Resistance exercise combined with KAATSU during simulated weightlessness

Abstract

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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