title: Validity of Urine Specific Gravity When Compared With Plasma Osmolality as a Measure of Hydration Status in Male and Female NCAA Collegiate Athletes.
abstract: Sommerfield, LM, McAnulty, SR, McBride, JM, Zwetsloot, JJ, Austin, MD, Mehlhorn, JD, Calhoun, MC, Young, JO, Haines, TL, and Utter, AC. Validity of urine specific gravity when compared with plasma osmolality as a measure of hydration status in male and female NCAA collegiate athletes. J Strength Cond Res 30(8): 2219-2225, 2016-The purpose of this study was to evaluate the response of urine specific gravity (Usg) and urine osmolality (Uosm) when compared with plasma osmolality (Posm) from euhydration to 3% dehydration and then a 2-hour rehydration period in male and female collegiate athletes. Fifty-six National Collegiate Athletic Association (NCAA) wrestlers (mean ± SEM); height 1.75 ± 0.01 m, age 19.3 ± 0.2 years, and body mass (BM) 78.1 ± 1.8 kg and 26 NCAA women's soccer athletes; height 1.64 ± 0.01 m, age 19.8 ± 0.3 years, and BM 62.2 ± 1.2 kg were evaluated. Hydration status was obtained by measuring changes in Posm, Uosm, Usg, and BM. Male and female subjects dehydrated to achieve an average BM loss of 2.9 ± 0.09% and 1.9 ± 0.03%, respectively. Using the medical diagnostic decision model, the sensitivity of Usg was high in both the hydrated and dehydrated state for males (92%) and females (80%). However, the specificity of Usg was low in both the hydrated and dehydrated states for males (10 and 6%, respectively) and females (29 and 40%, respectively). No significant correlations were found between Usg and Posm during either the hydrated or dehydrated state for males or females. Based on these results, the use of Usg as a field measure of hydration status in male and female collegiate athletes should be used with caution. Considering that athletes deal with hydration status on a regular basis, the reported low specificity of Usg suggests that athletes could be incorrectly classified leading to the unnecessary loss of competition.
authors.affiliation: Department of Health and Exercise Science, Appalachian State University, Boone, North Carolina.
authors.forename: Lesley M
authors.initials: LM
authors.lastname: Sommerfield
authors.forename: Steven R
authors.initials: SR
authors.lastname: McAnulty
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: McBride
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Zwetsloot
authors.forename: Melanie D
authors.initials: MD
authors.lastname: Austin
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Mehlhorn
authors.forename: Mason C
authors.initials: MC
authors.lastname: Calhoun
authors.forename: Juliane O
authors.initials: JO
authors.lastname: Young
authors.forename: Traci L
authors.initials: TL
authors.lastname: Haines
authors.forename: Alan C
authors.initials: AC
authors.lastname: Utter
mesh_terms: D000293:Adolescent; D003681:Dehydration / Q000097:blood / Q000175:diagnosis* / Q000628:therapy / Q000652:urine; D005260:Female; D005440:Fluid Therapy; D006801:Humans; D008297:Male; D009994:Osmolar Concentration; D010949:Plasma / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012916:Soccer / Q000502:physiology*; D013046:Specific Gravity; D014495:Universities; D014556:Urine / Q000737:chemistry*; D014952:Wrestling / Q000502:physiology*; D055815:Young Adult