Validation of a New Colorimetric Device for Monitoring Hydration Status in Athletes

Abstract

1670 Hydration status is critically important to performance and safety of an athlete, especially in a heat stressed environment. When plasma and urine osmolarity can be assumed to be in equilibrium, urine specific gravity (USG) is a useful indicator of hydration status. PURPOSE: The purpose of this study was to determine the validity of a new colorimetric dipstick device for monitoring athlete hydrations status via USG. METHODS: 20 NCAA DII football players and six college-aged student trainers participated in the study during pre-season training camp. Over a three-day period, subject body weight (BW) was determined and urine samples collected prior to and following six practice sessions. USG was determined by refractometery (USG-R) and by dipstick (USG-S) as per the manufacturer's instructions. 282 comparisons of USG were made between the two devices. Pearson product moment (r) was determined as a measure of association between devices, while a Bland/Altman plot and concordance correlation coefficient (Pc) were used to determine inter-device agreement. RESULTS: Mean ambient air temperature and relative humidity (32.5 ± 1.2 oC & 72.1 ± 5 %RH) imposed substantial heat stress to subjects resulting in a mean reduction in subject BW (−2.6 ± 0.76 kg) per practice. USG, as measured by both devices, ranged from 1.000 to 1.030. USG-R and U SG-S values were significantly correlated (r = 0.95) indicating both devices are sensitive throughout the physiological range of USG. Bland/Altman plotting of data revealed a bias of 0.0006 ± 0.0028 and pc = 0.90 indicating USG-S agreed with USG-R. CONCLUSION: These data indicate the dipstick device tested here is a valid alternative to refractometery for monitoring changes in athlete hydration status. Supported by a grant from Uridynamics Inc, Indianapolis, IN