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00005768-200403000-0002200005768_2004_36_510_bartok_dehydration_3miscellaneous-article< 117_0_12_18 >Medicine & Science in Sports & Exercise©2004The American College of Sports MedicineVolume 36(3)March 2004pp 510-517Hydration Testing in Collegiate Wrestlers Undergoing Hypertonic Dehydration[APPLIED SCIENCES: Physical Fitness and Performance]BARTOK, CYNTHIA1; SCHOELLER, DALE A.1; SULLIVAN, JUDE C.2; CLARK, R. RANDALL2; LANDRY, GREGORY L.21Department of Nutritional Sciences, University of Wisconsin, Madison, WI; and2U.W. Health Sports Medicine Center, University of Wisconsin, Madison, WIAddress for correspondence: Cynthia Bartok, 2 Hidden Ledge Dr., Conway, MA 01341; E-mail: for publication April 2003.Accepted for publication November 2003.ABSTRACTBARTOK, C., D. A. SCHOELLER, J. C. SULLIVAN, R. R. CLARK, and G. L. LANDRY. Hydration Testing in Collegiate Wrestlers Undergoing Hypertonic Dehydration. Med. Sci. Sports Exerc., Vol. 36, No. 3, pp. 510–517, 2004. Because dehydration (DEH) violates assumptions used in the assessment of body composition, hydration testing has become an integral part of minimal weight (MW) assessment.Purpose: To determine the accuracy of hydration tests for the detection and quantification of hypertonic DEH.Methods: 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.Results: 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.Conclusion: 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.Over 250,000 high school and college athletes participate in the sport of wrestling each year in the United States (15,18). To minimize unhealthy weight reduction practices, several states have implemented minimal weight (MW) programs (8), and the National Federation of State High School Associations has recommended all states have MW programs in place by 2004 (17). In addition, the National Collegiate Athletic Association implemented a MW program regulating collegiate wrestling in 1998 (16). It has recently become clear that some wrestlers arrive for MW testing in a dehydrated state to secure a lower predicted MW. For example, unannounced reweighing of wrestlers within days of MW testing showed that almost 25% had gained more than 1.4 kg (3 lb), with a maximum weight gain of 8.2 kg (18 lb) (8). In response to this problem, the NCAA and many state associations have included hydration testing in the MW testing protocol.Hydration testing of wrestlers is designed to ensure that athletes are in euhydration (EUH) when weighed, and that their weight is not artificially lower due to dehydration (DEH) (21). DEH violates assumptions critical to the accuracy of approved methods (e.g., skinfolds, hydrostatic weighing, and air displacement plethysmography) of MW testing (5,28). In addition, DEH directly reduces predicted MW through the use of an artificially low body weight term in the equation to predict MW at 5% body fatness (5). These effects of DEH on MW assessment could place athletes in danger of losing too much weight for a competition (21). The NCAA and some state associations use urine specific gravity (Usg) for the detection of DEH. Wrestlers must produce a urine sample with a specific gravity ≤ 1.020 immediately before assessment of MW (16,17). Athletes who test positive for DEH are required to postpone body composition testing for at least 24 h, during which time they would presumably rehydrate. Cutoff values for urine color (2), osmolality (27), conductivity (27), and specific gravity (7), and plasma osmolality (22) have been proposed. In addition, preliminary data suggest alternative tests such as urine protein and potassium (30–32) or bioimpedance analysis (20) may have some value in the detection of DEH.A potential second use of hydration testing data could be to assist with prediction of a euhydrated weight when an athlete arrives for MW testing in a dehydrated state. If the concentration of a test could accurately and precisely predict the % DEH by weight (% weight loss), the athlete’s weight in EUH could be predicted from the combination of hydration testing data and their weight in DEH. For a hydration test to be used in this way, it would need to vary predictably with % DEH by weight and have low interindividual variation. Ideally, this test would be field-ready: accurate, inexpensive to analyze, and fairly noninvasive for athletes. Previous research has demonstrated that urine conductance (27), color (1), specific gravity (22), and osmolality (22) increase in relation to progressive hypertonic DEH. Investigations of the sensitivity of blood-borne indices to progressive hypertonic DEH have produced conflicting results (1,3,9,22).The purpose of this study was to determine the accuracy of hydration tests for the simple detection of DEH and for the quantification of the extent of DEH. The hydration tests included urine protein, osmolality, specific gravity, and potassium; plasma osmolality, sodium, potassium, chloride, and arginine vasopressin; urine:plasma ratio of osmolality; and the ratio of extracellular water (ECW) to intracellular water (ICW) as predicted by the Xitron Hydra 4200 multifrequency bioelectrical impedance spectroscopy (BIS) machine. We hypothesized that meaningful (>85% sensitivity and specificity) cutoff values could be defined to adequately detect DEH. We also hypothesized that the urine and blood hydration tests would vary linearly and predictably with % DEH and that the prediction of a euhydrated weight in DEH would be improved with the addition of a hydration test.METHODSSubjects.Twenty-five healthy male volunteers were recruited for the protocol. The subject pool consisted of collegiate wrestlers (18–23 yr) who represented all major weight classes of wrestling. The subjects’ descriptive data are summarized in Table 1.TABLE 1. Characteristics of subjects (N = 25).Protocol.The protocol was approved by the Human Subjects Committee of the University of Wisconsin and was in conformance with the human experimentation policy statement of the American College of Sports Medicine. Before participation, all subjects provided written informed consent. Subjects reported to the General Clinical Research Center of the University of Wisconsin Hospital and Clinics at 1700 h of day 1 of the protocol. The preparticipation protocol encouraged light exercise and consumption of adequate food and fluids on the day of admission. At approximately 1800 h, subjects consumed a regular research diet (evening meal) and a minimum of 30 mL·kg−1 bottled water to ensure they were euhydrated by morning. The research diet and water consumed contained (mean ± SD): 798 ± 101 kcal, 31 ± 4 g protein, 28 ± 4 g fat, 115 ± 14 g carbohydrate, 1456 ± 196 mg sodium, 1602 ± 199 mg potassium, and 2720 ± 518 g water. Subjects fasted (no food or beverage) after 2200 h and did not receive food or beverage until 1215 h the following day. To ensure adequate hydration during the 14-h span between fasting and EUH measurements, subjects were confined to the hospital unit (20°C, 40% relative humidity), remained under observation by nursing staff, were instructed to sleep for 8–10 h, and were not allowed to exercise.During the morning of day 2 of the protocol, subjects underwent four-component body composition testing in EUH for a substudy (5). At 1100 h, subjects emptied their bladder so that they could produce a 1-h spot urine sample at 1200 h. At 1200 h, the EUH time point, the spot urine sample was collected, blood samples were taken for hydration analysis by the hospital laboratory, BIS measurements were made, and weight was measured. At 1215 h, subjects received two to four Boost Bars (Mead Johnson Nutritionals, Evansville, IN), depending on their estimated calorie needs and 120 mL water. The average intake from the bars and water was (mean ± SD): 509 ± 131 kcal, 11 ± 3 g protein, 19 ± 5 g fat, 78 ± 20 g carbohydrate, 241 ± 62 mg sodium, 281 ± 72 mg potassium, 0 mg chloride, and 128 ± 2 g water. After the snack, subjects were moved to a hot room (32°C, 25% relative humidity) and instructed to exercise and/or rest as desired to lose weight. Six wrestlers were randomly assigned to each dehydration level (2, 3, 4, or 5%) and were instructed on the weight loss necessary to achieve this dehydration level. The goal weight was listed on nursing flow sheets and nurses monitored weight loss, vital signs, and exercise time throughout the exercise session to ensure subjects stopped exercising when they achieved their assigned weights. In a few cases, subjects were unable to reach assigned levels due to exhaustion, so their participation was terminated early. Upon achievement of weight reduction, subjects emptied their bladder. They were moved to a cool room (20°C) for 1 h during which time they took a cool shower and rested. No food or beverages were allowed. Exactly 1 h after being moved from the hot room, a spot urine sample was collected, blood samples were taken for hydration analysis by the hospital laboratory, BIS measurements were made, and weight was measured (DEH time point).Criteria measures for quantifying dehydration.At the start of the study, height was measured to the nearest millimeter using a stadiometer. At each study time point, weight was measured to the nearest 0.05 kg using a calibrated digital scale. Weight change during EUH and DEH phases of the study was calculated by measuring subjects without shoes and in the same minimal, dry clothing at the beginning and end of the study phase. Percent DEH by weight (% DEH WT) was calculated as:EQUATIONEquation U1where WTEUHend = weight (kg) at the end of the EUH phase, WT DEHend = weight (kg) at end of DEH phase, solidsIN = intake (kg) in solids from nutritional bars, and solidsOUT = solids lost via respiration estimated as 1 g·min−1 exercise (14).Total body water (TBW) and extracellular water (ECW) volumes were measured using deuterium and bromide dilution techniques described by Schoeller et al. (24,25) and Miller et al. (12,13). In brief, subjects had baseline blood samples collected for deuterium and bromide analysis at 0800 on day 2 of the protocol. Subjects were then dosed with 40 g of 10% deuterium solution and 10 mg·kg−1 NaBr. Postdose blood samples were collected at the end of EUH and DEH study phases. TBW was quantified using the deuterium dilution, isotope ratio mass spectrometry technique and equations of Schoeller (24). Corrections were made for lost dosage of deuterium in urine, sweat, breath vapor, as well as nonaqueous hydrogen exchange (14,26,29). ECW was quantified using the anion exchange high-pressure chromatography technique and equations of Miller et al. (12,13), except that we added a correction of 0.987 for the concentration of water in serum ultrafiltrate (4). Corrections were made for lost dosage of bromide in urine and sweat (5). Intracellular water (ICW) was calculated as the difference between TBW and ECW volumes. Percent DEH by TBW (% DEH TBW) was calculated as:EQUATIONEquation U2where TBWEUH = measured TBW (kg) at end of EUH phase and TBWDEH = TBW (kg) at end of DEH phase.Blood and urine tests.MultistixTM 10 dipsticks (Miles Diagnostics, Elkhart, IN) were used to assess specific gravity (Usg-dip) and urine protein content. Dipsticks were inserted into EUH and DEH 1-h spot samples and read according to manufacturer’s directions. Usg was read independently by the investigator and staff nurse. When there was a discrepancy, the values were averaged. Per NCAA and WWMWP standards, a Usg > 1.020 was considered dehydrated (16,17). Urine protein was read independently by the investigator and staff nurse, and no discrepancies occurred. Detectable content of protein included trace, 1+, 2+, or 3+.The University of Wisconsin Hospital Clinical Laboratories completed all remaining blood and urine tests. An IRIS 900 UDEX automated urinalysis system (International Remote Imaging Systems, Chatsworth, CA) was used to test for urine specific gravity (USG-IRIS) by the harmonic oscillation densitometry method. A freezing point osmometer was used to measure the osmolality (Osm) of serum and urine samples. Urine potassium, and plasma sodium, potassium, and chloride were measured using ion specific electrodes. Plasma arginine vasopressin was assessed by radioimmunoassay. Subjects were seated during phlebotomy measurements at the EUH and DEH time points. The duration of this posture varied between 1 and 10 min.Bioelectrical impedance spectroscopy analysis.A Xitron Hydra 4200 BIS analyzer with Cole-Cole modeling software was used to estimate TBW, ECW, and ICW in subjects. Four electrodes were placed in the proximal (elbow/knee) position for the measurement of resistance and reactance (23). The output variables of the Cole-Cole analysis included resistance of extracellular fluid (Re) and resistance of the intracellular fluid (Ri) in ohms. TBW, ECW, and ICW were calculated using previously published proximal technique equations for the general adult population (10):EQUATIONEquation U3where Ht = height in cm.Statistics.Data are presented as mean ± standard deviation unless otherwise noted. Paired two-tailed t-tests were used to test for significant differences between EUH and DEH time points. To address our first hypothesis, MedCalc software (v., MedCalc, Belgium) was used to complete sensitivity (true positive rate), specificity (true negative rate), and Receiver Operating Characteristic (ROC) analysis. ROC analysis included the following four steps (33). First, a ROC curve was constructed by plotting sensitivity versus specificity for the spectrum of cutoff values. Second, the area under the ROC curve was calculated. The area under the curve corresponds to the proportion of time that a randomly selected laboratory value from DEH would be larger than a randomly selected laboratory value from EUH. Third, the 95% confidence interval for the area under the ROC curve was calculated. An interval that does not include 0.5 suggests the ability of the laboratory test to distinguish between EUH and DEH. Finally, the criterion value, the laboratory value associated with the lowest false positive and false negative results, was calculated. Minimum recommended sample sizes for ROC analysis are typically 50–100 (11). To address our second hypothesis, plots of DEH indices versus % DEH were constructed and visually inspected for linearity. If a linear relationship existed, linear regression analysis was completed and best-fit lines, SEE, and correlation coefficients were calculated. For all analyses, a P value less than 0.05 was considered significant.RESULTSAll 25 subjects completed the protocol activities without difficulty. BIS data are missing for one subject due to machine malfunction during the EUH time point. One faulty data point for arginine vasopressin in EUH was discarded. Due to a national shortage of SG-10 type dipsticks, specific gravity was unavailable for two subjects and protein was unavailable for four subjects.Baseline data for the entire subject pool, including % body fat, MW, % DEH WT, and % DEH TBW are presented in Table 1. Subjects lost between 1.9 and 5.2% of body weight (average = 3.2%), and between 2.4 and 7.3% (average = 4.3%) of TBW. The % DEH TBW was significantly larger (P < 0.001) than the % DEH WT. According to dilution techniques, DEH resulted in a loss of 2.20 ± 0.79 kg TBW, 1.13 ± 1.1 kg ECW, and 1.09 ± 1.3 kg ICW (all P < 0.001). This corresponds to an average 6.6% decrease in ECW and 3.2% decrease in ICW.Table 2 shows the means and standard deviations for the hydration tests in EUH and DEH. All urine and plasma analytes except for plasma potassium significantly increased from EUH to DEH. BIS ECW:ICW ratio significantly decreased from 55.6% to 51.1% with DEH. The ECW:ICW ratio as determined by dilution techniques significantly decreased from 55.3% to 53.2%.TABLE 2. Hydration tests in euhydration (EUH) and dehydration (DEH).Figure 1 depicts the percentage of subjects correctly classified by IRIS (panel A) and dipstick (panel B) methods at three possible cutoff Usg concentrations. At a Usg cutoff of 1.020 g·mL−1, the current cutoff concentration used by the NCAA and several state associations, the sensitivity and specificity were both 96% for the IRIS technique, and the sensitivity was 87% and specificity 91% for the dipstick technique.FIGURE 1— A. Percent of subjects testing positive for dehydration at three cutoff Usg concentrations using the IRIS harmonic oscillation method (N = 25) or (B) Multistix-10TM dipsticks (N = 23) in known euhydration (EUH) and dehydration (DEH).Table 3 depicts the ROC analysis results for continuous-type hydration tests. For all tests except plasma potassium, the area under curve did not include 0.5. The criterion value, which is the cutoff value associated with the lowest false positive and false negative results, as well as the sensitivity and specificity of the criterion value, is shown for the various hydration tests.TABLE 3. Receiver operating characteristic (ROC) curve analysis for hydration tests.The percentage of subjects with detectable and undetectable protein in their urine was assessed using the urinary dipstick technique. In EUH, only one subject (5%) had detectable levels of protein (trace) in the urine. In DEH, 100% of subjects had detectable proteinuria (57% trace, 14% 1+ proteinuria, and 29% 2+ proteinuria).Table 4 depicts the regression analyses completed to determine relationships between various indices of hydration in DEH and the % DEH achieved by subjects assessed on the basis of weight change and TBW change. Significant correlations were observed between % DEH WT and urine osmolality, plasma sodium, and urine:plasma osmolality. No significant correlations were found between hydration indices and % DEH TBW. Figures 2–11 display the relationship between hydration tests in DEH and the % DEH by weight.TABLE 4. Correlation between hydration tests and % DEH.FIGURE 2— Relationship between urine osmolality and percent dehydration by weight in DEH.FIGURE 3— Relationship between urine specific gravity by harmonic oscillation and percent dehydration by weight in DEH.FIGURE 4— Relationship between urine potassium concentration and percent dehydration by weight in DEH.FIGURE 5— Relationship between plasma osmolality and percent dehydration by weight in DEH.FIGURE 6— Relationship between plasma sodium concentration and percent dehydration by weight in DEH.FIGURE 7— Relationship between plasma potassium concentration and percent dehydration by weight in DEH.FIGURE 8— Relationship between plasma chloride concentration and percent dehydration by weight in DEH.FIGURE 9—- Relationship between plasma arginine vasopressin (AVP) concentration and percent dehydration by weight in DEH.FIGURE 10— Relationship between the ratio of urine:plasma osmolality and percent dehydration by weight in DEH.FIGURE 11— Relationship between the ratio of extracellular water:intracellular water (ECW:ICW) by bioelectrical impedance spectroscopy and percent dehydration by weight in DEH.DISCUSSIONThis study evaluated hydration testing techniques for the purpose of detection of hypertonic DEH as well as the estimation of severity of DEH. The hydration techniques tested included urine protein, osmolality, specific gravity (by IRIS harmonic oscillation and dipstick techniques), and potassium; plasma osmolality, sodium, potassium, chloride, and arginine vasopressin; urine:plasma ratio of osmolality; and ECW:ICW ratio assessed by BIS. These techniques were tested under well-controlled conditions of euhydration (EUH) and acute, hypertonic DEH induced by fluid restriction and exercise in a hot environment.The EUH urine and plasma values (Table 2) suggest that our protocol provided adequate hydration and environmental conditions for subjects to achieve a euhydrated state. For example, previous research has documented that euhydrated plasma osmolality ranges from 284 to 289 mOsm·L−1, euhydrated Usg ranges from 1.009 to 1.023 g·mL−1, and euhydrated urine osmolality ranges from 325 to 858 mOsm·L−1 (1–3,22).In addition, data suggest that our DEH intervention achieved the desired goals. Subjects achieved significant losses in body weight, ECW, ICW, and TBW. In addition, signs of hypertonic DEH (21), including significant increases in plasma osmolality, sodium, and chloride, urine osmolality, and specific gravity, were seen in the subject pool. The increases in urine and plasma analyte concentrations are consistent with a recent study documenting increases in urine osmolality to 643 mOsm·L−1, Usg to 1.024 g·mL−1, and plasma osmolality to 305 mOsm·L−1 with progressive DEH to 5% of body weight (22).Sensitivity (true positive rate) and specificity (true negative rate) data from the ROC analysis (Table 3 and Fig. 1) suggest which cutoff values may be most useful in hydration testing of wrestlers. The data from these analyses support the use of a Usg cutoff of 1.020 g·mL−1. First, the highest sensitivity (96%) and specificity (100%) for the IRIS data is seen when the Usg ≤ 1.024 g·mL−1 is used. However, because many MW testing sites utilize dipsticks, which are read in 0.005 increments, we must choose between cutoff values of 1.020 and 1.025 g·mL−1. Raising the cutoff to 1.025 g·mL−1 reduces the sensitivity to 68% while keeping the specificity at 100%. Lowering the cutoff to 1.020 g·mL−1 keeps the sensitivity at 96% and lowers the specificity to 96%, which are very acceptable values. When using dipstick data, a cutoff value of 1.025 g·mL−1 (83% sensitivity, 100% specificity) was recommended by ROC analysis over the cutoff of 1.020 g·mL−1 (87% sensitivity, 91% specificity). ROC analysis equally values both sensitivity and specificity in determining a cutoff. Although this approach is useful in many settings, MW hydration testing places a higher value on detecting athletes that are dehydrated (sensitivity) than occasionally misclassifying a euhydrated wrestler as dehydrated (specificity). This is simply because the penalty for poor sensitivity may be assigning a low MW to a wrestler, whereas the penalty for poor specificity is returning for MW retesting at a later time. With this in mind, the increase in sensitivity and decrease in specificity when going from dipstick technique Usg of 1.025 to 1.020 g·mL−1 is warranted.The ROC analysis of other urine, blood, and BIS tests suggests that the vast majority of hydration tests may be useful as screening tools. All tests but plasma potassium and chloride had AUC values greater than 0.85. In cases where the AUC values were ≥ 0.90, 90% of the time a randomly selected DEH value would exceed a randomly selected EUH value. This is particularly promising given that the extent of DEH used in this study ranged from mild to moderate. In addition, in the cases of Usg, urine potassium, plasma osmolality, and plasma sodium, cutoff values with sensitivities and specificities exceeding 80% were found. Although these results are promising, they should be interpreted with caution. Minimum recommended sample sizes for ROC analysis are typically 50–100 (11). Thus, we recommend that these preliminary results only guide future studies of hydration tests.Previous studies of wrestlers at competition weigh-in time (31,32) have found alarmingly high rates (76–82%) of urine protein (proteinuria). It was not clear from these studies whether these wrestlers had chronic proteinuria or whether it was a transient condition due to making weight for competition. The data from the current study suggest that proteinuria is not typically found in euhydrated wrestlers but rather that acute, hypertonic DEH may significantly increase protein content of the urine. Because there were several interventions in the study (dehydration, exercise, heat stress, and food restriction), and because both exercise and DEH may cause proteinuria (6), we cannot ascertain the reason for this phenomenon. Future studies should be aimed at determining the reason urine protein is detected under these conditions.Data from BIS and dilution analyses suggest that the subject pool experienced preferential DEH of the ECW over ICW. This phenomenon has been seen with exercise in the heat before (19). For this small, exploratory subject pool, BIS and dilution data suggest a decrease in ECW:ICW from 55% to 51% is associated with acute, hypertonic DEH. ROC analysis suggested a cutoff of 53.3% would have a sensitivity of 83% and a specificity of 88%. Unfortunately, to achieve a sensitivity of over 90% the cutoff would have to be raised significantly (to 55.8%) and the specificity would drop to 42%. Given our sample size, more research is warranted to explore the potential of this minimally invasive, easy to operate hydration testing device.Our second hypothesis was that urine and blood hydration tests would vary linearly and predictably with % DEH. We had hoped to find a DEH index that would correlate highly enough with % DEH WT or % DEH TBW to be able to predict a euhydrated weight or TBW from a dehydrated weight or TBW. Unfortunately, the correlations between the various urine, blood, and BIS tests and % DEH WT or % DEH TBW were too poor to accurately predict EUH weight or TBW. Only urine osmolality, plasma sodium, and urine:plasma osmolality had moderate, significant correlations with % DEH WT. In addition, urine specific gravity and urine osmolality showed negative associations with % DEH. We believe that this is simply a matter of interindividual variation. When subjects serve as their own control (22), the data clearly show that with increasing dehydration, the group average for both urine specific gravity and osmolality increase. In the present study, all 25 subjects showed an increased urine specific gravity with DEH. For urine osmolality, 24 of 25 showed increases with DEH. Thus, subjects showed an expected response to the treatment. However, because each subject’s baseline (EUH) was so variable, the extent of dehydration could not be accurately predicted from a simple cross-sectional spot sample. In addition, the tests were more related to % DEH WT than % DEH TBW, despite the obvious direct effects of DEH on body water content. This is likely an artifact due to the error involved in detecting within-day losses of TBW by the dilution technique. Previous research from our laboratory has shown that random measurement error is greater for the measurement of within-day changes in water by dilution than the within-day changes in body weight (10).In conclusion, hypertonic DEH produced significant increases in most plasma, urine, and BIS hydration tests, and potential cutoff values could be established for many hydration tests. Our data suggest that a Usg cutoff value of 1.020 g·mL−1 optimally detects acute hypertonic DEH with minimal false positives. 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RANDALL; LANDRY, GREGORY L.APPLIED SCIENCES: Physical Fitness and Performance336InternalMedicine & Science in Sports & Exercise20053761061-1068JUN 2005Is Leg-to-Leg BIA Valid for Predicting Minimum Weight in Wrestlers?CLARK, RR; BARTOK, C; SULLIVAN, JC; SCHOELLER, DA & Science in Sports & Exercise10.1249/mss.0b013e31802ca5972007392377-390FEB 2007Exercise and Fluid Replacement