Validation of Urinary Biomarkers of Hydration Status in College Athletes

Abstract

Adequate hydration is critical for optimal performance and health. Fluid requirements of collegiate athletes are unique due to training and competition, travel, school schedules, and stressors common in college environments. Inattention to these factors may contribute to suboptimal hydration. Importantly, loss of 1-2% of body weight by dehydration can impair physical and cognitive performance. As such, development of valid and reliable tools to assess hydration status in collegiate athletes is needed. The purpose of this study was to assess the validity of urine color (UC) as a measure of hydration status in collegiate athletes. A secondary purpose was to evaluate the utility of indexes of hydration status for UC and urine specific gravity (USG) established by the American College of Sports Medicine (ACSM) and the National Athletic Trainers' Association (NATA). To address this, 62 NCAA Division I collegiate athletes provided a urine sample ≤30 minutes of exercise for UC self-assessment (UCsub) and experimenter-assessment (UCres) using the UC chart developed by Armstrong et al. (1994) and for USG measurement via refractometry (1). Habitual dietary intake was assessed by 24-hr recalls. There was a significant positive correlation between USG and both UCsub (r=0.679, p<0.001) and UCres (r=0.772, p<0.001). In addition, the USG based on UC was inconsistent with hydration/dehydration categories established by ACSM and NATA. These findings suggest that UC, even when self-assessed by the athlete, is a valid method for assessing hydration status in NCAA division I college athletes. However, some modification of ACSM and NATA hydration categories may be warranted.

Armstrong LE, Maresh CM, Castellani JW, et al. Urinary indices of hydration status. Int J Sport Nutr. 1994;4(3):265-279. http://www.ncbi.nlm.nih.gov/pubmed/7987361. Accessed October 26, 2016.