Date of Graduation


Document Type


Degree Name

Bachelor of Science

Degree Level



Health, Human Performance and Recreation


Ganio, Matthew

Committee Member/Reader

Washington, Tyrone

Committee Member/Second Reader

Greene, Nicholas


Background: Void Frequency (VF) has recently been determined as a valid and reliable marker of 24-hr hydration status when void urgency is controlled (i.e., urinating at “first urge”). Limitations for real world applicability of this technique are apparent because individuals often void at varying urge levels throughout the day. Purpose: The purpose of this study was to determine if urgency affects the validity of void number as a marker of hydration status. We hypothesized that void urgency would not affect the validity of void number as a way to assess hydration status. Methodology: Participants included 18 females and 13 males (Age= 239 yrs, BMI=25.14.1 kg/m2). Participants visited the lab 5 times; one familiarization visit and 4 experimental trials. The 4 randomized and counter-balanced experimental trials included: euhydrated ad libitum urge trial (EA), dehydrated ad libitum urge trial (DA), euhydrated first urge trial (E1) and dehydrated first urge trial (D1), where urgency was measured with a 0-4 scale (0= no sensation, 1 =first sensation, 2= first urge to void, 3 = strong urge and 4= uncomfortable urge). Ad libitum means individuals urinated “at free will”, while first urge meant individuals urinated at a “2” on the scale indicting the first urge to void. During the dehydrated trials, fluid intake was restricted to 500 mL per 24-hour period, while euhydrated trials encouraged fluid consumption. Regardless of the trial, participants were asked to collect their voids in medical grade urine containers and record the time of day, urgency, and thirst level while marking a line indicating the level of urine in the container. Lab analysis included measuring urine color, urine specific gravity (USG), and osmolality (OSM). Results: Urinary values for the E1 trial were: OSM= 451 165 mosm/kg, USG= 1.012 .004, void number= 73. Urinary values for the EA trial were: OSM= 429187 mosm/kg, USG= 1.011.004, void number= 73. Urinary values for the D1 trial were: OSM=878133 mosm/kg, USG=1.023.003, void number= 42. Urinary values for the DA trial were: OSM=895 143 mosm/kg, USG= 1.024 .003, void number= 41.Urinary values between the first urge and ad libitum trials were not significantly different from each other independent of hydration status (p >.05). By using a two-way ANOVA test it was determined that hydration status affects void number (p-value < .001), however there was no effect of ad libitum urgency or first urge urgency on void number (p-value = .50. Additionally, there was no interaction between hydration status and urge to void instructions on void number (p-value= .73) Conclusion: These findings suggest that void urgency does not ultimately affect the validity of void number as a way to assess hydration status. Therefore, individuals can be instructed to urinate at any level of urgency and the number of times they void in 24 h is still a valid indicator of hydration status.