CHANGE IN BODY WEIGHT, URINE OSMOLALITY, AND USG IN FREE LIVING CONDITIONS OVER THE COURSE OF 29 DAYS
LynnDee G. Summers, Evan C. Johnson, Ainsley Huffman, Thomas Vidal, Mikell L. Hammer, Catalina Capitan & Stavros A. Kavouras, FACSM
Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, Arkansas
Body weight and hydration markers change greatly during strenuous exercise, especially in the heat. However, in a non-athletic population, changes in body weight and hydration markers may not be so obvious. It’s important to classify the normal fluctuation of these measurements for future studies in order to delineate when an intervention results in a change outside of what can be expected during normal daily living. PURPOSE: The purpose of this study was to describe the normal fluctuations in body weight and urine hydration markers over the course of 29 days. METHODS: Forty-five male and female participants, ranging from 18 to 61 years were measured on 12 separate morning visits over the course of 29 days. All the subjects were apparently healthy and none of them exercised more than 4 hours per week. During each visit, subjects were weighed and provided a urine sample foranalysis of osmolality (UOsm) and specific gravity (USG) measurement. The results from these measurements were analyzed using a one-way, repeated measures analysis of variance test to evaluate main effects of time on body weight, UOsm, and USG. Additionally, percent change compared to the first day of testing was calculated for the 11 data points after the first visit, for all variables. RESULTS: No main effect of time was observed across the 29 days for any variable (body weight, p= 0.214; UOsmo, p=0.357; USG, p=0.472). The average percent change for body weight was 0.1% (95% CI: -2.6 to +2.7%), for UOsm, -5.3% (95% CI: -125% to 115%), and USG, -0.3% (95% CI: -1.6 to 1.1%). Each variable showed relative stability over the course of the 29 days. CONCLUSION: Fluctuation in body weight and urine hydration markers over the course of the 29 days appeared to be stable.
Summers, LG; Johnson, EC; Huffman, A; Vidal, T; Hammer, ML; Capitan, C; and Kavouras, SA FACSM
"CHANGE IN BODY WEIGHT, URINE OSMOLALITY, AND USG IN FREE LIVING CONDITIONS OVER THE COURSE OF 29 DAYS,"
International Journal of Exercise Science: Conference Proceedings:
2, Article 62.
Available at: http://digitalcommons.wku.edu/ijesab/vol11/iss2/62
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