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 >1.020 and 24-Uosm >700 mOsm/kg). RESULTS: As designed, total fluid intake from all sources was the same across treatments (2659 ± 400 ml; p>0.05). There were no differences between treatments in 24-Uosm or 24-Uvol (grand mean: 607 ± 211 mOsm/kg and 1536 ± 593 ml, respectively; p>0.05). 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>0.05). 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.

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