Document Detail

Effects of an eight-day space flight on microvibration and physiological tremor.
MedLine Citation:
PMID:  9249536     Owner:  NLM     Status:  MEDLINE    
Microgravity was used to study accelerometrically recorded microvibration (MV) and postural tremor (PT) at reduced muscle tone on one cosmonaut before, during, and after an 8-day space flight on the Russian Mir station. MV of the relaxed forearm in the 1 g environment showed the typical 7- to 13-Hz resonance oscillations triggered by the heart beat. In 0 g, these pulsations shifted to below 5 Hz and the waveform became similar to an ultralow frequency acceleration ballistocardiogram. PT of the arm stretched forward showed an irregular waveform in 1 g. In 0 g, the higher-frequency components were reduced and again an ultralow frequency ballistocardiogram emerged. As a control, hand force tremor was recorded as well; it was not affected by the gravity condition. A second-order analog with muscle stiffness (C) as parameter was used to evaluate the measurements. For MV it could be shown that cardiac impacts produce damped resonance oscillations when C is high enough (1 g). At low C (0 g), this resonance phenomenon is essentially filtered out. For PT both neuromuscular and cardiovascular forces produce an irregular output; when C is lowered (0 g) the higher-frequency content is strongly reduced. It is concluded that both MV and PT waveforms are sensitive to musculoskeletal stiffness, such that at the lowest stiffness achieved the cardiac impact dominates. In 1 g, the cosmonaut's data were not significantly different from the results in a control group (n = 6).
E Gallasch; M Moser; I B Kozlovskaya; T Kenner; A Noordergraaf
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Publication Detail:
Type:  Case Reports; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of physiology     Volume:  273     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1997 Jul 
Date Detail:
Created Date:  1997-09-03     Completed Date:  1997-09-03     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  R86-92     Citation Subset:  IM; S    
Physiologisches Institut, Universität Graz, Austria.
Space Flight Mission:
Flight Experiment; Mir Project; Soyuz Project; Soyuz TM13 Project; long duration; manned; short duration
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MeSH Terms
Cardiovascular Physiological Phenomena
Isometric Contraction*
Motor Activity / physiology
Movement / physiology
Muscle Tonus
Muscle, Skeletal / physiology*,  physiopathology
Space Flight*
Time Factors
Tremor / physiopathology*

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

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