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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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Subcutaneous hydration and medications infusions (effectiveness, safety, acceptability): A systematic review of systematic reviews.
Broadhurst, D, Cooke, M, Sriram, D, Gray, B
PloS one. 2020;(8):e0237572
Abstract
OBJECTIVE To synthesize the current evidence for subcutaneous hydration and medication infusions from systematic reviews and to assess their methodological quality. INTRODUCTION Peripheral intravascular cannula/catheter insertion is a common invasive procedure for administering fluids and medications. Venous depletion is a growing concern for several patient populations. Subcutaneous access for the administration of isotonic solutions and medications is an alternative; however, vascular access assessment and planning guidelines rarely consider this route. METHODS Systematic review of systematic reviews (PROSPERO CRD42018046504). We searched 6 databases published in English language from 1990 to June 2020, identifying subcutaneous infusions an alternate route for fluids or medication. Methodological quality was evaluated using AMSTAR 2 criteria and data for mechanisms of infusion and outcomes related to effectiveness, safety, efficiency and acceptability extracted. The Johanna Briggs Institute's grades of recommendation informed the strength of recommendation. RESULTS The search yielded 1042 potential systematic reviews; 922 were excluded through abstract and duplicate screen. Of the remaining articles, 94 were excluded, and 26 were included. Overall, evidence is strong for recommending subcutaneous hydration infusions for older adults, weak for pediatric patients and inconclusive for palliative patients. There is strong evidence for 10 medications; weak evidence supporting 28 medications; however, there are eight medications with inconclusive evidence to make a recommendation and four medications not appropriate for subcutaneous delivery. CONCLUSION Subcutaneous access should be considered alongside intravenous therapy for hydration in older adults, and several medications. There are additional benefits in terms of ease of use and cost-effectiveness of this mode. Inclusion of subcutaneous access in clinical guidelines may promote uptake of this route to help preserve vessel health of vulnerable patients. Further high-quality research is needed to inform subcutaneous infusion therapy in a variety of populations (including pediatrics and palliative care) and medications and clarifying the mechanism of delivery.
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Up in the Air: Evidence of Dehydration Risk and Long-Haul Flight on Athletic Performance.
Zubac, D, Buoite Stella, A, Morrison, SA
Nutrients. 2020;(9)
Abstract
The microclimate of an airline cabin consists of dry, recirculated, and cool air, which is maintained at lower pressure than that found at sea level. Being exposed to this distinctive, encapsulated environment for prolonged durations, together with the short-term chair-rest immobilization that occurs during long-haul flights, can trigger distinct and detrimental reactions to the human body. There is evidence that long-haul flights promote fluid shifts to the lower extremity and induce changes in blood viscosity which may accelerate dehydration, possibly compromising an athlete's potential for success upon arrival at their destination. Surprisingly, and despite several recent systematic reviews investigating the effects of jet lag and transmeridian travel on human physiology, there has been no systematic effort to address to what extent hypohydration is a (health, performance) risk to travelers embarking on long journeys. This narrative review summarizes the rationale and evidence for why the combination of fluid balance and long-haul flight remains a critically overlooked issue for traveling persons, be it for health, leisure, business, or in a sporting context. Upon review, there are few studies which have been conducted on actual traveling athletes, and those that have provide no real evidence of how the incidence rate, magnitude, or duration of acute dehydration may affect the general health or performance of elite athletes.
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The Influence of Heat Acclimation and Hypohydration on Post-Weight-Loss Exercise Performance.
Barley, OR, Chapman, DW, Mavropalias, G, Abbiss, CR
International journal of sports physiology and performance. 2020;(2):213-221
Abstract
PURPOSE To examine the influence of fluid intake on heat acclimation and the subsequent effects on exercise performance following acute hypohydration. METHODS Participants were randomly assigned to 1 of 2 groups, either able to consume water ad libitum (n = 10; age 23 [3] y, height 1.81 [0.09] m, body mass 87 [13] kg; HAW) or not allowed fluid (n = 10; age 26 [5] y, height 1.76 [0.05] m, body mass 79 [10] kg; HANW) throughout 12 × 1.5-h passive heat-acclimation sessions. Experimental trials were completed on 2 occasions before (2 baseline trials) and 1 following the heat-acclimation sessions. These sessions involved 3 h of passive heating (45°C, 38% relative humidity) to induce hypohydration followed by 3 h of ad libitum food and fluid intake after which participants performed a repeat sled-push test to assess physical performance. Urine and blood samples were collected before, immediately, and 3 h following hypohydration to assess hydration status. Mood was also assessed at the same time points. RESULTS No meaningful differences in physiological or performance variables were observed between HANW and HAW at any time point. Using pooled data, mean sprint speed was significantly (P < .001) faster following heat acclimation (4.6 [0.7] s compared with 5.1 [0.8] s). Furthermore, heat acclimation appeared to improve mood following hypohydration. CONCLUSIONS Results suggest that passive heat-acclimation protocols may be effective at improving short-duration repeat-effort performance following acute hypohydration.
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Mild dehydration impaired intermittent sprint performance and thermoregulation in females.
Driscoll, RL, McCarthy, DG, Palmer, MS, Spriet, LL
Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme. 2020;(9):1045-1048
Abstract
The effects of mild dehydration during ice hockey are well-studied in males but not females. In a randomized, crossover design, 11 female varsity hockey players drank no fluid (1.7% ± 0.3% body mass loss) or water to maintain hydration during simulated-hockey exercise. Core temperature (P < 0.01) and perceived fatigue (P = 0.02) were higher and sprint power lower (P < 0.01) when mildly dehydrated. Thus, mild dehydration may impair hockey performance and thermoregulation while increasing perceived fatigue in females. Novelty Female stop-and-go sport athletes may benefit their in-game sprint performance and thermoregulation by following personalized in-game hydration to prevent becoming mildly dehydrated.
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Pathophysiological Mechanisms by which Heat Stress Potentially Induces Kidney Inflammation and Chronic Kidney Disease in Sugarcane Workers.
Hansson, E, Glaser, J, Jakobsson, K, Weiss, I, Wesseling, C, Lucas, RAI, Wei, JLK, Ekström, U, Wijkström, J, Bodin, T, et al
Nutrients. 2020;(6)
Abstract
BACKGROUND Chronic kidney disease of non-traditional origin (CKDnt) is common among Mesoamerican sugarcane workers. Recurrent heat stress and dehydration is a leading hypothesis. Evidence indicate a key role of inflammation. METHODS Starting in sports and heat pathophysiology literature, we develop a theoretical framework of how strenuous work in heat could induce kidney inflammation. We describe the release of pro-inflammatory substances from a leaky gut and/or injured muscle, alone or in combination with tubular fructose and uric acid, aggravation by reduced renal blood flow and increased tubular metabolic demands. Then, we analyze longitudinal data from >800 sugarcane cutters followed across harvest and review the CKDnt literature to assess empirical support of the theoretical framework. RESULTS Inflammation (CRP elevation and fever) and hyperuricemia was tightly linked to kidney injury. Rehydrating with sugary liquids and NSAID intake increased the risk of kidney injury, whereas electrolyte solution consumption was protective. Hypokalemia and hypomagnesemia were associated with kidney injury. DISCUSSION Heat stress, muscle injury, reduced renal blood flow and fructose metabolism may induce kidney inflammation, the successful resolution of which may be impaired by daily repeating pro-inflammatory triggers. We outline further descriptive, experimental and intervention studies addressing the factors identified in this study.
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Hypotheses about sub-optimal hydration in the weeks before coronavirus disease (COVID-19) as a risk factor for dying from COVID-19.
Stookey, JD, Allu, PKR, Chabas, D, Pearce, D, Lang, F
Medical hypotheses. 2020;:110237
Abstract
To address urgent need for strategies to limit mortality from coronavirus disease 2019 (COVID-19), this review describes experimental, clinical and epidemiological evidence that suggests that chronic sub-optimal hydration in the weeks before infection might increase risk of COVID-19 mortality in multiple ways. Sub-optimal hydration is associated with key risk factors for COVID-19 mortality, including older age, male sex, race-ethnicity and chronic disease. Chronic hypertonicity, total body water deficit and/or hypovolemia cause multiple intracellular and/or physiologic adaptations that preferentially retain body water and favor positive total body water balance when challenged by infection. Via effects on serum/glucocorticoid-regulated kinase 1 (SGK1) signaling, aldosterone, tumor necrosis factor-alpha (TNF-alpha), vascular endothelial growth factor (VEGF), aquaporin 5 (AQP5) and/or Na+/K+-ATPase, chronic sub-optimal hydration in the weeks before exposure to COVID-19 may conceivably result in: greater abundance of angiotensin converting enzyme 2 (ACE2) receptors in the lung, which increases likelihood of COVID-19 infection, lung epithelial cells which are pre-set for exaggerated immune response, increased capacity for capillary leakage of fluid into the airway space, and/or reduced capacity for both passive and active transport of fluid out of the airways. The hypothesized hydration effects suggest hypotheses regarding strategies for COVID-19 risk reduction, such as public health recommendations to increase intake of drinking water, hydration screening alongside COVID-19 testing, and treatment tailored to the pre-infection hydration condition. Hydration may link risk factors and pathways in a unified mechanism for COVID-19 mortality. Attention to hydration holds potential to reduce COVID-19 mortality and disparities via at least 5 pathways simultaneously.
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Impairment of Thermoregulation and Performance via Mild Dehydration in Ice Hockey Goaltenders.
McCarthy, DG, Wickham, KA, Vermeulen, TF, Nyman, DL, Ferth, S, Pereira, JM, Larson, DJ, Burr, JF, Spriet, LL
International journal of sports physiology and performance. 2020;(6):833-840
Abstract
UNLABELLED During play, ice hockey goaltenders routinely dehydrate through sweating and lose ≥2% body mass, which may impair thermoregulation and performance. PURPOSE This randomized, crossover study examined the effects of mild dehydration on goaltender on-ice thermoregulation, heart rate, fatigue, and performance. METHODS Eleven goaltenders played a 70-minute scrimmage followed by a shootout and drills to analyze reaction time and movements. On ice, they either consumed no fluid (NF) and lost 2.4% (0.3%) body mass or maintained body mass with water (WAT) or a carbohydrate-electrolyte solution (CES). Save percentage, rating of perceived exertion, heart rate, and core temperature were recorded throughout, and a postskate questionnaire assessed perceived fatigue. RESULTS Relative to NF, intake of both fluids decreased heart rate (interaction: P = .03), core temperature (peak NF = 39.0°C [0.1°C], WAT = 38.6°C [0.1°C], and CES = 38.5°C [0.1°C]; P = .005), and rating of perceived exertion in the scrimmage (post hoc: P < .04), as well as increasing save percentage in the final 10 minutes of scrimmage (NF = 75.8% [1.9%], WAT = 81.7% [2.3%], and CES = 81.3% [2.3%], post hoc: P < .04). In drills, movement speed (post hoc: P < .05) and reaction time (post hoc: P < .04) were slower in the NF versus both fluid conditions. Intake of either fluid similarly reduced postskate questionnaire scores (condition: P < .0001). Only CES significantly reduced rating of perceived exertion in drills (post hoc: P < .05) and increased peak movement power versus NF (post hoc: P = .02). Shootout save percentage was similar between conditions (P = .37). CONCLUSIONS Mild dehydration increased physiological strain and fatigue and decreased ice hockey goaltender performance versus maintaining hydration. Also, maintaining hydration with a CES versus WAT may further reduce perceived fatigue and positively affect movements.
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Does Dehydration Affect the Adaptations of Plasma Volume, Heart Rate, Internal Body Temperature, and Sweat Rate During the Induction Phase of Heat Acclimation?
Sekiguchi, Y, Filep, EM, Benjamin, CL, Casa, DJ, DiStefano, LJ
Journal of sport rehabilitation. 2020;(6):847-850
Abstract
Clinical Scenario: Exercise in the heat can lead to performance decrements and increase the risk of heat illness. Heat acclimation refers to the systematic and gradual increase in exercise in a controlled, laboratory environment. Increased duration and intensity of exercise in the heat positively affects physiological responses, such as higher sweat rate, plasma volume expansion, decreased heart rate, and lower internal body temperature. Many heat acclimation studies have examined the hydration status of the subjects exercising in the heat. Some of the physiological responses that are desired to elicit heat acclimation (ie, higher heart rate and internal body temperature) are exacerbated in a dehydrated state. Thus, euhydration (optimal hydration) and dehydration trials during heat acclimation induction have been conducted to determine if there are additional benefits to dehydrated exercise trials on physiological adaptations. However, there is still much debate over hydration status and its effect on heat acclimation. Clinical Question: Does dehydration affect the adaptations of plasma volume, heart rate, internal body temperature, skin temperature, and sweat rate during the induction phase of heat acclimation? Summary of Findings: There were no observed differences in plasma volume, internal body temperature, and skin temperature following heat acclimation in this critically appraised topic. One study found an increase in sweat rate and another study indicated greater changes in heart rate following heat acclimation with dehydration. Aside from these findings, all 4 trials did not observe statistically significant differences in euhydrated and dehydrated heat acclimation trials. Clinical Bottom Line: There is minimal evidence to suggest that hydration status affects heat acclimation induction. In the studies that met the inclusion criteria, there were no differences in plasma volume concentrations, internal body temperature, and skin temperature. Strength of Recommendation: Based on the Oxford Centre for Evidence-Based Medicine Scale, Level 2 evidence exists.
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10.
Anhydrobiosis: Inside yeast cells.
Rapoport, A, Golovina, EA, Gervais, P, Dupont, S, Beney, L
Biotechnology advances. 2019;(1):51-67
Abstract
Under natural conditions yeast cells as well as other microorganisms are regularly subjected to the influence of severe drought, which leads to their serious dehydration. The dry seasons are then changed by rains and there is a restoration of normal water potential inside the cells. To survive such seasonal changes a lot of vegetative microbial cells, which belong to various genera and species, may be able to enter into a state of anhydrobiosis, in which their metabolism is temporarily and reversibly suspended or delayed. This evolutionarily developed adaptation to extreme conditions of the environment is widely used for practical goals - for conservation of microorganisms in collections, for maintenance and long storage of different important strain-producers and for other various biotechnological purposes. This current review presents the most important data obtained mainly in the studies of the structural and functional changes in yeast cells during dehydration. It describes the changes of the main organelles of eukaryotic cells and their role in cell survival in a dry state. The review provides information regarding the role of water in the structure and functions of biological macromolecules and membranes. Some important intracellular protective reactions of eukaryotic organisms, which were revealed in these studies and may have more general importance, are also discussed. The results of the studies of yeast anhydrobiosis summarized in the review show the possibilities of improving the conservation and long-term storage of various microorganisms and of increasing the quality of industrially produced dry microbial preparations.