Early cardiovascular adaptation to simulated zero gravity

Nixon, J.V.; Murray, R. G.; Bryant, Carol A.; Johnson, Robert L.; Mitchell, Jere H.; Holland, O. B.; Gomez-Sanchez, C.; Vergne-Marini, P.; Blomqvist, C. Gunnar

doi:10.1152/jappl.1979.46.3.541

Cited by 144 publications

(90 citation statements)

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“…Blood and plasma volume was decreased by a mean value of 4.4% and 7.9%, respectively. This fluid volume loss was reflected in the significant decrease in body mass, which was comparable with previous results (Nixon et al, 1979;Gaffney et al, 1985). They reported a significant reduction in PV of up to 500 ml in 24 h. Furthermore, head-down bed rest induces an initial cephalad fluid shift with an inhibition of the renin-angiotensin system and ADH.…”

supporting

confidence: 88%

“…The central hypervolemia affects hormonal regulation of fluid excretion and stimulates central cardiac volume receptors, resulting in a loss of plasma volume (Norsk et al, 1993;Duranteau et al, 1995). Some papers have reported that plasma volume (PV) decreases during bed rest within 1-2 d and this lower level was maintained during subsequent bed rest (Volicer et al, 1976;Nixon et al, 1979;Fortney et al, 1991;Norsk et al, 1993;Johansen et al, 1997). In the present study, 24 h 6˚head-down tilt bed rest resulted in a total urine volume (2052 ± 249 ml·d -1 ) that was in excess of fluid intake (1320 ± 67 ml·d -1 ).…”

mentioning

confidence: 99%

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Resistance exercise combined with KAATSU during simulated weightlessness

Kubota¹,

Takano²,

Tsutsumi³

et al. 2008

Int. J. KAATSU Ttaining Res.

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The application of a gravity-specific stress (e.g. LBNP), in combination with exercise, prevents cardiovascular deconditioning in space flight. KAATSU training is a method to induce blood pooling in capacitance vessels by restricting venous return (as with LBNP) and which when combined with lowintensity resistance (RE) exercise produces remarkable muscle mass and muscle strength gains. The purpose of this study was to investigate the hemodynamic and neurohumonal responses induced by KAATSU in combination with leg RE (30 % 1 RM), during simulated weightlessness (6˚ head-down tilt for 24 h, n=7). Following 24 h bed rest 6˚ head-down tilt, body mass was decreased from 75.3 ± 3.9 to 73.3 ± 3.8 Kg (P<0.01). Blood volume (BV) and plasma volume (PV) were reduced by -4.4 ± 1.4% and -7.9 ± 2.5%, respectively. During RE, BV and PV were significantly decreased; the changes with KAATSU induced a lower-body venous pooling, resulting in a sustained decrease in stroke volume (SV; from 77.0 ± 4.4 ml to 55.9 ± 5.1 ml; P<0.01) that was comparable to resting SV while standing. Consequently, RE heart rate (HR) was greater with KAATSU. The serum concentrations of plasma renin activity (PRA), vasopressin (ADH), noradrenaline (NOR), and lactate were also significantly elevated during RE with KAATSU as compared to control RE. These hemodynamic and neurohumoral responses following head-down tilt and during RE closely approximate the gravity-specific stress observed with LBNP. Thus, when used in combination with RE, KAATSU may be a useful countermeasure in microgravity. Key words: KAATSU training, leg press, bed rest, plasma renin activity, noradrenaline ORIGINAL ARTICLECorrespondence to: Toshiaki Nakajima, MD, Department of Ischemic Circulatory Physiology, KAATSU Training, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan 113-8655 masamasa@pb4.so-net.ne.jp See end of article for authors' affiliations ProtocolSubjects maintained a 24-hour period of bed rest in -6˚head-down tilt position (-6˚bed rest). Transportation and toilet procedures were restricted to the head-down recumbent position. Subjects were allowed to rest on their elbows during meals and could move volitionally but remained horizontal to the bed. Subject's diet, fluid intake, and urine volume were monitored.After 24 h -6˚bed rest, control blood samples were taken. Following bed rest subjects were randomly assigned to one of two groups: one group performed leg press RE without KAATSU, followed by a 2-h rest interval and then repeated the leg press RE with KAATSU ( 150-160 mmHg cuff pressure; Fig.1). The other group performed leg press RE with KAATSU followed by a 2-h rest interval and then repeated the leg press RE without KAATSU. Hemodynamic parameters and venous blood samples were collected prior to, during, and following RE. All exercise was performed in the head-down tilt position. Immediately following RE, the KAATSU was released and hemodynamic parameters and blood samples were again collected during a 5-10 min recovery period. After 60 min recovery, the subjec...

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supporting

confidence: 88%

mentioning

confidence: 99%

Resistance exercise combined with KAATSU during simulated weightlessness

Kubota¹,

Takano²,

Tsutsumi³

et al. 2008

Int. J. KAATSU Ttaining Res.

View full text Add to dashboard Cite

show abstract

“…Then, blood and plasma volume was decreased by a mean value of 4.4 and 7.9%, respectively. This fluid volume loss was reflected in the significant decrease in body mass and IVC diameter, which was compatible with the previous papers (Nixon et al 1979;Gaffney et al 1985). Furthermore, head-down bed rest induces an initial cephalad-fluid shift with an inhibition of the renin-angiotensin system and ADH.…”

Section: Discussionsupporting

confidence: 90%

Hemodynamic responses to simulated weightlessness of 24-h head-down bed rest and KAATSU blood flow restriction

et al. 2008

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The KAATSU training is a unique method of muscle training with restricting venous blood flow, which might be applied to prevent muscle atrophy during space flight, but the effects of KAATSU in microgravity remain unknown. We investigated the hemodynamic responses to KAATSU during actually simulated weightlessness (6°h ead-down tilt for 24 h, n = 8), and compared those to KAATSU in the seated position before bed rest. KAATSU was applied to the proximal ends of both the thighs. In the seated position before bed rest, sequential incrementing of KAATSU cuff pressure and altering the level of blood flow restriction resulted in a decrease in stroke volume (SV) with an increase in heart rate (HR). KAATSU (150-200 mmHg) decreased SV comparable to standing.Following 24-h bed rest, body mass, blood volume (BV), plasma volume (PV), and diameter of the inferior vena cava (IVC) were significantly reduced. Norepinephrine (NOR), vasopressin (ADH), and plasma renin activity (PRA) tend to be reduced. A decrease in SV and CO induced by KAATSU during the simulated weightlessness was larger than that in the seated position before bed rest, and one of eight subjects developed presyncope due to hypotension during 100 mmHg KAATSU. High-frequency power (HF RR ) decreased during KAATSU and standing, while low-frequency/high-frequency power (LF RR /HF RR ) increased significantly. NOR, ADH and PRA also increased during KAATSU. These results indicate that KAATSU blood flow restriction reproduces the effects of standing on HR, SV, NOR, ADH, PRA, etc., thus stimulating a gravity-like stress during simulated weightlessness. However, syncope due to lower extremity blood pooling and subsequent reduction of venous return may be induced during KAATSU in microgravity as reported in cases of lower-body negative pressure.

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“…Applying LBNP at -40 to -50 mmHg causes a decrease in central venous pressure similar to that during a change from the supine to upright position (37, 167,244,250,355).…”

Section: Intravascular and Intracardiac Pressuresmentioning

confidence: 97%

“…Parker and Case (259) recently suggested that the normal human left ventricle operates at or near its maximal functional size at rest in the supine position, but data obtained during head-down tilt (250,251), supine exercise (262), and immersion clearly indicate a diastolic reserve capacity. The increased central venous pressure during upright immersion is associated with a large increase in heart size and stroke volume (4,18,40,81,95,195,269).…”

Section: Cardiac Dimensions and Pump Performancementioning

confidence: 99%