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The purpose of this study was to evaluate the response of urine specific gravity (Usg) and urine osmolality (Uosm) when compared to plasma osmolality (Posm) from euhydration to 3% dehydration and then a 2-hr rehydration period in male and female collegiate athletes. Fifty-six National Collegiate Athletic Association (NCAA) wrestlers (mean ± SEM); h...
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... In practice, the same hydration assessment methods and cutoffs are commonly used for both males and females, even though there may be dissimilarities to consider Sommerfield et al., 2016). Research has shown that males can have up to ∼10% greater total body water (TBW) than females (Langan-Evans et al., 2022) due to lean body mass (BM) and fat mass differences (Matias et al., 2013). ...
... Consequently, females may have a lower absolute capacity for fluid loss than males, which could result in a sex-specific biomarker response (Wickham et al., 2021). Sommerfield et al. reported greater USG and Uosm in males but found similar Posm between sexes at baseline (Sommerfield et al., 2016). Although informative, this study has some limitations, such as comparing male wrestlers with female soccer players and not controlling for BML when comparing biomarkers (Sommerfield et al., 2016). ...
... Sommerfield et al. reported greater USG and Uosm in males but found similar Posm between sexes at baseline (Sommerfield et al., 2016). Although informative, this study has some limitations, such as comparing male wrestlers with female soccer players and not controlling for BML when comparing biomarkers (Sommerfield et al., 2016). ...
This study investigated (a) differences between males and females for changes in serum, tear, and urine osmolality, hematocrit, and urine specific gravity following acute passive dehydration and (b) assessed the reliability of these biomarkers separately for each sex. Fifteen males (age: 26.3 ± 3.5 years, body mass: 76 ± 7 kg) and 15 females (age: 28.8 ± 6.4 years, body mass: 63 ± 7 kg) completed a sauna protocol twice (5-28 days apart), aiming for 4% body mass loss (BML). Urine, blood, and tear markers were collected pre-and postdehydration, and change scores were calculated. Male BML was significantly greater than that of females in Trial 1 (3.53% ± 0.55% vs. 2.53% ± 0.43%, p < .001) and Trial 2 (3.36% ± 0.66% vs. 2.53% ± 0.44%, p = .01). Despite significant differences in BML, change in hematocrit was the only change marker that displayed a significant difference in Trial 1 (males: 3% ± 1%, females: 2% ± 1%, p = .004) and Trial 2 (males: 3% ± 1%, females: 1% ± 1%, p = .008). Regression analysis showed a significant effect for sex (male) predicting change in hematocrit (β = 0.8, p = .032) and change in serum osmolality (β = −3.3, p = .005) when controlling for BML but not for urinary or tear measures. The intraclass correlation coefficients for females (ICC 2, 1) were highest for change in urine specific gravity (ICC = .62, p = .006) and lowest for change in tear osmolarity (ICC = −.14, p = .689), whereas for males, it was posthematocrit (ICC = .65, p = .003) and post tear osmolarity (ICC = .18, p = .256). Generally, biomarkers showed lower test-retest reliability in males compared with females but, overall, were classified as poor-moderate in both sexes. These findings suggest that the response and reliability of hydration biomarkers are sex specific and highlight the importance of accounting for BML differences.
... For Usg, a dichotomized variable was created to classify participants as either hydrated (< 1.020) or dehydrated (> 1.020). 4,28 Repeated-measures analysis of variance (ANOVA) was used to evaluate differences in the various urine markers between the two interventions over time. In order to determine the relationship between body composition and water intake, researchers created a dichotomized variable to classify participants as either obese (BMI > 30 kg/m 2 ) or normal-to-overweight (BMI 18.5 to 29.9 kg/m 2 ), and conducted correlations between Ucol and BMI at baseline, 5 weeks, and follow-up. ...
... Based on the established cut-off and frequencies for Usg, 45% (n = 10) of participants were classified as dehydrated. 4,28 At baseline, there was no association between Usg and Ucol in classifying hydration (r = -0.23, p = 0.31). ...
... Based on the established cut-off of Usg < 1.020 for a classification of hydrated, participants who met this criterion consumed an average daily intake of at least 65.79 ounces of water, which corroborates the recommended minimum intake of 64 ounces for adequate hydration by the Mayo Clinic. 6,28 Participants with increased water intake from baseline selfreported improvements in energy level, sleep quality, memory/ability to concentrate, and regular bowel movements. However, only the cognitive functions of memory and ability to concentrate significantly improved in the hydrated participants. ...
Introduction: This pilot study examined the effectiveness of two different 5-week reminder interventions to achieve adequate water intake and hydration in women as well as the effects of body composition and self-efficacy on hydration. Methods: Twenty-two apparently healthy adult women were randomly assigned to the 64 oz. motivational water bottle group (n = 11), or the water reminder – daily tracker app group (n = 11). Body composition, predicted VO2max, and self-efficacy were assessed at baseline, post 5-week intervention, and after a 30-day follow-up period. Urine markers (color, specific gravity, and pH) were reported at baseline, weekly throughout the 5-week intervention, and the last 3 days of the 30-day follow-up period. During the interventions, participants self-reported daily step count, resting heart rate, water intake, and symptoms of dehydration. Results: Both 5-week reminder interventions successfully increased water intake by an average of 29% with a mean daily consumption of 72.05 + 18.75 ounces, meeting recommendations. Based on regression analysis, self-efficacy predicted daily water intake at the end of the 5-week intervention (p = 0.03). Urine markers of hydration classified several participants as dehydrated at the end of 5 weeks. In addition, there was a significant inverse relationship between BMI and Ucol at baseline (p = 0.05), week 5 (p = 0.05), and follow-up (p = 0.04), indicating that women with a higher BMI were more dehydrated. In hydrated participants, memory and ability to concentrate significantly improved (p = 0.019). Results indicated there were no significant differences in water intake and hydration between the two groups at baseline, week 5, and follow-up. Conclusions: Both 5-week interventions successfully increased water intake. However, based on urine markers of hydration women may be more prone to involuntary, chronic dehydration due to a higher body fat percentage.
... USG values did not demonstrate significant differences between the moments of collection in this study. However, based on the USG it can be considered that the athletes in this study presented hypohydration at all moments (Broglio et al., 2014;Ceylan, Barley, et al., 2022;Ceylan & Balci, 2021), and these results are reliable for assessing hydration status, since there is a high association between USG measurements and urine osmolarity, including in analyses performed during the body mass loss period in wrestlers (Fernández-Elías et al., 2014;Sommerfield et al., 2016). These results are similar to previous findings with mixed martial arts athletes and Judokas, with the USG assessment demonstrating hypohydration of the fighters (Alves et al., 2018;Ceylan, Barley, et al., 2022;Ceylan & Balci, 2021). ...
Objective. To measure rapid weight loss and urinary indicators of hydration status, as well as to assess the effects and symptoms of dehydration in Brazilian jiu-jitsu (BJJ) athletes at different moments. Methods. 17 male BJJ athletes (aged: 24.4 ± 3.5 years; body mass (BM): 76.8 ± 14.6 kg; body fat: 16.6 ± 6.4%), were evaluated between 8 and 9 am at three different moments: Baseline (10 days pre- competition), measurement of BM and stature, collection of urine samples, and food record of the previous 24 hours; pre-competition, measurement of BM, urine samples, and questionnaire to assess rapid weight loss (RWL), and post-competition (24h after), day after competition, with measurement of BM, and urine samples for analysis of specific gravity. Results. There was a tendency to decrease BM to compete (baseline: 76.8 ± 14.6 kg, pre-competition: 75.4 ± 13.4 kg, post-competition: 77.3 ± 13.7 kg; p < 0.07), with 88.2% of athletes using methods that increase dehydration. The majority of athletes were dehydrated at the three time points of the study (94.1%; USG = 1.021 ± 0.005 Usg at baseline, 88.2%; 1.020 ± 0.007 Usg at pre-competition, 88.2%; 1.022 ± 0.008 Usg on the post-competition day), accompanied by symptoms associated with RWL (82.4% increased heart rate, 52.9% headache, 47.1% hot flashes, 41.2% nausea, 41.2% disorientation, and 29.4% dizziness). Conclusions. Rapid pre-competitive weight loss and symptoms associated with dehydration were observed in the BJJ athletes. It is recommended that educational measures are promoted to inhibit RWL among BJJ athletes, requiring the engagement of health professionals and organizations that govern the sport (federations and confederations).
... Determination of urine osmolality is more important than specific gravity because it gives the most accurate measurement of total solute concentration and therefore provides the best measurement of the kidneys' concentrating ability [39]. Athletes and their trainers must use USG in conjunction with alternative measures to ensure safe weight-loss methods in weight-classified sports [40]. ...
Physiological and biological markers in different body fluids are used to measure the body’s physiological or pathological status. In the field of sports and exercise medicine, the use of these markers has recently become more popular for monitoring an athlete’s training response and assessing the immediate or long-term effects of exercise. Although the effect of exercise on different physiological markers using various body fluids is well substantiated, no article has undertaken a review across multiple body fluids such as blood, saliva, urine and sweat. This narrative review aims to assess various physiological markers in blood, urine and saliva, at rest and after exercise and examines physiological marker levels obtained across similar studies, with a focus on the population and study methodology used. Literature searches were conducted using PRISMA guidelines for keywords such as exercise, physical activity, serum, sweat, urine, and biomarkers, resulting in an analysis of 15 studies for this review paper. When comparing the effects of exercise on physiological markers across different body fluids (blood, urine, and saliva), the changes detected were generally in the same direction. However, the extent of the change varied, potentially as a result of the type and duration of exercise, the sample population and subject numbers, fitness levels, and/or dietary intake. In addition, none of the studies used solely female participants; instead, including males only or both male and female subjects together. The results of some physiological markers are sex-dependent. Therefore, to better understand how the levels of these biomarkers change in relation to exercise and performance, the sex of the participants should also be taken into consideration.
... In this study, urine indices of hydration status did not correlate with the blood hydration status markers, which is consistent with the results of previous studies [47][48][49]. Based on serum osmolality, adequate hydration was maintained in 83% of foresters before work on the following day. ...
... Raines et al. [26] demonstrated that the percentage of discordant classifications of dehydration before the shift was 20% for U col and plasma osmolality indices. It was suggested that weak correlations or lack of relationships between urine and blood hydration indices might be due to a delayed response to acute changes in hydration status measured in blood and urine [48]. On the other hand, significant correlations were observed between urine indices of hydration such as urine color, urine-specific gravity, and urine osmolality, which has been confirmed by others [28,47,49]. ...
The aim of this study was to determine the effects of different seasons of the year and the time of day (before work vs. after work) on hydration status in men. The study involved sixty foresters who spent most of the work outdoors. During three seasons of the year (summer, autumn, and winter), indices of hydration status (body mass (BM) and percentage change of BM, total body water (TBW) and percentage change of TBW, serum osmolality (Sosm) and percentage change of Sosm, urine osmolality, urine-specific gravity (USG), urine color, and thirst) were determined before work on the first day (time point 1 used as baseline), immediately after work on the first day (time point 2), and before work on the following day (time point 3). USG decreased at time point 2 compared to time point 1 (p < 0.001) and time point 3 (p = 0.03). At time point 2 (p = 0.002) in winter and time point 3 in autumn (p = 0.049), serum osmolality was higher than in summer. In conclusion, the differences in hydration status depended on the time of day and season. A large percentage of foresters come to work inadequately hydrated, especially in colder seasons compared to summer.
... Urine-specific gravity (USG) can be measured using a refractometer, which is a reliable method but with considerations regarding specificity and validity. 117 Another method is assessing the color of the urine with reference to a color chart. This method is very easy to implement, as it requires no equipment other than a color chart for comparison. ...
Women’s football is an intermittent sport characterized by frequent intense actions throughout the match. The high number of matches with limited recovery time played across a long competitive season underlines the importance of nutritional strategies to meet these large physical demands. In order to maximize sport performance and maintain good health, energy intake must be optimal. However, a considerable proportion of female elite football players does not have sufficient energy intake to match the energy expenditure, resulting in low energy availability that might have detrimental physiologic consequences and impair performance. Carbohydrates appear to be the primary fuel covering the total energy supply during match‐play, and female elite football players should aim to consume sufficient carbohydrates to meet the requirements of their training program and to optimize the replenishment of muscle glycogen stores between training bouts and matches. However, several macro‐ and micronutrients are important for ensuring sufficient energy and nutrients for performance optimization and for overall health status in female elite football players. The inadequacy of macro‐and micronutrients in the diet of these athletes may impair performance and training adaptations, and increase the risk of health disorders, compromising the player’s professional career. In this topical review, we present knowledge and relevant nutritional recommendations for elite female football players for the benefit of sports nutritionists, dietitians, sports scientists, healthcare specialists, and applied researchers. We focus on dietary intake and cover the most pertinent topics in sports nutrition for the relevant physical demands in female elite football players as follows: energy intake, macronutrient and micronutrient requirements and optimal composition of the everyday diet, nutritional and hydration strategies to optimize performance and recovery, potential ergogenic effects of authorized relevant supplements, and future research considerations.
... 16 Questions have been raised about the validity of USG to identify acute dehydration in athletes, especially when other methods such as plasma osmolality are not available. 40 Although USG measurements were conducted in the morning after an overnight fasting, we are not able to assure that a correct identification of hydration status was provided based on this single assessment. Nevertheless, a non-significant trend was observed toward a lower ICW and FFM hydration between WH and DH group. ...
We aimed to validate bioelectrical impedance spectroscopy (BIS), compared to tracer dilution measurements, for assessing total body water (TBW), intracellular water (ICW), and extracellular water (ECW) in athletes differing in hydration status. A total of 201 athletes participated. Reference TBW and ECW were determined by deuterium and bromide dilution methods, respectively; ICW was calculated as TBW‐ECW. Water compartments were estimated by BIS. Urine specific gravity (USG) classified athletes into well‐hydrated (WH) (USG<1.023), euhydrated (EH) (USG:1.024‐1.026), and dehydrated (DH) (USG>1.027).
No significant differences were found between BIS and the reference methods for WH, EH, and DH athletes for TBW, ICW nor ECW (p>0.05). Concordance of TBW and its compartments by method was significant (p<0.001) with coefficients of determination ranging by hydration classification [EH:52‐96%;DH:56‐98%;WH:71‐96%]. Bland‐Altman analyses showed no trend for TBW and its compartments with the exception of ICW in the WH athletes. The 95% confidence BIS intervals for the WH group ranged from ‐3.08 to 2.68kg for TBW, ‐4.28 to 4.14kg for ICW and ‐3.29 to 3.02kg for ECW. For the EH athletes, the 95% confidence intervals ranged from ‐2.78 to 2.24kg for TBW, ‐4.10 to 3.94kg for ICW and ‐3.44 to 3.06kg for ECW. In DH group, TBW ranged between ‐1.99 to 2.01kg, ICW between ‐3.78 to 6.34kg and ECW between ‐6.22 to 3.74kg.
These findings show that BIS is useful at a group level in assessing water compartments in athletes differing in hydration status. However, the usefulness of BIS is limited at an individual level, especially in dehydrated athletes.
... Sensitivity and specificity scores are preferred to be above 0.80. Sensitivity is defined as the number of true positive (TP) scores suggesting underhydration, divided by the sum of TP and false-negative (FN) scores [13]. Specificity is defined as the number of true negatives (TN) divided by the sum of false positives (FP) and TN. ...
Our objective was to determine self-reported accuracy of an athletic population using two different urine color (Uc) charts (8-color vs. 7-color Uc chart). After approval by the Institutional Review Board, members of an athletic population (n = 189, 20 (19–22) year old student- or tactical athletes and coaches, with n = 99 males and n = 90 females) scored their Uc using two charts. To determine the diagnostic value of Uc, results were compared with urine concentration (osmolality and urine specific gravity, USG). Uc was scored slightly darker with the 8-color vs. 7-color Uc chart (2.2 ± 1.2 vs. 2.0 ± 1.2, respectively, p < 0.001), with a moderate correlation between charts (r = 0.76, 95% CI: 0.69–0.81). Bland-Altman analysis showed a weak reporting bias (r = 0.15, p = 0.04). The area under the curve for correct urine sample classification ranged between 0.74 and 0.86. Higher accuracy for both methods was found when Uc scores were compared to USG over osmolality, indicated by 4.8–14.8% range in difference between methods. The optimal Uc cut-off value to assess a low vs. a high urine concentration for both Uc charts varied in this study between 1 and ≤2 while accuracy for charts was similar up to 77% when compared to USG.
... At the beginning, a urine sample was tested for its specific gravity using chemical multiparameter test strips (Combi Screen 10 SL Plus, Analyticon Biotechnologies AG, Lichtensfels, Germany). When specific gravity was ≥ 1.020 a participant was considered dehydrated 30 and was given another half-liter of water with 4.5 g of salt (NaCl). To investigate the total sweat loss, nude body mass was measured to the nearest 50 g before and after a subsequent running protocol. ...
Background:
The aim was to examine the impact of personal protective equipment (PPE) on human thermoregulation and its alteration in groups of different training status.
Methods:
45 men performed a maximum voluntary contraction test in an upright pull position to determine lower body strength and a graded treadmill test to determine maximum oxygen uptake (VO2max). Body composition was estimated via bioelectric impedance analysis. According to specific cutoff values, participants were assigned to a group of endurance-trained, strength-trained, endurance- and strength-trained, or untrained individuals. Subsequently, they completed two graded exercise tests until volitional exhaustion, once wearing sports wear (SPW) and once wearing PPE (20.9 kg). Participants were weighed before and afterward to investigate sweat loss and sweat rate. Body temperature was measured continuously from the tympanic membrane. Energy expenditure was derived from breathing gas analysis.
Results:
Sweat rate was 91% higher in PPE than in SPW but not significantly differnt between groups (p > 0.05). Body temperature was significantly higher in PPE during submaximal (+1.14 ± 0.45 °C) and maximal exercise intensity (+0.68 ± 0.57 °C) and was poorely related to VO2max and body composition. Energy expenditure significantly differed between both garments (+37% in PPE) and groups (p < 0.05). Additionally, energy expenditure significantly correlated with body weight (r = 0.84 in SPW and r = 0.68 in PPE).
Conclusions:
Strength training alone does not seem to have any or negligible effects on thermoregulation. Endurance training and weight management might lead to rather small improvements in heat tolerance.
... Так, L.M. Sommerfield и соавт. [18] доказали, что чувствительность удельного веса мочи высокая как в гидратированном, так и деги дратированном состоянии для мужчин (92 %) и жен щин (80 %). Однако спе ци фичность этого маркера была низкой как в гидратированном, так дегидратирован ном состояниях для мужчин (10 и 6 % соответственно) и женщин (29 и 40 % соответственно). ...
