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Maximal exercise as a countermeasure to orthostatic intolerance after spaceflightPrevious investigators have suggested that maximal exercise performed 24 h before the end of bed rest, a spaceflight analog, restores prebed rest plasma volume, baroreflex responses, and orthostatic tolerance. PURPOSE: In this case report, we examined the effect of a similar exercise protocol 24 h before a Shuttle landing on the orthostatic responses of four crewmembers (EX) after spaceflights of 8-14 d. Four additional crewmembers (CON) served as controls and did not perform exercise during the final day of the flight. METHODS: Each crewmember performed a 10-min stand test approximately 10 d before launch (L-10) and within 1-2 h of landing (R+0). Cardiac stroke volume was measured (Doppler ultrasound) supine and during each min of standing for three EX and three CON subjects. RESULTS: Preflight, all crewmembers completed the stand test and each group had similar heart rate and blood pressure responses. Postflight, all subjects also completed the 10-min stand test. Each group had similarly elevated supine and standing heart rates, elevated diastolic and mean arterial blood pressures, and reduced pulse pressures compared to L-10. However, postflight cardiac output, mean +/- SEM, (EX: 4.5+/-0.6 L x min(-1); CON: 3.1+/-0.3 L x min(-1)) and stroke volume (EX: 43+/-7 mL x beat; CON: 30+/-6 mL x beat) were higher after 10 min standing in the EX subjects compared to CON subjects. CONCLUSIONS: For these four crewmembers, maximal exercise performed 24 h before landing may have helped maintain stroke volume but did not maintain heart rate and blood pressure responses during standing compared to preflight.
Document ID
20040112566
Acquisition Source
Johnson Space Center
Document Type
Reprint (Version printed in journal)
Authors
Moore, A. D. Jr
(NASA Johnson Space Center Houston TX United States)
Lee, S. M.
Charles, J. B.
Greenisen, M. C.
Schneider, S. M.
Date Acquired
August 21, 2013
Publication Date
January 1, 2001
Publication Information
Publication: Medicine and science in sports and exercise
Volume: 33
Issue: 1
ISSN: 0195-9131
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
Flight Experiment
manned
NASA Discipline Cardiopulmonary
short duration
NASA Center JSC
STS Shuttle Project

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