Document Detail


Effect of 28-day head-down bed rest with countermeasures on heart rate variability during LBNP.
MedLine Citation:
PMID:  8002908     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effect of exercise and LBNP countermeasures on the cardiovascular deconditioning response have been evaluated by the study of heart rate variability during progressive LBNP tests before, during (day 15), and after 28 d continuous 6 degrees head-down tilt bed rest. Twelve healthy men (age 27-42 years) were studied in two groups. Six were assigned to a countermeasure regime (CM) consisting of strenuous short-term resistance exercise once per day, 6 days per week from day 7 to day 28, combined with lower body negative pressure (LBNP, -28 mm Hg) for 15 min on days 16, 18, 20, and 22-28. Results were compared with data from six subjects, matched on the basis of maximum oxygen uptake, who received no countermeasures (No-CM). The main effects of bed rest were seen in reductions in RR-interval, and in total spectral power. The results of spectral analysis showed a significant reduction in an index of parasympathetic activity with a nonsignificant increase in a sympathetic indicator. The fractal component of heart rate variability was reduced also, suggesting a change in cardiovascular control mechanisms. Although there were significant differences between CM and No-CM for a number of variables, there were no bed rest by countermeasure interaction effects in the statistical analysis. These results suggested that this particular series of countermeasures was ineffective in preventing at least certain changes indicative of cardiovascular deconditioning with 28 d head-down tilt bed rest.
Authors:
R L Hughson; Y Yamamoto; A P Blaber; A Maillet; J O Fortrat; A Pavy-LeTraon; J F Marini; A Güell; C Gharib
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  65     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  1994 Apr 
Date Detail:
Created Date:  1994-07-13     Completed Date:  1994-07-13     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  293-300     Citation Subset:  IM; S    
Affiliation:
Department of Kinesiology, University of Waterloo, Ont., Canada.
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MeSH Terms
Descriptor/Qualifier:
Adult
Bed Rest*
Exercise / physiology
Fractals
Heart Rate / physiology*
Humans
Lower Body Negative Pressure*
Male
Spectroscopy, Fourier Transform Infrared
Time Factors

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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