HYDRATION BIOMARKERS: CREATING A NEW HYDRATION ASSESSMENT TECHNIQUE

Jenna M. Burchfield, Matthew S. Ganio, Stavros A. Kavouras, FACSM, J. D. Adams1, Melina A. Gonzalez, & Christian B. Ridings; 1Human Performance Laboratory, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, Arkansas Despite the necessity of euhydration, an optimal, user-friendly, accurate hydration assessment technique fails to exist for the general population. PURPOSE: The purpose of this study was to investigate a new hydration assessment technique, which utilizes no equipment or technical expertise to administer. We hypothesized that the number of urine voids over a 24-hr time period correlates to hydration status. METHODS: Forty-seven healthy individuals (n=24 females) participated (age 22±4 years, body mass 76±17 kg, height 1.64±0.27 m, body fat 20.4±8.7%). Participants abstained from caffeine and alcohol during the experiment. Participants were educated on how to record diet, fluid intake, and void output measurements. For 24-hours participants voided at a normal urge into a standard medical-grade container. Participants indicated volume, time, and urge of each void. Ad libitum fluid and food intake also were recorded over the 24 hrs. Total 24-hr urine volume, osmolality, specific gravity (USG), and color were measured. Subjects were classified as euhydrated (USG≤1.020) or hypohydrated (USG\u3e1.020) according to standard criteria. RESULTS: Euhydrated (n=41) versus dehydrated (n=6) individuals had more voids (6±2 versus 4±1, respectively, P=0.02), greater 24-hr urine volume (2007±863 versus 1193±434 ml, P\u3c0.001), lower urine color (2±1 versus 4±1, P\u3c0.001), lower USG (1.012±0.004 versus 1.023±0.003, P\u3c0.001), and lower osmolality (431±143 versus 841±137 mOsm/kgH20, P\u3c0.001). As hypothesized, void number moderately correlated to hydration status as identified by USG (r=0.37, P\u3c0.001), and osmolality (r=0.38, P\u3c0.001). CONCLUSION: Void number positively correlated with USG and urine osmolality. This indicates that individuals with higher void numbers are more hydrated than those with lower void numbers over a 24-hr time period. Using void number as a hydration biomarker could be an optimal technique for the general public to self-assess hydration, considering it is as simple as counting void numbers over a 24-hr period. Funding provided by the University of Arkansas College of Education & Health Professions and the Office of Research & Economic Development

HYDRATION STATUS WHEN INCREASING DAILY FLUID INTAKE WITH VARIOUS BEVERAGES

Matthew A. Tucker1, Matthew S. Ganio1, John D. Adams1, Lemuel A. Brown1, Christian Ridings1, Jenna Burchfield1, Blake Robinson1, Jamie McDermott2, Nicole E. Moyen1, Brett Schreiber1, Tyrone Washington1, Andrea Bermudez1, Meredith Bennett1, and Maxime Buyckx3; 1University of Arkansas, Fayetteville, Arkansas; 2McDermott Nutrition, Fayetteville, Arkansas; 3The Coca-Cola Company, Atlanta, Georgia. Few studies have examined how drinking fluids of varying composition may affect hydration status in healthy, free-living adults. Further, relatively little is known about how hydration status is affected when increasing fluid ingestion with various beverages. PURPOSE: To investigate the hydration status of healthy, free-living adult males when given varying volumes of different beverage types. METHODS: Thirty-six healthy males (age 24±5 y; height 177.7±8.2 cm; mass 75.1±11.4 kg) volunteered for this study. Subjects were randomly divided into four treatment groups for two weeks of testing: water only, water+cola, water+diet cola, or water+cola+diet cola+orange juice. Volumes of fluid were split evenly between beverages within each treatment. Each week consisted of 24-h of testing in which food was provided. Total fluid consumed (including moisture content of food) was equivalent between treatment groups. Week 1 total fluid ingestion over the 24-h period was 35 ml/kg body mass; week 2 total fluid ingestion was 40 ml/kg body mass. At the beginning of each 24-h testing period, equivalent hydration status was confirmed via serum osmolality (Osmserum; 292±5 vs. 291±5 mOsm, for weeks 1 and 2, respectively; p \u3e.05). Urine was collected over the 24-h period and analyzed for osmolality (Osmurine) and volume (Volurine). Osmserum and total body water (TBW) via bioelectrical impedance was collected and analyzed after 24-h of beverage intervention. RESULTS: Per the protocol, total beverage consumption, independent of treatment increased from week 1 (1721±384 ml) to week 2 (2096±437 ml) by 22±2 % (375±57 ml). There was no effect of beverages on hydration differences between weeks (i.e., no interaction; p \u3e.05). Independent of week, there were no hydration differences between beverage groups (p \u3e.05). The increase in fluid consumption between week 1 and week 2 did not change TBW (43.7±5.5 vs. 43.5±5.2 kg), Osmserum (292± 4 vs. 293±5 mOsm), Osmurine (599±221 vs. 561±217 mOsm) or Volurine (1526±624 vs. 1621±651 ml) (all p \u3e.05). CONCLUSION: Regardless of fluid volume consumed, there were no differences between the beverages in providing adequate hydration over a 24-h period in free-living adult males. This suggests that the fluid contained in various beverages is equally effective in hydrating the body. Funded by The Coca-Cola Company