The purpose of this investigation was to quantify the effects of storage temperature, duration, and the urinary sediment on urinary hydration markers. Thirty-six human urine samples were analyzed fresh and then the remaining sample was separated into 24 separate vials, six in each of the following four temperatures: 22 °C, 7 °C, -20 °C, and -80 °C. Two of each sample stored in any given temperature, were analyzed after 1, 2, and 7 days either following vortexing or centrifugation. Each urine sample was analyzed for osmolality (UOsm), urine specific gravity (USG), and urine color (UC). UOsm was stable at 22 °C, for 1 day (+5–9 mmol∙kg-1, p > .05) and at 7 °C, UOsm up to 7 days (+8–8 mmol∙kg-1, p > .05). At -20 and -80 °C, UOsm decreased after 1, 2, and 7 days (9–61 mmol∙kg-1, p < .05). Vortexing the sample before analysis further decreased only UOsm in the -20 °C and -80 °C storage. USG remained stable up to 7 days when samples were stored in 22 °C or 7 °C (p > .05) but declined significantly when stored in -20 °C, and -80 °C (p < .001). UC was not stable in any of the storing conditions for 1, 2, and 7 days. In conclusion, these data indicate that urine specimens analyzed for UOsm or USG remained stable in refrigerated (7 °C) environment for up to 7 days, and in room temperature for 1 day. However, freezing (-20 and -80 °C) samples significantly decreased the values of hydration markers.
J.D. Adams, Stavros A. Kavouras, Evan C. Johnson, Lisa T. Jansen, Catalina Capitan-Jimenez, Joseph I. Robillard and Andy Mauromoustakos
Mary Caitlin Stevenson Wilcoxson, Samantha Louise Johnson, Veronika Pribyslavska, James Mathew Green and Eric Kyle O’Neal
Runners are unlikely to consume fluid during training bouts increasing the importance of recovery rehydration efforts. This study assessed urine specific gravity (USG) responses following runs in the heat with different recovery fluid intake volumes. Thirteen male runners completed 3 evening running sessions resulting in approximately 2,200 ± 300 ml of sweat loss (3.1 ± 0.4% body mass) followed by a standardized dinner and breakfast. Beverage fluid intake (pre/postbreakfast) equaled 1,565/2,093 ml (low; L), 2,065/2,593 ml (moderate; M) and 2,565/3,356 mL (high; H). Voids were collected in separate containers. Increased urine output resulted in no differences (p > .05) in absolute mean fluid retention for waking or first postbreakfast voids. Night void averages excluding the first void postrun (1.025 ± 0.008; 1.013 ± 0.008; 1.006 ± 0.003), first morning (1.024 ± 0.004; 1.015 ± 0.005; 1.014 ± 0.005), and postbreakfast (1.022 ± 0.007; 1.014 ± 0.007; 1.008 ± 0.003) USG were higher (p < .05) for L versus M and H respectively and more clearly differentiated fluid intake volume between L and M than color or thirst sensation. Waking (r = -0.66) and postbreakfast (r = -0.71) USG were both significantly correlated (p < .001) with fluid replacement percentage, but not absolute fluid retention. Fluid intake M was reported as most similar to normal consumption (5.6 ± 1.0 on 0–10 scale) after breakfast and equaled 122 ± 16% of sweat losses. Retention data suggests consumption above this level is not warranted or actually practiced by most runners drinking ad libitum, but that periodic prerun USG assessment may be useful for coaches to detect runners that habitually consume low levels of fluids between training bouts in warm seasons.
Giannis Arnaoutis, Stavros A. Kavouras, Yiannis P. Kotsis, Yiannis E. Tsekouras, Michalis Makrillos and Costas N. Bardis
There is a lack of studies concerning hydration status of young athletes exercising in the heat.
To assess preexercise hydration status in young soccer players during a summer sports camp and to evaluate bodywater balance after soccer training sessions.
Initial hydration status was assessed in 107 young male soccer players (age 11–16 yr) during the 2nd day of the camp. Seventy-two athletes agreed to be monitored during 2 more training sessions (3rd and 5th days of the camp) to calculate dehydration via changes in body weight, while water drinking was allowed ad libitum. Hydration status was assessed via urine specific gravity (USG), urine color, and changes in total body weight. Mean environmental temperature and humidity were 27.2 ± 2 °C and 57% ± 9%, respectively.
According to USG values, 95 of 107 of the players were hypohydrated (USG ≥ 1.020) before practice. The prevalence of dehydration observed was maintained on both days, with 95.8% and 97.2% of the players being dehydrated after the training sessions on the 3rd and 5th days, respectively. Despite fluid availability, 54 of the 66 (81.8%) dehydrated players reduced their body weight (–0.35 ± 0.04 kg) as a response to training, while 74.6% (47 out of the 63) further reduced their body weight (–0.22 ± 0.03 kg) after training on the 5th day.
Approximately 90% of the young soccer players who began exercising under warm weather conditions were hypohydrated, while drinking ad libitum during practice did not prevent further dehydration in already dehydrated players.
Lindsay A. Ellis, Brandon A. Yates, Amy L. McKenzie, Colleen X. Muñoz, Douglas J. Casa and Lawrence E. Armstrong
Urine color (Ucol) as a hydration assessment tool provides practicality, ease of use, and correlates moderately to strongly with urine specific gravity (Usg) and urine osmolality (Uosm). Indicative of daily fluid turnover, along with solute and urochrome excretion in 24-hr samples, Ucol may also reflect dietary composition. Thus, the purpose of this investigation was to determine the efficacy of Ucol as a hydration status biomarker after nutritional supplementation with beetroot (880 mg), vitamin C (1000 mg), and riboflavin (200 mg). Twenty males (Mean ± SD; age, 21 ± 2 y; body mass, 82.12 ± 15.58 kg; height, 1.77 ± 0.06 m) consumed a standardized breakfast and collected all urine voids on one control day (CON) and 1 day after consuming a standardized breakfast and a randomized and double-blinded supplement (SUP) over 3 weeks. Participants replicated exercise and diet for one day before CON, and throughout CON and SUP. Ucol, Usg, Uosm, and urine volume were measured in all 24-hr samples, and Ucol and Usg were measured in all single samples. Ucol was a significant predictor of single sample Usg after all supplements (p < .05). Interestingly, 24-hr Ucol was not a significant predictor of 24-h Usg and Uosm after riboflavin supplementation (p = .20, p = .21). Further, there was a significant difference between CON and SUP 24-h Ucol only after riboflavin supplementation (p < .05). In conclusion, this investigation suggests that users of the UCC (urine color chart) should consider riboflavin supplementation when classifying hydration status and use a combination of urinary biomarkers (e.g., Usg and Ucol), both acutely and over 24 hr.
Pamela Jane Magee, Alison M. Gallagher and Jacqueline M. McCormack
Although dehydration of ≥ 2% body weight (BW) loss significantly impairs endurance performance, dehydration remains prevalent among athletes and may be owing to a lack of knowledge in relation to fluid requirements. The aim of this study was to assess the hydration status of university/club level athletes (n = 430) from a range of sports/activities (army officer cadet training; bootcamp training; cycling; Gaelic Athletic Association camogie, football and hurling; golf; hockey; netball; rugby; running (sprinting and endurance); Shotokan karate and soccer) immediately before and after training/competition and to assess their nutritional knowledge. Urine specific gravity (USG) was measured immediately before and after exercise and BW loss during exercise was assessed. Nutritional knowledge was assessed using a validated questionnaire. 31.9% of athletes commenced exercise in a dehydrated state (USG >1.020) with 43.6% of participants dehydrated posttraining/competition. Dehydration was particularly prevalent (>40% of cohort) among karateka, female netball players, army officer cadets, and golfers. Golfers that commenced a competitive 18 hole round dehydrated took a significantly higher number of strokes to complete the round in comparison with their euhydrated counterparts (79.5 ± 2.1 vs. 75.7 ± 3.9 strokes, p = .049). Nutritional knowledge was poor among participants (median total score [IQR]; 52.9% [46.0, 59.8]), albeit athletes who were euhydrated at the start of exercise had a higher overall score in comparison with dehydrated athletes (55.2% vs. 50.6%, p = .001). Findings from the current study, therefore, have significant implications for the education of athletes in relation to their individual fluid requirements around exercise.
Khaled Trabelsi, Stephen R. Stannard, Ronald J. Maughan, Kamel Jammoussi, Khaled Zeghal and Ahmed Hakim
The aim of this study was to evaluate the effects of a hypertrophic training program during Ramadan on body composition and selected metabolic markers in trained bodybuilders. Sixteen male recreational bodybuilders (9 Ramadan fasters and 7 nonfasters) participated in the study. All visited the laboratory 2 d before the start of Ramadan (Bef-R) and on the 29th day of Ramadan (End-R). In the morning of each session, subjects underwent anthropometric measurement, completed a dietary questionnaire, and provided fasting blood and urine samples. Body mass and body-mass index in nonfasters increased by 2.4% (p = .05 and p = .04, respectively) from Bef-R to End-R but remained unchanged in fasters over the period of the investigation. Fasters experienced an increase in the following parameters from Bef-R to End-R: urine specific gravity (1%, p = .022) and serum concentrations of urea (5%, p = .008), creatinine (5%, p = .007), uric acid (17%, p < .001), sodium (2%, p = .019), potassium (6%, p = .006), chloride (2%, p = .028), and high-density lipoprotein cholesterol (10%, p = .005). However, only serum creatinine and low-density lipoprotein cholesterol increased in nonfasters (3%, p < .001 and 14%, p = .007, respectively) during the same period. Creatinine clearance values of fasters decreased by 3% (p = .03) from Bef-R to End-R. Continuance of hypertrophic training through Ramadan had no effect on body mass and body composition of bodybuilders, but a state of dehydration and reduced renal function were apparent, perhaps because of the restricted opportunity for fluid intake imposed by the study design.
Composition Assessed Using DXA and Surface Anthropometry Show Good Agreement in Elite Rugby Union Athletes Adam J. Zemski * Shelley E. Keating * Elizabeth M. Broad * Gary J. Slater * 1 01 2019 29 1 24 31 10.1123/ijsnem.2018-0019 ijsnem.2018-0019 Urine Specific Gravity as a Practical Marker for
.3.220 Accuracy of Urine Specific Gravity and Osmolality as Indicators of Hydration Status Robert A. Oppliger * Scott A. Magnes * LeRoy A. Popowski * Carl V. Gisolfi * 6 2005 15 15 3 3 236 236 251 251 10.1123/ijsnem.15.3.236 Fluid, Electrolyte, and Renal Indices of Hydration during 11 Days of Controlled
Eric D.B. Goulet, Adrien De La Flore, Félix A. Savoie and Jonathan Gosselin
Dual; Owen Mumford, Oxford, United Kingdom) and participants emptied their bladder, provided a urine sample, were weighed and baseline urine specific gravity (PAL-10S; Atago, Bellevue, WA), osmolality (5004 micro osmette; Precision Systems, Inc., Natick, MA), color ( Armstrong et al., 1998 ), and
Christopher Byrne and Jason K.W. Lee
Respironics, Bend, OR) systems. 26 Prerace resting TC and HR values were obtained during a 5-minute period of seated rest. Measures of prerace hydration status (including urine-specific gravity) and fluid balance were assessed as previously described. 25 Environmental conditions were measured throughout the