Hypergravity exercise against bed rest induced changes in cardiac autonomic control

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

doi:10.1007/s00421-004-1308-x

Cited by 39 publications

(28 citation statements)

References 19 publications

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“…In both groups, although LFBP tended to increase, these were not statistically signiWcant. In contrast with our results, Iwasaki et al (2005) reported that the LFBP decreased signiWcantly after 14 days of bed rest. However, this result is contradictory with his Wnding of increases in cardiac sympathetic activity detected by HRV spectrum analysis in the same study.…”

Section: Discussioncontrasting

confidence: 99%

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Artificial gravity with ergometric exercise as a countermeasure against cardiovascular deconditioning during 4 days of head-down bed rest in humans

Wang

Yang

et al. 2011

Eur J Appl Physiol

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We have shown previously that combined short-arm centrifuge and aerobic exercise training preserved several physiologically important cardiovascular functions in humans. We hypothesized that artificial gravity (AG) and exercise is effective to prevent changes of physical problems during head-down bed rest (HDBR). To test this hypothesis, 12 healthy male subjects had undergone 4 days of 6° HDBR. Six of them were exposed to AG of an alternating 2-min intervals of +1.0 and +2.0 Gz at foot level for 30 min twice per day with ergometric exercise of 40 W as a countermeasure during bed rest (CM group), while the remaining six served as untreated controls (no-CM group). Before and after 4 days of bed rest, leg venous hemodynamics was assessed by venous occlusion plethysmography and autonomic cardiovascular control estimated by power spectral analysis of blood pressure and heart rate. Further, orthostatic tolerance was evaluated by a 75° head-up tilt test and physical working capacity was surveyed by near maximal physical working capacity test before and after bed rest. The data showed that combined centrifuge and exercise applied twice daily for a total of 60 min during 4 days of HDBR prevented (a) a decrease in working capacity, (b) autonomic dysfunction (a decrease in the activity of parasympathetic cardiac innervation) and (c) an increase in leg venous flow resistance. The combination of a 30 min alternating of +1.0 and +2.0 Gz for twice per day of AG with 40 W ergometric exercise may offer a promising countermeasure to short duration simulated microgravity.

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Section: Discussioncontrasting

confidence: 99%

“…Moreover, LFBP showed no signiWcant changes after bed rest in the CM group. These results are similar to those of previous studies (Evans et al 2004;Iwasaki et al 2001Iwasaki et al , 2005. These results may suggest that AG with exercise might attenuate the changes in autonomic modulation of cardiac period.…”

Section: Discussionsupporting

confidence: 92%

Artificial gravity with ergometric exercise as a countermeasure against cardiovascular deconditioning during 4 days of head-down bed rest in humans

Wang

Yang

et al. 2011

Eur J Appl Physiol

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“…Katayama et al 2004 was the only study to prevent the decrease in stroke volume with AG coupled with cycling. There was no significant decrease in the control group of the other AG plus cycling study, Iwasaki et al 2005. This might be due to its shorter duration of 14 days versus a duration of 28 days for the Katayama study.…”

Section: Cardiovascular Systemmentioning

confidence: 75%

“…For parasympathetic activity, or HF heart rate, all three Japanese studies prevented its decrease. However, the increase in sympathetic activity, or HF/LF heart rate was only prevented with AG coupled with cycling (Iwasaki et al 2005). Dissections of arteries were performed in some animal studies.…”

Section: Cardiovascular Systemmentioning

confidence: 99%

A critical benefit analysis of artificial gravity as a microgravity countermeasure

2010

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Human physiological systems, especially the cardiovascular and musculo-skeletal systems, are well-known to decondition during spaceflight. Several countermeasures that are in use today have been rigorously developed over the decades to combat this deconditioning. However, these countermeasures are system specific and have proven to be only partially effective. Artificial gravity has been persistently discussed as a countermeasure that potentially has salutary effects on all physiological systems, though few ground-based studies have been performed in comparison to other countermeasures. The current analysis attempts to elucidate the effectiveness of artificial gravity by directly comparing results of previously published and unpublished deconditioning studies with those of more traditional, ground-based countermeasures (i.e. resistive exercise, aerobic exercise, lower body negative pressure, or some variation of these). Animal studies were also evaluated to supplement the knowledge base and to fill gaps in the human countermeasure literature. Designs of published studies, such as study duration, deconditioning paradigm, subject selection criteria, measurements taken, etc., were confounding variables; however, studies that had some measure of consistency between these variables were compared, although notable differences were cited in the analysis and discussion. Results indicate that for prolonged spaceflight an artificial gravity-based countermeasure may provide benefits equivalent to traditional countermeasures for the cardiovascular system. Too few comparable, human studies have been performed to draw any conclusions for the musculoskeletal system, although animal studies show some positive results. Gaps in the current knowledge of artificial gravity are identified and guidance for future deconditioning studies is offered. Based on the results of this study, a comprehensive artificial gravity protocol is proposed and future research topics using this countermeasure are

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“…The autonomic nervous system is known to be altered under microgravity (10) and hypergravity (11,12). We have previously examined the role of AC5 in the regulation of the autonomic nervous system in the heart under micro-and hypergravity induced by parabolic flights using transgenic mouse models with AC5 overexpressed in the heart (AC5TG) or with disrupted AC5 (AC5KO) and analyzed heart rate variability during parabolic flight.…”

Section: Introductionmentioning

confidence: 99%

Pharmacological Stimulation of Type 5 Adenylyl Cyclase Stabilizes Heart Rate Under Both Microgravity and Hypergravity Induced by Parabolic Flight

et al. 2012

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Abstract. We previously demonstrated that type 5 adenylyl cyclase (AC5) functions in autonomic regulation in the heart. Based on that work, we hypothesized that pharmacological modulation of AC5 activity could regulate the autonomic control of the heart rate under micro-and hypergravity. To test this hypothesis, we selected the approach of activating AC5 activity in mice with a selective AC5 activator (NKH477) or inhibitor (vidarabine) and examining heart rate variability during parabolic flight. The standard deviation of normal R-R intervals, a marker of total autonomic variability, was significantly greater under micro-and hypergravity in the vidarabine group, while there were no significant changes in the NKH477 group, suggesting that autonomic regulation was unstable in the vidarabine group. The ratio of low frequency and high frequency (HF) in heart rate variability analysis, a marker of sympathetic activity, became significantly decreased under micro-and hypergravity in the NKH477 group, while there was no such decrease in the vidarabine group. Normalized HF, a marker of parasympathetic activity, became significantly greater under micro-and hypergravity in the NKH477 group. In contrast, there was no such increase in the vidarabine group. This study is the first to indicate that pharmacological modulation of AC5 activity under micro-and hypergravity could be useful to regulate the autonomic control of the heart rate.

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Hypergravity exercise against bed rest induced changes in cardiac autonomic control

Cited by 39 publications

References 19 publications

Artificial gravity with ergometric exercise as a countermeasure against cardiovascular deconditioning during 4 days of head-down bed rest in humans

Artificial gravity with ergometric exercise as a countermeasure against cardiovascular deconditioning during 4 days of head-down bed rest in humans

A critical benefit analysis of artificial gravity as a microgravity countermeasure

Pharmacological Stimulation of Type 5 Adenylyl Cyclase Stabilizes Heart Rate Under Both Microgravity and Hypergravity Induced by Parabolic Flight

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