[On medical screening of civilian candidates for cosmonauts by exposure to the head-to-pelvis acceleration profiles].

The subject of analysis was the data on +3 and +5 Gz tolerance of 130 civilian non-pilot applicants for cosmonauts (men and women, aged 23 to 55) gathered over the past 30 years. Length of the centrifuge arm was 7.25 meters and the total number of primary centrifuge runs was 309. For nearly every second of the applicants (46.7%) acceleration at +5 Gz was an ordeal causing distinct vascular or coronary decompensation. Thus, 29.7% exhibited various combinations of brief visual disturbances, tachycardia, tachypnea, and systolic arterial pressure in the shoulders; in 17%, visual disturbances and/or their precursors were combined with exaggerated cardio-vascular functional parameters, arrhythmia, and serious vegetative disorders. Most of those who had failed to endure the first centrifugation were unable to improve G tolerance during next runs; indeed, they showed negative G-tolerance dynamics. G intolerance grew in significance or was exacerbated by new disorders and their combinations. These results testify against exposure of non-pilot applicants for cosmonauts to +5 G, during the primary medical screening.

[Correlation of the cosmonauts' physiological reactions to +Gx loads during deorbit with the hemodynamic shifts in the period of short-term microgravity].

Physiological reactions of four cosmonauts to +Gx during the descent after short-term (less than 30 d) space flights were correlated with the hemodynamic shifts developed previously during the LBNP test and occlusive plethysmography in microgravity. The cosmonauts who had exhibited a sharp decrease in cerebral circulation during the in-flight LBNP tests showed signs of deteriorated cerebral blood flow (vertigo, weakness, hyperhydration) at the attempt to assume the vertical posture and to climb out of the landing module. Also, the cosmonauts found to have the arterial and venous tone significantly dropped in microgravity, suffered petechial hemorrhages in the back integument during the exposure to +Gx. These data suggest a correlation between the physiological reactions of cosmonauts to +Gx at the end of short-term space flight and the shifts in hemodynamics earlier in microgravity.

[+Gx-tolerance by the Cosmonauts of ISS crews 1, 6-9 and visiting crews 1-7 aboard Soyuz vehicles].

Analysis of +Gx tolerance of 15 members of short-term ISS missions and 9 members of long-term ISS missions aboard the Soyuz vehicles showed good tolerance during insertion and satisfactory during descent provided the use of in-flight countermeasures and anti-g suit Kentaur inside the vehicle. Objective data about the tolerance of off-nominal +Gx (6.26 and 8.1 G) pointed to a more pronounced sinus tachycardia and tachypnea in a ballistic descent following long-duration weightlessness as compared with nominal. Physiological deviations were transient, functional by character. Cardiac arrhythmia was largely observed during return to Earth. Two cosmonauts were found to develop prognostically unfavorable ECG indications during off-nominal descent. Main factors in these deviations could be age (above 45) and existence of some individual specifics of cardiac rhythm regulation. These results emphasize the necessity of more careful screening of candidates older than 45 years, as weightlessness may impact their general condition and tolerance of g-loads during return to Earth.

[Effects of occlusive cuffs "Braslet" on crew hemodynamics in short space flights and orthostatic stability post flight]. / Vliianie perezhimnykh manzhet "Braslet" na izmeneniia gemodinamiki v kratkovremennykh kosmicheskikh poletakh i poslepoletnuiu ortostaticheskuiu ustoichivost' kosmonavtov.

Effects of prophylactic device Braslet (occlusive cuffs wrapped around the calf) on hemodynamics were studied at rest and during the LBNP test during and on orthostatic stability post short (one-month) space flights. The ultrasonic procedure was applied to seven cosmonauts who had and six cosmonauts who had not worn the cuffs while in orbit. The device markedly alleviated the subjective feeling of discomfort caused by blood shift toward the cranial end at the beginning of adaptation to microgravity. Reductions in the central and peripheral hemodynamics, cervico-cephalic venous plethora specifically, were sequel to staying in microgravity. Testing of the hemodynamic reactions to LBNP during and after shortflights failed to discover noticeable deltas among the cosmonauts who had and had not worn the cuffs. The first analysis of objective in- and postflight data did not suggest any determent in orthostatic stability of cosmonauts due to application of the Braslet cuffs.

[Effects of centrifugation-related artificial gravity on the human organism. Positive and negative effects]. / Vliianie na organizm cheloveka iskusstvennoi gravitatsii, sozdavaemoi s pomoshch'iu tsentrifugi. Polozhitel'nye i otritsatel'nye éffekty.

Data of investigations of the artificial gravity issues in centrifuge experiments in Russian, USA and Japan over the past 40 years were analyzed. Periodic +Gz centrifugation was used to prevent or eliminate body deconditioning after 3- to 56-d simulated microgravity, and to increase the body functional reserve (orthostatic stability) in ordinary life. Positive effects included prevention of a decline of gravitational stability and reduction or averting the negative effects of simulated microgravity on various physiological systems. Better results can be achieved by combining artificial g-loads with the well-proven methods of combating deconditioning, i.e. physical training on bicycle ergometer and induced hydration. Human tolerance of g-loads on a short-arm centrifuge with a high (100%) gravitational gradient was found no worse than on a mid-arm centrifuge with a lower (20%) gravitational gradient. Negative effects of +Gz on a short-arm centrifuge were revealed and counteracting measures were determined.

[The problem of creation of artificial gravity with the use of a short-radius centrifuge for medical support of interplanetary piloted missions]. / Problema sozdaniia iskusstvennoi sily tiazhesti s pomoshch'iu tsentrifugi korotkogo radiusa dlia meditsinskogo obespecheniia mezhplanetnykh pilotiruemykh poletov.

On the evidence of orbital flights, the system of countermeasures against the effects of microgravity does not fully make for deconditioning of a number of human organs and systems and recovery of preflight physical status and working ability of members of long-term missions takes 1.5 to 2 mos. of the post-flight rehabilitation. In order to maintain the physical form, health and performance of crews in future interplanetary missions, we should be ready to offer them a novel countermeasure, i.e. regular sessions of artificial gravity generated by a short-radius centrifuge (SRC) on board vehicles. The articles presents the substantiation and concept of ground-based simulation studies of health benefits from SRC in interplanetary missions. Of primary concern is development of SRC regimens that will put up a strong opposition to microgravity, assure crew safety, and reduce to the minimum time to fulfill the in-flight countermeasure program. Answers to arising questions can be found by consolidation of the expertise and resources of the countries willing to meet this challenge.

[G-tolerance of female cosmonauts during descent in space flights of 8 up to 169 days in duration]. / Perenosimost' peregruzok zhenshchinami-kosmonavtami na uchastke spuska v kosmicheskikh poletakh dlitel'nost'iu ot 8 do 169 sutok.

Investigations into g-tolerance of female cosmonauts during descent in space flights of varying duration are topical for the present day, as there are little data on this issue. Tolerance of +Gz-loads during descent was analyzed based on the data about 4 female cosmonauts in 5 space flights. The space flights were conventionally divided into short- (8-16 days) and long-term (169 days). In two space flights (16 and 169-d long), tubeless anti-g suit Centaur was warn during descent. In these space flights, g-tolerance of females was quite satisfactory advocating for the possibility for women to fly to space without any constraints. When the anti-g suit was not used, female physiological systems were stressed heavier than male. The spacesuit smoothed away this difference. Our results evidence a distinct positive effect of wearing the anti-g suit by female cosmonauts during descent as it reduces stress to their physiological systems.

[The effect of G-loads on gravity tolerance of monkeys Macaca rhesus during antiorthostatic hypokinesia]. / Vliianie gravitatsionnykh nagruzok v usloviiakh antiortostaticheskoi gipokinezii na gravitatsionnuiu ustoichivost' obez'ian makak rezusov.

Reported are results of 200 centrifuge runs of 24 monkeys Macaca mulatta. Microgravity effects were simulated by 4-wk immobilization with the head tilted down at -6 degrees. The investigation was divided into two series. During series-1, one group of animals was not exposed to centrifugal training, whereas the other group was exposed to +Gz at the magnitudes of 1.2, 1.4 and 1.6 G for 30-40 min 4 to 5 times a week. In series-2, again one group of animals was not trained on the centrifuge but the other was trained at +1.2 Gz for 30 min 2 or 3 times a week. Functional testing by 30-s runs at +3 Gz was performed before and after head-down immobilization. Deterioration of g-load tolerance following simulated microgravity in both groups of untrained macaques was ascribed to the deconditioning effect of simulated microgravity on the body systems. Centrifugal training had, as a rule, positive effect on g-tolerance of the animals though it failed to fully eliminate the negative consequences of simulated microgravity. This means that search after optimal protocols of application of artificial gravity generated by centrifuge needs to be continued. Evaluation of the effectiveness of combining centrifugation with other countermeasures against the adverse effects of microgravity and development of associated protocols can be another area of future research.

[Technique for registration of auricular pulsogram in macaca mulatta monkeys]. / Metodika registratsii ushnoi pul'sogrammy u obez'ian makakov rezusov.

An upgraded technique for registration of auricular pulsogram in monkeys (Macaca mulatta) has been proposed to study shifts in the common artery bed. The measurement is made with a photo-electrical sensor taped to the cartilage of the floor of the auricle and secured with a special cap and helmet of elastic net, and a system for data transfer from the sensor to a register enhanced by preamplifiers. Potentialities of the technique are exemplified by the investigation of Macaca mulatta's tolerance of +Gz loads.

[Role of age in +Gz and +Gx tolerance by female candidates to astronauts]. / Vliianie vozrasta na perenosimost' peregruzok +Gz i +Gx zhenshchinami pri otbore v kosmonavty.

Analyzed was the role of age in the tolerance of +Gz (up to 5 units) and +Gx (up to 8 units) by female candidates to cosmonauts on the stage of initial centrifuge selection in the years of 1979 through to 1993. Selection was made of 26 healthy non-flying women aged 23 to 39 who were divided into 4 groups with 5-year intervals. Female tolerance of g-loads and shifts in a number of physiological parameters during centrifugation were discovered to be age-dependent. The poorest tolerance of +Gz and +Gx loads was typical of women below 25 years, the best, at the age of 31 to 40 years. It was stated that tolerance of these demanding g-loads by women, especially below 30, was generally worse compared with men. There were also some distinctions in the cardiovascular response in women and men. These results point to the significance of centrifugation in selection female candidates to cosmonauts irrespective of their age.

[Human tolerance of +Gx loads in anti-G suits during deorbiting of the "Soiuz" space vehicles]. / Perenosimost' chelovekom peregruzok napravleniia +Gx na uchastke spuska s orbity kosmicheskikh korablei tipa "Soiuz" pri ispol'zovanii protivoperegruzochnykh kostiumov.

Reported are results of the study of tolerance of the "thorax-back" g-loads (+Gx) during deorbiting of 83 total suited and unsuited cosmonauts in the period of 1997-1997. G-loads averaged 3.7 +/- 0.058 units (from 3.1 up to 5.1 units). Pneumatic gradient G-suits (PGS) Karkas and Centaur had a positive effect on the +Gx tolerance of humans following microgravity. As compared with unsuited crews returning from missions of similar duration, wearing PGS has proven to improve the general health of cosmonauts and to reduce the strain of the leg and abdominal muscles. Tight fitting of PGS abolished visual disorders due to the longitudinal component of G-loads that were registered in 6.6% of observations of unsuited cosmonauts. Sinus tachycardia was significantly weaker (P < 0.05). The authors recommend the use of the standard antiblackout Centaur suit as the efficacy of this PGS was equal to that of Karkas while its ergonomic characteristics were superior.

[Tolerance of +Gz loads by space physician Poliakov VV during the active phases of his 438-days space mission]. / Prenosimost' peregruzok +Gx vrachom-kosmonavtom V.V. Poliakovym na aktivnykh uchastkakh kosmicheskogo poleta dlitel'nost'iu 438 sutok.

Tolerance of +Gz loads was assessed in space physician V.V. Polyakov during the active phases of his record, 438-day space mission. On the phases of insertion into orbit the +Gz-tolerance of the space physician was good; a fairly satisfactory g-tolerance during departure of orbit was extenuated by wearing of two anti-g suits (KARKAS-3 and CENTAUR) and administration of countermeasures against the unfavorable effects of space microgravity. His general health state and self-rating were not noticeably altered. +Gz loads in the course of descent from orbit instigated a syndrome characteristic of return to Earth from prolonged microgravity, i.e. a sensation of fierce pressure on the body, difficult breathing and speech, sine tachycardia, tachypnea, singular arrhythmias, petechial hemorrhage in the back integument, and vestibular/autonomous reactions. However, no evidence of any unusual physiological reactions that had never been seen in the other cosmonauts donned in the anti-g suits on earlier and less extended (from 65- to 366-day) missions were found. Extra systoles were registered on the phase of return to Earth after the 438-day but not previous 241-day mission of the space physician; they were probably associated with aging as he made his maiden flight at 47, and the second, at 53. The results speak in favor of the countermeasures against the adverse effects of microgravity applied during the mission, and the anti-g suits worn on the stage of return to Earth.

[Tolerance of +Gx-loads by females before and after a 120-day hypokinesia]. / Perenosimost' peregruzok napravleniia +Gx zhenshchinami do i posle 120-sutochnoi gipokinezii.

The goal of the work was to study female tolerance of g-loads before and after simulated weightlessness, and evaluate the effectiveness of countermeasures and anti-g means proposed for space flight. Centrifuge with a 7.25 m arm was used for 29 runs of 8 female subjects. The subjects were exposed to the transverse loads (+GX) at 8.2 g on a special regimen with the total run time of 9 min to simulate the ballistic descent from orbit in a SOYUZ-TM vehicle. Baseline tolerance of the females to transverse loads up to +8GX was good and satisfactory. Following 120 days of bed rest without the countermeasures or the anti-g suit g-tolerance was significantly lowered as evidenced by visual disorders in 67% of cases and exaggerated, if compared with the pre-hypokinesia levels, heart and respiration rates, i.e. 20% and 23.5%, respectively. The countermeasures and anti-g suit Centaur maintained g-tolerance at essentially the baseline level and precluded visual disorders. Results of the study speak in favor of the countermeasures and anti-g means used by the females in simulated long-duration weightlessness which can be recommended for the final phase of extended space mission.

[Dynamics of tolerance of +G loads by non-flying subjects: a longitudinal study]. / Dinamika perenosimosti peregruzok +G, litsami neletnykh professii pri dlitel'nom nabliudenii.

Selected cosmonauts-investigators may be held on wait for many years. The longitudinal health study is of great significance in the context of prediction of tolerance to various flight stresses. The purpose of this work was to investigate the tolerance to +Gz-loads during extended (up to 18 years) dynamic longitudinal study of 50 male cosmonauts and candidates of non-flying occupations by the data of 363 medical observation runs on a centrifuge with the radius of 7.25 m. Analysis of these data showed that 82 % of the subjects sustained good tolerance of G-loads and only 18 % of the subjects displayed its decrement or instability. A new proof received the data concerning better +Gz-tolerance by subjects aged 31-35 and less tolerance by the subjects younger than 30 and older than 46-50 years. The longitudinal study allowed to identify 4 types of G-tolerance variation, i.e., stable, relatively stable with individual drops down to decreased, non-stable with periodic drops, and a distinct trend towards a decrease. These investigations provided new scientific data about the dynamics of separate physiological functions during exposure to +Gz-loads resultant from longitudinal study of the same group of subjects, and allowed to make an expert prediction of shifts in the G-tolerance.

[Prognostication of man's health status in response to gravity-induced blood shifts based on continuous noninvasive measurement of arterial blood pressure using the Pen'iaz method]. / Prognozirovanie sostoianiia cheloveka v usloviiakh gravitatsionnogo pereraspredeleniia krovi na osnove nepreryvnogo neinvazivnogo izmereniia arterial'nogo davleniia po metodu Pen'iaza.

Exposure to +Gz acceleration, orthostatic tilt tests and LBNP tests causes distinct blood shifts and deterioration of cerebral circulation. In this case syncope episodes may be prevented by continuous monitoring of circulation parameters, specifically arterial pressure (AP). Our investigations have shown that continuous AP measurement by the Penjaz noninvasive technique may help earlier prediction of the health status in response to gravity-induced blood shifts. In this situation the development of a pre-collapse state is preceded by an emergence of distinct AP waves of the second-third order accompanied by a critical drop of pulse pressure. It is concluded that continuous AP measurement in the finger according to the Penjaz noninvasive technique holds promise as a medical monitoring method in a altered gravitational field.

[Tolerance to +G(z) acceleration in rhesus monkeys]. / Perenosimost' peregruzok +G(z) obez'ianzmi makakami rezus.

The procedure of Cosmos-1514 selection and training of rhesus-monkeys included +Gz acceleration tests. Two experimental series were performed. In the first experimental series (52 monkeys) acceleration tolerance was determined with respect to general health condition and behavioral responses of animals, electrocardiographic data (in three standard leads), heart rate and respiration rate. In the second experimental series acceleration tolerance was measured on the basis of blood pressure and flow velocity in the common carotid artery. Rhesus-monkeys exhibited noticeable individual variations in +Gz tolerance as well as in circulation responses to this exposure. The tests helped to select flight animals with a high level of acceleration tolerance.

[+Gz load tolerance in nonflight personnel of different ages]. / Perenosimost' peregruzok +Gz litsami neletnykh professii razlichnogo vozrasta.

Ninety-six healthy nonpilots, aged 21 to 50 years, were exposed to 228 rotations on a 7.25 m arm human centrifuge. The study demonstrated age-related changes in +Gz tolerance of 3 to 5 G (for 30 sec). The subjects at the age 31 to 40 years showed the highest tolerance while the subjects at the age 21 to 25 and 46 to 50 years the lowest tolerance. Young subjects (21-25 years old) often developed an asthenic type of the systolic pressure reaction in the ear lobe and visual disorders whereas older subjects (46-50 years old) displayed cardiac arrhythmias, lower heart rate and delayed recovery of blood pressure after exposure. It was also found that 60-80% subjects aged over 40 well tolerated acceleration of up to 5 G and therefore can be viewed as potential candidates for cosmonauts.

[Resistance to +Gz and +Gx loads of subjects in older age groups, healthy and with initial signs of atherosclerosis]. / Ustoichivost' k peregruzkam +Gz i +Gx u lits starshikh vozrastnykh grupp, zdorovykh i s nachal'nymi priznakami ateroskleroza.

Tolerance to +Gz and +Gx acceleration of healthy and atherosclerotic subjects, aged 40-49, was investigated during 256 centrifugation tests in Bulgaria and the USSR. As compared to the healthy people, the atherosclerotic subjects showed a lower tolerance: when exposed to 7 +Gz the tolerance threshold decreased from 5.93 +/- 0.57 g to 5.7 +/- 0.44 g (i. e. by 0.23 g). Visual disorders in the healthy and atherosclerotic subjects were recorded in 29 and 50%, respectively, and loss of consciousness in 9.56 and 15.15%, respectively (Bulgarian data). When exposed to 5 +Gz and 6 +Gx no subjects displayed visual disorders or loss of consciousness (Soviet data). However, lower tolerance of 5 +Gz due to cardiac arrhythmias was observed in 4.8% atherosclerotic patients and in none healthy subjects. Lower tolerance to 6 +Gx associated with cardiac arrhythmias was recorder in 23.8% atherosclerotic versus 11.8% healthy subjects (i. e. 12% more). Nevertheless, in most subjects, both healthy and atherosclerotic, acceleration tolerance was good. These findings indicate that individual assessment of acceleration tolerance is of great importance for people older than 40 years with health abnormalities.

[Tailward acceleration tolerance of middle-aged persons before and after a 7-day immersion]. / Perenosimost' peregruzok golova-taz litsami starshego vozrasta do i posle 7-sutochnoi immersii.

Before and after 7-day immersion 6 healthy male test subjects, aged 41 to 49, were exposed to +3 GZ for 60 sec in a centrifuge with an arm of 7.25 m. The runs were repeated 12 times. The test subjects well tolerated the exposure before and after immersion. However, after immersion the physiological systems functioned in a more stressful manner than prior to immersion. This can be attributed to the deconditioning caused by simulated weightlessness. The comparison of the experimental findings with the literature data gives evidence that the pattern and level of physiological changes induced by an exposure to +3 GZ for 60 sec in the test subjects, aged 41 to 49, do not differ significantly from those in younger (aged 23 to 36) people.