ABSTRACT
Sampling irradiation of spacesuit "Orlan-M" allowed construction of a simulation model of the spacesuit shielding function for critical body organs. The critical organs self-shielding model is a Russian standard anthropomorphic phantom. Radiation protective quality of the spacesuit was assessed by calculating the dose attenuation rates for several critical body organs of an ISS crewmember implementing EVA. These calculations are intended for more accurate assessment of radiation risk to the ISS crews donning "Orlan-M" in near-Earth orbits.
Subject(s)
Extravehicular Activity , Radiation Protection/instrumentation , Space Suits , Spacecraft , Equipment Design , HumansABSTRACT
Additional energy expenses due to stretching of the elastic elements of anti-loading suit (ALS) "Penguin" as a whole (shoulders-feet) or only its lower part (waist-feet) in the course of cyclic leg movements were measured in five female and five male volunteers. ALS design enabled tensometric monitoring of efforts applied to specific elastic elements, and total efforts applied to the shoulder or pelvic girdles separately. Energy spend were determined with the indirect calorimetric techniques from the data of the expired air analysis. Registered were electromyograms of m. longus spinae, femoral extensor (m. biceps femoris) and femoral flexor (m. rectus femoris), and m. gastrocnemius. On the first stage, bicycle ergometer was pedaled w/o loading with a frequency of 60 cycles/min. The next stage included testing by incremental loading in which pedaling ceased at the pulse rate of 150/min. Results of the experiments that did not require stretching elastic parts of the suit and in which the total strain effort made up 20 to 25 kg and 15 to 16 kg by males and females, respectively, were compared. It was ascertained that ALS enhanced metabolism during motion by 20 to 30%; however, there was no significant difference in energy expenses when loaded by the whole suit or only its lower part.
Subject(s)
Adaptation, Physiological/physiology , Energy Metabolism , Movement/physiology , Space Suits , Weight-Bearing/physiology , Adult , Aerospace Medicine , Electromyography , Exercise Test , Female , Heart Rate , Humans , Male , Muscle Contraction , Muscle, Skeletal/physiologyABSTRACT
According to the previous study [2], simulation of the physiological effects of weightlessness leads to deconditioning of the respiratory muscles which, in its turn, may be a factor impacting the aerobic working capacity. In the present work the experimental findings laid the basis for a physiological concept for medical/engineering requirements to countermeasures against deconditioning of the respiratory muscles, designing and laboratory and physiological testing of a prototype of training loading vest Elastik-R. The vest was shown to enhance speed and force qualities of the respiratory muscles in training athletes, to improve ventilation and gas-exchange functions of the lung, and to increase physical performance and aerobic capacity. Recommendations on utilization of the Elastik-R vest during space flight have been issued.
Subject(s)
Exercise/physiology , Hypokinesia/prevention & control , Respiratory Muscles/physiopathology , Weightlessness , Work Capacity Evaluation , Adolescent , Adult , Aerobiosis/physiology , Aerospace Medicine , Follow-Up Studies , Humans , Hypokinesia/metabolism , Hypokinesia/physiopathology , Male , Middle Aged , Respiratory Function Tests , Respiratory Muscles/metabolismABSTRACT
Changes in cardiovascular parameters of test subjects wearing anti-G suits were studied under static conditions. The study was carried out, using methods of radioactive label dilution, radiocardiography and tetrapolar rheography. The study demonstrated the highest level of physiological reactions within short transition periods after inflation and deflation of suit bladders.
Subject(s)
Gravitation , Hemodynamics , Protective Clothing , Adolescent , Adult , Blood Pressure , Blood Volume , Heart/physiology , Heart Rate , Humans , Male , Time FactorsABSTRACT
The paper gives the experimental findings on the pattern and value of circulation changes in ten test subjects exposed to oxygen breathing at positive pressure of 20 mm Hg. The major parameters of central circulation were registered by the method of radioactive label (I131) dilution. During the exposure the test subjects showed an average 27% decrease in the cardiac output as compared with the control level. The test subjects who were pretrained to the exposure displayed a smaller reduction of cardiac output. It is suggested that the circulation changes found under the experimental conditions were mainly induced by peripheral changes rather than by the cardiac function. It is concluded that the reduction of cardiac output is associated with a decrease of the venous return to the heart caused by the diminished circulating blood volume and by the increased total peripheral resistance.
