The Effect of Fluid Intake Following Dehydration on Subsequent Athletic and Cognitive Performance: a Systematic Review and Meta-analysis

Background: The deleterious effects of dehydration on athletic and cognitive performance have been well documented. As such, dehydrated individuals are advised to consume fluid in volumes equivalent to 1.25 to 1.5 L kg−1 body mass (BM) lost to restore body water content. However, individuals undertaking subsequent activity may have limited time to consume fluid. Within this context, the impact of fluid intake practices is unclear. This systematic review investigated the effect of fluid consumption following a period of dehydration on subsequent athletic and cognitive performance. Methods: PubMed (MEDLINE), Web of Science (via Thomas Reuters) and Scopus databases were searched for articles reporting on athletic (categorized as: continuous, intermittent, resistance, sport-specific and balance exercise) or cognitive performance following dehydration of participants under control (no fluid) and intervention (fluid intake) conditions. Meta-analytic procedures determined intervention efficacy for continuous exercise performance. Results: Sixty-four trials (n = 643 participants) derived from 42 publications were reviewed. Dehydration decreased BM by 1.3–4.2%, and fluid intake was equivalent to 0.4–1.55 L kg−1 BM lost. Fluid intake significantly improved continuous exercise performance (22 trials), Hedges’ g = 0.46, 95% CI 0.32, 0.61. Improvement was greatest when exercise was performed in hotter environments and over longer durations. The volume or timing of fluid consumption did not influence the magnitude of this effect. Evidence indicating a benefit of fluid intake on intermittent (10 trials), resistance (9 trials), sport-specific (6 trials) and balance (2 trials) exercise and on cognitive performance (15 trials) was less apparent and requires further elucidation. Conclusions: Fluid consumption following dehydration may improve continuous exercise performance under heat stress conditions, even when the body water deficit is modest and fluid intake is inadequate for complete rehydration.Griffith Health, School of Allied Health SciencesFull Tex

Integrated plasma proteomic and single-cell immune signaling network signatures demarcate mild, moderate, and severe COVID-19

The biological determinants underlying the range of coronavirus 2019 (COVID-19) clinical manifestations are not fully understood. Here, over 1,400 plasma proteins and 2,600 single-cell immune features comprising cell phenotype, endogenous signaling activity, and signaling responses to inflammatory ligands are cross-sectionally assessed in peripheral blood from 97 patients with mild, moderate, and severe COVID-19 and 40 uninfected patients. Using an integrated computational approach to analyze the combined plasma and single-cell proteomic data, we identify and independently validate a multi-variate model classifying COVID-19 severity (multi-class area under the curve [AUC]training = 0.799, p = 4.2e-6; multi-class AUCvalidation = 0.773, p = 7.7e-6). Examination of informative model features reveals biological signatures of COVID-19 severity, including the dysregulation of JAK/STAT, MAPK/mTOR, and nuclear factor κB (NF-κB) immune signaling networks in addition to recapitulating known hallmarks of COVID-19. These results provide a set of early determinants of COVID-19 severity that may point to therapeutic targets for prevention and/or treatment of COVID-19 progression

RELATIONSHIP BETWEEN 24-H VOID FREQUENCY, HYDRATION STATUS, AND INGESTED BEVERAGE COMPOSITION IN HEALTHY MALES

Matthew A. Tucker, Matthew S. Ganio, Jenna M. Burchfield & Nicole E. Moyen Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, Arkansas Void frequency (VF) increases with increased fluid intake; however, the relationship between VF and hydration status with controlled fluid intake is unknown. Further, the influence of different beverage types on VF is unclear. PURPOSE: To investigate the relationship between hydration status and VF in healthy males when given a fixed volume of different beverages. METHODS: In a randomized order, 32 healthy males (age 23.7 ± 4.9 y; mass 75.9 ± 11.7 kg) completed four weeks of testing consuming various beverage treatments (Txt) over 24-h with total daily fluid intake equal to 35 ml/kg body mass (including fluids from beverages and moisture content of a prescribed diet). Txt were: water only (A), water+caloric cola (B), water+non-caloric cola (C), or water+caloric cola+non-caloric cola+orange juice (D). Volumes of fluid were split evenly between beverages within each 24-h treatment. 24-h urine osmolality (24-Uosm), specific gravity (24-USG), volume (24-Uvol) and VF were measured during 24-h of intervention. 24-h urine samples were classified as euhydrated (24-USG ≤1.020 and 24-Uosm ≤700 mOsm/kg) or hypohydrated (24-USG \u3e1.020 and 24-Uosm \u3e700 mOsm/kg). RESULTS: As designed, total fluid intake from all sources was the same across treatments (2659 ± 400 ml; p\u3e0.05). There were no differences between treatments in 24-Uosm or 24-Uvol (grand mean: 607 ± 211 mOsm/kg and 1536 ± 593 ml, respectively; p\u3e0.05). VF over 24-h was not different between Txt A, B, C, and D (5.2 ± 1.7, 5.3 ± 1.8, 5.6 ± 2.0, and 5.1 ± 1.8, respectively; p\u3e0.05). Independent of beverage treatment, VF significantly correlated with 24-USG (r= -.47; posm (r= -.46; pSG and 24-Uosm values, a receiver operating curve analysis produced an area under the curve of 73.7% with a 95% CI [64.9, 82.5] (pCONCLUSION: These results indicate that VF is significantly correlated with hydration status, such that higher values of 24-USG and 24-Uosm are inversely related to VF. Further, urinary measures of hydration status and VF were not different between beverage treatments, suggesting that ingestion of different beverages does not affect voiding behavior in healthy males. Funded by The Coca-Cola Company

VALIDITY OF UCHEK IPHONE APPLICATION ON ASSESSING DEHYDRATION FROM URINE SAMPLES

1Christian B. Ridings, 1J.D. Adams, 1Matthew S. Ganio, 1Brendon P. McDermott, 2Dimitris Bougatsas, 1Stavros A. Kavouras, FACSM. 1Human Performance Laboratory, Department of Health, Human Performance, and Recreation, University of Arkansas, Fayetteville, AR; 2Laboratory of Nutrition & Clinical Dietetics, Harokopio University, Athens, Greece The widespread acceptance of smartphones presents an opportunity for the development of mobile health applications and accessories. These devices can help reduce costs and improve accessibility of healthcare. PURPOSE: To determine the validity of the uChek iPhone application on measuring hydration status compared to urine refractometry and urine dipstick applicators. METHODS: Fifty-three urine samples were analyzed for urine specific gravity (USG) by a refractometer under a well-lit area. Urine strips (Multistix 10 SG Reagent Strips) were used to record USG by the Multistix label compared to an 8-color control stick, and was then analyzed by the uChek application. RESULTS: Sensitivity analysis showed that overall accuracy of USG via strips and uChek were 68 and 67.3%, respectively. Specifically, the sensitivity of a positive urine test for dehydration (USG≥1.020) was 55.6% with the strips and 51.9% with the iPhone app. The specificity for detecting hypohydrated persons was 36.4% and 31.8% for the strips and iPhone app, respectively. CONCLUSION: We concluded that the iPhone application uChek is not accurately detecting dehydration mainly due to limitations of the urine strips

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