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Dynamic Leg Exercise Improves Tolerance to Lower Body Negative PressureThese results clearly demonstrate that dynamic leg exercise against the footward force produced by LBNP substantially improves tolerance to LBNP, and that even cyclic ankle flexion without load bearing also increases tolerance. This exercise-induced increase of tolerance was actually an underestimate, because subjects who completed the tolerance test while exercising could have continued for longer periods. Exercise probably increases LBNP tolerance by multiple mechanisms. Tolerance was increased in part by skeletal muscle pumping venous blood from the legs. Rosenhamer and Linnarsson and Rosenhamer also deduced this for subjects cycling during centrifugation, although no measurements of leg volume were made in those studies: they found that male subjects cycling at 98 W could endure 3 Gz centrifugation longer than when they remained relaxed during centrifugation. Skeletal muscle pumping helps maintain cardiac filling pressure by opposing gravity-, centrifugation-, or LBNP-induced accumulation of blood and extravascular fluid in the legs.
Document ID
19970009631
Document Type
Reprint (Version printed in journal)
Authors
Watenpaugh, D. E. (NASA Ames Research Center Moffett Field, CA United States)
Ballard, R. E. (NASA Ames Research Center Moffett Field, CA United States)
Stout, M. S. (NASA Ames Research Center Moffett Field, CA United States)
Murthy, G. (NASA Ames Research Center Moffett Field, CA United States)
Whalen, R. T. (NASA Ames Research Center Moffett Field, CA United States)
Hargens, A. R. (NASA Ames Research Center Moffett Field, CA United States)
Date Acquired
August 17, 2013
Publication Date
May 1, 1994
Publication Information
Publication: Aviation and Space and Environmental Medicine
Subject Category
Aerospace Medicine
Report/Patent Number
NASA-CR-202620
NAS 1.26:202620
Funding Number(s)
PROJECT: RTOP 199-14-12-04
Distribution Limits
Public
Copyright
Public Use Permitted.
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