Date of Graduation

5-2017

Document Type

Thesis

Degree Name

Bachelor of Science

Degree Level

Undergraduate

Department

Health, Human Performance and Recreation

Advisor/Mentor

Ganio, Matthew S.

Committee Member/Reader

Greene, Nicholas

Committee Member/Second Reader

Washington, Tyrone

Abstract

Context: Few user-friendly hydration assessment techniques exist for the general population to use on a daily basis. Objective: This study evaluated 24-h urine duration as a valid indicator of hydration status. Design:For two trials, subjects voided into a large, medical grade container at the first urge to void. For the other two trials, subjects voided at any level of urgency they desired. Participants were given a stopwatch and asked to record the duration of each void to the nearest whole second, voiding at a “normal”, unforced pace. Specific order of the trials was randomized and counter-balanced. Setting: Materials were distributed and returned to the Human Performance Laboratory at the University of Arkansas, Fayetteville. Participants collected their voids outside of the laboratory. Participants: 13 males and 18 females volunteered for this study (Age=23± 9y, Body Mass=25.1±4.1kg). Interventions: The intervention was hydration status, euhydrated versus dehydrated. For the dehydrated trials, participants were given 500 mL of water and asked to only drink that during the 24-h collection period. For the euhydrated trials, fluid consumption was encouraged. Participants were instructed to void into the container at the first urge to void during one of the euhydrated trials and one of the dehydrated trials. For the other euhydrated and dehydrated trials, the participants voided at free will (i.e., ad libitum). The participants were asked to draw a straight line on the container at the level of urine, mark the urge to void, and the duration of each void. The hydration status of each sample was classified by urine specific gravity (USG) as either euhydrated (USG <1.020) or dehydrated (USG ≥ 1.020). Results: USG was different in the euhydrated and dehydrated trials (1.012 ± .004 versus 1.023 ± .003 for first urge and 1.012 ± .004 versus 1.024 ± .003 for ad libitum urge, respectively; p<0.05). For both the first urge and ad libitum trials, individual voids were longer when euhydrated versus dehydrated (19 ± 5s versus 15 ± 6s for first urge and 20± 5s versus 16 ± 3s for ad libitum urge, p<.05). Total duration of all voids over 24-h were longer in the euhydrated compared to the dehydrated trials (133 ± 84s versus 61 ± 45s, p<.0001 for first urge and 149 ± 93s versus 64 ± 52s, p<.0001 for ad libitum urge). Duration was not affected by void urgency when voiding in a euhydrated (P=0.208) and dehydrated (P=.097) state. Conclusions: This data suggests that over 24-h, healthy adults tend to void for a longer period of time when they are hydrated compared to dehydrated, regardless if voiding at first urge or ad libitum. These findings validate 24-h urine duration as a valid and simple indicator of hydration status for the general public.

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