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Exercise intolerance at high altitude (5050m): Critical power and W'
MedLine Citation:
PMID:  21621651     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The relationship between work rate (WR) and its tolerable duration (t(LIM)) has not been investigated at high altitude (HA). At HA (5050m) and at sea level (SL), six subjects therefore performed symptom-limited cycle-ergometry: an incremental test (IET) and three constant-WR tests (% of IET WR(max), HA and SL respectively: WR(1) 70±8%, 74±7%; WR(2) 86±14%, 88±10%; WR(3) 105±13%, 104±9%). The power asymptote (CP) and curvature constant (W') of the hyperbolic WR-t(LIM) relationship were reduced at HA compared to SL (CP: 81±21 vs. 123±38W; W': 7.2±2.9 vs. 13.1±4.3kJ). HA breathing reserve (estimated maximum voluntary ventilation minus end-exercise ventilation) was also compromised (WR(1): 25±25 vs. 50±18lmin(-1); WR(2): 4±23 vs. 38±23lmin(-1); WR(3): -3±18 vs. 32±24lmin(-1)) with near-maximal dyspnea levels (Borg) (WR(1): 7.2±1.2 vs. 4.8±1.3; WR(2): 8.8±0.8 vs. 5.3±1.2; WR(3): 9.3±1.0 vs. 5.3±1.5). The CP reduction is consistent with a reduced O(2) availability; that of W' with reduced muscle-venous O(2) storage, exacerbated by ventilatory limitation and dyspnea.
Authors:
G Valli; A Cogo; C Passino; D Bonardi; G Morici; V Fasano; M Agnesi; L Bernardi; A M Ferrazza; S A Ward; P Palange
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-5-19
Journal Detail:
Title:  Respiratory physiology & neurobiology     Volume:  -     ISSN:  1878-1519     ISO Abbreviation:  -     Publication Date:  2011 May 
Date Detail:
Created Date:  2011-5-30     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101140022     Medline TA:  Respir Physiol Neurobiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011. Published by Elsevier B.V.
Affiliation:
Department of Clinical Medicine, University of Rome "La Sapienza", viale dell'università, 37-00185 Rome, Italy.
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