Hydration Testing in Collegiate Wrestlers Undergoing Hypertonic Dehydration

Department of Nutritional Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
Medicine &amp Science in Sports &amp Exercise (Impact Factor: 3.98). 04/2004; 36(3):510-7. DOI: 10.1249/01.MSS.0000117164.25986.F6
Source: PubMed

ABSTRACT Because dehydration (DEH) violates assumptions used in the assessment of body composition, hydration testing has become an integral part of minimal weight (MW) assessment.
To determine the accuracy of hydration tests for the detection and quantification of hypertonic DEH.
Twenty-five male collegiate wrestlers (mean +/- SD, age: 20.0 +/- 1.4 yr, height: 175.0 +/- 7.1 cm, body mass: 81.7 +/- 15.3 kg) had their hydration assessed under well-controlled conditions of euhydration (EUH) and DEH. The DEH phase occurred on the same day as EUH, after subjects acutely dehydrated 2-6% of body weight through fluid/food restriction and exercise in a hot environment.
All hydration tests except plasma potassium significantly increased from EUH to DEH, and meaningful cutoff values could be established for most tests. Cutoff values for urine tests were 586 mOsm.L(-1) for osmolality and 71 mEq.L(-1) for potassium. Plasma cutoff values were 293 mOsm.L(-1) for osmolality, 140 mEq.L(-1) for sodium, 103 mEq.L(-1) for chloride, and 3.5 pg.mL(-1) for arginine vasopressin. For ratio tests, a urine:plasma osmolality of 2.06 and an extracellular:intracellular water of 0.533 measured by the bioelectrical impedance spectroscopy were cutoff values. For urine specific gravity, a cutoff value of 1.020 g.mL(-1) had a sensitivity and specificity of 96% each for the automated harmonic oscillation technique and 87% and 91% (respectively) for the dipstick technique. Protein (by dipstick) was detected in 5% of subjects in EUH, and 100% of subjects in DEH. Correlations between hydration tests and dehydration were only low to moderate.
This study supports a specific gravity cutoff of 1.020 g.mL(-1) for the identification of hypertonic DEH. Future research should test the cutoff values established in this study and explore the relationship between DEH and urine protein.

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    • "However, both BM and USG showed a small mean reduction from pre-to post-training across the three sessions . There was a large inter-individual variation in fluid intake, BM loss, and USG changes, again in line with other findings (Bartok et al., 2004; Cheuvront et al., 2010). Participants in this study were not required to complete a standardised pre-exercise fluid intake strategy, and fluid was consumed in an unstructured fashion during training. "
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    ABSTRACT: The objective of the study was to investigate the hydration status and fluid balance of elite European youth soccer players during three consecutive training sessions. Fourteen males (age 16.9 ± 0.8 years, height 1.79 ± 0.06 m, body mass (BM) 70.6 ± 5.0 kg) had their hydration status assessed from first morning urine samples (baseline) and pre-and post-training using urine specific gravity (USG) measures, and their fluid balance calculated from pre- to post-training BM change, corrected for fluid intake and urine output. Most participants were hypohydrated upon waking (USG >1.020; 77% on days 1 and 3, and 62% on day 2). There was no significant difference between first morning and pre-training USG (p = 0.11) and no influence of training session (p = 0.34) or time (pre- vs. post-training; p = 0.16) on USG. Significant BM loss occurred in sessions 1-3 (0.69 ± 0.22, 0.42 ± 0.25, and 0.38 ± 0.30 kg respectively, p < 0.05). Mean fluid intake in sessions 1-3 was 425 ± 185, 355 ± 161, and 247 ± 157 ml, respectively (p < 0.05). Participants replaced on average 71.3 ± 64.1% (range 0-363.6%) of fluid losses across the three sessions. Body mass loss, fluid intake, and USG measures showed large inter-individual variation. Elite young European soccer players likely wake and present for training hypohydrat-ed, when a USG threshold of 1.020 is applied. When training in a cool environment with ad libitum access to fluid, replacing ∼71% of sweat losses results in minimal hypohydration (<1% BM). Consumption of fluid ad libitum throughout training appears to prevent excessive (≥2% BM) dehydration, as advised by current fluid intake guidelines. Current fluid intake guidelines appear applicable for elite European youth soccer players training in a cool environment.
    Journal of sports science & medicine 12/2014; 13(4). · 1.03 Impact Factor
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    • "The NATA associates minimal dehydration (1% to 3% of weight) with straw-colored urine and SpG of 1.010 to 1.020 [29]. Popowski et al. [31] monitored urine osmolality and SpG progressively as subjects dehydrated from baseline to 5% body weight. "
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    ABSTRACT: Typical emergency department (ED) shifts are physically demanding. The aim of this study was to assess the hydration status of ED physicians and nurses by the end of their shifts. A prospective cross-sectional clinical study of ED physicians and nurses assessing fluid intake, activities, vital signs, weight, urine specific gravity and ketones at the end of the shift. Forty-three participants were tested over 172 shifts distributed over 48% in the morning, 20% in the evening and 32% at night. Fifty-eight percent were females, and 51% were physicians. Overall, participants lost 0.3% of their body weight by the end of the shift. While physicians lost a mean of 0.57 kg (+/- SD 0.28; P < 0.0001, 95% CI 0.16-0.28), nurses lost 0.12 kg (+/- SD 0.25; P < 0.0001, 95% CI 0.07-1.7). While nurses drank more fluid (P < 0.0001), physicians had a higher specific gravity of 1.025 (P < 0.01), visited the washroom less often (P <0.0001) and reported less workload and stress (P = 0.01 and 0.008, respectively). There were no major changes in vital signs or urinary ketones (OR.0.41, 95% CI 0.1-2.1). In a multivariate analysis, being male (OR 13.5, 95% CI 1.6-112.5), being of younger age (OR 4.1, 95% CI 1.7-10.2), being Middle Eastern (OR 5.3, 95% CI 1.1-26.2), working the morning shift (OR 2.7, 95% CI 0.7-10.5) and having less fluid intake (OR 5.7, 95% CI 1.2- 26.6) were significant predictors of decreased hydration. The majority of physicians and to a lesser extent nurses working in a tertiary care emergency department have decreased hydration status at the end of the shift. Therefore, awareness of the hydration status by emergency department staff is needed. A further study in a similar setting with more subjects and a better balance among the variables is recommended.
    International Journal of Emergency Medicine 07/2013; 6(1):27. DOI:10.1186/1865-1380-6-27
    • "Our data suggest that to regain specificity, a higher U sg cut-off point to detect hypohydration (i.e., [1.020) should be proposed in athletes with large muscle mass. An increase in U sg cut-off point has already been suggested by other authors (Bartok et al. 2004). Previous studies have compared U sg to plasma osmolality to test U sg specificity. "
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    ABSTRACT: To determine if athletes' muscle mass affects the usefulness of urine specific gravity (U(sg)) as a hydration index. Nine rugby players and nine endurance runners differing in the amount of muscle mass (42 +/- 6 vs. 32 +/- 3 kg, respectively; P = 0.0002) were recruited. At waking during six consecutive days, urine was collected for U (sg) analysis, urine osmolality (U(osm)), electrolytes (U[Na+], U[K+] and U[Cl-]) and protein metabolites (U([Creatinine]), U([Urea]) and U([Uric acid])) concentrations. In addition, fasting blood serum osmolality (S(osm)) was measured on the sixth day. As averaged during 6 days, U(sg) (1.021 +/- 0.002 vs. 1.016 +/- 0.001), U(osm) (702 +/- 56 vs. 554 +/- 41 mOsmol kg(-1) H(2)O), U([Urea]) (405 +/- 36 vs. 302 +/- 23 mmol L(-1)) and U([Uric acid]) (2.7 +/- 0.3 vs. 1.7 +/- 0.2 mmol L(-1)) were higher in rugby players than runners (P < 0.05). However, urine electrolyte concentrations were not different between groups. A higher percentage of rugby players than runners (56 vs. 11%; P = 0.03) could be cataloged as hypohydrated by U(sg) (i.e., >1.020) despite S (osm) being below 290 mOsmol kg(-1) H(2)O in all participants. A positive correlation was found between muscle mass and urine protein metabolites (r = 0.47; P = 0.04) and between urine protein metabolites and U(sg) (r = 0.92; P < 0.0001). In summary, U(sg) specificity to detect hypohydration was reduced in athletes with large muscle mass. Our data suggest that athletes with large muscle mass (i.e., rugby players) are prone to be incorrectly classified as hypohydrated based on U(sg).
    Arbeitsphysiologie 05/2010; 109(2):213-9. DOI:10.1007/s00421-009-1333-x · 2.19 Impact Factor
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Dale A Schoeller