Hypergravity exercise against bed rest induced changes in cardiac autonomic control

Ken Ichi Iwasaki, Tomoki Shiozawa, Atsunori Kamiya, Daisaku Michikami, Kaname Hirayanagi, Kazuyoshi Yajima, Satoshi Iwase, Tadaaki Mano

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29 Citations (Scopus)

Abstract

An intermittent exposure to artificial hypergravity with physical exercise by a human centrifuge may provide a countermeasure against various physiological problems after space flight. To test the effects of hypergravity with ergometric exercise on dynamic regulation of heart rate during weightlessness, we quantified autonomic cardiovascular control before and after head-down-tilt bed rest (HDBR) with and without the countermeasure. Twelve male subjects underwent a 14-day period of HDBR. Six of them were exposed to a hypergravity (+1.2 Gz acceleration at heart level) for 30 min with ergometric exercise (60 W, n = 4; 40 W, n = 2) as a countermeasure on day 1, 2, 3, 5, 7, 9, 11, 12, 13 and 14, during HDBR (CM group). The remaining six were not exposed to a hypergravity exercise during HDBR (control group). Blood pressure and ECG were recorded at a supine position before and after HDBR. The high frequency power of R-R interval (HFRR; 1,008±238 to 353±56 ms2 P < 0.05) as an index of cardiac parasympathetic activity, and transfer function gain between BP and R-R interval in the high frequency range (GainHF; 21.9±5.4 to 14.5±4.2 ms/mmHg, P < 0.01) as an index of vagally mediated arterial-cardiac baroreflex, decreased significantly after HDBR in the control group. However, these changes were not statistically significant in the CM group (HFRR, 1,150±344 to 768±385 ms2; GainHF, 21.5±3.3 to 18.6±3.4 ms/mmHg). Moreover, baroreflex gain by sequence analysis showed similar results. This observation suggests that the intermittent exposure to hypergravity with ergometric exercise may attenuate the decreases in the parasympathetic activity and the spontaneous arterial-cardiac baroreflex function after weightlessness.

Original languageEnglish
Pages (from-to)285-291
Number of pages7
JournalEuropean Journal of Applied Physiology
Volume94
Issue number3
DOIs
Publication statusPublished - Jun 1 2005
Externally publishedYes

Keywords

  • Artificial gravity
  • Autonomic nervous system
  • Baroreflex
  • Ergometer
  • Microgravity

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Public Health, Environmental and Occupational Health
  • Physiology (medical)

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  • Cite this

    Iwasaki, K. I., Shiozawa, T., Kamiya, A., Michikami, D., Hirayanagi, K., Yajima, K., Iwase, S., & Mano, T. (2005). Hypergravity exercise against bed rest induced changes in cardiac autonomic control. European Journal of Applied Physiology, 94(3), 285-291. https://doi.org/10.1007/s00421-004-1308-x