Document Detail


Effect of hypohydration and altitude exposure on aerobic exercise performance and acute mountain sickness.
MedLine Citation:
PMID:  20864559     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Hypoxia often causes body water deficits (hypohydration, HYPO); however, the effects of HYPO on aerobic exercise performance and prevalence of acute mountain sickness (AMS) at high altitude (ALT) have not been reported. We hypothesized that 1) HYPO and ALT would each degrade aerobic performance relative to sea level (SL)-euhydrated (EUH) conditions, and combining HYPO and ALT would further degrade performance more than one stressor alone; and 2) HYPO would increase the prevalence and severity of AMS symptoms. Seven lowlander men (25 ± 7 yr old; 82 ± 11 kg; mean ± SD) completed four separate experimental trials. Trials were 1) SL-EUH, 2) SL-HYPO, 3) ALT-EUH, and 4) ALT-HYPO. In HYPO, subjects were dehydrated by 4% of body mass. Subjects maintained hydration status overnight and the following morning entered a hypobaric chamber (at SL or 3,048 m, 27°C) where they completed 30 min of submaximal exercise immediately followed by a 30-min performance time trial (TT). AMS was measured with the Environmental Symptoms Questionnaire-Cerebral Score (AMS-C) and the Lake Louise Scoring System (LLS). The percent change in TT performance, relative to SL-EUH, was -19 ± 12% (334 ± 64 to 278 ± 87 kJ), -11 ± 10% (334 ± 64 to 293 ± 33 kJ), and -34 ± 22% (334 ± 64 to 227 ± 95 kJ), for SL-HYPO, ALT-EUH, and ALT-HYPO, respectively. AMS symptom prevalence was 2/7 subjects at ALT-EUH for AMS-C and LLS and 5/7 and 4/7 at ALT-HYPO for AMS-C and LLS, respectively. The AMS-C symptom severity score (AMS-C score) tended to increase from ALT-EUH to ALT-HYPO but was not significant (P = 0.07). In conclusion, hypohydration at 3,048 m 1) degrades aerobic performance in an additive manner with that induced by ALT; and 2) did not appear to increase the prevalence/severity of AMS symptoms.
Authors:
John W Castellani; Stephen R Muza; Samuel N Cheuvront; Ingrid V Sils; Charles S Fulco; Robert W Kenefick; Beth A Beidleman; Michael N Sawka
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2010-09-23
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  109     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-12-14     Completed Date:  2011-03-25     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1792-800     Citation Subset:  IM    
Affiliation:
Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, 42 Kansas St., Natick, MA 01760-5007, USA. john.castellani@us.army.mil
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MeSH Terms
Descriptor/Qualifier:
Acute Disease
Adolescent
Adult
Altitude*
Altitude Sickness / blood,  physiopathology*,  psychology
Biological Markers / blood
Dehydration / blood,  physiopathology*,  psychology
Exercise*
Exercise Test
Humans
Male
Perception
Questionnaires
Severity of Illness Index
Task Performance and Analysis
Time Factors
Water-Electrolyte Balance*
Young Adult
Chemical
Reg. No./Substance:
0/Biological Markers

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