18th Annual Student Research Conference
Human Potential and Performance
Does Time of Day, Water Intake and Food Influence Hydration Levels?
Abbie E. Smith
Dr. Jerry Mayhew and Dr. Alex J. Koch, Faculty Mentors
NCAA regulations prohibit wrestlers from competing when urine specific gravity (Usg) is >1.020, no evaluation of the within-and between-day variability of measurement has been done. Six moderately trained individuals collected 138 urine samples over a 5-day period. Fluids and food were allowed ad libitum. Usg was measured in duplicate using a refractometer and Uosm was determined using freezing-point depression. Usg was highly correlated with Uosm (r = 0.98). Repeated-measures ANOVA across days indicated no significant pattern to either Usg or Uosm. Daily water intake was significantly inversely correlated with Usg (r = -0.43) or Uosm (r = -0.38). Use of protein supplements was significantly directly correlated with Usg (r = 0.68) and Uosm (r = 0.70). Time of day does not appear to be an essential criteria for assessing Usg and Uosm. However, water intake and/or protein supplementation may increase both the within-day and between- day variations of measurement.
Keywords: hydration, urine, time of day
Topic(s):Exercise Science
Presentation Type: Oral Paper
Session: 5-4
Location: VH 1000
Time: 9:00