title: Hydration Status as a Predictor of High-altitude Mountaineering Performance.
abstract: Hydration status is a controversial determinant of athletic performance. This relationship has not been examined with mountaineering performance.
  
  
  
  This was a prospective observational study of mountaineers who attempted to climb Denali in Alaska. Participants' urine specific gravity (SG), and ultrasound measurements of the inferior vena cava size and collapsibility index (IVC-CI) were measured at rest prior to ascent. Upon descent, climbers reported maximum elevation gained for determination of summit success.
  
  
  
  One hundred twenty-one participants enrolled in the study. Data were collected on 111 participants (92% response rate); of those, 105 (87%) had complete hydration data. Fifty-seven percent of study participants were found to be dehydrated by IVC-CI on ultrasound, and 55% by urine SG. No significant association was found with summit success and quantitative measurements of hydration: IVC-CI (50.4% +/- 15.6 vs. 52.9% +/- 15.4, p = 0.91), IVC size (0.96 cm +/- 0.3 vs. 0.99 cm +/- 0.3, p = 0.81), and average SG (1.02 +/- 0.008 vs. 1.02 +/- 0.008, p = 0.87). Categorical measurements of urine SG found 24% more successful summiters were hydrated at 14 Camp, but this was not found to be statistically significant (p = 0.56). Summit success was associated with greater water-carrying capacity on univariate analysis only: 2.3 L, 95% confidence interval (2.1 - 2.5) vs. 2.1 L, 95% confidence interval (2 - 2.2); p < 0.01.
  
  
  
  Intravascular dehydration was found in approximately half of technical high-altitude mountaineers. Hydration status was not significantly associated with summit success, but increased water-carrying capacity may be an easy and inexpensive educational intervention to improve performance.
authors.affiliation: Department of Emergency Medicine, Stanford University School of Medicine.
authors.forename: Eric
authors.initials: E
authors.lastname: Ladd
authors.affiliation: Department of Emergency Medicine, Stanford University School of Medicine.
authors.forename: Katherine M
authors.initials: KM
authors.lastname: Shea
authors.affiliation: University of New England College of Osteopathic Medicine, University of New England.
authors.forename: Patrick
authors.initials: P
authors.lastname: Bagley
authors.affiliation: Department of Rehabilitation Medicine, University of Washington
authors.forename: Sean
authors.initials: S
authors.lastname: Rundell
authors.affiliation: Department of Emergency Medicine, Stanford University School of Medicine.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Auerbach
authors.affiliation: Department of Emergency Medicine, Stanford University School of Medicine.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Pirrotta
authors.affiliation: Department of Emergency Medicine, Stanford University School of Medicine.
authors.forename: Ewen
authors.initials: E
authors.lastname: Wang
authors.affiliation: Department of Emergency Medicine, Stanford University School of Medicine.
authors.forename: Grant S
authors.initials: GS
authors.lastname: Lipman
keywords: dehydration; hydration; mountaineering; performance; ultrasound