Hypohydration produced by high-intensity intermittent running increases biomarkers of renal injury in males

Abstract Purpose Whilst there is evidence to suggest that hypohydration caused by physical work in the heat increases renal injury, whether this is the case during exercise in temperate conditions remains unknown. This study investigated the effect of manipulating hydration status during high-intensity intermittent running on biomarkers of renal injury. Methods After familiarisation, 14 males (age: 33 ± 7 years; V̇O2peak: 57.1 ± 8.6 ml/kg/min; mean ± SD) completed 2 trials in a randomised cross-over design, each involving 6, 15 min blocks of shuttle running (modified Loughborough Intermittent Shuttle Test protocol) in temperate conditions (22.3 ± 1.0 °C; 47.9 ± 12.9% relative humidity). During exercise, subjects consumed either a volume of water equal to 90% of sweat losses (EU) or 75 mL water (HYP). Body mass, blood and urine samples were taken pre-exercise (baseline/pre), 30 min post-exercise (post) and 24 h post-baseline (24 h). Results Post-exercise, body mass loss, serum osmolality and urine osmolality were greater in HYP than EU (P ≤ 0.024). Osmolality-corrected urinary kidney injury molecule-1 (uKIM-1) concentrations were increased post-exercise (P ≤ 0.048), with greater concentrations in HYP than EU (HYP: 2.76 [1.72–4.65] ng/mOsm; EU: 1.94 [1.1–2.54] ng/mOsm; P = 0.003; median [interquartile range]). Osmolality-corrected urinary neutrophil gelatinase-associated lipocalin (uNGAL) concentrations were increased post-exercise (P < 0.001), but there was no trial by time interaction effect (P = 0.073). Conclusion These results suggest that hypohydration produced by high-intensity intermittent running increases renal injury, compared to when euhydration is maintained, and that the site of this increased renal injury is at the proximal tubules.

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Small Differences in Everyday Hydration Status Influence Mood (P04-134-19)

Current Developments in Nutrition ◽

10.1093/cdn/nzz051.p04-134-19 ◽

2019 ◽

Vol 3 (Supplement_1) ◽

Author(s):

David Benton ◽

Alecia Cousins ◽

Hayley Young

Keyword(s):

Body Mass ◽

Psychological Functioning ◽

Fluid Intake ◽

Urine Osmolality ◽

Normal Diet ◽

Hydration Status ◽

Funding Sources ◽

Lower Baseline ◽

Urine Production ◽

The Impact

Abstract Objectives Reviews consistently find that a loss of about 2% of body mass was needed before either athletic or psychological functioning is disrupted. However, although it is usually assumed that the minor changes in hydration status, that occur during normal life, do not impact on performance, experimentally the topic has been virtually ignored. The impact of everyday variations in hydration was therefore examined. Methods 168 subjects were randomly allocated to drinking water, or not drinking, and in addition consume capsules containing either 300 mg of sodium chloride or a placebo. Subjects were monitored over a three-hour period, during which urine osmolality, loss of body mass and urine production were monitored. Repeatedly subjects reported their mood. Results Subjects came having consumed their normal diet, without any restriction on fluid intake: on average 0.5% body mass was lost during the study. The major finding was that the hydration status on arrival had a greater influence, than subsequent fluid intake and changes in osmolality during the study. With ratings of being agreeable rather than hostile, those with lower baseline osmolality who drank water had better mood than if baseline osmolality was high. As another example, the mood of those who did not drink water only declined during the study when baseline osmolality was high rather than low. With measures of being composed rather than anxious, and being confidence rather than unsure, those who had lower baseline osmolality had a better mood, irrespective of whether water was consumed. Thus, baseline osmolality had an impact greater than drink induced changes in osmolality. Traditionally the normal range of urine osmolality has been said to be 200–800 mOsmoles/kg, yet the critical point at which the response to fluid intake changed was 600 mOsmoles/kg: 61% had a baseline osmolality over 600 and 38% over 800 mOsmoles/kg. Conclusions Some individuals are in a state of dehydration that adversely influences mood; a state not reversed by acute fluid consumption. The pattern of consumption associated with mild-dehydration and its functional consequences needs to be established. Funding Sources There was no funding external other than provided by ** University.

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Hydration status of Greco-Roman wrestlers in an authentic precompetition situation

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2012-0334 ◽

2013 ◽

Vol 38 (6) ◽

pp. 621-625 ◽

Cited By ~ 9

Author(s):

Vahur Ööpik ◽

Saima Timpmann ◽

Andres Burk ◽

Innar Hannus

Keyword(s):

Specific Gravity ◽

Body Mass ◽

Urine Osmolality ◽

Mass Gain ◽

The Body ◽

Urine Specific Gravity ◽

Hydration Status ◽

Greco Roman ◽

Reduced Body ◽

Body Mass Gain

We assessed the urinary indexes of hydration status of Greco-Roman wrestlers in an authentic precompetition situation at the time of official weigh-in (OWI). A total of 51 of 89 wrestlers competing in the Estonian Championship in 2009 donated a urine sample. Questionnaire responses revealed that 27 wrestlers (body mass losers (BMLs)) reduced body mass before the competition, whereas 24 wrestlers (those who do not lose body mass (n-BMLs)) did not. In 42 wrestlers, values of urine specific gravity ≥1.020 and urine osmolality ≥700 mOsmol·kg−1 revealed a hypohydrated status. The prevalence of hypohydration in the BMLs (96%) was higher than in the n-BMLs (67%) (χ2 = 7.68; p < 0.05). The prevalence of serious hypohydration (urine specific gravity >1.030) was 5.3 times greater (χ2 = 8.32; p < 0.05) in the BMLs than in the n-BMLs. In the BMLs, the extent of body mass gain during the 16-h recovery (2.5 ± 1.2 kg) was associated (r = 0.764; p < 0.05) with self-reported precompetition body mass loss (4.3 ± 2.0 kg) and exceeded the body mass gain observed in the n-BMLs (0.7 ± 1.2 kg; p < 0.05). We conclude that hypohydration is prevalent among Greco-Roman wrestlers at the time of OWI. The prevalence of hypohydration and serious hypohydration is especially high among wrestlers who are accustomed to reducing body mass before competition. These results suggest that an effective rehydration strategy is needed for Olympic-style wrestlers, and that changes in wrestling rules should be considered to reduce the prevalence of harmful body mass management behaviours.

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Both hyperthermia and dehydration during physical work in the heat contribute to the risk of acute kidney injury

Journal of Applied Physiology ◽

10.1152/japplphysiol.00787.2019 ◽

2020 ◽

Vol 128 (4) ◽

pp. 715-728 ◽

Cited By ~ 12

Author(s):

Christopher L. Chapman ◽

Blair D. Johnson ◽

Nicole T. Vargas ◽

David Hostler ◽

Mark D. Parker ◽

...

Keyword(s):

Acute Kidney Injury ◽

Core Temperature ◽

Renal Injury ◽

Kidney Injury ◽

Proximal Tubules ◽

Tissue Inhibitor Of Metalloproteinase ◽

Physical Work ◽

Control Group ◽

Water Cooling ◽

Urine Production

Occupational heat stress increases the risk of acute kidney injury (AKI) and kidney disease. This study tested the hypothesis that attenuating the magnitude of hyperthermia (i.e., increase in core temperature) and/or dehydration during prolonged physical work in the heat attenuates increases in AKI biomarkers. Thirteen healthy adults (3 women, 23 ± 2 yr) exercised for 2 h in a 39.7 ± 0.6°C, 32 ± 3% relative-humidity environmental chamber. In four trials, subjects received water to remain euhydrated ( Water), continuous upper-body cooling ( Cooling), a combination of both ( Water + Cooling), or no intervention ( Control). The magnitude of hyperthermia (increased core temperature of 1.9 ± 0.3°C; P < 0.01) and dehydration (percent loss of body mass of −2.4 ± 0.5%; P < 0.01) were greatest in the Control group. There were greater increases in the urinary biomarkers of AKI in the Control trial: albumin (increase of 13 ± 11 μg/mL; P ≤ 0.05 compared with other trials), neutrophil gelatinase-associated lipocalin (NGAL) (increase of 16 ± 14 ng/dL, P ≤ 0.05 compared with Cooling and Water + Cooling groups), and insulin-like growth factor-binding protein 7 (IGFBP7) (increase of 227 ± 190 ng/mL; P ≤ 0.05 compared with other trials). Increases in IGFBP7 in the Control trial persisted after correcting for urine production/concentration. There were no differences in the AKI biomarker tissue inhibitor of metalloproteinase 2 (TIMP-2) between trials ( P ≥ 0.11). Our findings indicate that the risk of AKI is highest with greater magnitudes of hyperthermia and dehydration during physical work in the heat. Additionally, the differential findings between IGFBP7 (preferentially secreted in proximal tubules) and TIMP-2 (distal tubules) suggest the proximal tubules as the location of potential renal injury. NEW & NOTEWORTHY We demonstrate that the risk for acute kidney injury (AKI) is higher in humans with greater magnitudes of hyperthermia and dehydration during physical work in the heat and that alleviating the hyperthermia and/or limiting dehydration equally reduce the risk of AKI. The biomarker panel employed in this study suggests the proximal tubules as the location of potential renal injury.

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Ad Libitum Fluid Consumption via Self- or External Administration

Journal of Athletic Training ◽

10.4085/1062-6050-49.3.76 ◽

2015 ◽

Vol 50 (1) ◽

pp. 51-58 ◽

Cited By ~ 4

Author(s):

Susan W. Yeargin ◽

Megan E. Finn ◽

Lindsey E. Eberman ◽

Matthew J. Gage ◽

Brendon P. McDermott ◽

...

Keyword(s):

Body Mass ◽

Repeated Measures ◽

Athletic Trainers ◽

Urine Osmolality ◽

Time Frame ◽

Hydration Status ◽

Fluid Consumption ◽

Self Administration ◽

Average Volume ◽

Ad Libitum

Context: During team athletic events, athletic trainers commonly provide fluids with water bottles. When a limited number of water bottles exist, various techniques are used to deliver fluids. Objective: To determine whether fluid delivered via water-bottle administration influenced fluid consumption and hydration status. Design: Crossover study. Setting: Outdoor field (22.2°C ± 3.5°C). Patients or Other Participants: Nineteen participants (14 men, 5 women, age = 30 ± 10 years, height = 176 ± 8 cm, mass = 72.5 ± 10 kg) were recruited from the university and local running clubs. Intervention(s): The independent variable was fluid delivery with 3 levels: self-administration with mouth-to-bottle direct contact (SA-DC), self-administration with no contact between mouth and bottle (SA-NC), and external administration with no contact between the mouth and the bottle (EA-NC). Participants warmed up for 10 minutes before completing 5 exercise stations, after which an ad libitum fluid break was given, for a total of 6 breaks. Main Outcome Measure(s): We measured the fluid variables of total volume consumed, total number of squirts, and average volume per squirt. Hydration status via urine osmolality and body-mass loss, and perceptual variables for thirst and fullness were recorded. We calculated repeated-measures analyses of variance to assess hydration status, fluid variables, and perceptual measures to analyze conditions across time. Results: The total volume consumed for EA-NC was lower than for SA-DC (P = .001) and SA-NC (P = .001). The total number of squirts for SA-DC was lower than for SA-NC (P = .009). The average volume per squirt for EA-NC was lower than for SA-DC (P = .020) and SA-NC (P = .009). Participants arrived (601.0 ± 21.3 mOsm/L) and remained (622.3 ± 38.3 mOsm/L) hydrated, with no difference between conditions (P = .544); however, the EA-NC condition lost more body mass than did the SA-DC condition (P = .001). There was no main effect for condition on thirst (P = .147) or fullness (P = .475). Conclusions: External administration of fluid decreased total volume consumed via a decreased average volume per squirt. The SA-DC method requires fewer squirts within a specific time frame. Fluid breaks every 15 minutes resulted in maintenance of euhydration; however, loss of body mass was influenced by fluid administration. Athletic trainers should avoid external administration to promote positive hydration behaviors. When fluid is self-administered, individual bottles may be the best clinical practice because more volume can be consumed per squirt.

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The Utility of Thirst as a Measure of Hydration Status Following Exercise-Induced Dehydration

Nutrients ◽

10.3390/nu11112689 ◽

2019 ◽

Vol 11 (11) ◽

pp. 2689 ◽

Cited By ~ 4

Author(s):

William M. Adams ◽

Lesley W. Vandermark ◽

Luke N. Belval ◽

Douglas J. Casa

Keyword(s):

Body Mass ◽

Prolonged Exercise ◽

Recovery Period ◽

Fluid Replacement ◽

Hydration Status ◽

Post Exercise ◽

Visual Analog Scales ◽

Hot Environment ◽

Ad Libitum ◽

Exercise Induced

The purpose of this study was to examine the perception of thirst as a marker of hydration status following prolonged exercise in the heat. Twelve men (mean ± SD; age, 23 ± 4 y; body mass, 81.4 ± 9.9 kg; height, 182 ± 9 cm; body fat, 14.3% ± 4.7%) completed two 180 min bouts of exercise on a motorized treadmill in a hot environment (35.2 ± 0.6 °C; RH, 30.0 ± 5.4%), followed by a 60 min recovery period. Participants completed a euhydrated (EUH) and hypohydrated (HYPO) trial. During recovery, participants were randomly assigned to either fluid replacement (EUHFL and HYPOFL; 10 min ad libitum consumption) or no fluid replacement (EUHNF and HYPONF). Thirst was measured using both a nine-point scale and separate visual analog scales. The percent of body mass loss (%BML) was significantly greater immediately post exercise in HYPO (HYPOFL, 3.0% ± 1.2%; HYPONF, 2.6% ± 0.6%) compared to EUH (EUHFL, 0.2% ± 0.7%; EUHNF, 0.6% ± 0.5%) trials (p < 0.001). Following recovery, there were no differences in %BML between HYPOFL and HYPONF (p > 0.05) or between EUHFL and EUHNF (p > 0.05). Beginning at minute 5 during the recovery period, thirst perception was significantly greater in HYPONF than EUHFL, EUHNF, and HYPOFL (p < 0.05). A 10 min, ad libitum consumption of fluid post exercise when hypohydrated (%BML > 2%), negated differences in perception of thirst between euhydrated and hypohydrated trials. These results represent a limitation in the utility of thirst in guiding hydration practices.

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Appetite, food intake and gut hormone responses to intense aerobic exercise of different duration

Journal of Endocrinology ◽

10.1530/joe-16-0570 ◽

2017 ◽

Vol 235 (3) ◽

pp. 193-205 ◽

Cited By ~ 18

Author(s):

Adrian Holliday ◽

Andrew Blannin

Keyword(s):

Food Intake ◽

Aerobic Exercise ◽

Energy Intake ◽

High Intensity ◽

Exercise Bout ◽

Relative Energy ◽

Acylated Ghrelin ◽

Post Exercise ◽

Time Interaction ◽

Gut Hormone

The purpose of the study is to investigate the effect of acute bouts of high-intensity aerobic exercise of differing durations on subjective appetite, food intake and appetite-associated hormones in endurance-trained males. Twelve endurance-trained males (age = 21 ± 2 years; BMI = 21.0 ± 1.6 kg/m2; VO2max = 61.6 ± 6.0 mL/kg/min) completed four trials, within a maximum 28 day period, in a counterbalanced order: resting (REST); 15 min exercise bout (15-min); 30 min exercise bout (30-min) and 45 min exercise bout (45-min). All exercise was completed on a cycle ergometer at an intensity of ~76% VO2max. Sixty minutes post exercise, participants consumed an ad libitum meal. Measures of subjective appetite and blood samples were obtained throughout the morning, with plasma analyzed for acylated ghrelin, total polypeptide tyrosine-tyrosine (PYY) and total glucagon-like peptide 1 (GLP-1) concentrations. The following results were obtained: Neither subjective appetite nor absolute food intake differed between trials. Relative energy intake (intake – expenditure) was significantly greater after REST (2641 ± 1616 kJ) compared with both 30-min (1039 ± 1520 kJ) and 45-min (260 ± 1731 kJ), and significantly greater after 15-min (2699 ± 1239 kJ) compared with 45-min (condition main effect, P < 0.001). GLP-1 concentration increased immediately post exercise in 30-min and 45-min, respectively (condition × time interaction, P < 0.001). Acylated ghrelin was transiently suppressed in all exercise trials (condition × time interaction, P = 0.011); the greatest, most enduring suppression, was observed in 45-min. PYY concentration was unchanged with exercise. In conclusion, high-intensity aerobic cycling lasting up to 45 min did not suppress subjective appetite or affect absolute food intake, but did reduce relative energy intake, in well-trained endurance athletes. Findings question the role of appetite hormones in regulating subjective appetite in the acute post-exercise period.

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The Relationship between %BML, Urine Color, Thirst Level and Urine Indices of Hydration Status

Annals of Nutrition and Metabolism ◽

10.1159/000515217 ◽

2021 ◽

Author(s):

Yasuki Sekiguchi ◽

Courteney L. Benjamin ◽

Cody R. Butler ◽

Margaret C. Morrissey ◽

Erica M. Filep ◽

...

Keyword(s):

Body Mass ◽

Pairwise Comparison ◽

Urine Osmolality ◽

Urine Specific Gravity ◽

Venn Diagram ◽

Hydration Status ◽

Urine Color ◽

Health Quality ◽

No Gold Standard ◽

The Relationship

Introduction: Dehydration is known to impair health, quality of daily life, and exercise performance [<xref ref-type="bibr" rid="ref1">1</xref>]. While several methods are utilized to assess fluid balance, there is no gold standard to assess hydration status [<xref ref-type="bibr" rid="ref2">2</xref>]. Cheuvront and Kenefick [<xref ref-type="bibr" rid="ref3">3</xref>] suggested the use of a Venn diagram, which consists of % body mass weight (BML), urine color, and thirst level (WUT) to measure hydration status and fluid needs. However, no study to date has examined the relationship between the WUT criteria and hydration status measured by urine indices. Objective: The purpose of this study was to investigate the relationships between urine-specific gravity (USG), urine osmolality (UOSM), and the WUT criteria. Methods: Twenty-two females (mean ± SD; age, 20 ± 1 year; weight, 65.4 ± 12.6 kg) and twenty-one males (age, 21 ± 1 year; body mass, 78.7 ± 14.6 kg) participated in this study. First-morning body mass, urine color, USG, UOSM, and thirst level were collected for 10 consecutive days. First 3 days were utilized to establish a euhydrated baseline body weight. %BML >1%, urine color >5, and thirst level ≥5 were used as the dehydration thresholds. The number of markers that indicated dehydration levels was summed when each variable met each threshold. One-way ANOVA with Tukey pairwise comparison was used to assess the differences in USG and UOSM, followed by a calculation of effect size (ES). Results: Figure <xref ref-type="fig" rid="f01">1</xref> indicates the differences of UOSM based on the WUT criteria. For UOSM, “2 markers indicated” (mean [M] ± SD [ES], 705 ± 253 mOsmol [0.43], p = 0.018) was significantly higher than “1 marker indicated” (M ± SD, 597 ± 253 mOsmol). Additionally, “zero marker indicated” (509 ± 249 mOsmol) was significantly lower than “3 markers indicated” (M ± SD [ES], 761 ± 250 mOsmol, [1.01], p = 0.02) and “2 markers indicated” ([ES], [0.78], p = 0.004). However, there was no statistical difference between “3 markers indicated” ([ES], [0.65], p = 0.13) and “1 marker indicated.” For USG, “3 markers indicated” (M ± SD [ES], 1.021 ± 0.007 [0.57], p = 0.025) and “2 markers indicated” (M ± SD [ES], 1.019 ± 0.010 [0.31], p = 0.026) were significantly higher than “1 marker indicated” (M ± SD, 1.016 ± 0.009). Additionally, “zero marker indicated” (1.014 ± 0.005) was significantly lower than “3 markers indicated” ([ES], [1.21], p = 0.005) and “2 markers indicated” ([ES], [0.54], p = 0.009). Conclusion: When 3 markers indicated dehydration levels, UOSM and USG were greater than euhydrated cut points. When 2 markers indicated dehydration levels, USG was higher than the euhydrated cut point. Additionally, UOSM and USG were significantly lower when zero or 1 marker indicated dehydration levels. Thus, the WUT criteria are a useful tool to assess hydration status. Athletes, coaches, sports scientists, and medical professions can use this strategy in the field settings to optimize their performance and health without consuming money and time.

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Does the Nutritional Composition of Dairy Milk Based Recovery Beverages Influence Post-exercise Gastrointestinal and Immune Status, and Subsequent Markers of Recovery Optimisation in Response to High Intensity Interval Exercise?

Frontiers in Nutrition ◽

10.3389/fnut.2020.622270 ◽

2021 ◽

Vol 7 ◽

Author(s):

Isabella Russo ◽

Paul A. Della Gatta ◽

Andrew Garnham ◽

Judi Porter ◽

Louise M. Burke ◽

...

Keyword(s):

Body Mass ◽

High Intensity ◽

Immune Status ◽

Recovery Period ◽

Performance Outcomes ◽

Body Water ◽

Functional Disturbance ◽

Post Exercise ◽

High Intensity Interval ◽

Dairy Milk

This study aimed to determine the effects of flavored dairy milk based recovery beverages of different nutrition compositions on markers of gastrointestinal and immune status, and subsequent recovery optimisation markers. After completing 2 h high intensity interval running, participants (n = 9) consumed a whole food dairy milk recovery beverage (CM, 1.2 g/kg body mass (BM) carbohydrate and 0.4 g/kg BM protein) or a dairy milk based supplement beverage (MBSB, 2.2 g/kg BM carbohydrate and 0.8 g/kg BM protein) in a randomized crossover design. Venous blood samples, body mass, body water, and breath samples were collected, and gastrointestinal symptoms (GIS) were measured, pre- and post-exercise, and during recovery. Muscle biopsies were performed at 0 and 2 h of recovery. The following morning, participants returned to the laboratory to assess performance outcomes. In the recovery period, carbohydrate malabsorption (breath H2 peak: 49 vs. 24 ppm) occurred on MBSB compared to CM, with a trend toward greater gut discomfort. No difference in gastrointestinal integrity (i.e., I-FABP and sCD14) or immune response (i.e., circulating leukocyte trafficking, bacterially-stimulated neutrophil degranulation, and systemic inflammatory profile) markers were observed between CM and MBSB. Neither trial achieved a positive rate of muscle glycogen resynthesis [−25.8 (35.5) mmol/kg dw/h]. Both trials increased phosphorylation of intramuscular signaling proteins. Greater fluid retention (total body water: 86.9 vs. 81.9%) occurred on MBSB compared to CM. Performance outcomes did not differ between trials. The greater nutrient composition of MBSB induced greater gastrointestinal functional disturbance, did not prevent the post-exercise reduction in neutrophil function, and did not support greater overall acute recovery.

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Relationships Between WUT (Body Weight, Urine Color, and Thirst Level) Criteria and Urine Indices of Hydration Status

Sports Health A Multidisciplinary Approach ◽

10.1177/19417381211038494 ◽

2021 ◽

pp. 194173812110384

Author(s):

Yasuki Sekiguchi ◽

Courteney L. Benjamin ◽

Cody R. Butler ◽

Margaret C. Morrissey ◽

Erica M. Filep ◽

...

Keyword(s):

Specific Gravity ◽

Mass Loss ◽

Body Mass ◽

Urine Osmolality ◽

Urine Specific Gravity ◽

Venn Diagram ◽

Hydration Status ◽

Body Mass Loss ◽

Living Situation ◽

Urine Color

Background: A Venn diagram consisting of percentage body mass loss, urine color, and thirst perception (weight, urine, thirst [WUT]) has been suggested as a practical method to assess hydration status. However, no study to date has examined relationships between WUT and urine hydration indices. Thus, the purpose of this study was to investigate relationships between urine specific gravity, urine osmolality, and the WUT criteria. Hypothesis: Urine specific gravity and urine osmolality indicate hypohydration when the WUT criteria demonstrate hypohydration (≥2 markers). Study Design: Laboratory cohort study. Level of Evidence: Level 3. Methods: A total of 22 women (mean ± SD; age, 20 ± 1 years; mass, 65.4 ± 12.6 kg) and 21 men (age, 21 ± 1 years; body mass, 78.7 ± 14.6 kg) participated in this study. First morning body mass, urine color, urine specific gravity, urine osmolality, and thirst level were collected for 10 consecutive days in a free-living situation. Body mass loss >1%, urine color >5, and thirst level ≥5 were used as the dehydration thresholds. The number of markers that indicated dehydration levels were counted and categorized into either 3, 2, 1, or 0 WUT markers that indicated dehydration. One-way analysis of variance with Tukey pairwise comparisons was used to assess the differences in urine specific gravity and urine osmolality between the different number of WUT markers. Results: Urine specific gravity in 3 WUT markers (mean ± SD [effect size], 1.021 ± 0.007 [0.57]; P = 0.025) and 2 WUT markers (1.019 ± 0.010 [0.31]; P = 0.026) was significantly higher than 1 WUT marker (1.016 ± 0.009). Urine mosmolality in 2 WUT markers (705 ± 253 mOsmol [0.43]; P = 0.018) was significantly higher than 1 WUT (597 ± 253 mOsmol). Meeting at least 2 WUT markers resulted in sensitivities of 0.652 (2 WUT criteria met) and 0.933 (3 WUT criteria met) to detect urine osmolality >700 mOsmol. Conclusion: These results suggest that when 3 WUT markers are met, urine specific gravity and urine osmolality were greater than euhydration cutoff points. The WUT criterion is a useful tool to use in field settings to assess hydration status when first morning urine sample was used. Clinical Relevance: Athletes, coaches, sports scientists, and medical professionals can use WUT criteria to monitor dehydration with reduced cost and time.

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Novel hydration assessment techniques employing thirst and a water intake challenge in healthy men

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2012-0369 ◽

2014 ◽

Vol 39 (2) ◽

pp. 138-144 ◽

Cited By ~ 22

Author(s):

Lawrence E. Armstrong ◽

Matthew S. Ganio ◽

Jennifer F. Klau ◽

Evan C. Johnson ◽

Douglas J. Casa ◽

...

Keyword(s):

Body Mass ◽

Urine Volume ◽

Urine Osmolality ◽

Fluid Replacement ◽

Urine Specific Gravity ◽

Hydration Status ◽

Healthy Men ◽

Hydration State ◽

Assessment Techniques ◽

Hydration Assessment

Exploring novel hydration indices is important because no human biomarker has been shown to be incontrovertibly valid in all life situations. The present investigation was designed to identify inexpensive, nontechnical methods to use when self-assessing hydration status. This investigation evaluated the validity and efficacy of 2 novel techniques (i.e., thirst sensation and urine volume) to assess hydration state of 29 active men (mean ± SD; age, 23 ± 4 years; body mass, 76.02 ± 11.94 kg) at rest. Eight combinations of 4 water challenges (4.8, 9.3, 11.0, or 14 mL·kg−1) and 2 hydration states (mildly hypohydrated (HY), –2.0%; euhydrated (EU), –0.2% body mass) were employed. First, thirst was linearly related to body water loss, and ratings of thirst distinguished HY from EU (p < 0.001) subsequent to 19 h of controlled food and fluid intake. Second, measurements of urine volume 60 min after consuming a water bolus (11.0 or 14 mL·kg−1) were strongly and inversely correlated with entering hydration state, assessed by urine specific gravity (r2 = 0.76, p < 0.0001) and urine osmolality (r2 = 0.77, p < 0.0001). We concluded that healthy men can employ simple measurements of morning thirst sensation and urine volume to identify the presence of mild hypohydration and to guide fluid replacement. These 2 techniques are relevant because HY (–2% body mass) is the approximate threshold for the onset of thirst, reduced endurance exercise performance, and decrements of working memory and mood.

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