Total water intake guidelines are sufficient for optimal hydration in United States adults.

Purpose: Recent studies suggest that 24-h urine osmolality (UOsm) for optimal water intake should be maintained < 500 mmol·kg. The purpose of this study was to determine the total water intake (TWI) requirement for healthy adults to maintain optimal hydration as indicated by 24-h urine osmolality < 500 mmol·kg.

Methods: Twenty-four-hour UOsm was assessed in 49 men and 50 women residing in the United States (age: 41 ± 14 y, body mass index: 26.

A review of risk factors and prevention strategies for exercise associated hyponatremia.

Exercise-associated hyponatremia (EAH) is defined as a serum sodium concentration under 135 mmol·L during or within 24 h of exercise. Increasing interest in endurance events has led to a higher number of athletes presenting with this potentially life-threatening condition. EAH is largely caused by the overconsumption of hypotonic fluids leading to weight gain during exercise.

Cellular dehydration acutely degrades mood mainly in women: a counterbalanced, crossover trial.

It is unclear if mild-to-moderate dehydration independently affects mood without confounders like heat exposure or exercise. This study examined the acute effect of cellular dehydration on mood. Forty-nine adults (55 % female, age 39 (sd 8) years) were assigned to counterbalanced, crossover trials.

Incidence of Hyponatremia During a Continuous 246-km Ultramarathon Running Race.

The purpose of this observational study was to examine the incidence of exercise-associated hyponatremia (EAH) in a 246-km continuous ultra-marathon. Over 2 years, 63 male finishers of the annual Spartathlon ultra-marathon foot race from Athens to Sparta, Greece were included in the data analysis. A blood sample was drawn from an antecubital vein the day before the race as well as within 15 min post-race and analyzed for sodium concentration.

Afternoon urine osmolality is equivalent to 24 h for hydration assessment in healthy children.

Background/objectives: While daily hydration is best assessed in 24-h urine sample, spot sample is often used by health care professionals and researchers due to its practicality. However, urine output is subject to circadian variation, with urine being more concentrated in the morning. It has been demonstrated that afternoon spot urine samples are most likely to provide equivalent urine concentration to 24-h urine samples in adults.

Osmotic stimulation of vasopressin acutely impairs glucose regulation: a counterbalanced, crossover trial.

Background: Epidemiological studies in humans show increased concentrations of copeptin, a surrogate marker of arginine vasopressin (AVP), to be associated with increased risk for type 2 diabetes.

Objectives: To examine the acute and independent effect of osmotically stimulated AVP, measured via the surrogate marker copeptin, on glucose regulation in healthy adults.

Methods: Sixty subjects (30 females) participated in this crossover design study.

Dehydration Impairs Cycling Performance, Independently of Thirst: A Blinded Study.

Purpose: The aim of the present study was to examine the effect of dehydration on exercise performance independently of thirst with subjects blinded of their hydration status.

Methods: Seven male cyclists (weight, 72 ± 9 kg; body fat, 14% ± 6%; peak oxygen uptake, 59.4 ± 6 mL·kg·min) exercised for 2 h on a cycle ergometer at 55% peak oxygen uptake, in a hot-dry environment (35°C, 30% relative humidity), with a nasogastric tube under euhydrated-non-thirst (EUH-NT) and dehydrated-non-thirst (DEH-NT) conditions.

Fluid consumption pattern and hydration among 8-14 years-old children.

Background/objectives: Children consume various fluids to meet dietary water intake needs. However, the contribution of different fluid types on hydration is unclear. The purpose of this study was to develop fluid intake patterns and examine their association with hydration, as indicated by 24-h urine osmolality.

Progressive Dehydration in Junior Laser Class Sailors During World Championship.

The purpose of this article is to assess the hydration status of elite young sailing athletes during World Championship competition. Twelve young, elite, male, Laser Class sailors (age: 15.8 ± 1.

Coffee with High but Not Low Caffeine Content Augments Fluid and Electrolyte Excretion at Rest.

Background: Low levels of caffeine ingestion do not induce dehydration at rest, while it is not clear if larger doses do have an acute diuretic effect. The aim of the present investigation was to examine the acute effect of low and high levels of caffeine, coffee, on fluid balance in habitual coffee drinkers (at least one per day) at rest.

Methods: Ten healthy adults (eight males and two females; age: 27 ± 5 years, weight: 89.