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Evaluation of positive G sub Z tolerance following simulated weightlessness (bedrest)The magnitude of physiologic changes which are known to occur in human subjects exposed to varying levels of + G sub Z acceleration following bed rest simulation of weightlessness was studied. Bed rest effects were documented by fluid and electrolyte balance studies, maximal exercise capability, 70 deg passive tilt and lower body negative pressure tests and the ability to endure randomly prescribed acceleration profiles of +2G sub Z, +3G sub Z, and +4G sub Z. Six healthy male volunteers were studied during two weeks of bed rest after adequate control observations, followed by two weeks of recovery, followed by a second two-week period of bed rest at which time an Air Force cutaway anti-G suit was used to determine its effectiveness as a countermeasure for observed cardiovascular changes during acceleration. Results showed uniform and significant changes in all measured parameters as a consequence of bed rest including a reduced ability to tolerate +G sub Z acceleration. The use of anti-G suits significantly improved subject tolerance to all G exposures and returned measured parameters such as heart rate and blood pressure towards or to pre-bed-rest (control) values in four of the six cases.
Document ID
19740001979
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Jacobson, L. B. (PHS Hospital San Francisco, United States)
Hyatt, K. H. (PHS Hospital San Francisco, United States)
Sullivan, R. W. (PHS Hospital San Francisco, United States)
Cantor, S. A. (PHS Hospital San Francisco, United States)
Sandler, H. (PHS Hospital San Francisco, United States)
Rositano, S. A. (NASA Ames Research Center Moffett Field, CA, United States)
Mancini, R. E. (NASA Ames Research Center Moffett Field, CA, United States)
Date Acquired
September 3, 2013
Publication Date
August 1, 1973
Subject Category
Biosciences
Report/Patent Number
NASA-TM-X-62311
Accession Number
74N10091
Funding Number(s)
PROJECT: RTOP 970-23-30-02
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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