Urinary indices during dehydration, exercise, and rehydration

Lawrence E. Armstrong, Jorge A. Herrera Soto, Frank T. Hacker, Douglas J. Casa, Stavros A. Kavouras, Carl M. Maresh

Research output: Contribution to journalArticlepeer-review

325 Scopus citations


This investigation evaluated the validity and sensitivity of urine color (Ucol), specific gravity (Usg), and osmolality (Uosm) as indices of hydration status, by comparing them to changes in body water. Nine highly trained males underwent a 42-hr protocol involving dehydration to 3.7% of body mass (Day 1, -2.64 kg), cycling to exhaustion (Day 2, -5.2% of body mass, -3.68 kg), and oral rehydration for 21 hr. The ranges of mean (across time) blood and urine values were Ucol, 1-7; Usg, 1.004-1.029; Uosm, 117-1,081 mOsm · kg-1; and plasma osmolality (Posm), 280-298 mOsm · kg-1. Urine color tracked changes in body water as effectively as (or better than) Uosm, Usg, urine volume, Posm, plasma sodium, and plasma total protein. We concluded that (a) Ucol, Uosm, and Usg are valid indices of hydration status, and (b) marked dehydration, exercise, and rehydration had little effect on the validity and sensitivity of these indices.

Original languageEnglish (US)
Pages (from-to)345-355
Number of pages11
JournalInternational Journal of Sport Nutrition and Exercise Metabolism
Issue number4
StatePublished - Dec 1998
Externally publishedYes


  • Osmolality
  • Plasma
  • Sodium
  • Specific gravity
  • Sweat
  • Urine color

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Orthopedics and Sports Medicine
  • Nutrition and Dietetics


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