-encoded V2 vasopressin receptor (V2R), a G protein-coupled receptor on the basolateral [...]

BACKGROUND: Voluntary dehydration is a condition where humans do not drink appropriately in the presence of an adequate fluid supply. This may adversely affect their physical and intellectual performance. The present study aimed to describe the prevalence of voluntary dehydration among elementary school children of different ethnicities and countries of birth. METHODS: Four hundred and [...]

While dehydration has well-documented negative effects on adult cognition, there is little research on hydration and cognitive performance in children. We investigated whether having a drink of water improved children's performance on cognitive tasks. Fifty-eight children aged 7-9 years old were randomly allocated to a group that received additional water or a group that did [...]

In 21 healthy children aged 6-11 years water balance studies were performed for 3 days at home. Water intake was assessed from dietary records based on the precise weighing method and water loss was calculated from repeated measurements of body weight and urine collection. Mean values (+/- SD) of all parameters of water balance are [...]

Thermoregulation during exposure to hot or cold environments differs between children and adults. Many physical and physiological changes occur during growth and maturation that can affect thermoregulation during rest as well as during exercise. Thus, physical as well as physiological differences between children and adults may explain the different response to thermal stress. The main [...]

This study examined changes in children's thirst and drink preferences during exercise-induced hypohydration and their spontaneous rehydration during a 30-min recovery. Twenty-four 9- to 13-year-old children (14 females, 10 males) participated in four intermittent 90-min cycling sessions in the heat (35 degrees C, 20% relative humidity); the sessions differed in the drinks the children were [...]

This study was performed to determine whether a) children voluntarily dehydrate while exercising in hot climate; b) such dehydration affects their well-being and thermoregulation. Eleven 10p to 12-yr old, partially acclimatized boys underwent two work-in-the-heat protocols (cycle rides, 45% aerobic capacity at 39 degrees C, 45% rh). During one session they drank only voluntarily when [...]

Sweating rate (SR) of boys is lower than that of men. To assess the association between the response of individual sweat glands and physical growth and maturation, three groups of circumpubertal boys cycled at 50% VO2max in a climatic chamber (42 degrees C, 20% relative humidity). Based on Tanner staging (pubic hair), 16 were classified [...]

Urination was studied in 15 normal infants and young children on 150 occasions in the course of metabolic balance studies. With increasing age, mean urine volume increased if expressed as ml/day and decreased if expressed as ml/kg/day. Urine volume was correlated with volume of intake (r = 0.697) and accounted for a similar percentage of [...]

PURPOSE: In healthy children who exercise in the heat, the addition of flavor, carbohydrate, and 18 mmol x L(-1) NaCl to water induced a major increase in voluntary drink intake compared with the intake of unflavored water. This increase was sufficient to prevent voluntary dehydration. We hypothesized that, to achieve a similar effect in children [...]