Effect of standing or walking on physiological changes induced by head down bed rest: Implications for spaceflight

J. Vernikos, D. A. Ludwig, A. C. Ertl, C. E. Wade, L. Keil, D. O'Hara

Research output: Contribution to journalArticlepeer-review

73 Scopus citations

Abstract

Background/Hypothesis: To simulate exposure to microgravity and to determine the effectiveness of intermittent exposure to passive and active +1 Gz force (head-to-foot) in preventing head-down bed rest (HDBR) deconditioning, 4 d of 6° HDBR were used. Methods: Volunteers were 9 males, 30-50 yr, who performed periodic standing or controlled walking for 2 or 4 h · d-1 in 15-min bouts, one bout per hour, or remained in a continuous HDBR control condition (0 Gz). Results: Standing 4 h (S4) completely prevented, and standing 2 h (S2) partially prevented, decreases in post-HDBR orthostatic tolerance (survival rates with 30 min of upright tilt at 60°). Walking, both 2 h (W2) and 4 h (W4), and S4 attenuated decreases in peak oxygen uptake compared to 0 Gz. Compared to 0 Gz, both S4 and W4 attenuated plasma volume loss during HDBR. Urinary Ca2+ excretion increased over time with HDBR; the quadratic trend for urinary Ca2+, however, was attenuated with W2 and W4. Conclusions: We concluded that various physiological systems benefit differentially from passive +1 Gz or activity in +1 Gz and, in addition to the duration of the stimulus, the number of exposures to postural stimuli may be important moderating factor.

Original languageEnglish (US)
Pages (from-to)1069-1079
Number of pages11
JournalAviation Space and Environmental Medicine
Volume67
Issue number11
StatePublished - Nov 1 1996

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health

Fingerprint Dive into the research topics of 'Effect of standing or walking on physiological changes induced by head down bed rest: Implications for spaceflight'. Together they form a unique fingerprint.

Cite this