Usefulness of daily +2Gz load as a countermeasure against physiological problems during weightlessness

Iwasaki, Katsurô; Sasaki, Tsuyoshi; Hirayanagi, Kaname; Yajima, Kazuyoshi

doi:10.1016/s0094-5765(01)00101-1

Cited by 47 publications

(46 citation statements)

References 24 publications

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“…Hence, cardiac parasympathetic activity may be reduced during 14-day simulated weightlessness. These results are consistent with previous reports (Cooke et al 2000;Custaud et al 2002;Hughson et al 1994;Iwasaki et al 2000Iwasaki et al , 2001Pavy-LeTraon et al 1997;Sigaudo et al 1998). Associated with that, the ratio of low to high frequency power increased after bed rest in the control group, suggesting relative sympathetic dominance of the heart.…”

Section: Discussionsupporting

confidence: 93%

“…Hence, associated with decreased cardiac parasympathetic activity, the vagally mediated spontaneous arterial-cardiac baroreflex function may be reduced during 14-day simulated weightlessness. These results are also remarkably consistent with previous reports (Cooke et al 2000;Custaud et al 2002;Hughson et al 1994;Iwasaki et al 2000Iwasaki et al , 2001Pavy-LeTraon et al 1997;Sigaudo et al 1998). However, there are some possible limitations and concerns of this method (Iwasaki et al 2000(Iwasaki et al , 2001.…”

Section: Spontaneous Arterial-cardiac Baroreflexsupporting

confidence: 92%

“…Therefore, it is considered that intermittent exposure to artificial hypergravity might provide a countermeasure against changes in the cardiovascular system when it is used in space (Convertino 1998;Iwasaki et al 1998). In fact, our preliminary study (Iwasaki et al 2001), and the other (Korolkov et al 2001), showed the positive effects of an intermittent exposure to artificial hypergravity on cardiovascular changes during simulated microgravity. Also, artificial hypergravity may be effective in various other physiological problems induced by microgravity (e.g.…”

Section: Introductionmentioning

confidence: 69%

“…For example, cardiac parasympathetic activity and spontaneous arterial-cardiac baroreflex function (Cooke et al 2000;Custaud et al 2002;Hughson et al 1994;Iwasaki et al 2000Iwasaki et al , 2001Pavy-LeTraon et al 1997;Sigaudo et al 1998) are reduced after space flight or bed rest, associated with a reduction in plasma volume (Alfrey et al 1996;Buckey et al 1996;Custaud et al 2002;Hughson et al 1994;Iwasaki et al 2000Iwasaki et al , 2001. These changes may reduce the ability to control cardiovascular systems of astronauts.…”

Section: Introductionmentioning

confidence: 99%

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Hypergravity exercise against bed rest induced changes in cardiac autonomic control

et al. 2005

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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 ms(2) 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 ms(2); 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.

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Section: Discussionsupporting

confidence: 93%

Section: Spontaneous Arterial-cardiac Baroreflexsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 99%

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Hypergravity exercise against bed rest induced changes in cardiac autonomic control

et al. 2005

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“…Other studies of physiological responses to intermittent gravity have been performed in groundbased laboratories, but most have targeted cardiovascular responses (Iwasaki et al 2001, Iwase et al 2002, Evans et al 2004 or motion sickness responses (Young et al 2001, Hecht et al 2002. Intermittent rotating room studies discussed in Section 5.2 provide some insight into per-and post-rotatory adaptation of body segment movements related to posture and gait.…”

Section: Effects Of Artificial Gravitymentioning

confidence: 99%