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Effects of a 14-Day Hydration Intervention on Individuals with Habitually Low Fluid Intake.
Caldwell, AR, Rosa-Caldwell, ME, Keeter, C, Johnson, EC, Péronnet, F, Ganio, MS
Annals of nutrition & metabolism. 2020;:67-68
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Abstract
BACKGROUND Debate continues over whether or not individuals with low total water intake (TWI) are in a chronic fluid deficit (i.e., low total body water) [1]. When women with habitually low TWI (1.6 ± 0.5 L/day) increased their fluid intake (3.5 ± 0.1 L/day) for 4 days 24-h urine osmolality decreased, but there was no change in body weight, a proxy for total body water (TBW) [2]. In a small (n = 5) study of adult men, there were no observable changes in TBW, as measured by bioelectrical impedance, after increasing TWI for 4 weeks [3]. However, body weight increased and salivary osmolality decreased indicating that the study may have been underpowered to detect changes in TBW. Further, no studies to date have measured changes in blood volume (BV) when TWI is increased. OBJECTIVES Therefore, the purpose of this study was to identify individuals with habitually low fluid intake and determine if increasing TWI, for 14 days, resulted in changes in TBW or BV. METHODS In order to identify individuals with low TWI, 889 healthy adults were screened. Participants with a self-reported TWI less than 1.8 L/day (men) or 1.2 L/day (women), and a 24-h urine osmolality greater than 800 mOsm were included in the intervention phase of the study. For the intervention phase, 15 participants were assigned to the experimental group and 8 participants were assigned to the control group. The intervention period lasted for 14 days and consisted of 2 visits to our laboratory: one before the intervention (baseline) and 14 days into the intervention (14-day follow-up). At these visits, BV was measured using a CO-rebreathe procedure and deuterium oxide (D2O) was administered to measure TBW. Urine samples were collected immediately prior, and 3-8 h after the D2O dose to allow for equilibration. Prior to each visit, participants collected 24-h urine to measure 24-h hydration status. After the baseline visit, the experimental group increased their TWI to 3.7 L for males and 2.7 L for females in order to meet the current Institute of Medicine recommendations for TWI. RESULTS Twenty-four-hour urine osmolality decreased (-438.7 ± 362.1 mOsm; p < 0.001) and urine volume increased (1,526 ± 869 mL; p < 0.001) in the experimental group from baseline, while there were no differences in osmolality (-74.7 ± 572 mOsm; p = 0.45), or urine volume (-32 ± 1,376 mL; p = 0.89) in the control group. However, there were no changes in BV (Fig. 1a) or changes in TBW (Fig. 1b) in either group. CONCLUSIONS Increasing fluid intake in individuals with habitually low TWI increases 24-h urine volume and decreases urine osmolality but does not result in changes in TBW or BV. These findings are in agreement with previous work indicating that TWI interventions lasting 3 days [2] to 4 weeks [3] do not result in changes in TBW. Current evidence would suggest that the benefits of increasing TWI are not related changes in TBW.
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The kidney stone and increased water intake trial in steel workers: results from a pilot study.
Lotan, Y, Antonelli, J, Jiménez, IB, Gharbi, H, Herring, R, Beaver, A, Dennis, A, Von Merveldt, D, Carter, S, Cohen, A, et al
Urolithiasis. 2017;(2):177-183
Abstract
Preventing dehydration in subjects at risk may provide a means of primary prevention of kidney stones. The purpose of this pilot study was to assess the hydration status of an at-risk group of steel plant workers based on end-of-shift ('post-shift') spot urine osmolality and 24-h urinary stone risk parameters. 100 volunteers were recruited from Gerdau Midlothian steel mill in Texas on 11/14/14 and 12/5/14. Clinical data were recorded and post-shift spot urine sample was used to measure urine osmolality. Participants were invited to submit a 24-h urine sample within 4 weeks of enrollment. The mean age was 41 years and 95 % were men. The majority of subjects were white (75 %), followed by 10 % Hispanic and 9 % black. The mean body mass index was 30.1 kg/m2 and overall 16 % had a past history of stone disease. Mean post-shift urine spot osmolality was 704.5 mOsm (169-1165 mOsm) and was >800 and >700 mOsm in 39 and 57 %, respectively. Among 59 24-h urines samples, the mean volume was 1.89 ± 0.92 l/day, with 56 % < 2 L and 17 % < 1 L. Elevated levels of urinary analytes were found in 29 % of subjects for calcium (>250 mg/TV), 39 % for uric acid (>700 mg/TV), 25 % for oxalate (>45 mg/TV) and 50 % for sodium (>200 meq/TV). The prevalence of stone disease in this population of steel workers was higher than the published prevalence of stone disease in the general population. A significant number of workers had concentrated post-shift and 24-h urines and elevated levels of urinary analytes.
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Favorable outcome of blood urea nitrogen/creatinine-based hydration therapy 3 months after acute ischemic stroke.
Lin, CJ, Yang, JT, Huang, YC, Tsai, YH, Lee, MH, Lee, M, Hsiao, CT, Hsiao, KY, Lin, LC
The American journal of emergency medicine. 2016;(12):2414-2418
Abstract
BACKGROUND Dehydration is associated with acute ischemic stroke. However, the relationship between hydration therapy given during acute ischemic stroke and clinical outcomes remains unclear. AIMS We determined whether hydration therapy in patients with a blood urea nitrogen/creatinine (BUN/Cr) ratio of at least 15 improved clinical outcome. METHODS We conducted a nonblinded, phase II, single-arm, prospective study of patients with acute ischemic stroke and BUN/Cr ratio of at least 15 with historical controls. The hydration group received intravenous bolus (300-500 mL) saline followed by maintenance saline infusion (40-80 mL/h for the first 72 hours), whereas the control group received maintenance saline infusion (40-60 mL/h for the first 24 hours and 0-60 mL/h for 24-72 hours after stroke). The study end point was the percentage of patients with a favorable outcome defined as modified Rankin scale score of 2 or lower at 3 months after stroke. RESULTS A total of 237 patients were enrolled (hydration, n = 134; control, n = 103). The mean volume of saline infused within the first 72 hours was significantly larger (P < .001), and the rate of favorable outcome at 3 months after stroke was significantly higher (P = .016) in the hydration group than in the controls. Further analysis revealed that the difference was significant in the lacunar stroke subtype (P = .020) but not in the nonlacunar subtype. CONCLUSIONS Blood urea nitrogen/Cr ratio-based saline hydration therapy in patients with acute ischemic stroke significantly increased the rate of favorable clinical outcome with functional independence at 3 months after stroke.
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Sodium chloride 0.9% versus Lactated Ringer in the management of severely dehydrated patients with choleriform diarrhoea.
Cieza, JA, Hinostroza, J, Huapaya, JA, León, CP
Journal of infection in developing countries. 2013;(7):528-32
Abstract
INTRODUCTION Although experience within Peru suggests clinical and physiological benefits of treating dehydration caused by diarrhoea with Lactated Ringer's solution (LR) over sodium chloride 0.9%, (NaCl) there is little documented scientific evidence supporting this view. It is important to clarify this issue and determine the best solution for use during epidemics. METHODOLOGY Forty patients suffering from dehydration due to choleriform diarrhoea were enrolled in the study. Twenty patients were treated using NaCl (Group A) and the other twenty with LR (Group B). After diuresis recovery was achieved, the patients were continued on a course of oral rehydration salts. Serum electrolytes, arterial pH, HCO3-, and pCO2 were measured at three stages: at admission, after diuresis recovery, and after 12 hours. RESULTS Acidosis was corrected more quickly with LR that NaCl. The hyperosmolality and hypernatremic states were corrected with both solutions. CONCLUSION LR use resulted in a better clinical response than NaCl, illustrated by more rapid physiological correction, showing that mixed metabolic acidosis was corrected more quickly and more appropriately with this treatment.
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The effects of progressive dehydration on strength and power: is there a dose response?
Hayes, LD, Morse, CI
European journal of applied physiology. 2010;(4):701-7
Abstract
This study examined the effect of exercise- and heat-induced dehydration on strength, jump capacity and neuromuscular function. Twelve recreationally active males completed six resistance exercise bouts (baseline and after each 5 exposure sessions) in an increasing state of hypohydration obtained by repeated heat exposure and exercise sessions (5 periods of 20 min jogging at up to approximately 80% age predicted heart rate maximum at 48.5 +/- 0.48 degrees C, relative humidity 50 +/- 4%). Relative to starting values, body mass decreased 1.0 +/- 0.5, 1.9 +/- 0.7, 2.6 +/- 0.8, 3.3 +/- 0.9 and 3.9 +/- 1.0% after exposure 1, 2, 3, 4 and 5, respectively. However, plasma volume remained constant. No significant differences existed amongst trials in vertical jump height, electromyography data or isokinetic leg extension at a rate of 120 degrees s(-1). Isometric leg extensions were significantly reduced (P < 0.05) after the first (1% body mass loss) and subsequent exposures in comparison to baseline. Isokinetic leg extensions at a rate of 30 degrees s(-1) were significantly reduced after the third (2.6% body mass loss) and subsequent exposures compared with baseline. No dose response was identified in any of the tested variables yet a threshold was observed in isometric and isokinetic strength at 30 degrees s(-1). In conclusion, dehydration caused by jogging in the heat had no effect on vertical jumping or isokinetic leg extensions at a rate of 120 degrees s(-1). Alternatively, exercise-induced dehydration was detrimental to isometric and isokinetic leg extensions at a rate of 30 degrees s(-1), suggesting the force-velocity relationship in hypohydration merits further research.
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Voluntary fluid intake, hydration status, and aerobic performance of adolescent athletes in the heat.
Wilk, B, Timmons, BW, Bar-Or, O
Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. 2010;(6):834-41
Abstract
We determined whether beverage flavoring and composition would stimulate voluntary drink intake, prevent dehydration, and maintain exercise performance in heat-acclimated adolescent males running in the heat. Eight adolescent (age, 13.7 ± 1.1 years) runners (peak oxygen uptake, 59.5 ± 4.0 mL·kg-1·min-1) underwent at least four 80-min exercise heat-acclimation sessions before completing 3 experimental sessions. All sessions were performed at 30 °C and 60%-65% relative humidity. Each experimental session consisted of five 15-min treadmill runs at a speed eliciting 65% peak oxygen uptake, with a 5 min rest prior to each run. Ten minutes after the final run, a time to exhaustion test was performed at a speed eliciting 90% peak oxygen uptake. Counterbalanced experimental sessions were identical, except for fluid intake, which consisted of tap water (W), flavored water (FW), and FW with 6% carbohydrate and 18 mmol·L-1 NaCl (CNa) consumed ad libitum. Fluid intake and body weight were monitored to calculate dehydration. Voluntary fluid intake was similar to fluid losses in W (1032 ± 130 vs. 1340 ± 246 g), FW (1086 ± 86 vs. 1451 ± 253 g), and CNa (1259 ± 119 vs. 1358 ± 234 g). As a result, significant dehydration was avoided in all trials (-0.45% ± 0.68% body weight in W, -0.66% ± 0.50% body weight in FW, and -0.13% ± 0.71% body weight in CNa). Core temperature increased by ~1 °C during exercise, but was not different between trials. Time to exhaustion was not different between trials and averaged 8.8 ± 1.7 min. Under exercise conditions more closely reflecting real-life situations, heat-acclimatized adolescent male runners can appropriately gauge fluid intake regardless of the type of beverage made available, resulting in consistency in exercise performance.
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The different effects of fluid with and without carbohydrate ingestion on subjective responses of untrained men during prolonged exercise in a hot environment.
Ishijima, T, Hashimoto, H, Satou, K, Muraoka, I, Suzuki, K, Higuchi, M
Journal of nutritional science and vitaminology. 2009;(6):506-10
Abstract
This study examined the effects of maintaining euhydration by ingesting fluids with or without carbohydrate on subjective responses of untrained men during prolonged exercise in a hot environment. Six healthy untrained subjects completed 90 min of cycling exercises at 55% maximal oxygen consumption (V(O2max)) in a hot environment (temperature: 28(o)C, humidity: 50%) under three different experimental conditions. During the first trial, subjects did not ingest fluids during exercise (dehydration (DH) trial). In the second and third trials, subjects received mineral water (MW) and hypotonic fluid containing carbohydrate (HF), respectively, in amounts equaling their weight loss in the DH trial. At the end of exercise, the overall rating of perceived exertion (RPE-O) was lower in the MW and HF trials than in the DH trial (14.3+/-1.0 and 13.7+/-0.6 vs 17.7+/-1.0, p<0.05, respectively). RPE-cardiovascular and RPE-legs were lower at the end of exercise in the HF trial compared with the DH trial. V(O2), heart rate (HR), and rectal temperature increased during exercise in the three trials. At the end of exercise, the drift in V(O2) was lower in the MW and HF trials than in the DH trial (304+/-41 and 339+/-40 vs 458+/-33 mL, p<0.05, respectively). HR at the end of exercise in the HF trial was lower than in the DH trial (158+/-5 vs 173+/-7 bpm, p<0.05). These results suggest that maintaining euhydration during prolonged exercise in untrained men could attenuate RPE-O and that hypotonic electrolyte-carbohydrate solution could attenuate RPE-legs during exercise.
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Active dehydration impairs upper and lower body anaerobic muscular power.
Jones, LC, Cleary, MA, Lopez, RM, Zuri, RE, Lopez, R
Journal of strength and conditioning research. 2008;(2):455-63
Abstract
We examined the effects of active dehydration by exercise in a hot, humid environment on anaerobic muscular power using a test-retest (euhydrated and dehydrated) design. Seven subjects (age, 27.1 +/- 4.6 years; mass, 86.4 +/- 9.5 kg) performed upper and lower body Wingate anaerobic tests prior to and after a 1.5-hour recovery from a heat stress trial of treadmill exercise in a hot, humid environment (33.1 +/- 3.1C = 55.1 +/- 8.9% relative humidity) until a 3.1 +/- 0.3% body mass loss was achieved. Dehydration was confirmed by a significant body mass loss (P < 0.001), urine color increase (P = 0.004), and urine specific gravity increase (P = 0.041). Motivation ratings were not significantly different (P = 0.059), and fatigue severity was significantly (P = 0.009) increased 70% in the dehydrated compared to the euhydrated condition. Compared to the euhydrated condition, the dehydrated condition mean power was significantly (P = 0.014) decreased 7.17% in the upper body and 19.20% in the lower body. Compared to the euhydrated condition, the dehydrated condition peak power was significantly (P = 0.013) decreased 14.48% in the upper body and 18.36% in the lower body. No significant differences between the euhydrated and dehydrated conditions were found for decrease in power output (P = 0.219, power = 0.213). Our findings suggest that dehydration of 2.9% body mass decreases the ability to generate upper and lower body anaerobic power. Coaches and athletes must understand that sports performance requiring anaerobic strength and power can be impaired by inadequate hydration and may contribute to increased susceptibility to musculoskeletal injury.
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No effect of 5% hypohydration on running economy of competitive runners at 23 degrees C.
Armstrong, LE, Whittlesey, MJ, Casa, DJ, Elliott, TA, Kavouras, SA, Keith, NR, Maresh, CM
Medicine and science in sports and exercise. 2006;(10):1762-9
Abstract
PURPOSE Although running economy (RE) is recognized as an integral component of successful endurance performance and is affected by numerous factors, little is known about the influence of body water loss on RE. This investigation examined the effects of hypohydration (HY) on RE and associated physiological responses. METHODS Ten highly trained collegiate distance runners (mean +/- SD; age, 20 +/- 3 yr; height, 178.5 +/- 6.3 cm; body mass, 66.7 +/- 5.4 kg; VO2max, 66.5 +/- 4.1 mL x kg(-1) x min(-1)) participated in four experiments on separate days, twice in a euhydrated (EU) and twice in a HY state (-5.5 and -5.7% body mass loss achieved during 24 h). At each hydration level, subjects performed one 10-min treadmill run per day (23 degrees C environment), at either 70% VO2max (EU 70% or HY 70%) or 85% VO2max (EU 85% or HY 85%) in a randomized, repeated-measures design. Cardiopulmonary, metabolic, thermal, hormonal, and perceptual variables were measured. RESULTS No between-treatment differences existed for RE (EU 70%, 46.3 +/- 3.2; HY 70%, 47.2 +/- 3.8; EU 85%, 58.6 +/- 2.8; HY 85%, 58.9 +/- 4.1 mL x kg(-1) x min(-1)), postexercise plasma lactate concentration (EU 70%, 1.9 +/- 0.6; HY 70%, 1.8 +/- 0.6; EU 85%, 6.5 +/- 3.5; HY 85%, 6.4 +/- 3.5 mmol x L(-1)), or rating of perceived exertion. HY resulted in a greater (P < 0.05 to 0.001) heart rate (HR), rectal temperature, and plasma norepinephrine concentration (NE), concurrent with reduced cardiac output, stroke volume, and respiratory exchange ratio. CONCLUSION HY did not alter the RE or lactate accumulation of endurance athletes during 10 min of exercise at 70 and 85% VO2max. These findings indicate that HY had no effect on RE, but that it increased physiological strain in a 23 degrees C environment.
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Fluid, electrolyte, and renal indices of hydration during 11 days of controlled caffeine consumption.
Armstrong, LE, Pumerantz, AC, Roti, MW, Judelson, DA, Watson, G, Dias, JC, Sokmen, B, Casa, DJ, Maresh, CM, Lieberman, H, et al
International journal of sport nutrition and exercise metabolism. 2005;(3):252-65
Abstract
This investigation determined if 3 levels of controlled caffeine consumption affected fluid-electrolyte balance and renal function differently. Healthy males (mean +/- standard deviation; age, 21.6 +/- 3.3 y) consumed 3 mg caffeine . kg(-1) . d(-1). on days 1 to 6 (equilibration phase). On days 7 to 11 (treatment phase), subjects consumed either 0 mg (C0; placebo; n= 20), 3 mg (C3; n = 20), or 6 mg (C6; n = 19) caffeine . kg(-1) . d(-1) in capsules, with no other dietary caffeine intake. The following variables were unaffected (P > 0.05) by different caffeine doses on days 1, 3, 6, 9, and 11 and were within normal clinical ranges: body mass, urine osmolality, urine specific gravity, urine color, 24-h urine volume, 24-h Na+ and K+ excretion, 24-h creatinine, blood urea nitrogen, serum Na+ and K+, serum osmolality, hematocrit, and total plasma protein. Therefore, C0, C3, and C6 exhibited no evidence of hypohydration. These findings question the widely accepted notion that caffeine consumption acts chronically as a diuretic.