The Comparison Of Home And Laboratory Urine Hydration Assessments In Collegiate Women Lacrosse Athletes

Hydration monitoring in athletes presents difficult measurement and evaluation issues. PURPOSE: To investigate measurement concerns of hydration monitoring with DII collegiate female lacrosse athletes; specifically, the comparison between urine specific gravity (USG) between urine samples collected at Home versus the Lab and the relationship between urine color (UCOL) and USG. METHODS: 22 female lacrosse athletes (aged 20 ± 1 y) completed hydration assessments over three consecutive days. Each day participants collected morning urine samples after waking (Home) and then transported the sample to the laboratory and provided a second urine sample (Lab). Each urine sample had USG assessed by two raters with analog refractometer and by one rater with digital refractometer, in triplicate. The average of each raters’ triplicate was used for analysis (n = 198; mean differences between Home and Lab). For the digital refractometer, USG was rounded to the nearest 0.001 when combined with analog data. UCOL was assessed by a chart; the manual raters used a paper chart, and the digital rater used a digital chart. RESULTS: Paired-samples, t-Tests found differences between Home (n = 198; 1.023 ± 0.005) and Lab USG (n = 198; 1.022 ± 0.005, p < 0.001). This is a small effect size (d = 0.21); however, 48% (95/198 Home to Lab comparisons) changed hydration status categories between the Home and Lab samples (60/40 split for category change direction). Also, 68% of the samples were categorized as hypohydrated (n = 273, USG > 1.020). Positive moderate-to-strong Spearman Rho correlations were found between All USG measures and their respective UCOL chart (r = 0.61). CONCLUSION: Practitioners should be cautious of only using a lab-provided sample in hydration-monitoring practice because in real-life it is difficult for athletes to provide their first urine void of the day after reporting to the athletic complex. When first morning voids are required, practitioners can have athletes collect a home sample and bring it to the location to be analyzed - allowing for athletes to follow normal morning routines (e.g., preparing for the day, eating, drinking, and completing other non-sport related tasks). Adopting this practice in the field will improve everyone’s ability to support athlete safety, performance, and quality, field-based research.