Abstract
Background: Reference values and confidence intervals for the hydration indices of a large athletic population are currently lacking. Methods: Urine indices were gathered from an athletic population (n = 189) based on spot-urine samples. Results: High urine concentration was associated with a low volume and short void duration. When stratifying the data, differences for urine volume were seen for race and ethnicity and for athletic affiliation (p < 0.05), but no differences were found for urine concentration markers or volume for time of day of collection, thirst sensation, or age (p > 0.05). When classifying urine samples for a low vs. a high urine concentration by scoring urine color (Uc), the athletic population reported a slightly lower accuracy (4–7%) compared to investigators (p < 0.02). Subjects scored samples as lighter than the investigators, with a higher misclassification of the more concentrated urine samples. Conclusions: In this convenience sample of a predominantly young athletic population, urinary indices did not differ for subgroups within a large athletic population aside from some difference for race and ethnicity on urine volume. Although well-trained investigators reported better accuracy for Uc scoring, both athletes and investigators reported the highest accuracy for correctly classifying samples with a very low or a very high urine concentration.
Highlights
It is recommended that athletic populations should monitor their hydration status [1]
The dataset consisted of a convenience sample of one hundred and eighty-nine university NCAA Division I athletes, student club athletes, Army Reserve Officer Training Corps (ROTC) cadets, and a group of Chinese coaches visiting the USA (52% male, 22.3 ± 1.6 years) that were asked to score the color of their urine while handing in a single urine sample without any requirements or interventions towards their hydration status
After classifying urine samples in seven percentile groups from low to high urine concentration, there was a weak but significant inverse relationship between urine concentration and urine volume (r = −0.34 with 95%CI −0.46 to −0.21, p < 0.001)
Summary
It is recommended that athletic populations should monitor their hydration status [1]. A wide range of publications has explained the value of different hydration markers [3–6], but normative data for athletes reporting urinary indices are missing. Low water intake results in a high urine concentration [7], a useful marker of suboptimal hydration status [8]. When classifying urine samples for a low vs a high urine concentration by scoring urine color (Uc), the athletic population reported a slightly lower accuracy (4–7%) compared to investigators (p < 0.02). Conclusions: In this convenience sample of a predominantly young athletic population, urinary indices did not differ for subgroups within a large athletic population aside from some difference for race and ethnicity on urine volume. Well-trained investigators reported better accuracy for Uc scoring, both athletes and investigators reported the highest accuracy for correctly classifying samples with a very low or a very high urine concentration
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