Document Detail

Effect of human exposure to altitude on muscle endurance during isometric contractions.
MedLine Citation:
PMID:  11718277     Owner:  NLM     Status:  MEDLINE    
The aim of this study was to evaluate the influence of exposure to altitude on muscle endurance during isometric contractions. Six sedentary subjects were studied. Surface electromyograph (sEMG) activity was recorded from the right biceps brachii (BB) during exhausting isometric exercise at 80% maximal voluntary contraction. Experiments were performed before, during and 6 months after a 12 day stay at the EV-K2 laboratory (Nepal, 5,050 m above sea level). From the sEMG signals from BB, the median frequencies (fmed) were computed for consecutive 1 s epochs. The sEMG was also analysed using a non-linear tool, the recurrence quantification analysis, and the percentage of determinism (%DET) was then calculated. The haemoglobin saturation significantly decreased at altitude. The mean (SD) BB endurance time decreased from 22.4 (4) s to 18.3 (4.7) s (P < 0.05). After exposure to altitude a significant variation in fmed and %DET slopes was observed. We concluded that during the first period of acclimatisation at altitude there was an impairment of isometric muscle endurance performance and there was also evidence of a modified myoelectric activity pattern suggesting a greater fatigability of the neuromuscular system.
F Felici; A Rosponi; P Sbriccoli; M Scarcia; I Bazzucchi; M Iannattone
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  European journal of applied physiology     Volume:  85     ISSN:  1439-6319     ISO Abbreviation:  Eur. J. Appl. Physiol.     Publication Date:  2001 Oct 
Date Detail:
Created Date:  2001-11-22     Completed Date:  2002-04-09     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  100954790     Medline TA:  Eur J Appl Physiol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  507-12     Citation Subset:  IM; S    
University Institute of Motor Sciences, Faculty of Motor Sciences, Laboratory of Exercise Physiology, Rome, Italy.
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MeSH Terms
Isometric Contraction / physiology*
Muscle Fatigue / physiology
Nonlinear Dynamics
Physical Endurance / physiology*

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