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Effect of simulated weightlessness on exercise-induced anaerobic thresholdThe effect of simulated weightlessness, induced by ten days of continuous bedrest (BR) in the -6 deg head-down position, on the exercise-induced anaerobic threshold (AT) was determined by comparing specific ventilatory and gas-exchange measurements during an incremental ergometer test performed before and after BR. The primary index for determining the exercise-induced AT values of each subject was visual identification of the workrate or oxygen uptake (VO2) at which the ratio of the expired minute ventilation volume (VE) to VO2 exhibited a systematic increase without a concomitant increase in the VE/VCO2 value. Following BR, the mean VO2max of the subjects decreased by 7.0 percent, and the AT decreased from a mean of 1.26 L/min VO2 before BR to 0.95 L/min VO2 after BR. The decrease in AT was manifested by a decrease in both absolute and relative workrates. The change in AT correlated significantly with the change in plasma volume but not with the change in VO2max. The results suggest that the reduction in AT cannot be completely explained by the reduction in VO2, and that the AT decrease is associated with the reduction in intravascular fluid volume.
Document ID
Document Type
Reprint (Version printed in journal)
Convertino, V. A.
(NASA John F. Kennedy Space Center Cocoa Beach, FL, United States)
Karst, G. M.
(NASA John F. Kennedy Space Center Cocoa Beach, FL, United States)
Kirby, C. R.
(NASA John F. Kennedy Space Center Cocoa Beach, FL, United States)
Goldwater, D. J.
(NASA Kennedy Space Center; Bionetics Corp., Cocoa Beach, FL; NASA, Ames Research Center Moffett Field, CA, United States)
Date Acquired
August 12, 2013
Publication Date
April 1, 1986
Publication Information
Publication: Aviation, Space, and Environmental Medicine
Volume: 57
ISSN: 0095-6562
Subject Category
Aerospace Medicine
Accession Number
Distribution Limits

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