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1.
Nutrients ; 12(4)2020 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-32224908

RESUMO

Nationally representative data from the National Health and Nutrition Examination Survey (NHANES) indicate that over 65% of adults aged 51-70 years in the U.S. do not meet hydration criteria. They have hyponatremia (serum sodium < 135 mmol/L) and/or underhydration (serum sodium >145 mmol/L, spot urine volume <50 mL, and/or spot urine osmolality ≥500 mmol/kg). To explore potential public health implications of not meeting hydration criteria, data from the NHANES 2009-2012 and National Center for Health Statistics Linked Mortality Files for fasting adults aged 51-70 years (sample n = 1200) were used to determine if hyponatremia and/or underhydration were cross-sectionally associated with chronic health conditions and/or longitudinally associated with chronic disease mortality. Underhydration accounted for 97% of the population group not meeting hydration criteria. In weighted multivariable adjusted Poisson models, underhydration was significantly associated with increased prevalence of obesity, high waist circumference, insulin resistance, diabetes, low HDL, hypertension, and metabolic syndrome. Over 3-6 years of follow-up, 33 chronic disease deaths occurred in the sample, representing an estimated 1,084,144 deaths in the U.S. Alongside chronic health conditions, underhydration was a risk factor for an estimated 863,305 deaths. Independent of the chronic health conditions evaluated, underhydration was a risk factor for 128,107 deaths. In weighted multivariable Cox models, underhydration was associated with 4.21 times greater chronic disease mortality (95% CI: 1.29-13.78, p = 0.019). Zero chronic disease deaths were observed for people who met the hydration criteria and did not already have a chronic condition in 2009-2012. Further work should consider effects of underhydration on population health.

2.
Nutrients ; 12(4)2020 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-32260197

RESUMO

Research on hyponatremia during mountain marathons is scarce. The present study aimed to investigate the prevalence of exercise-associated hyponatremia during a 44-km trail running race that reached an altitude of 2780 m (Olympus Marathon). Sixty-two runners (five women) who completed the race participated in the study (age: 34.4 ± 8.6 years; height: 1.77 ± 0.06 m; and weight: 75.3 ± 10.0 kg). Anthropometric characteristics, blood, and urine samples were collected pre- and post-race. Food and fluid intake were recorded at each checkpoint. Due to race regulations, the runners could not carry any additional food and fluids besides the ones provided at specific checkpoints. Five runners (8%) exhibited asymptomatic hyponatremia (serum sodium <135 mmol∙L-1). Serum sodium in the hyponatremic runners decreased from 138.4 ± 0.9 (pre) to 131.4 ± 5.0 mmol∙L-1 (post), p < 0.05. Plasma osmolality increased only in the eunatremic runners (pre: 290 ± 3; post: 295 ± 6 mmol∙kg-1; p < 0.05). Plasma volume decreased more in the hyponatremic compared to eunatremic runners (-4.4 ± 2.0 vs. -3.2 ± 1.4%, p < 0.05). Lastly, dietary sodium intake was lower in the hyponatremic runners compared to eunatremic (789 ± 813 vs. 906 ± 672 mg; p < 0.05). The incidence of hyponatremia among the athletes was relatively low, possibly due to race conditions.

3.
Eur J Clin Nutr ; 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31624367

RESUMO

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. The aim of the present study was to examine whether urine osmolality (UOsm) assessed from a spot urine sample in specific time-windows was equivalent to 24-h UOsm in free-living healthy children. SUBJECTS/METHODS: Among 541 healthy children (age: 3-13 years, female: 45%, 77% non-Hispanic white, BMI:17.7 ± 4.0 kg m-2), UOsm at specific time-windows [morning (0600-1159), early afternoon (1200-1559), late afternoon (1600-1959), evening (2000-2359), overnight (2400-0559), and first morning] was compared with UOsm from the corresponding pooled 24-h urine sample using an equivalence test. RESULTS: Late afternoon (1600-1959) spot urine sample UOsm value was equivalent to the 24-h UOsm value in children (P < 0.05; mean difference: 62 mmol kg-1; 95% CI: 45-78 mmol kg-1). The overall diagnostic ability of urine osmolality assessed at late afternoon (1600-1959) to diagnose elevated urine osmolality on the 24-h sample was good for both cutoffs of 800 mmol kg-1 [area under the curve (AUC): 87.4%; sensitivity: 72.6%; specificity: 90.5%; threshold: 814 mmol kg-1] and 500 mmol kg-1 (AUC: 83.5%; sensitivity: 75.0%; specificity: 80.0%; threshold: 633 mmol kg-1). CONCLUSION: These data suggest that in free-living healthy children, 24-h urine concentration may be approximated from a late afternoon spot urine sample. This data will have practical implication for health care professionals and researchers.

4.
Am J Clin Nutr ; 110(6): 1344-1352, 2019 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-31562496

RESUMO

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. On 2 trial days, separated by ≥7 d (males) or 1 menstrual cycle (females), subjects were infused for 120 min with either 0.9% NaCl [isotonic (ISO)] or 3.0% NaCl [hypertonic (HYPER)]. Postinfusion, a 240-min oral-glucose-tolerance test (OGTT; 75 g) was administered. RESULTS: During HYPER, plasma osmolality and copeptin increased (P < 0.05) and remained elevated during the entire 6-h protocol, whereas renin-angiotensin-aldosterone system hormones were within the lower normal physiological range at the beginning of the protocol and declined following infusion. Fasting plasma glucose did not differ between trials (P > 0.05) at baseline and during the 120 min of infusion. During the OGTT the incremental AUC for glucose from postinfusion baseline (positive integer) was greater during HYPER (401.5 ± 190.5 mmol/L·min) compared with the ISO trial (354.0 ± 205.8 mmol/L·min; P < 0.05). The positive integer of the AUC for insulin during OGTT did not differ between trials (HYPER 55,850 ± 36,488 pmol/L·min compared with ISO 57,205 ± 31,119 pmol/L·min). Baseline values of serum glucagon were not different between the 2 trials; however, the AUC of glucagon during the OGTT was also significantly greater in HYPER (19,303 ± 3939 ng/L·min) compared with the ISO trial (18,600 ± 3755 ng/L·min; P < 0.05). CONCLUSIONS: The present data indicate that acute osmotic stimulation of copeptin induced greater hyperglycemic responses during the oral glucose challenge, possibly due to greater glucagon concentrations.This study was registered at clinicaltrials.gov as NCT02761434.


Assuntos
Glicemia/metabolismo , Cloreto de Sódio/administração & dosagem , Vasopressinas/metabolismo , Adulto , Estudos Cross-Over , Feminino , Glucagon/sangue , Teste de Tolerância a Glucose , Glicopeptídeos/sangue , Humanos , Insulina/sangue , Masculino , Pessoa de Meia-Idade , Concentração Osmolar , Osmose , Plasma/química , Cloreto de Sódio/análise
5.
Scand J Med Sci Sports ; 29(5): 686-695, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30659665

RESUMO

The aim of the present study was to observe the effect of mild hypohydration on exercise performance with subjects blinded to their hydration status. Eleven male cyclists (weight 75.8 ± 6.4 kg, VO2peak : 64.9 ± 5.6 mL/kg/min, body fat: 12.0 ± 5.8%, Powermax : 409 ± 40 W) performed three sets of criterium-like cycling, consisting of 20-minute steady-state cycling (50% peak power output), each followed by a 5-km time trial at 3% grade. Following a familiarization trial, subjects completed the experimental trials, in counter-balanced fashion, on two separate occasions in dry heat (30°C, 30% rh) either hypohydrated (HYP) or euhydrated (EUH). In both trials, subjects ingested 25 mL of water every 5 minutes during the steady-state and every 1 km of the 5-km time trials. In the EUH trial, sweat losses were fully replaced via intravenous infusion of isotonic saline, while in the HYP trial, a sham IV was instrumented. Following the exercise protocol, the subjects' bodyweight was changed by -0.1 ± 0.1% and -1.8 ± 0.2% for the EUH and HYP trial, respectively (P < 0.05). During the second and third time trials, subjects averaged higher power output (309 ± 5 and 306 ± 5 W) and faster cycling speed (27.5 ± 3.0 and 27.2 ± 3.1 km/h) in the EUH trial compared to the HYP trial (Power: 287 ± 4 and 276 ± 5 W, Speed: 26.2 ± 2.9 and 25.5 ± 3.3 km/h, all P < 0.05). Core temperature (Tre ) was higher in the HYP trial throughout the third steady-state and 5-km time trial (P < 0.05). These data suggest that mild hypohydration, even when subjects were unaware of their hydration state, impaired cycle ergometry performance in the heat probably due to greater thermoregulatory strain.


Assuntos
Desempenho Atlético/fisiologia , Ciclismo/fisiologia , Desidratação/fisiopatologia , Temperatura Alta , Adulto , Glicemia/análise , Proteínas Sanguíneas/análise , Peso Corporal , Estudos Cross-Over , Ergometria , Humanos , Ácido Láctico/sangue , Masculino , Percepção , Gravidade Específica , Sudorese , Urinálise , Adulto Jovem
6.
Eur J Nutr ; 58(2): 475-496, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30506317

RESUMO

PURPOSE: Although low water intake has been associated with adverse health outcomes, available literature indicated that the majority of children do not meet the water intake guidelines and they are underhydrated based on elevated hydration biomarkers. This review examined the water intake habits and hydration status in children from 32 observational studies (n = 36813). METHODS: PubMed, Web of Science, and CINAHL were used to identify relevant articles. Total water/fluid intake from 25 countries was compared with water intake recommendations and underhydration (urine osmolality greater than 800 mmol kg-1) was assessed. Risk of bias was assessed using customized categories following the review guideline for observational studies. RESULTS: From 32 studies, only 11 studies reported both water intake and hydration status. 12 out of 24 studies reported mean/median water/fluid intake below the guidelines, while 4 out of 13 studies that assessed hydration status indicated underhydration based on urine osmolality (greater than 800 mmol kg-1). Among the 19 countries that reported comparison of water/fluid intake with guidelines, 60 ± 24% of children (range 10-98%) failed to meet them. CONCLUSION: These findings suggest that children are not consuming enough water to be adequately hydrated.


Assuntos
Desidratação/epidemiologia , Desidratação/fisiopatologia , Ingestão de Líquidos/fisiologia , Água/administração & dosagem , Criança , Desidratação/urina , Humanos , Internacionalidade , Estudos Observacionais como Assunto , Concentração Osmolar , Equilíbrio Hidroeletrolítico/fisiologia
7.
Med Sci Sports Exerc ; 50(8): 1697-1703, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29509643

RESUMO

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. In both trials, thirst was matched by drinking 25 mL of water every 5 min (300 mL·h). In the EUH-NT trial, sweat losses were fully replaced by water via the nasogastric tube (calculated from the familiarization trial). After the 2 h of steady state, the subjects completed a 5-km cycling time trial at 4% grade. RESULTS: Body mass loss for the EUH-NT and DEH-NT after the 2 h was -0.2% ± 0.6% and -2.2% ± 0.4%, whereas after the 5-km time trial, it was -0.7% ± 0.5% and 2.9% ± 0.4%, respectively. Thirst (35 ± 30 vs 42 ± 31 mm) and stomach fullness (46 ± 21 vs 35 ± 20 mm) did not differ at the end of the 2 h of steady state between EUH-NT and DEH-NT trials (P > 0.05). Subjects cycled faster during the 5-km time trial in the EUH-NT trial compared with the DEH-NT trial (23.2 ± 1.5 vs 22.3 ± 1.8 km·h, P < 0.05), by producing higher-power output (295 ± 29 vs 276 ± 29 W, P < 0.05). During the 5-km time trial, core temperature was higher in the DEH-NT trial (39.2°C ± 0.7°C) compared with the EUH-NT trial (38.8°C ± 0.2°C; P > 0.05). CONCLUSIONS: These data indicated that hypohydration decreased cycling performance and impaired thermoregulation independently of thirst, while the subjects were unaware of their hydration status.


Assuntos
Desempenho Atlético/fisiologia , Ciclismo/fisiologia , Desidratação/fisiopatologia , Exercício Físico/fisiologia , Sede , Regulação da Temperatura Corporal , Humanos , Intubação Gastrointestinal , Masculino , Percepção , Método Simples-Cego
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