Nine months in space: Effects on human autonomic cardiovascular regulation

William H. Cooke, James E. Ames IV, Alexandra A. Crossman, James F. Cox, Tom A. Kuusela, Kari U O Tahvanainen, L. Boyce Moon, Jürgen Drescher, Friedhelm J. Baisch, Tadaaki Mano, Benjamin D. Levine, C. Gunnar Blomqvist, Dwain L. Eckberg

Research output: Contribution to journalArticle

77 Scopus citations


We studied three Russian cosmonauts to better understand how long-term exposure to microgravity affects autonomic cardiovascular control. We recorded the electrocardiogram, finger photoplethysmographic pressure, and respiratory flow before, during, and after two 9-mo missions to the Russian space station Mir. Measurements were made during four modes of breathing: 1) uncontrolled spontaneous breathing; 2) stepwise breathing at six different frequencies; 3) fixed-frequency breathing; and 4) random-frequency breathing. R wave-to-R wave (R-R) interval standard deviations decreased in all and respiratory frequency R-R interval spectral power decreased in two cosmonauts in space. Two weeks after the cosmonauts returned to Earth, R-R interval spectral power was decreased, and systolic pressure spectral power was increased in all. The transfer function between systolic pressures and R-R intervals was reduced in-flight, was reduced further the day after landing, and had not returned to preflight levels by 14 days after landing. Our results suggest that long-duration spaceflight reduces vagal-cardiac nerve traffic and decreases vagal baroreflex gain and that these changes may persist as long as 2 wk after return to Earth.

Original languageEnglish (US)
Pages (from-to)1039-1045
Number of pages7
JournalJournal of applied physiology
Issue number3
StatePublished - 2000


  • Baroreflex
  • Cardiac control
  • Space station Mir

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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  • Cite this

    Cooke, W. H., Ames IV, J. E., Crossman, A. A., Cox, J. F., Kuusela, T. A., Tahvanainen, K. U. O., Moon, L. B., Drescher, J., Baisch, F. J., Mano, T., Levine, B. D., Blomqvist, C. G., & Eckberg, D. L. (2000). Nine months in space: Effects on human autonomic cardiovascular regulation. Journal of applied physiology, 89(3), 1039-1045.