Urinary Indices during Dehydration, Exercise, and Rehydration

1998 ◽  
Vol 8 (4) ◽  
pp. 345-355 ◽  
Author(s):  
Lawrence E. Armstrong ◽  
Jorge A. Herrera Soto ◽  
Frank T. Hacker ◽  
Douglas J. Casa ◽  
Stavros A. Kavouras ◽  
...  
Keyword(s):  
Specific Gravity ◽  
Body Mass ◽  
Urine Volume ◽  
Plasma Osmolality ◽  
Body Water ◽  
Hydration Status ◽  
Plasma Sodium ◽  
Oral Rehydration ◽  
Urine Color ◽  
Better Than

This investigation evaluated the validity and sensitivity of urine color (Ucol), specific gravity (Usg), and osmolality (Uosm) as indices of hydration status, by comparing them to changes in body water. Nine highly trained males underwent a 42-hr protocol involving dehydration to 3.7% of body mass (Day 1, −2.64 kg), cycling to exhaustion (Day 2, −5.2% of body mass, −3.68 kg), and oral rehydration for 21 hr. The ranges of mean (across time) blood and urine values were Ucol, 1-7; Usg, 1.004-1.029; U08m, 117-1,081 mOsm • kg−1; and plasma osmolality (Posm), 280-298 mOsm ⋅ kg−1. Urine color tracked changes in body water as effectively as (or better than) Uosm, Usg, urine volume, Posm, plasma sodium, and plasma total protein. We concluded that (a) Ucol, Uosm, and Usg are valid indices of hydration status, and (b) marked dehydration, exercise, and rehydration had little effect on the validity and sensitivity of these indices.

scholarly journals The psychophysiological effects of a three day dry fast: A self-experimentation case study

2020 ◽  
Author(s):  
Harriet Carroll
Keyword(s):  
Blood Pressure ◽  
Blood Glucose ◽  
Specific Gravity ◽  
Sleep Quality ◽  
Body Mass ◽  
Urine Volume ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Fluid Restriction ◽  
Urine Colour

Background: A commonly held belief is that humans cannot survive more than a few days without fluid intake. The source of this is unclear, but does not accord with the few controlled studies that have been conducted to investigate the effects of fluid abstention, nor the few extreme cases of fluid restriction. Methods: This was a self-experimentation, with one day pre-load of fluid and salt (DAY 0), three days complete fluid abstention (< 45 g/d water from food only) (DAYS 1-3), and 24 h rehydration (DAY 4). Days ran from 1500 h to 1500 h. The following measures were taken across various time points across each day: body mass; urine volume; urine colour; urine specific gravity; finger-prick blood glucose concentration; blood pressure; pulse; body temperature; dietary intake; and visual analogue scales (VAS) of food-appetites (satiety and desires), thirst-appetites, mood, wakefulness, and sleep quality. Results: By the end of DAY 3, body water (excluding estimated lean/adipose loss from negative energy balance) decreased by ~1.8 % from 1500 h on DAY 0, or ~4.0 % from 1500 h on DAY 1 (after a fluid preload). With this reduction in body mass came expected reductions in urine volume and increased in urine colour, though trends in urine specific gravity were less pronounced. Blood pressure trended towards being lower during DAYS 1-3 and increased during DAY 4. Whole blood glucose concentrations also tended towards being lower during DAYS 1-3 compared to DAY 4, particularly postprandially. Hunger tended to be reduced during DAYS 1-3, but increased again during DAY 4. Wanting to eat appeared to be a separate construct to hunger/fullness. True-thirst was higher during DAYS 1-3 relative to DAY 4, and this synchronised well with true-xerostomia and ratings of dryness of lips. However, sensational-xerostomia was the dominant thirst experienced during DAY 1-3. Sadness was moderately inversely correlated with body mass loss (r = 0.57) and tiredness was strongly positively correlated (r = 0.94). Sleep quality was unrelated to hydration status. Conclusion: Overall, the expected changes occurred in terms of hydration physiology, but with some unexpected findings in terms of gluco-regulation, blood pressure, and thirst appetites.

Development of Individual Hydration Strategies for Athletes

2008 ◽  
Vol 18 (5) ◽  
pp. 457-472 ◽  
Author(s):  
Ronald J. Maughan ◽  
Susan M. Shirreffs
Keyword(s):  
Specific Gravity ◽  
Body Mass ◽  
Environmental Conditions ◽  
Fluid Intake ◽  
Sweat Rate ◽  
Hydration Status ◽  
Additional Information ◽  
Urine Color ◽  
Individual Needs ◽  
Exercise Environment

Athletes are encouraged to begin exercise well hydrated and to consume sufficient amounts of appropriate fluids during exercise to limit water and salt deficits. Available evidence suggests that many athletes begin exercise already dehydrated to some degree, and although most fail to drink enough to match sweat losses, some drink too much and a few develop hyponatremia. Some simple advice can help athletes assess their hydration status and develop a personalized hydration strategy that takes account of exercise, environment, and individual needs. Preexercise hydration status can be assessed from urine frequency and volume, with additional information from urine color, specific gravity, or osmolality. Change in hydration during exercise can be estimated from the change in body mass that occurs during a bout of exercise. Sweat rate can be estimated if fluid intake and urinary losses are also measured. Sweat salt losses can be determined by collection and analysis of sweat samples, but athletes losing large amounts of salt are likely to be aware of the taste of salt in sweat and the development of salt crusts on skin and clothing where sweat has evaporated. An appropriate drinking strategy will take account of preexercise hydration status and of fluid, electrolyte, and substrate needs before, during, and after a period of exercise. Strategies will vary greatly between individuals and will also be influenced by environmental conditions, competition regulations, and other factors.

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

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.

Urinary Indices of Hydration Status

1994 ◽  
Vol 4 (3) ◽  
pp. 265-279 ◽  
Author(s):  
Lawrence E. Armstrong ◽  
Carl M. Maresh ◽  
John W. Castellani ◽  
Michael F. Bergeron ◽  
Robert W. Kenefick ◽  
...  
Keyword(s):  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Field Studies ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Plasma Sodium ◽  
Strongly Correlated ◽  
Laboratory Studies ◽  
Urine Color ◽  
Precision And Accuracy

Athletes and researchers could benefit from a simple and universally accepted technique to determine whether humans are well-hydrated, euhydrated, or hypohydrated. Two laboratory studies (A, B) and one field study (C) were conducted to determine if urine color () indicates hydration status accurately and to clarify the interchangeability of , urine osmolality (), and urine specific gravity () in research. , , and were not significantly correlated with plasma osmolality, plasma sodium, or hemato-crit. This suggested that these hematologic measurements are not as sensitive to mild hypohydration (between days) as the selected urinary indices are. When the data from A, B, and C were combined, was strongly correlated with and U„sm. It was concluded that (a) may be used in athletic/industrial settings or field studies, where close estimates of or are acceptable, but should not be utilized in laboratories where greater precision and accuracy are required, and (b) and may be used interchangeably to determine hydration status.

Human Hydration Indices: Acute and Longitudinal Reference Values

2010 ◽  
Vol 20 (2) ◽  
pp. 145-153 ◽  
Author(s):  
Lawrence E. Armstrong ◽  
Amy C. Pumerantz ◽  
Kelly A. Fiala ◽  
Melissa W. Roti ◽  
Stavros A. Kavouras ◽  
...  
Keyword(s):  
Specific Gravity ◽  
Body Mass ◽  
Reference Values ◽  
Fluid Intake ◽  
Pure Water ◽  
Urine Volume ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Total Fluid Intake ◽  
Free Living

It is difficult to describe hydration status and hydration extremes because fluid intakes and excretion patterns of free-living individuals are poorly documented and regulation of human water balance is complex and dynamic. This investigation provided reference values for euhydration (i.e., body mass, daily fluid intake, serum osmolality; M ± SD); it also compared urinary indices in initial morning samples and 24-hr collections. Five observations of 59 healthy, active men (age 22 ± 3 yr, body mass 75.1 ± 7.9 kg) occurred during a 12-d period. Participants maintained detailed records of daily food and fluid intake and exercise. Results indicated that the mean total fluid intake in beverages, pure water, and solid foods was >2.1 L/24 hr (range 1.382–3.261, 95% confidence interval 0.970–3.778 L/24 hr); mean urine volume was >1.3 L/24 hr (0.875–2.250 and 0.675–3.000 L/24 hr); mean urine specific gravity was >1.018 (1.011–1.027 and 1.009–1.030); and mean urine color was ≥4 (4–6 and 2–7). However, these men rarely (0–2% of measurements) achieved a urine specific gravity below 1.010 or color of 1. The first morning urine sample was more concentrated than the 24-h urine collection, likely because fluids were not consumed overnight. Furthermore, urine specific gravity and osmolality were strongly correlated (r2 = .81–.91, p < .001) in both morning and 24-hr collections. These findings provide euhydration reference values and hydration extremes for 7 commonly used indices in free-living, healthy, active men who were not exercising in a hot environment or training strenuously.

Quantification of chromatographic effects of vitamin B supplementation in urine and implications for hydration assessment

2015 ◽  
Vol 119 (2) ◽  
pp. 110-115 ◽  
Author(s):  
Robert W. Kenefick ◽  
K. R. Heavens ◽  
W. E. Dennis ◽  
E. M. Caruso ◽  
K. I. Guerriere ◽  
...  
Keyword(s):  
Specific Gravity ◽  
Body Mass ◽  
Urine Osmolality ◽  
Vitamin Supplementation ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Vitamin B ◽  
Color Classification ◽  
Urine Color ◽  
Hydration Assessment

Changes in body water elicit reflex adjustments at the kidney, thus maintaining fluid volume homeostasis. These renal adjustments change the concentration and color of urine, variables that can, in turn, be used as biomarkers of hydration status. It has been suggested that vitamin supplementation alters urine color; it is unclear whether any such alteration would confound hydration assessment via colorimetric evaluation. We tested the hypothesis that overnight vitamin B2 and/or B12 supplementation alters urine color as a marker of hydration status. Thirty healthy volunteers were monitored during a 3-day euhydrated baseline, confirmed via first morning nude body mass, urine specific gravity, and urine osmolality. Volunteers then randomly received B2 ( n = 10), B12 ( n = 10), or B2 + B12 ( n = 10) at ∼200 × recommended dietary allowance. Euhydration was verified on trial days (two of the following: body mass ± 1.0% of the mean of visits 1–3, urine specific gravity < 1.02, urine osmolality < 700 mmol/kg). Vitamin purity and urinary B2 concentration ([B2]) and [B12] were quantified via ultraperformance liquid chromatography. Two independent observers assessed urine color using an eight-point standardized color chart. Following supplementation, urinary [B2] was elevated; however, urine color was not different between nonsupplemented and supplemented trials. For example, in the B2 trial, urinary [B2] increased from 8.6 × 104 ± 7.7 × 104 to 5.7 × 106 ± 5.3 × 106 nmol/l ( P < 0.05), and urine color went from 4 ± 1 to 5 ± 1 ( P > 0.05). Both conditions met the euhydrated color classification. We conclude that a large overnight dose of vitamins B2 and B12 does not confound assessment of euhydrated status via urine color.

scholarly journals Effects of sex and menstrual cycle on volume-regulatory responses to 24-h fluid restriction

2020 ◽  
Vol 319 (5) ◽  
pp. R560-R565
Author(s):  
Gabrielle E. W. Giersch ◽  
Abigail T. Colburn ◽  
Margaret C. Morrissey ◽  
Cody R. Butler ◽  
Michaela L. Pruchnicki ◽  
...  
Keyword(s):  
Menstrual Cycle ◽  
Specific Gravity ◽  
Body Mass ◽  
Urine Osmolality ◽  
Reproductive Hormones ◽  
Urine Specific Gravity ◽  
Fluid Restriction ◽  
Urine Color ◽  
Fluid Regulation ◽  
The Impact

Reproductive hormones have significant nonreproductive physiological effects, including altering fluid regulation. Our purpose was to explore the impact of sex and menstrual cycle (MC) phase on volume-regulatory responses to 24-h fluid restriction (24-h FR). Participants (men: n = 12, 20 ± 2 yr; women: n = 10, 20 ± 1 yr) were assigned two randomized and counterbalanced fluid prescriptions [Euhy: euhydrated, urine specific gravity (USG) < 1.020; Dehy: 24-h FR, USG > 1.020]. Men completed both (MEuhy, MDehy), while women completed both in the late-follicular ( days 10–13; FDehy, FEuhy) and midluteal ( days 18–22; LDehy, LEuhy) phases. We measured body mass, plasma and urine osmolality (Posm, Uosm), urine specific gravity (USG), urine color (Ucol), and serum copeptin; 24-h FR yielded mild dehydration without influence of sex or MC ( P > 0.05). Copeptin increased in men following Dehy (pre: 8.2 ± 5.2, post: 15.8 ± 12.6, P = 0.04) but not in women (FDehy pre: 4.3 ± 1.6, post: 10.5 ± 6.9, P = 0.06; LDehy pre: 5.6 ± 3.5, post: 10.4 ± 6.2, P = 0.16). In FDehy, Posm increased following FR (pre: 288 ± 2, post: 292 ± 1, P = 0.03) but not in men (pre: 292 ± 3, post: 293 ± 2, P = 0.46). No MC differences were observed between body mass loss, Posm, Uosm, USG, and copeptin ( P > 0.05). These results suggest that volume-regulatory responses to 24-h FR were present in men but not in women, without apparent effects of the menstrual cycle.

scholarly journals Impact of Nutrient Intake on Hydration Biomarkers Following Exercise and Rehydration Using a Clustering-Based Approach

Nutrients ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1276 ◽  
Author(s):  
Colleen X. Muñoz ◽  
Evan C. Johnson ◽  
Laura J. Kunces ◽  
Amy L. McKenzie ◽  
Michael Wininger ◽  
...  
Keyword(s):  
Body Mass ◽  
Nutrient Intake ◽  
Glycemic Load ◽  
Real Life ◽  
Plasma Osmolality ◽  
Urine Specific Gravity ◽  
Body Mass Change ◽  
Urine Color ◽  
Before And After ◽  
The Impact

We investigated the impact of nutrient intake on hydration biomarkers in cyclists before and after a 161 km ride, including one hour after a 650 mL water bolus consumed post-ride. To control for multicollinearity, we chose a clustering-based, machine learning statistical approach. Five hydration biomarkers (urine color, urine specific gravity, plasma osmolality, plasma copeptin, and body mass change) were configured as raw- and percent change. Linear regressions were used to test for associations between hydration markers and eight predictor terms derived from 19 nutrients merged into a reduced-dimensionality dataset through serial k-means clustering. Most predictor groups showed significant association with at least one hydration biomarker: (1) Glycemic Load + Carbohydrates + Sodium, (2) Protein + Fat + Zinc, (3) Magnesium + Calcium, (4) Pinitol, (5) Caffeine, (6) Fiber + Betaine, and (7) Water; potassium + three polyols, and mannitol + sorbitol showed no significant associations with any hydration biomarker. All five hydration biomarkers were associated with at least one nutrient predictor in at least one configuration. We conclude that in a real-life scenario, some nutrients may serve as mediators of body water, and urine-specific hydration biomarkers may be more responsive to nutrient intake than measures derived from plasma or body mass.

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

2013 ◽  
Vol 38 (6) ◽  
pp. 621-625 ◽  
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.

scholarly journals Adaptation and Validation of the Hydration Status Questionnaire in a Spanish Adolescent-Young Population: A Cross Sectional Study

Nutrients ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 565 ◽  
Author(s):  
Ana Isabel Laja García ◽  
Maria de Lourdes Samaniego-Vaesken ◽  
Teresa Partearroyo ◽  
Gregorio Varela-Moreiras
Keyword(s):  
Specific Gravity ◽  
Water Intake ◽  
Total Body Water ◽  
Body Water ◽  
Urine Specific Gravity ◽  
Hydration Status ◽  
Young Population ◽  
Dietary Record ◽  
Adequate Hydration ◽  
Total Body

The achievement of adequate hydration status is essential for mental and physical performance and for health in general, especially in children and adolescents. Nevertheless, little is known about hydration status of this population, mainly due to the limited availability of research tools; thus, the objective of the current study was to adapt and validate our hydration status questionnaire in a Spanish adolescent-young population. The questionnaire was validated against important hydration markers: urine colour, urine specific gravity, haemoglobin, haematocrit and total body water and involved 128 subjects aged between 12–17 years. Water intake was also estimated through a three-day dietary record and physical activity was assessed through accelerometers. Participants completed the questionnaire twice. Water balance and water intake were correlated with urine specific gravity and with total body water content. Water intake obtained by the questionnaire was correlated with results from the three-day dietary record. The intraclass correlation coefficient indicated moderate concordance between both recordings and the Cronbach’s alpha revealed high consistency. The Bland and Altman method indicated that the limits of agreement were acceptable to reveal the reliability of the estimated measures. In conclusion, this is the first time that a questionnaire is valid and reliable to estimate hydration status of adolescent-young populations.

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