acceleration tolerance: effect of exercise, acceleration ... · artificial gravity created by the...

NASA Technical Memorandum 112214

Acceleration Tolerance: Effect ofExercise, Acceleration Training;Bed Rest and WeightlessnessDeconditioningA Compendium of Research (1950-1996)

J. L. Chou, M. A. McKenzie, N. J. Stad, and P. R. Barnes, California State University atSan Francisco

C. G. R. Jackson, California State University at Fresno

F. Ghiasvand and J. E. Greenleaf, Ames Research Center, Moffett Field, California

October 1997

National Aeronautics andSpace Administration

Ames Research CenterMoffett Field, California 94035-1000

https://ntrs.nasa.gov/search.jsp?R=19980000268 2020-07-18T09:02:30+00:00Z

Contents

Page

Summary ................................................................................................ iv

Introduction ............................................................................................. v

Abstracts and Annotations ............................................................................ 1

Additional Selected Bibliography .................................................................... 45

Author Index ............................................................................................ 47

Keyword Index ......................................................................................... 51

iii

Summary

This compendium includes abstracts and annotations of clinical observations and of more

basic studies involving physiological mechanisms concerning interaction of acceleration, training

and deconditioning. If the author's abstract or summary was appropriate, it was included. In

other cases a more detailed annotation of the paper was prepared under the subheadings Purpose,

Methods, Results, and Conclusions. Author and keyword indices are provided, plus an additional

selected bibliography of related work and of those papers received after the volume was prepared

for publication. This volume includes material published from 1950-1996.

iv

Introduction

The purpose of this compendium is to present summaries of clinical observations and

results from more basic studies that help to elucidate physiological mechanisms for control of

acceleration tolerance as affected by exercise training and deconditioning. It the author's abstract

or summary was appropriate, it was utilized. In some cases a more detailed annotation was

provided under the subheadings Purpose, Methods, Results, and Conclusions.

This volume includes studies published from 1950 through 1996. Author and keyword

indices are provided. The material is listed in alphabetical order by first author and numbered

consecutively by abstract number, not page number.

We thank our many colleagues who sent us reprints, and apologize to those whose work

we have inadvertently overlooked.

The authors thank Esther Johnson for valuable technical assistance.

J.E.G.

1. Antonutto G, D Linnarsson, CJSundberg, PE diPrampero.Artificial gravity in Space: vestibulartolerance assessed by humancentrifuge spinning on Earth.Acta Astronautica 27:71-73. 1992.

Authors' Abstract

Artificial gravity created by the astronautsthemselves, without any external powersupply, by pedalling on a couple ofcounterrotating bicycles along the inner wallof the space module (Twin Bikes System,TBS), was previously suggested (Antonuttoet al., 1991) to prevent musculo-skeletaldecay and cardiovascular deconditioningduring long term space flights. Toinvestigate whether this unusual rotatingenvironment would determine abnormal

stimulations of the vestibular system due toCoriolis cross coupled accelerations, thusleading to acute motion sickness (AMS), theconditions of a rotating environment werereproduced in a human centrifuge. Acycloergometer was fixed to the arm of thecentrifuge, the rotation speed of which wasequal to that yielding 1 g at the feet level inthe TBS (i.e. ranging from 19 to 21 RPM).The ergometer position was such that thecombination of the horizontal and

gravitational acceleration vectors was 1.414at the inner ear level and was aligned alongthe head to feet axis. Three subjects,pedalling at 50 W on a cycloergometer duringcentrifuge's spinning, were asked to movethe head following an AMS' provocationprotocol. None of them developed any AMSsymptoms. This supports the look of theTBS as tool for avoiding musculo-skeletaland cardiovascular deconditioning during

long term space flights.

• Asyamolov BF, LI Voronin, VSPanchenko, NV Ulyatovsiy,RA Bondarenko, AVKaliberdin, SYu Elizarov, VGPIokhova, AS Yarov.Effectiveness of antigravity devices ofthe chamberless type after 7 days ofhypokinesia with head-down tilt.

Kosmicheskaya Biologiya i

Aviakosmicheskaya Meditsina22:37-40, 1988.

Authors' Abstract

The goal of this study was to provideinformation for developing means to protectoperators from +Gz acceleration. A total of36 subjects, aged 20 to 31, participated in thestudy. All had been certified fit forcentrifugation and hypokinesia with head-down tilt. Three conditions were run. In the

first, 10 subjects s_nt 60 hours inhypokinesia with -60 head-down tilt duringthe night and -150 during the day. Beforeand after this treatment, subjects' enduranceof +3Gz was assessed for 15 minutes with

and without antigravity device I (AGD-1).In the second condition, the effectiveness of

AGD-1 was tested on 24 subjects before andafter a 7-day period of hypokinesia withhead-down tilt (-10°). The followingacceleration schedule was used: 2.5- and 3.0-

G for 5 minutes each, 3.5-, 4.0- and 4.5-Gfor 30 minutes each. In the third condition,

endurance of 6 subjects was measured beforeand after a 7-day period of hypokinesia usingthe AGD-2 device and the same accelerationschedule as in condition 2. In all cases,

acceleration increased at a rate of 0. I-G persecond. AGD-I consisted of closely fittingtrousers made of stretch fabric with a high

elasticity modulus which could maintain theperimeter and volume of the lower bodyunder exposure to longitudinal G-load.AGD-2 was a shortened modification of

AGD-1 reaching to the knees. Operator

performance was evaluated in condition 3during exposure to acceleration with a control

task using a flight instrument providinginformation about flight parameters.Physiological parameters were assessed byan EKG with tetrapolar chest leads,photoplethysmography of the ear, and amyogram of the femur and abdominalmuscles. Subjects were all trained tocriterion on the control task before

centrifugation.

3. Balldin UI, K Myhre, PA Tesch,U Wilheimsen, HT Andersen•Isometric abdominal muscle trainingand G tolerance.

Aviation, Space, and EnvironmentalMedicine 56: 120-124, 1985.

Authors' Abstract

Methodsto increaseG toleranceof pilotsflying highperformanceaircraftareof vitalimportance.Strainingmaneuversto increaseG toleranceinvolveabdominalmuscles,andhighintra-abdominalpressures(IAP) arerecordedduring G exposure. This study wascarried out to examine the effects of an 11-

week abdominal muscle training program onmaximal IAP, G tolerance and muscle

strength/endurance in 10 fighter pilots. Gtolerance was measured in a human

centrifuge using simulated aerial combatmaneuvers (ACM). The pilots had a highermaximal IAP before training than a controlgroup. G tolerance, maximal lAP, andmaximal peak torque of knee extensors werenot changed by the training. In contrast, legmuscle endurance increased (p<0.01) andratings of local perceived exertion decreased(p<0.01). Static endurance of the kneeextensors was positively correlated (p<0.05)with G tolerance. It is concluded that the

present abdominal training program,employed in experienced fighter pilots, is notsufficient to increase IAP or G tolerance.

4. Balidin UI, P Kuronen, H Rusko,E. Svensson.

Perceived exertion duringsubmaximal G exposures before andafter physical training.

Aviation, Space, and EnvironmentalMedicine 65:199-203, 1994.

Authors' Abstract

Ratings of perceived exertion (RPE) wereregistered at submaximal levels in Gendurance tests of a combined strength andendurance training program in 17 pilots.After 12 months of physical training, theendurance G tolerance (time to exhaustion

during simulated aerial combat maneuver),increased by a mean of 40% (p<0.001),while the mean RPE at 5 rain submaximal G

exposure decreased by 1.2 units (p<0.02).Following 12 months of physical training, asignificant relationship was observedbetween the improvement of the endurance Gtolerance and the decrease of the RPE at 5

min (p = 0.05). Mean SaO 2 at 5 rainincreased from 84 to 90% (p<0.01) aftertraining, while heart rate responses to Gstress did not change. It is concluded thatmean RPE and, to some extent, mean SaO 2

during submaximal G exposures may be usedas indicators of shifts in endurance G

tolerance. The procedure may reduce theneed for exhaustive G tolerance tests withassociated risks and discomfort.

5. Beckman MC, KR Coburn, RMChambers, RE DeForest, WSAugerson, VG Benson.Physiological changes observed in

human subjects during zero Gstimulation by immersion in water upto neck level.

Aerospace Medicine 32:1031-1041,1961.

Authors' Abstract

Knowledge relative to the effects ofprolonged weightlessness is needed inpreparing man for space flight. The buoyantforce exerted upon immersed bodieseffectively simulates the weightless state withrespect to proprioceptive sensory responsesand perhaps in other ways. An investigationinto the physiological effects of immersing

subjects in water up to neck level wasundertaken. It was found that water

immersion produces an unnaturalphysiological situation in that, duringrespiration, the inspired air inflates the lungsto atmospheric pressure while the externalpressure against the chest, abdomen, andlegs, due to the water, is greater thanatmospheric. This situation is equivalent to

"negative pressure breathing."A series of experiments involving seven

subjects immersed in water up to neck levelfor periods of 5 to 23 hours (five subjects for12 hours) showed a significant weight lossduring the period of immersion, which wasexplained by the diuresis which occurred.Pulmonary volume measurements showed adecrease in the expiratory reserve volume andin the respiratory minute volume duringimmersion. There was no significantdecrement in the performance of a trackingtask, attributable to the water immersion,

during exposure to a simulated space vehiclereentry deceleration profile. Exposure to 4.5positive G for 15 seconds following waterimmersion revealed a decrement in tolerance

in most subjects.1. Immersion of subjects in water up to

neck level produced a continuous diuresis

presumablyon thebasisof theGauer-Henryleft atrialvolumereceptorreflex.

2. Immersionin waterupto necklevelcauseschangesin pulmonarycompartmentationrepresentedbya slightdecreasein vital capacity,decreasein theexpiratoryreservevolumeswith anincreasein the inspiratoryvolume,andadecreaseintidal volumewhichis compensatedfor by anincreasein respiratoryrate.

3. Immersionof subjectsin waterup tonecklevel for periodsof 12to 23hoursresultedin adecreasein toleranceto positiveacceleration.

4. Immersionof subjectsin waterup tonecklevel for 12hoursproducedamoderatechangein ability toperformatrackingtaskduringexposureto 8 G,transverseacceleration,butwithoutsignificantchangeinphysicalability to toleratethisacceleration.

6. Bjurstedt H, G Rosenhamer, OWigertz.High-G environment and responsesto graded exercise.

Journal of Applied Physiology25:713-719, 1968.

Authors' Abstract

Ventilatory and circulatory responses tograded leg exercise on a bicycle ergometer(300, 600, and 900 kpm/min, i.e., 49, 98,and 147 W, for 6 min at each work load)

were studied in eight healthy, untrainedsubjects in the sitting position at normalgravity (+1 Gz) and at +3 G z. The effect ofincreased G on the average work performed

by the leg muscles was calculated to benegligible. At the highest work load, meanexpired minute volume, oxygen uptake, heartrate, and arterial lactate levels for the 6t" minof exercise were 19.6 liters/min, 241 ml/min,

32 beats/min, and 1.43 mM/liter higher at +3

G z than at +1 Gz; the increases werestatistically significant except for arteriallactate. No electrocardiogram (ECG)abnormalities occurred at +3 G z even at thehighest work load. An increase in the workload from 600 to 900 kpm/min at +3 G zcaused leveling off of oxygen uptake and riseof arterial lactate in two subjects and, inanother, inability to complete the workbecause of exhaustion. It is concluded that

during leg exercise with increasing work

loads on the bicycle ergometer while in thesitting position at +3 G z, the oxygentransport to working muscles is limitedprimarily by disturbances in the pulmonarygas exchange; the exaggerated hydrostaticpressure differences in this condition presenta greater handicap to the pulmonary than thesystemic circulation.

7. Bulbulian R.

Physical training and +Gz tolerancereevaluted.


Author's Abstract

The effect of physical training on +Gztolerance is of vital interest in the aerospacecommunity. The data on the effect ofphysical training on orthostatic tolerance orsimulated air combat maneuvers are

equivocal. The effects of aerobic andstrength training programs are brieflyreviewed. The data suggest a need forcareful reinterpretation of research results inlight of conflicting reports andmethodological shortcomings. Aerobictraining cannot be assumed to always bedetrimental nor can strength training beassumed to be universally effective inimproving +Gz tolerance. In selectingappropriate screening criteria and trainingregimens for aircraft personnel, it seemsprudent to reinvestigate strength andendurance training effects on +Gz toleranceusing multivariate research paradigms.Special attention should be directed tocommonly accepted physiological principleswhich may vary under conditions of alteredgravitation.

8. Chase GA, C Grave, LB Rowell.Independence of changes infunctional and performance capacitiesattending prolonged bed rest.

Aerospace Medicine 37: 1232-1238,1966.

Authors' Abstract

Eighteen young men were studied beforeand after 15 and 30 days bed rest to examinethe effects of absolute bed rest and recumbent

exercise during bed rest on the pulse rateresponse to submaximal work,cardiovascular functional capacity (max

902 ), physicalworkcapacity,andorthostatictolerance.Changesin thesubmaximalpulserateasaresultof theconditionsof thisstudydid notpredictthetrendin eitherworkcapacityor max 902whereas,changesin work capacityoccurredindependentlyof changesin max 902 andviceversa.Thehighest902 attainableduringexerciseto exhaustiononabicycleergometerunderestimatedmax902 4 to 23percent. Whenrecumbentexercisewascarriedout duringbedrest,thedifferenceinthehighest'_O2 attainableonabicycleergometerandthemax 902 wasdecreasedafterbedrestby anincrementin "_/O2 duringthebicycle test. Unlessmax'v'O2 wasincreasedduringbedrest,subjectshaddecreasedadaptabilityto postureafterward.

9. Cherepakhin MA.Effectof areduceddietandhypokinesiaonhumantolerancetostaticloads.Kosmicheskaya Biologiya iMeditsina

4:67-72, 1970.Author's Abstract

Three series of experiments, each 15 daysin duration, were ran; there were 18 subjectsin the age group 24-27 years. In all theexperiments the subjects were fed a ration of1,800 Cal/day consisting of lyophilizedfoods. In the first series the motor activityregime was unrestricted. In the second seriesthe subjects adhered to a rigorous bedconfinement. In the third series theconditions differed from those in the second

in that before and after the experiments thetest subjects were exposed to accelerations ina chest-to-back direction (8 g) for a period of120 seconds. A diet of lyophilized foods (15

days, 1,800 Cal) with a normal motor activityregime exerts no effect on man's tolerance tostatic loads. Hypokinesia in the form ofbedrest confinement for 15 days with a dietof lyophilized foods in a quantity of 1,800Cal/day exerts a negative effect on man'stolerance to stress. A static functional test

consisting of isometric exercise can berecommended for predicting man's tolerance

to accelerations. This test can be made in

small-volume chambers, in bed, in a fixed

position, or in a spacesuit.

10. Clark WG, IDR Gardiner, AKMclntyre, H Jorgenson.

The effect of positive acceleration onfluid loss from blood to tissue spacesin human subject on the centrifuge.

Federation Proceedings 5: 17-18,1956.

(Abstract)Authors' Abstract

As estimated by hematocrits and plasmaprotein determinations, fluid loss from bloodto tissue spaces occurred in six seated humansubjects on the centrifuge. At near blackoutlevels of G (3.5 to 5.0 G) maintained for 3-5

minutes, a significant loss of fluid (3.6-4.5cc./100 cc. blood; or 216-270 cc. total) wasfound. The loss in four subjects exposed to4 G for 5 minutes was reduced by anti-Gsuits to an average of 75% (range 28-96%) oftheir loss when unprotected. In two casessubjected to 3.5 G for 5 minutes, the losswas less than that of the four subjectsexposed to 4.0 G for 5 minutes. In onesubject submitted to 5 G for 3 minutes, theloss was less than that he obtained at 4 G for

5 minutes, although after-effects were noticedin vision. A smaller loss ( 132 cc. total)

occurred in one of the subjects who had 30runs of 4.7 G for 10 seconds with a 2 minute

interval between runs, than occurred in thesame subject after a 5 minute uninterruptedrun at 4.0 G (288cc.).

At 4.0 G, the fluid losses observed were

much less than those reported elsewhere forcentrifuged dogs, but recovery occurred morerapidly. The losses also were less than thosereported elsewhere for postural changes ofhumans from the recumbent to the uprightpositions. It is unlikely that fluid losses dueto G contribute to any fatiguing effects ordetrimental residual effects possibly resultingfrom positive acceleration experienced by test

pilots or fighter pilots in combat.

11. Cooper KH, S Leverett.Physical conditioning versus +Gztolerance.


Authors' Abstract

An attempt was made in this study todetermine the effect of endurance training on+Gz tolerance in experienced centrifugesubjects. Eleven subjects were divided intosix exercisers and five controls. For three

months the exercisers engaged in a daily (5times a week) progressive running programwhile the controls were asked to avoid

vigorous exercise. Frequently during thisperiod, all eleven subjects were subjected toboth rapid onset and gradual onset runs onthe USAF School of Aerospace Medicinecentrifuge. At the conclusion of the threemonths, significant differences were noticedbetween the exercise and control groups inendurance capacity as indicated by anincrease in maximal oxygen consumption.However, no significant difference was notedbetween the two groups in their ability totolerate positive Gs during either gradual orrapid onset centrifuge runs.

In this study, neither an increase nor adecrease in +Gz tolerance could be correlated

with endurance capacity.

12. Crisman RP, RR Burton.

Physical fitness program to enhanceaircrew G tolerance.

Brooks Air Force Base, TX:

USAF School of AerospaceMedicine,

USAFSAM-SR-88-1, 1988.50p.Authors' Abstract

A physical fitness program of resistancetraining, such as weight lifting, directedtoward increasing strength and anaerobiccapacity will increase G-duration tolerance.This tolerance increase is particularly usefulfor USAF/USN pilots flying high-

performance fighters during aerial combatmaneuvers. A weight-training programincluding exercise equipment to be used byaviators to increase (and maintain thisincrease) their strength and anaerobic capacityis described. Aerobics conditioning withprecautions and limitations for G tolerance isdiscussed. Figures show recommendedweight-training exercises. This special reportis a combined U.S. Air Force and U.S. Navyeffort that came from a 1987 Joint-Service G-

Tolerance Conference that was hosted by the

Naval Aerospace Medical ResearchLaboratory, NAS, Pensacola, FL.

13. Dlusskaya IG, MN Khomenko.Distinctions in reactions to active

orthostatic and water-loading tests ofsubjects differing in tolerance to +Gzaccelerations.



Authors' Abstract

Thirty-seven healthy male test subjects,aged 19-21, with different +Gz accelerationtolerance were examined. Their blood

pressure (BP) and heart rate (HR) during 5-min tilt tests and 2% water loading tests weremeasures 2-3 weeks prior to centrifugation.Quantitative evaluation of orthostatictolerance using an orthostatic index and BPand HR responses to tilt tests before and afterwater loading revealed specific features ofcardiovascular regulation in the subjects withhigh and low +Gz acceleration tolerance.The negative predictive indicators include:decreased BP, HR and cardiac index in the

supine position in combination with highorthostatic tolerance, as well as decreasedorthostatic tolerance in combination with alower function of vasoconstrictor

mechanisms in the upright position and alower sensitivity of carotid sinus reflexes toblood volume changes during tilt and waterloading tests. When examining test subjectswith high +Gz tolerance, preference shouldbe given to those who can well tolerate tilttests and show moderately high BP and HR

in the supine position, as well as to thosewho exhibit a noticeable increment of

diastolic BP during 5-min tilt tests.

14. Epperson WL, RR Burton, EMBernauer.

The effect of physical conditioning on+Gz tolerance.

Aerospace Medical Association

Preprints, 1977. p. 82-83.(Abstract).

Authors' Abstract

New high performance aircraft arecapable of developing levels of highsustained G that places increased G-tolerance

demandsonpilots. It is important,therefore,that methodsbe foundfor improvingGtolerancein thepilot population.Severalpossibilitiesexist;however,oneof themostpromisingnow availableto thepilot isaphysicalconditioningprogram.Yet little isknownaboutthetypesof physicalexerciseswhich wouldbebestsuitedto increaseG-tolerance.Consequently,a studywasconductedtodeterminetheinfluenceof 2typesof physicalconditioningprogramsonG-tolerance,asmeasuredin 26youngmen,usingthecentrifugeattheUSAFSchoolofAerospaceMedicine(SAM),BrooksAFB,Texas. G-tolerancewasmeasuredasthedurationthesubjectcontinuedtheaccelerationprofile-calledthesimulatedaerialcombatmaneuver(SACM)-untilhebecamefatigued.Duringexposureto theSACM thesubjectworeastandardUSAFanti-GgarmentandperformedtheM-1 strainingmaneuverasnecessaryto maintainvision. TheSACMconsistedof alternating15secplateausof+4.5Gz and+7.0 Gz,continuinguntil thesubjectchoseto halttherun-usuallyhispointof fatigue.


The influence of differential physicalconditioning regimens on simulatedaerial combat maneuvering tolerance.


Authors' Abstract

The influence of physical conditioning ontolerance to a centrifugation profile called theSimulated Aerial Combat Maneuvering(SACM)--was determined using 24 youngmen as subjects. These subjects wereassigned to groups as controls (no physicaltraining, C), runners (R), and weight trainers(W). They followed a 2-week protocol ofspecified physical training. During thisstudy, tolerance to the SACM, maximumoxygen consumption, muscle strength, andbody composition were periodicallydetermined. SACM tolerance was defined as

the total time that a subject could withstandcontinuous exposure to a 4.5 and 7.0 +Gzcentrifugation profile as determined by hisvoluntary endpoint of fatigue. The +Gztolerance of the runners and controls

increased at an average rate of 4 s/week

during the course of the experiment. On theother hand, the weight trainers increased theirG tolerance at an average rate of 15 s/week.The difference between group W, comparedwith groups C and R, was statisticallysignificant at the 5% level. Fatigue scoresindicate that group W subjects take longer toreach a given level of fatigue than did thesubjects of the other groups. It appearstherefore that a physical conditioningprogram of weight training will improvehuman tolerance to aerial combat maneuvers.


The effectiveness of specific weight

training regimens on simulated aerialcombat maneuvering G tolerance.


Authors' AbstractTo assess the effectiveness of muscle-

strength (weight training) on simulated aerialcombat maneuvering (SACM) G tolerance,seven young men were exposed to a 12-weekprogram of whole-body weight training inwhich were measured strengths of variousmuscle groups, body circumferences, bodymass, and the percentage of body fat. Themagnitudes of the weights used in trainingwere used to measure muscle strength andwere compared and correlated with eachsubject's SACM tolerance--defined as thetotal time that a subject could withstandcontinuous exposure to a 4.5 and 7.0 +Gzcentrifuge profile using fatigue as hisvoluntary endpoint. Chest and bicepscircumferences increased 4.2% and 3.1%,

respectively; abdomen and thighcircumferences did not significantly change;body fat decreased 16.8%; and body massincreased 2.3%. Abdominal (sit ups) andbiceps (ann curl) strengths increased 99%and 26.2%, respectively, and were highlycorrelated with SACM tolerance time

(p<0.01); leg (leg press) and chest strengths(bench press) made less significantcontributions to the SACM tolerance time. Anet increase in SACM tolerance times of 53%

resulted from weight-training. Multipleregression analysis of all four muscle groupsbetween weeks l and 12 with the SACM

6

tolerancehadacorrelationof determinationof0.61.

17. Forster EM, JE Whinnery.Dynamic cardiovascular response to+Gz stress in aerobically trainedindividuals.


Authors' Abstract

Very high onset sustained +Gz stressrequires rapid cardiovascular response tosupport human tolerance. This study wasconducted following a previous studyconcerning +Gz tolerance in aerobicallytrained individuals, and was initiated to

determine if intense aerobic conditioningmight affect cardiovascular +Gz tolerancethrough reduction in heart rate response to+Gz stress. The study compared heart rateresponse data on 22 aerobically trainedrunners and 13 less-conditioned individuals.

All subjects were exposed to a standardmedical evaluation protocol, which consistedof a gradual-onset (0.1 G/s) accelerationexposure (GOR 1), followed by a series of

rapid-onset ( 1.0 G/s) acceleration exposures(ROR), a second gradual-onset rate exposure(GOR2), and a third gradual-onset rateexposure with the subjects performing anti-Gstraining maneuvers (GORS). Aerobicconditioning was not found to be associatedwith a reduced heart rate response to +Gzstress, compared to the response ofundconditioned subjects, when the followingvariables were considered: heart rate changefrom rest to maximum exposure heart rate,heart rate change from rest to the heart rateachieved at the onset of maximum G, and the

rate of change in heart rate per unit +Gz.Although enhanced parasympathetic tone,induced by long-term aerobic conditioning(running) results in a reduced heart rate atrest and during +Gz stress, it does not alterthe responsiveness of the heart rate to +Gzstress.

18. Gale RR, VV Usachev, LNGavrilova, LG Yelkina, PAYelkin, IS Krikum, VGOvechkin, BV Ustyushin.

Some human reactions to prolongedcentripetal accelerations [+Gz] of lowintensities.



Authors' Abstract

The effect of centripetal accelerations(+Gz) of low intensities (0.5-0.6 g) impartedfor four days against a background of relativehypokinesia was investigated. Peripheral andintracranial circulation, equilibrium functionand morphological composition of thecapillary blood were examined. During thefirst three days of centrifuging thehemodynamic state differed insignificantlyfrom the initial level. On the fourth day signsof cardiovascular deconditioning were found.This was indicated by the orthostatic test.

Changes in the peripheral blood indicated amoderate stress reaction which persistedthroughout the entire experiment.Equilibrium changes which were observed onthe first day of centrifuging regressed and thepost-test function did not essentially differfrom the initial level. The experimentalresults give evidence that inertial forces canbe used to lessen the unfavorable effects of

hypokinesia.

19. Georgiyevskiy VS, VMMikhaylov.Effect of hypokinesia on humancirculation.

Kosmicheskaya Biologiya iMeditsina 2:48-51, 1968.

Authors' AbstractThe combined effect of bedrest and

accelerations on human circulation was

studied using mechano- and poly-cardiographic techniques. The experimentswere conducted on young healthy male test

subjects. The experiments demonstrated anincrease in heart rate and average blood

pressure, a decrease in the ejection period anddevelopment of orthostatic hypotension.Variations in some hemodynamic indicesindicated a phasic pattern reaching amaximum on the 32-42nd day.

20. Gogolev KI.

Correction of transcapillary exchangein man under the influence of rotation

on a centrifuge while immersed inwater.



Author's AbstractAcceleration of +Gz induces both

intravascular redistribution of fluid and

shifting thereof from plasma to theperivascular space, and leads to a change inhydrocolloid balance of blood and theinterstitial medium in man. Such

disturbances could be the cause of changes intranscapillary exchange of fluid and proteins,the adequacy of which is determined by thefunctional state of mechanisms responsiblefor redistribution thereof in the case of

sudden increase in gravity and in theaftereffect period.

In this work, we submit the results of

testing the reactions of the system ofhydrocolloid equilibrium in man toacceleration of 3 units +Gz after 3-dayimmersion, combined or not with periodrotation on a small-radius centrifuge.

21. Goldwater D J, VA Convertino, HSandier.

Acceleration tolerance in 55 to 65 yearold men after shuttle flight simulation.

Aerospace Medical Associated

Preprints, 1981. p. 179-180.(Abstract).

Authors' Abstract

Healthy 55 to 65 y.o. men toleratedShuttle re-entry acceleration before and afterBR as well as subjects 35 to 55 years old.Although the G-suit improved postBRtolerance at all stress levels, it was

significantly more efficacious for older menduring postBR 3 Gz than for men a decadeyounger. These results suggest an importantrole for increased central blood volume in

restoring postBR acceleration tolerance for

older subjects. Pre BR "_/O2 max, PV,

estimated TBV, and height were significantindependent predictors of postBR 3-Gztolerance in these subjects. Bedrest-induceddecrease in 3 Gz acceleration tolerance was

directly proportional to the decrease of BV

8,

and PV, and inversely related to prior athleticconditioning level and height. Sinceindividuals in this age group are moresusceptible to cardiac and cerebrovascularsequelae following orthostatic hypotension,use of the anti-G suit is strongly indicatedduring Shuttle re-entry, especially in highlyaerobically conditioned individuals.

22. Goldwater D J, VA Convertino.

+3Gz tolerance in aerobically-trainedand sedentary men after shuttle flightsimulation.

Aviation, Space, and EnvironmentalMedicine 59:485, 1988.

Authors' Abstract

Thirteen men giving a history of regular

aerobic training (AT) ( VO 2 max 47.4 + 1.6

ml/kg.min) were compared to 8 age-matched

(35 to 50 y.o) sedentary controls (S) ( '_'O 2max 35.2 + 1.5) to assess +Gz tolerance

(GTOL) analogous to, although more intensethan, Shuttle re-entry stress. Subjects wentto greyout at +3 Gz pre-and post-6 days ofhead-down (-6 °) bedrest (BR). PreBRGTOL for AT was 372 sec vs 537 for S (ns).PostBR decrease in GTOL was different

(p<.05) for AT: -259 sec (-68%, p<.01) vsS: -165 sec (-35%, ns). PreBR resting (R)heart rates (HR) were lower (p<.05) in AT

(63bpm) than S (72). PostBR, resting HR ofAT increased 13% (p<.01); S HR's wereunchanged. PreBR HR increase from R to

peak 3 G was much larger (p<.05) in AT(+90%, P<.01) than in S (+63%, p<.01).After BR, 3 Gz increased HR similarly (mean

+85%, p<.01) in both groups. Restingdiastolic pressures (DBP) were lower(p<.05) in AT (54 mmHg) than S (63) preBRas well as postBR, whereas systolic BPswere similar in both groups. After BR,deconditioned AT had + 3 Gz HR and BP

responses, from rest to peak 3G, similar toS. Nevertheless, the decrease in GTOL

postBR was larger in AT. PreBR plasmavolume (PV, ml/kg) was inversely correlatedwith BR GTOL (r = -.64, p<.01). BRdecreases in PV were correlated with low BR

GTOL (r = .63, p<.01) and with preBR

VO 2 max ( r = .42, p<.05). Aerobic

training may be associated with greater +Gzintolerance in spaceflight participants after

weightlessnessexposurein theabsenceofcountermeasures.

23. Golovkina OL.

Extemal respiration and gas exchangereactions to exercise during rotationof man on a short-radius centrifuge.



Author's AbstractPeriodic rotation on a short-radius

centrifuge (SRC) combined with physicalexercise is one method of preventingfunctional disturbances of physiologicalsystems, which occur under the influence ofweightlessness. However, there has stillbeen very inadequate study of the reactions ofthe main physiological systems of the body torotation on an SRC combined with exercise.

Our objective here was to study thereactions of the system of external respirationand exchange of gases to rotations on anSRC ( R = 2 m) combined with exercise on a

bicycle ergometer (BE) during prolongedimmersion. Since the system of externalrespiration is functionally closely related tothe circulatory system, we considered thepossibility of using the parameters of externalrespiration to evaluate endurance for thesefactors.

24. Greenleaf JE, PJ Brock, DSciaraffa.

Effect of physical training in cool andhot environments on +Gz accelerationtolerance in women.


Authors' Abstract

Rectal temperature (Tr,), sweat rate,plasma volume (PV), peak oxygen uptake

(peak "{/0 2 ), and relaxed +Gz acceleration

tolerance (0.5 G min _ linear to grayout)were measured in 15 healthy women 21-41years old before and after submaximalisotonic exercise training for 2 h ° d _ on a

cycle ergometer. The women had 2 weeks of

acceleration runs and 'v'O 2 testing, followed

by 8 d of exercise training, post-training

acceleration runs on day 9, and peak VO 2

tests on day 10. They were divided into three

groups: an exercise (heat) group, ambienttemperature (T a) 40.6°C, relative humidity

(rh) 42%, and a peak 90 2 of 52%; an

exercise (cool) group, T a = 18.7°C, rh =

48%, and "v'O2 peak = 55%; and a sedentary

control (cool) group. There was no change

in peak ventilation, peak heart rate (HR),

peak VO 2, or in resting PV in any group

after training. Heart rate and T_, weresignificantly lower after training in both cooland hot environments; HR by 17 b ' min _

(p<0.05) and 27 b" min _ (12<0.05),

respectively, and Tr_ by 0.4uC (p<0.05) and0.4°C (p<0.05), respectively. Sweat rateswere not different in any group. In allgroups, acceleration tolerances were notdifferent after training; they ranged from 3.5to 3.8 G (373-410 s). The loss (shift) in PVduring acceleration ranged from -5.8% to -10.3% (nonsignificant). With the exceptionof the significant reductions in HR and T_,8 d of moderately heavy physical training at52-55% of peak oxygen uptake in cool or hotenvironments had no effect on slow-onset+Gz acceleration tolerance in women. These

findings may be of relevance for astronauts intraining.

25. Greenleaf JE, PJ Brock, DSciaraffa, A Polese, R.Elizondo.Effects of exercise-heat acclimation

on fluid, electrolyte, and endocrineresponses during tilt and +Gzacceleration in women and men.


Authors' Abstract

Plasma fluid, electrolyte, protein, renin,and vasoactive hormone (epinephrine,norepinephrine, vasopressin) responses weremeasured in six women (21-23 yr) and four

men (21-38 yr) before and immediatelyfollowing an orthostatic tolerance test (700head-up tilt) and a +Gz (head-to-foot)acceleration tolerance test (0.5 G ' min

linear ramp to grayout). These tests wereconducted before and after 12 consecutive

days of exercise-heat acclimation when thesubjects exercised on a cycle ergometer at arelative oxygen uptake of 44% to 49% peakoxygen uptake in a hot environment (T_ =

40°C,42%rh). Duringacclimationplasmavolumeincreasedby 10.6%(p<0.05)in thewomenandby 11.9%(p<0.05)in themen;in bothgroupsexerciseheartratedecreasedsignificantly.Afteracclimation,accelerationtolerancewasunchangedin bothgroups(range3.I to 3.4G); thewomen'stilttolerancewasunchanged(range33.6to 39.5min),but themen'stilt toleranceincreasedfrom 30.4min beforeto 58.3min (A =91%,p<0.05)afteracclimation.Sincethepatternof fluid, electrolyte,andproteinshiftsandaccelerationtolerancesin thewomenandmenwerevirtually thesame,thehormoneresponseswerehighly variable,andthemen'stilt toleranceincreasedsignificantlyafteracclimation,it isclearthatresponsestotilting cannotbeusedto predictresponsestoacceleration.Analysisof datafrom thepresentstudyandtheliteraturesuggeststhatcurrentexercisetrainingregimesshouldbeunrestrictedfor astronautswhohavenotpreviouslybeenhighlyendurancetrained.Until provenotherwise,careshouldbetakenin theselectionof astronautsandin thetypeandintensityof theexercisetrainingprogramsengagedin by thosewhohavebeenor arehighlyendurance-trainedathletes.

26. Greenleaf JE, RF Haines, EMBernauer, JT Morse, HSandier, R Armbruster, LSagan, W van Beaumont.+Gz tolerance in man after 14-daybedrest periods with isometric andisotonic exercise conditioning.


Authors' Abstract

The purpose of this study was todetermine the effects of isometric or isotonic

exercise training on post-bedrest +Gztolerance. Seven male volunteers, 19-22

years, underwent accelerations of +2.1 Gz(740s), +3Gz (327s), and +3.8 Gz (312s) ina selected, randomized order; the ramp topeak acceleration was 1.8 G/min. Thecentrifugation runs were terminated by lossof central vision (blackout) to a white lightwith a luminance of 3.15 x 10.5 logcandle/cm 2 (0.092 ft-lambert). The studybegan with a 14-d ambulatory control period,followed by three 14-d bedrest periods (each

10

separated by a 2 l-d recovery period) and thena final week of recovery. During theambulatory periods, the subjects exercised ona bicycle ergometer at 50% of their maximal

oxygen uptake (max "_/O2 ) for 1 h/d. During

two of the three bedrest periods, the subjects

performed in the supine position one of tworoutines, either isometric exercise (21% of

max leg extension force for 1 min followedby l-min rest) or isotonic exercise (68% of

max _,'O 2 ) for 0.5 h in the morning and

afternoon. During the third bedrest period,no exercise was performed. In general, +Gztolerance was reduced by 24% to 35%

p < 0.05) after bedrest. Compared withcontrol values, there were significantreductions in average tolerance times afterbedrest with no exercise and isotonic exerciseat all G levels. With isometric exercise, there

was a significant decrease in tolerance at 2.1Gz but not at 3.2 Gz or 3.8 Gz, even thoughthe latter tolerances were reduced by 15.6%and by 10.0%, respectively. Both exerciseregimens maintained tolerance at levels equalto or above that obtained with no exercise.

Compared with control values, averagetolerances were lower (p < 0.05) after thetwo recovery periods between the bedrestperiods (-24% to -26% at 3.2 Gz and 3.8Gz), indicating that 3 weeks of ambulationwas not sufficient time for full recovery fromthe deconditioning induced in this study. Aprediction equation was constructed with datafrom all comparable studies utilizingdeconditioned men riding relaxed withoutprotective garments: Tolerance (in seconds) =-334 + (1715/+Gz level). From this

equation, the calculated tolerance after bedrestis 13.5 min at 1.5 G, and the point of zerotolerance is 5.1 Gz.

27. Greenleaf JE, HO Stinnett, GLDavis, J Kollias, EM Bernauer.Fluid and electrolyte shifts in women

during +Gz acceleration after 15days' bed rest.


Authors' Abstract

Twelve women (23-34 yr), comprising abed-rest (BR) group of eight subjects and anambulatory (AMB) group of four subjects,were centrifuged after 14 days of ambulatory

control(C), after 15daysof a 17-dayBRperiod,andon thethird dayof recovery(R).Venousbloodwastakenbeforeandafterthethird +3.0G accelerationrun (1.8G/min).Relativeto (C),the+Gz toleranceafterBRwasreducedby 49.0%(P<0.05)in theBRgroupandby 38.7%(NS) in theAMBgroup;during (R) theBR groupregainedupto 89.4%andtheAMB groupup to 87.1%oftheir (C) tolerances.In eachof thethreetestperiods,theshiftsin plasmaNa,C1,PO 4,

and osmotic contents, which accompanied+Gz, followed the outward shift of plasmavolume (PV). The correlation of the shift ofPV during acceleration with the +Gztolerance was 0.72 (P<0.01). Duringacceleration, the PV and electrolyte loss forboth groups after BR was about half the lossof (C) and (R). Compared with (C) and (R)values, potassium shifts were variable but themean corpuscular volume and meancorpuscular Hb contents and concentrationswere unchanged during all +Gz runs. Theresults indicate that: 1) the higher the (C) +Gztolerance, the greater the tolerance decline dueto BR; 2) relative confinement and reduced

activity contribute as much to the reduction intolerance as does the horizontal body position

during BR; 3) bed-rest deconditioning has noeffect on the erythrocyte volume during +3.0Gz; and 4) about one-half the loss intolerance after BR can be attributed to PV and

electrolyte shifts.

28. Greenleaf JE, W van Beaumont,EM Bernauer, RF Haines, HSandier, RW Staley, HLYoung, JW Yusken.Effects of rehydration on +Gztolerance after 14-days' bed rest.


Authors' Abstract

To determine if rehydration increases+Gz tolerance following bed restdeconditioning, eight male volunteers (21-23yrs) were subjected to acceleration levels of2. I G (740 sec), 3.2 G (327 sec) and 3.8 G

(312 sec) presented in random order; the rateof acceleration was 1.8 G/min. Acceleration

tolerance was determined by either loss of

peripheral vision (greyout) or by loss ofcentral vision (blackout) to a white light with

a luminance of 1.2 x 10-2 candles/cm (35.3

foot-lamberts). The experimental designconsisted of a 3-week ambulatory controlperiod (C), 2 weeks of bed rest (BR1),followed by a 2-week ambulatory recoveryperiod (R), then 2 weeks of bed rest withrehydration prior to centrifugation (BR2) anda final week of recovery. +Gz tolerance wasmeasured immediately before and at the end

of each bed rest period. The subjects ate acalorically controlled, nutritionally balanced

diet and exercised _ hr each day on a bicycle

ergometer at 50% of their maximal oxygenuptake (approx. 450 kcal/day) during theentire study. The subjects were rehydratedwith 1.0 to 1.9 liters of a drink, containing

143 mEq/1 Na, 31 mEq/l K and a totalosmolarity of 620 mOsm/l, given over a 3-

hour period before centrifugation in BR2.There were significant (p<0.05)

reductions in average +Gz tolerancesfollowing both bed rest periods at all three G-levels. Compared with control values,following BRI, average ramp plus plateautolerances decreased 36% at 2.1 G, 30% at

3.2 G and 44% at 3.8 G. Compared withrecovery values, following BR2, averagetolerances decreased 23% at 2.1 G, 29% at

3.2 G and 34% at 3.8 G. Rehydrationincreased tolerance (p<0.001) only at 2.1 G,but tolerance was not completely restored tocontrol values. Compared with control

values, average tolerances at all three G-levels were lower after the recovery period,

suggesting that 2 weeks of recovery is notlong enough to permit tolerance to return topre-bed rest levels. After bed rest the timefull visual capability can be maintained atplateau during these acceleration profiles canbe estimated from the equation: Tolerance(sec) = 345 + (1605/G-level). In relaxed,deconditioned men without protective

garments, tolerance at 2.0 G is 7.6 min andthe level of instant blackout is about 4.7 G.It is concluded that 2 weeks of bed rest

results in a significant decrease incentrifugation to tolerance which occurreddespite the use of moderate daily isotonicexercise. Compared to nonhydration controlvalues, rehydration significantly improves+Gz tolerance only at 2.1 G but did notreturn tolerance to ambulatory control levels.

II

29. Grigoriev AI.Correction of changes in fluid-electrolyte metabolism in mannedspace flights.


Author's Abstract

In order to prevent and correcthypohydration and negative electrolytebalance, the effects of exercises, lower bodynegative pressure (LBNP) and water-saltsupplements (WSS) were investigated in

more than 100 test subjects durin_g 14-, 49-and 182-d headdown tilt tests (-4"). A

combined use of WSS and LBNP duringregular exercises led to a distinct water andsodium retention. These changes were

mainly determined by the stimulation of therenin-angiotensin-aldosterone and antidiureticsystems. After these countermeasures weretested in simulation studies, they were usedby 12 cosmonauts during the 63- and 185-dspace flights. The detailed analysis of thepostflight examinations of the crewmemberssuggests that these countermeasures mayexert a beneficial effect on fluid-electrolytebalance.

30. Grigor'yev AI, YeBShul'zhenko.

Effects of minimal gravitational loadson fluid-electrolyte metabolism andrenal function of man duringprolonged immersion.



Authors' AbstractIt was demonstrated that renal excretion

of fluid osmotically active substances andelectrolytes could be reduced, using lowgravitational exposures (+Gz). The degreeand duration of water and electrolyte retentionwere different with respect to theexperimental time. The major physiologicalmechanisms of the changes in fluid-electrolyte metabolism were a decrease in theglomerular filtration rate and a change inwater and ion transport in renal tubules.

31. Hoffler GW, RA Wolthuis, RLJohnson.Lower body negative pressure.

In: Physiological Effects of

Prolonged Positive +Gz

Acceleration following One and

Seven Days Bedrest, edited by WHShumate. Houston, TX: NASA

Manned Spacecraft Center, Chapt. 6,1971. p.111-124.

Authors' Abstract

1. Lower body negative pressure (LBNP)was used as a cardiovascular stressor to

measure orthostatic tolerance in 9 subjectswho underwent one and seven day bed restperiods.

2. Accelerative (centrifuge) +Gz tolerancetesting preceded all LBNP tests except a finalseries run expressly to assess the possibleeffect of centrifugation upon LBNPresponses. No correlation between the twowas found.

3. Orthostatic tolerance by LBNP testingwas decreased after both bed rest periods.The magnitude and extent of decrease wasgreater after the 7-day period of bed rest.This was best determined by elevations ofheart rate and decreases in stroke volume.

Resting mean pulse pressure was modestlydecreased, while change in leg size tended tobe variable and resting cardiac output wasunaltered. Three incidents of presyncopeoccurred during tests after bed rest.

4. Physiologic results from LBNP testsclosely parallel those of other orthostatic testsand may be used as an auxiliary test forpredicting human tolerance to reentry forces.

32. Houghton JO, DK McBride, KHannah.

Performance and physiological effectsof acceleration-induced (+Gz) loss ofconsciousness.


Authors' Abstract

Loss of consciousness (LOC) was

intentionally induced by exposing eightvolunteers to individually-titrated levels ofhead-to-foot acceleration (+Gz) using 2- and4-s onset rates (mean = 6.1 +Gz required toinduce LOC) and a gradual, 0.067 G • sonset rate (mean = 7.2 Gz required).

Subjects were trained over a prior 2-weekperiod on a multitask battery comprising threesimultaneously executed tasks representative

12

of those required in piloting, and thencentrifuged to LOC at each of the three onsetrates on alternate days. Performance wasassessed for 5 min prior and 7 min after eachLOC. Primary results indicated: a)significant and substantial impairment in thetwo discrete response secondary tasks(choice reaction time and arithmetic

computation), with mean recovery to pre-LOC levels within 3 min on each task, b) no

group mean impairment for the primary,compensatory tracking task, c) substantialindividual variation in physiologically andbehaviorally defined recovery from LOC, d)

a negative influence of aerobic fitness on Gtolerance and LOC recoverability, and e) that

recovery effects were not generally dependentupon onset rate. Mean absoluteincapacitation (head dropped) for the rapidonset rates was 12.1 s. For the gradual onsetrate, mean absolute incapacitation was 16.6s. Mean relative incapacitation (head erect,no voluntary task engagement) for the rapidonset rates was 11.6 s; for the gradual onsetrates, mean relative incapacitation was 15.7s. Evidence for retrograde anmesia effectswas equivocal.

33. Jacobson LB, KH Hyatt, HSandier.

Effects of simulated weightlessnesson responses of untrained men to+Gz acceleration.


Authors' Abstract

Space shuttle vehicle travel will exposecrew and untrained lay personnel toheadward-acting (+Gz) acceleration stresseswhich may be as high as 4 G followingperiods of weightlessness. Previous studies,using bed rest as an analog ofweightlessness, demonstrated the orthostaticintolerance and even syncope which occurson reexposure to a +lGz environment (700passive tilt) following periods of simulatedweightlessness, suggesting that postbed-restexposure to still higher +Gz accelerationstresses would exaggerate the undesirableresponses. This study documents bedrestinduced metabolic and physiologic changes insix untrained men exposed, following a 2-wkperiod of simulated weightlessness, to

possible +Gz acceleration profiles anticipatedfor space shuttle vehicle travel. All subjectsdemonstrated decreased +Gz tolerance

following simulated weightlessness. Whileonly one of six subjects could not tolerate the+Gz profile in the control phase of the study,three of the six could not complete thepostbed-rest study. The use of an inflatedstandard Air Force cutaway G-suit improved+Gz tolerance in all subjects, but two of six

subjects still failed to complete the profile.These findings are discussed in reference tothe selection of untrained humans for spaceshuttle vehicle travel.

34. Kakurin LI.

Effect of long-term hypokinesia onthe human body and the hypokineticcomponent of weightlessness.


Author's Abstract

An experimentally diminished muscularactivity of man can be used as a model toreproduce some human reactions similar tothose induced by weightlessness. Thepurpose of the 62-day experiment was tostudy adaptive processes of the human bodyand to establish the efficiency of physical

exercises during hypokinesia. Detailedclinical and physiological examinationsrevealed disturbances in the functioning of

the circulatory, respiratory andneuromuscular systems, changes in naturalimmunity and diuretic deterioration. Physicalexercises with a load up to 1,000-1,200

Cal/day produced a limited positive effect.

35. Kakurin LI, RM Akhrem-Akhremovieh, YuV

Vanyushina, RA Varbaronov,VS Georgiyevskiy, BSKatkovskiy, AR Kotovskaya,NM Mukharlyamov, NYePanferova, YuT Pushkar, YuASenkevich, SF Simpura, MA

Cherepakhin, PG Shamrov.The influence of restricted muscular

activity on man's endurance ofphysical stress, accelerations andorthostatics.

Soviet Conference on Space Biology

and Medicine 1996. p. 110-117.

13

Authors' Abstract

For the past few years the attention ofSoviet and foreign researchers has beendrawn to investigation of man's conditionwhen his muscular activity is restricted

(hypokinesia). The added interest in thisproblem is due to the fact that many of man' scontemporary professions are associated withrestricted muscular activity. This problem is

acquiring a prominent place in astronauticssince prolonged manned space flights havenow become a reality.

Weightlessness and the small volume ofthe spacecraft cabin place man's locomotorapparatus under unusual functioningconditions. The works of Kraus and Raab

(1961), Taylor et al. (1949), Dcitrick et al.(1949), Graveline et al. (1961, 1964),Beckman et al. (1961) as well as of the

groups headed by A.V. Korohkov, L.I.Kakurin, A.A. Demidov and otherresearchers have demonstrated that with

prolonged restriction of movements, mandevelops functional disorders of thelocomotor apparatus, circulatory system,neuro-endocrine system and higher nervousactivity. At the present time thesepolymorphous disorders are combined intothe syndrome of hypokinetic disease.

As applied to the problems of spacemedicine, hypokinesia should be investigatedfrom two aspects. First, investigation ofphysiological reactions in long experiments atEarth's gravitation, and the second-prophylaxis of hypokJnetic disorders thatcould arise in a low gravitation field andduring weightlessness in space flights. It isespecially important to investigate the limitsof endurance of acceleration, orthostatic

factors and physical stress during re-entry toEarth.

36. Kamenskii YuN, EBShui'zhenko.

Prophylaxis for disturbances ofexternal breathing in immersion.Kosmicheskie Issledovaniya14:474-476, 1976.

Authors' Abstracts

A protracted stay by man inweightlessness or in conditions whichsimulate it is accompanied by a reduction ofgravitational stability. Therefore, a search for

methods of normalization of physiologicalreactions after a protracted stay by man in theconditions mentioned has great significance.The study of the reactions of externalbreathing during "head-pelvis" overloading(+gz) by a three-unit amount after a 13-daystay by man in water immersion, and inimmersion which was combined with

"conditioning" gravitational effects,comprised the task of the presentinvestigation.

The investigation has been conductedwith the participation of two groups ofhealthy men of ages 24-36 yr. The testsubjects of the first group (5 men) weresituated in immersion without additional

effects ("pure" immersion); the test subjectsof the second group (5 men), starting fromthe 6 _ day of immersion, were subjecteddaily to a single effect of "head-pelvis"overloads of up to two units in amount andup to 1.5 h in duration.

Before and after immersion, the test

subjects of both groups were subjected tothree units of overloading for 300 sec.

External breathing was investigated by theDouglas-Holdern and pneumotachographymethods. We recorded and calculated the

following indices: breathing frequency (BF),

respiratory volume (RV), momentaryrespiratory volume (MRV), volume flow rateof air (intensity) at the intake (W,), theduration in inhalation (T_), the coefficients ofvariation of BF, RV, and T_ (CV), oxygen

consumption ( _/O 2 ), and the coefficient of

oxygen use (CUO2).The gas-exchange data have been

presented in the STPD system, and the dataof ventilation and the biomechanics of

breathing in the BTPS system. The resultshave been processed statistically by adifference method.

37. Kamenskiy YuN, YeBShul'zhenko, VG Andreyeva.

Effect of systematic exposures togravity on the external respirationfunction during prolongedimmersion.



Authors' Abstract

14

Test subjects were exposed to 13-dayimmersion alone or combined with

centrifuging. The immersion did notinfluence the state of ventilation and gasexchange at rest, but significantly diminishedthe functional capabilities of externalrespiration. An exposure of the test subjectsto acceleration during the second half ofwater immersion resulted in the normalizationof the functional reserves of external

respiration. This may be a consequence of anincrease in overall physical tone of the body.

38. Katkovskiy BS.Human basal metabolism during

prolonged bedrest.Kosmicheskaya Biologiya iMeditsina 1:67-71, 1967.

Author's Abstract

1. The metabolic rate and pulmonaryfunction of healthy test subjects were studiedduring 20- and 62- day bedrest experiments,before and after which they were subjected toaccelerations.

2. Three subjects who performed nophysical exercises during the 62-day bedrestrevealed a decreased metabolic rate and

virtually unaltered pulmonary function.3. Three test subjects who performed

physical exercises during the experimentsalso manifested a reduction of oxygenconsumption and metabolic rate beginningwith the third 10-day period.

4. It appears very probable that the latteris unrelated to hypokinesia but is due to anincreased physical conditioning or toadaptation to a changed hydrostatic pressureof body fluids.

39. Keil LC, S Ellis.Plasma vasopressin and renin activityin women exposed to bed rest and+Gz acceleration.


Authors' Abstract

To study the effect of prolongedrecumbency on plasma vasopressin and reninactivity, eight women (23-34 yr) weresubjected to 17 days of absolute bed rest.The +3 Gz tolerance of the subjects wastested before and after 14 days of bed rest.

From day 2 and through day 17 of bed rest,

plasma arginine vasopressin (AVP) levelswere reduced by 33%. Plasma renin activity(PRA) increased by 91% (P<0.05) above

ambulatory control values from days 10

though 15 of bed rest. When compared toprecentrifuge values, exposure to +3 Gz priorto bed rest provoked a 20-fold rise (P<0.05)in mean plasma AVP but resulted in only aslight increase in PRA. After bed rest,acceleration increased plasma AVP 7-fold(P<0.02); however, the magnitude of thisincrease was less than the post +3 Gz value

obtained prior to bed rest. After bed rest, nosignificant rise was noted in PRA following+3 Gz. This study demonstrates thatprolonged bed rest leads to a significant risein the PRA of female subjects, whileexposure to +Gz acceleration provokes amarked rise in plasma AVP.

40. Khapilov NV, VS Panchenko,NN Kotov, BF Asyamolov.

Effect of hypokinesia and +Gzaccelerations on transport function ofhuman blood.



Authors' AbstractThe results of 44 studies of circulation

parameters and blood transport function of 14test subjects exposed to 7-day bed rest(-10 ° head-down tilt) and acceleration of 4.5Gz have demonstrated that the blood

transport carriers and their actively bindingcenters form working structures in theadaptive reactions. As compared to thepretest level, the distribution ratio of '4C-adenine between two immiscible phases(plasma/oil, erythrocytes/oil) varies from - 12to 14% on bed rest day 3 to +32 to 40% onbed rest day 7; it increases by 145-150% afterexposure to +4.5 Gz acceleration. Theparameters of the blood transport functiongive a quantitative description of its adaptivereactions to environmental effects.

41. Khudyakova MA, YeBShul'zhenko.

Blood clotting function during 12-dayimmersion in water, and the

preventive role of revolving on acentrifuge.

15

Kosmicheskaya Biologiya iA viakosmicheskaya Meditsina3:79-81, 1977.

Authors' Abstract

There is a sparse literature dealing withhemostasis in the presence of hypodynamia.Ye. I Chazov and V.G. Ananchenko failed to

demonstrate changes in 3 out of 4 subjectsduring 3-day hypodynamia, while onepresented increased anticoagulant and lyticproperties of blood. In the case of 20-dayhypodynamia, the same authors foundincreased fibrinolytic activity of plasma andhigher blood heparin content, as well aslower heparin tolerance of plasma in the 4subjects.

According to the report of L.M. Filatovaand O.D. Anashkin, an increased

thrombogenic potential of blood wasobserved on the 8 thday of bedrest in thehorizontal position. Thereafter, a decrease incoagulating potential of blood was observedin the case of 64-day hypodynamia.

The results of Ye. I Dorokhova, which

were obtained with 70-day hypodynamia,revealed that there was a hypocoagulationreaction toward the end of the first 2 weeks.

As the period of hypodynamia increased thehemophilic reaction also increased in allsubjects.

V.A. Isabayeva and T.A. Ponomarevafailed to observe an increase in thrombogenicproperties of blood during 10-dayhypodynamia after adaptation to high altitude.Longer periods of hypodynamia (24 days)diminished coagulant properties.

Our objective here was to study thechanges in various indices of hemostasisduring 12-day immersion in water and todetermine whether it is possible to useincreased gravitation for prevention of"decondition" of the organism duringimmersion.

42. Klein KE, F Backhausen, H

Briiner, J Eichhorn, D Jovy, JSchotte, L Vogt, HMWegmann.Die Abh_ingigkeit der Orthostase- undBeschleunigungs- toleranz vonK/Srperbau und Leistungsf'zihigkeit.(The relation between tilt table and

acceleration-tolerance and their

dependence on stature and physicalfitness).

International Zeitschrift fiirAngewandte Physiologie

einschliesslich Arbeitsphysiologie26:205-226, 1968.

Authors' Abstract

Experimental studies in a group of 12

highly trained athletes ( 40 2 max: 4.6 1/min)

and a group of 12 untrained students ('v'O 2

max: 3.4 l/min) lead to the following results:1. During a 20 rain tilt (90°), which includedtwo additional respiratory maneuvers, thenumber of faints and the averagecardiovascular responses did not differsignificantly between the groups, except for alower heart rate level in athletes; 2. Duringlinear increase of acceleration with a rate of

1G/15 sec, the average +Gz-tolerance(blackout level) was almost identical in bothgroups being 6.9 for the athletes and 6.8 forthe students; 3. Statistically significantcoefficients of the product-momentcorrelation were calculated in the total of both

groups for the interrelation of the followingvariables: a) +Gz tolerance and arterial blood

pressure at rest (r = +0.48 to +0.55), b)+Gz-tolerance and heart-eye distance (r =-0.41), and c) total body length and

responses of mean arterial pressure to tilt (infainters: r = -0.11, in non-fainters: r =

+0.47); 4. The coefficient of multipledetermination computed for the dependenceof +Gz-tolerance on heart-eye distance andsystolic blood pressure at rest (r2_ 23= 0.492)allows the explanation of almost 50% of thevariation of +Gz-tolerance, instead of 16%,

respectively 23%, if the two independentvariables are used singly; 5. The maximaloxygen uptake showed the expectedsignificant correlation to the heart rate at rest(r = -0.68), but not to the acceleration-

tolerance or to the cardiovascular responsesto tilting.

43. See number 42.

16

44. Klein KH, H Br0ner, J Eichhorn,KL Schalk_iuser, J Schotte, ED

Voigt, HM Wegmann.Vergleichende Untersuchungen dekt_rperlichen Leistungf'_ihigkeit desMenschen bei Muskelarbeit, im

Sauerstoffmangel und beiBeschleunigung. (Evaluation of

physical fitness for exercise andtolerances for hypoxia andacceleration).

International Zeitschrift fiir

Angewandte Physiologie

einschliesslich Arbeitsphysiologie22:190-206, 1966.

Authors' abstract

Physical fitness for exercise andtolerances to hypoxia (287 mmHg) andacceleration (+Gz) were evaluated in 20

healthy male students (21-28 years), whichwere physically untrained and not adapted tounusual environments. A very closecorrelation (r = +0.78) was found for the true

maximal oxygen uptake ( "QO2 max) and the

aerobic capacity estimated from the heart rateduring submaximal exercise using theAstrand nomogram. From some step testsonly the Harvard index showed a moderate

correlation (r = -0.35) to the "QO 2 max. The

"_'O 2 max was nearly independent from

hypoxia and acceleration tolerances, whereasthe results of the step tests uniformly revealed

negative dependances (r = -0.41 to -0.64) onthe stress tolerances with the one exception ofthe Schneider index, which correlated

positively (r = 0.41) with the accelerationtolerance. Negative correlations (r = -0.46 to-0.60) were also computed between thedifferent criteria for hypoxia and accelerationtolerance. "Physical efficiency" proved to bean inhomogeneous characteristic, whichcannot be predestinated by "fitness" testsunder exercise alone, but has to be evaluated

by a test-battery combined in regard to eachspecific task.

45. Klein KE, H Briiner, D Jovy, LVogt, HM Wegmann.

Influence of stature and physicalfitness on tilt-table and accelerationtolerance.


Authors' Abstract

A comparison of 12 healthy, butphysically untrained, students with 12 highlytrained athletes proved significant differences

for the maximal working capacity ( 'v'O 2 max

in students: 43.9 ml/kg/min, in athletes: 64.9

ml/kg/min). As further indication for the bigdifferences in "physical fitness", the heartrate level of athletes was about 22 percentlower at rest and during a 900 tilt of 20 min.duration. However, "orthostatic tolerance,"

i.e., the number of fainters and the responsesof blood and pulse pressure to tilt in non-fainters, was almost identical in both groups.The same was true for "acceleration

tolerance;" i.e., the central light loss duringan acceleration, increasing linearly with a rateof 1G/15sec. (in students: 6.8 +Gz, inathletes: 6.9 +Gz). In the total of both

groups, statistically significant coefficients ofthe product-moment correlation could becomputed for the interrelation of thefollowing variables: body height and theresponses of arterial pressure to tilt (for meanpressure in non-fainters: r -- +0.47, for pulsepressure in fainters: r = -0.56); +Gz toleranceand arterial pressure at rest (r = +0.48 to+0.55); +Gz tolerance and heart-eye distance(r = -0.41). The coefficient of the "multiplecorrelation" computed for the dependance ofthe +Gz tolerance on systolic blood pressure

at rest and on heart-eye distance was R_23 =0.70. By means of the correspondingequation of the multiple regression, a diagramfor prediction of central light loss duringacceleration from the knowledge of the twoindependent variables was constructed; the"standard error of estimate" was 0.56 +Gz.

46. Klein KE, H Briiner, ED Voigt,

HM Wegmann.Comparative studies on physiologicalindices of fitness in man under

exercise, low pressure, andacceleration.

In: Human Adaptability and it's

Methodology, edited by HYoshimura, JS Weiner. Tokyo:Japanese Society for the Promotionof Science, 1966. p. 234-247.

Authors' Abstract

17

In 20malestudentsof oneagegroup,whichwerehealthyanduntrained,andneverhadbeenadaptedto unusualenvironment,physicalfitnessandtolerancesto lowpressureandaccelerationweremeasured,andthecoefficientsof correlationbetweentheresultscalculated.Thepredictionof _'O2max.with Astrand's procedureshowedaverycloserelationshipto thetrueaerobicworkingcapacity(r = 0.78),while from allsteptests,only theHarvardmethodcorrelatedmoderatelyto thesameindex(r = 0.35). The true VO2 max.wasabsolutelyindependentof theresistanceeitherto hypoxia,or to hypergravity,but the"cardiovascularfitness"measuredby steptestsshowedmoderateto highdependencyon them(r = 0.41-0.64),whichwasnegativein all cases,exceptfor therelationbetweenthe"Schneider"testandthetolerancetogravitationalforces,thelastbeinglikely,becauseof theorthostaticresponsein theSchneiderscore.Theinterrelationbetweenthetwo stresstoleranceswasalsonegative(r= -0.46to -0.60). Physicalfitness,asdeterminedby thedifferentmethods,isnotahomogeneousqualityof thebody. Theknowledgeof the interrelationsatthesametimerestrictsandextendsthemeaning,significanceandpracticalvalueof theindices.

47. Klein KE, HM Wegmann, HBriiner, L Vogt.Physical fitness and tolerances toenvironmental extremes.


Authors' Abstract

During "submaximum" loading tests of20-30 min duration at simulated altitude (312

mmHg), on the tilt table, during acceleration(2.5 +Gz), and during exercise (17 mkp/sec)at sea level and at moderate simulated altitude

(578 mmHg), heart rates were significantlylower for highly trained athletes, 20-25percent, than in non-athletes. In maximumtolerance tests, however, there was found

only a significant difference between the twogroups for maximum oxygen uptake atphysical exercise, but no indication was seenfor a positive cross-adaption effect ofphysical exercise training on the otherstressors. Statistical analysis of the

18

correlation between heart rate responses tothe different stressors and the correspondingtolerances proved negligible relationshipsonly; whereas heart rates were always highly

dependent on sea level "¢O 2 max (r = -0.61

to -0.83). The results do not support the ideaof an improvement of human tolerance toenvironmental extremes by physical exercise

training.

48. Klein KE, HM Wegmann, PKuklinski.

Athletic endurance training-advantagefor space flight?: The significance ofphysical fitness for selection andtraining of Spacelab crews.


Authors' Abstract

While intensive physical exercise hasbeen part of the conditioning of astronautsand cosmonauts for spaceflights, its benefitshave been questioned. After reviewing thepertinent literature, it is concluded that themorphological and functional changesobtained with athletic endurance training are

rather specific and of no general advantagefor the tolerance to space stresses.Particularly during gravitational loads, in the

relaxed subject, these changes allow a morepronounced shift of fluid into the lowerextremities, with the possible consequence ofa reduced tolerance. This unfavourable

response, obviously, is accentuated throughimmersion and weightlessness. The aerobicwork capacity is also more impaired inathletes. Based on these conclusions,

recommendations for crews and passengersof future Spacelab missions are given withrespect to selection and pre- and in-flightphysical exercise.

49. Kokova NI.

Effect of fluid and salt supplements tofood allowance on endurance of head-

to-pelvis accelerations following 7-day 'dry' immersion and underordinary motor activity conditions.

Kosmicheskaya Biologiya iAviakosmicheskaya Meditsina18:33-37, 1984.

Author's Abstract

The effect of water-salt supplements as an

agent increasing human tolerance to head-to-feet acceleration with a slow onset was

examined. The test subjects were rotated in a7.25 m centrifuge after 7-day dry immersionor normal motor activity. The water-saltsupplements were given at a dose of 0.15 gNaCI and 18 ml water per kg body weight(with the total dally dose consumed in fourfractions). During immersion fluid retentionwas significantly higher than during normalactivity (818 + 139.7 ml versus 478 + 69ml). Water-salt supplements consumedproduced a positive effect on tolerance tohead-to-feet acceleration. Duringcentrifugation after water-saltsupplementation the physiological responseswere less strained. Water-salt supplementstaken on the last immersion day increased thetolerance level as compared to the control.The amount of the fluid retained in the body

was found to be inversely proportional to thetolerance level. It is concluded that water-salt

supplements may be recommended toincrease tolerance to head-to-feet acceleration

in aerospace medicine.

50. Kotovskaya AR.Human tolerance to acceleration after

exposure to weightlessness.Life Sciences and Space Research14:129-135, 1976.

Authors' Abstract

The major role in the genesis of varyinghuman tolerance to decelerations that follow

weightlessness is evidently played byhypodynamic and hydrostatic factors.

Long disuse of compensatory antigravitymechanisms in weightlessness may bringabout their deconditioning and reduction oftheir functional capabilities, and may finallyaffect general tolerance of crewmembers todecelerations.

Laboratory experiments demonstratedchanges in the human tolerance to Gzaccelerations of varying duration (from 3 to100 days) and tested the efficacy of differentcountermeasures.

A decrease in human tolerance to +Gz is

on the average 2.0g. It should be noted that

an elongation of simulated weightlessness(from 7 to 100 days) caused no furtherdecrease in the +Gz tolerance.

Our investigations helped to assess thethreshold of human tolerance to accelerations

after an exposure to simulated weightlessnessand to delineate the value of real risk. Thetolerance limit to +Gz accelerations which

followed simulated weightlessness of theabove duration ranged from 9.5 to 13.0 g,averaging 11.6 _+ 1.6g.

The information on the tolerance ofSoviet and American astronauts to

decelerations shown during re-entry in realspace flights give support to the laboratoryresults and predictions.

51. Kotovskaya AR, RVVartbaronov, SF Simpura.

Human physiological reactions duringthe action of transverse accelerations

following hypodynamia.Problemy Kosmicheskoy Biologii6:106-117, 1967.

Authors' Abstract

The physiological reactions to, andtolerance for +Gx accelerations were studied

in tests on subjects following hypodynamiawhich lasted from 7 to 20 days.Examinations were made of the bioelectric

activity of the heart, the cerebral cortex, thefunction of external respiration, the arterial

pressure, and the visual function. Thedecrease in tolerance to accelerations in all

cases averaged 2 G units (range 1.2 to4.0G), and did not depend on the duration ofhypodynamia. Physiological reactions toaccelerations were greater followinghypodynamia. The decrease in tolerance toaccelerations was caused mainly by a

disorder in the regulation of the vasculartonus.

52. Kotovskaya AR, RAVartbaronov, SF Simpura.

Change in load-factor tolerance after70 days of hypodynamia.

Problemy Kosmicheskoy Biologii13:241-247, 1969.

Authors' Abstract

Stability to the action of transverse g-forces was investigated in 12 subjects before

and after a prolonged (70-day) confinementto bed. Overload tolerance was evaluated in

terms of the maximum g-force at which the

first signs of physiological-function

19

disturbancemadetheirappearance,andonthebasisof shiftsin thephysiologicalreactionsduringandafteractionof theloadfactor. A distinctdecreasein thetolerancetotransverselydirectedg's wasnotedafterthepassivesojournin bed. Useof drugs andphysical exercises during hypodynamia wasclearly helpful. The combination ofprophylactic measures resulted in an increasein the maximum load factor tolerated after

hypodynamia without any substantialdecrease of over-all stability. In all cases,

however, the physiological systems weremore severely stressed under a given g-forceafter hypodynamia.

53. Kotovskaya AR, RAVartbaronov, SF Simpura.Change in the capacity of man towithstand transverse stresses after

hypodynamia of varying duration.

Problemy Kosmicheskoy Biologii16:46-54, 1971.

Authors' Abstract

This work presents study of the capacityof 20 men to withstand transverse stresses

(+Gx) after hypdodynamia placed in a supineposition for a length of 3 to 60 days.Gradual reduction in the resistance to theaction of maximum stresses was detected at

time periods of hypodynamia from 7 to 15-20days: Later, resistance to stresses waspreserved approximately at the same level upto the 60 t_day of hypodynamia. Similarshifts were obtained in a study of thereactivity of the cardio-vascular and breathing

systems to stresses determined according tothe level of pulse strain and increase of

pulmonary ventilation before and afterhypodynamia of varying duration. Theresults obtained give a basis for supposingthe existence in the process of hypodynamiaof two phases in reactions of an organism to

stress. In the opinion of the authors, thepresence of the second phase (stabilization)may support the development of a uniqueadaptation to conditions of hypodynamia.

54. Krupina TN, AYa Tizul, NMBoglevskaya, BP Baranova, E1Matsnev, YeA Chertovskikh.

Functional changes in the nervoussystem and functioning and certain

analyzers in response to the combinedeffect of hypokinesia and radialacceleration.


Authors' AbstractThe functional state of the nervous

system and some analyzers was studied usingsix healthy male test subjects aged 23-36years who had been subjected to a 62-daybedrest combined with radial accelerations.

Three of the subjects performed physicalexercises using a bunjee cord and bicycleergometer. Prior to the bedrest experimentthe test subjects were twice (at an interval of4-6 days) exposed to transverseaccelerations. Some transientneuroautonomic disturbances were observed.The most distinct disturbances wereautonomic and vascular disorders and

asthenization phenomena which appearedearlier and disappeared later in test subjects

performing no physical exercises. Somefunctional changes of the acoustic andvestibular analyzers also were noted. Theywere related to an increase of the acousticthresholds and decrease of the vestibulo-

autonomic tolerance. The functional changesof the nervous system and some analyzersoccur due to hemodynamic disturbances andafferent-efferent changes.

55. Leach CS, PC Johnson, TBDriscoll.

Effects of bedrest and centrifugationof humans on serum thyroid functiontests.


Authors' Abstract

Changes in plasma volume and protein

concentration have been reported whennormal subjects are bedrested or centrifuged.Since thyroid hormones are transported byspecific plasma proteins, each of theseprocedures could be expected to changeplasma levels of these hormones. In thisstudy centrifugation of normal healthy humansubjects produced an increased concentrationof total protein and albumin. When thesesame subjects were bedrested for six days,

no change in total proteins, albumin orthyroxine binding globulin were found

2o

althoughtherewasaneightpercentdecreasein plasmavolume. Centrifugationand,to alesserextent,bedrestproducedchangesinserumT-4 levelsandtheT-3 Testresults.Thedirectionof thesechanges(decreased%T-3 valuesandincreasedT-4 levels)indicatethatthesetwo situationsproduceanincreasedplasmaconcentrationof thyroxinebindingsites.

56. Leach CS, J Vernikos-Danellis,JM Krauhs, H Sandier.Endocrine and fluid metabolism in

males and females of different agesafter bedrest, acceleration, and lower

body negative pressure.

Houston, TX: Johnson SpaceCenter. NASA Technical

Memorandum 58270, 1985. 52p.Authors' Abstract

Space Shuttle flight simulations wereconducted to determine the effects of

weightlessness, lower body negativepressure (LBNP), and acceleration on fluidand electrolyte excretion and the hormonesthat control it. Measurements were made on

male and female subjects of different agesbefore and after bedrest. After admission to a

controlled environment, groups of 6 to 14subjects in the age ranges 25 to 35, 35 to 45,45 to 55, and 55 to 65 years were exposed to+3 Gz for 15 minutes (G1) and to LBNP(LBNP1) on different days. On 3 daysduring this pre-bedrest period, no tests wereconducted. Six days of bedrest followed,and the Gz (G2) and LBNP (LBNP2) testswere run again. Hormones, electrolytes, andother parameters were measured in 24-hoururine pools throughout the experiment.During bedrest, cortisol and aldosteroneexcretion increased. Urine volume

decreased, and specific gravity andosmolality increased. Urinary electrolyteswere statistically unchanged from levelsduring the non-stress control period. DuringG2, cortisol increased significantly over itscontrol and bedrest levels. Urine volume,

sodium, and chloride were significantlylower; specific gravity and osmolality werehigher during G2 than during the controlperiod or bedrest. During LBNP2, volumewas lower than during the non-stress control

period, and specific gravity and osmolality

were higher than during control or bedrestperiods. The retention of fluids andelectrolytes after +Gz may at least partiallyexplain decreased urine volume and increasedosmolality observed during bedrest in thisstudy. There were some statisticallysignificant differences between the sexes andage groups. Results of the study indicatedthat space flight would not affect the fluid andelectrolyte metabolism of females or oldermales any more severely than it has affectedthat of male or female astronauts.

57. Lohrbauer LA, RL Wiley, SJShubrooks, M McCally.Effect of sustained muscularcontraction on tolerance to +Gzacceleration.


Authors' Abstract

The increase in +Gz acceleration (the

inertial force vector acting in a head-to-footdirection) tolerance afforded by static forearm

muscular contraction (handgrip) wasevaluated and compared with that of thestandard G suit. Acceleration tolerance was

assessed in eight subjects in each of fourconditions for both rapid onset ( 1.0 G/s) andslow onset (0.1 G/s) acceleration profiles.

The conditions were: 1) unprotected, 2)handgrip, 3) G suit, and 4) handgrip and Gsuit. The mean tolerance levels achieved for

those four conditions for the rapid onset runsas defined by peripheral light loss were 3.6,4.3, 4.8, and 5.4 G, respectively. For theslow onset runs, the tolerance levels were

4.6, 5.6, 5.8, and 6.3 G. Thus the handgripand G-suit procedures each providedapproximately 1 G of protection.Significantly, the effect of the two procedurescombined proved to be additive. In the rapidonset runs, the static contraction was begun60-90 s before the onset of acceleration and,

in the slow onset runs, the contraction was

begun with the onset of acceleration. Theprotection provided by the staticconcentration is, at least in part, due to theincrease in mean systemic blood pressurewhich accompanies any such contraction.This increase prolongs the time necessary foracceleration to result in a blood pressurebelow intravascular pressure, this latter being

21

thetimeatwhich peripherallightlossoccurs.Unlikeduringrespiratorystrainingmaneuvers,no increasein intrathoracicorintra-abdominalpressureoccurredduringhandgripexerciseat 1G.

58. Ludwig DA, VA Convertino, DJGoldwater, H Sandier.

Logistic risk model for the uniqueeffects of inherent aerobic capacity on+Gz tolerance before and after

simulated weightlessness.


Authors' Abstract

Small sample size (n<10) andinappropriate analysis of multivariate datahave hindered previous attempts to describewhich physiologic and demographic variablesare most important in determining how longhumans can tolerate acceleration. Data from

previous centrifuge studies conducted atNASA/Ames Research Center, utilizing a 7-14 d bed rest protocol to simulateweightlessness, were included in the currentinvestigation. After review, data on 25women and 22 men were available for

analysis. Study variables included gender,age, weight, height, percent body fat, resting

heart rate, mean arterial pressure, VO 2 max,

and plasma volume. Since the dependentvariable was time to greyout (failure), twocontemporary biostatistical modelingprocedures (proportional hazard and logisticdiscriminant function) were used to estimate

risk, given a particular subject's profile.After adjusting for pre-bed-rest tolerancetime, none of the profile variables remainedin the risk equation for post-bed-resttolerance greyout. However, prior to bedrest, risk of greyout could be predicted with91% accuracy. All of the profile variablesexcept weight, MAP, and those related to

inherent aerobic capacity ( VO 2 max, percent

body fat, resting heart rate) entered the riskequation for pre-bed-rest greyout. A cross-validation using 24 new subjects indicated avery stable model for risk prediction, accuratewithin 5% of the original equation. Theresult for the inherent fitness variables is

significant in that a consensus as to whetheran increased aerobic capacity is beneficial ordetrimental has not been satisfactorily

22

established. We conclude that tolerance to+Gz acceleration before and after simulated

weightlessness is independent of inherentaerobic fitness.

59. Meehan JP, JP Henry, S Brunjes,H deVries.

Investigation to determine the effectsof long-term bed rest on G-toleranceand on psychomotor performance.

Los Angeles, CA: University of

Southern California School of

Medicine. Final Report No. NAS

9-3500, August, 1965.48p.Author's Abstract

Fourteen young men were confined tobed for 28 days. They were randomlydivided into three subject groups of 5, 5 and4 individuals. One group exercised, anotherdid pressure breathing and the third did both.Each subject was exposed to a re-entryacceleration profile in the -Gx position whileperforming a three dimensional tracking taskprior to the bed rest and at the conclusion ofthe bed rest. Tilt table tolerance and bloodvolumes were determined in a similar

sequence.Cardiovascular deconditioning manifested

by plasma volume decrements of 20% anddecreased tolerance to passive tilting resultedin all subjects and was not differentiallyaffected by the exercise, pressure breathingor the combination maneuvers.

Performance on the tracking task duringacceleration was not affected by thecardiovascular deconditioning.

60. Mikhaylovskiy GP, TVBenevolenskaya, TA Petrova,IYa Yakovleva, OI Boykova,MP Kuz'min, AA Savilov, SNSolov'yeva.The combined effect of two-month

hypokinesia and radial accelerationson the cardiovascular system.


Authors' Abstract

Six healthy male test subjects were

exposed to a 62-day bedrest and radialaccelerations of the maximum tolerable

magnitude. The bedrest reduced the strengthof the muscular vessels, disturbed the

ophthalmicandnasalregionalcirculationanddecreasedtheorthostatictoleranceof all thesubjects.Thelatterwasassociatedwithsomecardiovasculardisordersanddeteriorationof circulatorymechanismsofadaptationto aphysicalload. Thecombinedeffectof bedrestandradialaccelerationsonthecardiovascularsystemwasmoredistinctthantheeffectof accelerationsalone.Physicalexercisesperformedduringbedrestyieldedpositiveresults.

61. Mikhaylorskiy GP, NNDobronravova, MI Kozar, MMKorotayev, NI Tsiganova, VMShilov, IYa Yakovleva.Variation in overall body toleranceduring a 62-day exposure tohypokinesia and acceleration.


Authors' Abstract

The overall tolerance of the human bodywas studied on six healthy male subjectsduring a 62-day period of hypokinesia.Beginning with the third week of theexperiment the protective properties of thebody deteriorated considerably (quantity ofblood properdin, phagocytic activity ofneutrophils, lysozymic activity of the salivaand bactericidal function of the skin). Inaddition to inhibition of natural immunity

there was development of inflammatorydiseases, mostly affecting the mucousmembranes and the vascular system. Theresults obtained should be taken into account

in developing preventive measures for useduring prolonged space missions.

62. Miller PB, SD Leverett Jr.Tolerance to transverse (+Gx) andheadward (+Gz) acceleration after

prolonged bed rest.Aerospace Medicine 36: 13-15,1965.

Authors' AbstractTolerance to the transverse (+Gx)

acceleration of a simulated Gemini re-entryprofile was determined before and after 4weeks of absolute bed rest. Tolerance to

headward (+Gz) acceleration was studiedbefore and after 4 weeks of absolute bed rest

and 2 weeks of modified bed rest.

As judged by the degree of physicaldiscomfort, the ability to respond to a centrallight, or the presence of electrocardiographicabnormalities, tolerance to +Gx was

unaffected by 4 weeks of absolute bed rest.In each subject studied, heart rates duringpeak acceleration were higher after bed restthan before.

As judged by the level of acceleration atwhich central vision was lost, no significant

change in tolerance to headward (+Gz)acceleration of rapid onset was observed after2 weeks of modified bed rest or after 4 weeks

of absolute bed rest. After each type of bedrest, the majority of the subjects haddecreased tolerance to headward (+Gz)

acceleration of gradual onset, but the meandecrease was not statistically significant.

Mean heart rates at equivalent levels of+Gz were significantly higher after bothperiods of bed rests. The only arrhythmia ofclinical importance noted was the appearanceof bursts of premature atrial contractionsduring G.O.R. +Gz in 1 subject after 2weeks of bed rest.

63. Murdoch DM, LG Meyer, RPCrisman.

Effects of running and weight liftingon +Gz tolerance.

Aviation, Space, and EnvironmentalMedicine 59:475, 1988. (Abstract)

Authors' Abstract

Introduction:Previous studies have shown the benefit

of resistance training over aerobic training toenhance +Gz-tolerance. Aircrew members

continue to enjoy aerobic exercise forrecreation and health. We studied the effects

of a regular aerobic training program on boththe physiological benefits gained from aweight lifting program and G-tolerance.Methods:

Twenty-four student naval aviators andstudent naval flight officers were tested foraerobic capacity, and muscular strength andendurance before and after a 10-week

conditioning program. Subjects wererandomly divided into two groups of weightlifting only (WL) (n = 10) and weight liftingand running (WR) (n = 13). The weightlifting program was performed 4-days perweek, 2 muscular strength and 2 muscular

23

enduranceworkouts.TheWR groupranameanof 12.7mi/week. Physicalfitnessassessmentwasaccomplishedbothprior toandfollowing thetrainingprogram.Gradualonsetrate(GOR)andsimulatedair combatmaneuver(SACM)G-tolerancewereassessedfollowing the 10-weekconditioningprogram.Results:

No statistically significant differenceswere seen between the WL group and theWR group for any of the measured physicalfitness parameters for either pre- or post-training. Mean post GOR tolerances for theWL and WR groups were 9.24 and 9.05+Gz, respectively. Mean post SACM timesfor the WL group was 134.6 and 153.6 s forthe WR group. Neither the GOR nor SACMtolerances differed significantly for thegroups.Conclusions:

Moderate levels of running accompaniedby weight training were not detrimental to G-tolerance.

64. Newsom BD, WL Goldenrath,WR Winter, H Sandier.Tolerance of females to +Gz

centrifugation before and afterbedrest.


Authors' Abstract

Because women may be included aspassengers in the proposed Space ShuttleSystem, this study was designed toinvestigate the +Gz tolerance of women andthe possible degradation of this tolerance aftera period of weightlessness as simulated bybedrest. Twelve healthy Air Force flightnurses served as test subjects. Over a 1-week period, each subject was exposed to+Gz levels starting at +2 Gz and increasingby 0.5 Gz increments to a grey-out point.This point was determined by peripheralvision loss with a standard lightbar and byreverse blood flow in the temporal artery.Ultimately, each women was subjected tothree runs at the +3 Gz level; each run was

approximately 55 min long, separated by 5-min rest periods. Eight subjects with the besttolerance times were selected for 14 d of

bedrest in a horizontal position; the other fourwere ambulatory controls. Tests before

bedrest, immediately following, and 5 d latershowed that average +Gz tolerance decreasedby 67% after bedrest.

65. Parnell M J, JE Whinnery.The effects of long term aerobicconditioning on tolerance to +Gzstress.


Preprints, 1982. p.22-23.(Abstract).

Annotation

Purpose:To investigate the relationship between

intense aerobic conditioning and tolerance to+Gz stress by investigating the response ofmarathon trained runners on the centrifuge.Method:

To measure tolerance to +Gz stress, each

subject rode a standard USAFSAM medicalevaluation protocol on the centrifugeconsisting of a gradual onset ( IG/I 5 sec)+Gz exposure in relaxed state, a series ofrapid onset (IG/sec) in a relaxed state, and aGOR exposure where subjects performedanti-G straining maneuvers.Results:

There was no increase in tolerance to +Gzstress associated with intense aerobic

training, and at least a low average tolerancefor these subjects when compared to data inthe USAFSAM acceleration repository.

Percent body fat and 40 2 max data

illustrate trained subjects. Endurance trainingenhances cardiovascular vagal tone,evidenced by lower heart rates. Increasedmotion sickness including vomiting, may beevidence of enhanced vagal tone throughvagal innervation of the GI tract.Conclusion:

Tolerance to +Gz stress can be influenced

by the type of physical conditioning HPApilots perform. Intense aerobic training is notnecessary to prepare a pilot to combat +Gzstress, and may decrease ability to perform ina high +Gz environment.

66. Petrovykh VA, RV Kudrova, MIKuznetsov, PP Lobzin, IG

Popov, IA Romanova, YuKSyzrantsev, AM Terpilovskiy,YuF Udalov, NA Chelnokova.

24

Nutritionalstateof humansubjectskept for longperiodsin ahorizontalpositionandsubsequentlyexposedtoacceleration.Problemy Kosmicheskoyi Biologii1:355-363, 1967.

Annotation

Purpose:To study the nutritional state of a human

subject kept in a horizontal position and withrestricted movement.

Method:

Aspects of nutritional state of subjectsduring hyperdynamia and preceding exposureto overloading were carried out on 3 healthyyoung persons (22-24 years) for 10 and 15

days.Results:

There was no significant difference

between uropepsin levels in subjects' urineduring hypodynamia and in the initial state;thus, there was no change in enzyme functionof the gastric glands on feeding theexperimental diet under these conditions.Negative nitrogen balance was observed in allsubjects during the initial period ofhypodynamia. Increase excretion of urea,ammonia, and uric acid in urine also

occurred. There were no significant changesin blood cholesterol with the diet and

hypodynamia. There was, however, adecrease in blood sugar due to do utilizationof CHO.

Conclusion:

The diet investigated proved adequate inits nutritional value and content of basic food

substances for the subjects kept underhypodynamic conditions preceded byoverloading, with the exception of its contentof certain vitamins.

67. Purakhin YuN, BN Petuknov.Neurological changes in healthysubjects induced by two-monthhypokinesia.


Authors' Abstract

Six healthy male test subjects were twiceexposed to acceleration followed by a 62-daybedrest during which three test subjects

performed physical exercises of a knownintensity. The study included tests of the

nervous system, electroencephalographicrecordings, physiological tremor andfluctuations of the body center of gravity(stabilography). Results: 1. During the firsttwo weeks of the experiment the test subjectsexhibited symptoms of asthenic reactions intheir behavior and nervous system. 2. Later

the symptoms become more serious,acquiring the form of neurological symptomsand an asthenic syndrome (neurasthenia). 3.

An analysis of data on the tremor,electroencephalogram and stabilography alsoindicated the development of changes in thecentral nervous system, autonomic nervous

system and orthostatic tolerance in responseto long-term hypokinesia. Functional shiftswere accompanied by morphological changesin the muscular system.

68. Rusko H, P Kuronen, P Tesch, UBalldin.

Effects of aerobic and strengthtraining on physical fitness and G-tolerance of fighter pilots.

Aviation, Space, and EnvironmentalMedicine 59:474, 1988. (Abstract).

Authors' Abstract

Introduction:

Strength training has been shown toimprove the G-tolerance, contrary to aerobictraining. In our previous study modifiedendurance training was also able to increaseG-tolerance of fighter pilots. This studyinvestigated the effects of changes fromaerobic to strength training and from strengthto aerobic training on physical fitness and G-

tolerance of fighter pilots.Methods:

After one year of combined strength andaerobic conditioning 8 pilots started amodified endurance training (3 times a week)for 9 weeks and thereafter trained 9 weeks

strength training (3-4 times a week). Anothergroup of 8 pilots started first the 9 weekstrength training and thereafter the modifiedendurance training for 9 weeks. Physicalfitness and G-tolerance was measured before

the experimental period, after the first 9week, period and after the second 9 weekperiod.Results:

Both groups improved significantly themaximal isometric leg extension (LEF) and

25

trunk extension(TEF)forces,aswell asG-tolerance,significantlyduringthefirst 9weekperiod. In addition,strengthtrainingimprovedthemaximalisometrictrunkflexionforce(TFF)significantly. Duringthesecond9 weekperiodthemodifiedendurancetrainingdecreasedsignificantlyLEF,TFFandG-tolerance.ThestrengthtrainingimprovedfurtherTFF whilethechangesinTEF, LEFandG-tolerancewereinsignificant.Conclusions:

G-tolerance and muscular force are

decreased if endurance training is started afterstrength training period.

69. Rusko H, P Kuronen, P Tesch, UBalldin.

Relationship between G-tolerance andphysical fitness of fighter pilots.


Authors' Abstract

Introduction:

Strength training has been shown toincrease the g-tolerance in fighter pilots,contrary to aerobic training. During a M-1maneuver the pilots are supposed to activateboth abdominal and leg musculature. This

study investigated the correlations between g-tolerance and variables related to the strengthand endurance of the fighter pilots.Methods:

The pilots (n = 19) were studied twicewith 6 months' interval. G-tolerance was

measured with repeated 15 s periods at 3.5and 5.5 G without anti-G-suit untilexhaustion.

Results:

In the first measurement of isometric legextension (LEF, r = .46, p<0.05), trunkflexion (TFF, r = .59, p<0.01) and trunkextension (TEF, r = .57, p<0.01) forces aswell as jumping height (JUHE, r = .78,p<0.001) correlated significantly with G-tolerance. Maximal oxygen uptake (r = .63,p<0.001) and maximal blood lactateconcentration (r = .57, p<0.01) aftertreadmill running test to exhaustion alsocorrelated highly significantly with G-tolerance. In the second measurement onlyTFF (r = .48, p<0.05) and TEF (r = .49,p<0.05) demonstrated significant correlations

with G-tolerance. When the two

measurements were combined (n = 38) TFF,TEF and JUHE were found to correlate

significantly with G-tolerance (p<0.01).Conclusions:

Although a good overall fitness seems tobe necessary for the pilot, the abdominal andback muscle strength are the most indicativecharacteristics.

70. Sandier H, D Goidwater, SARositano.

Physiologic response of male subjectsages 46 to 55 years to Shuttle flightsimulation.


Preprints, 1979. p.43-44. (Abstract).Authors' Abstract

The present study was conducted onseven untrained older male subjects (ages 46to 55) to assess the magnitude ofphysiological changes occurring during aground-based simulation of Shuttle flight. Inaddition, G-suit effectiveness was evaluated

as a countermeasure for the expectedcardiovascular deconditioning occurring with

bed rest (10_ days) since it is anticipated

that antigravity suits will be used or providedfor use during future Shuttle missions. Onthe seventh day of BR, each subject received+1.5 Gz with a G-suit and without a G-suit.

On the following day, the subjects underwent+2 Gz with and without a G-suit. On the

ninth day, the subjects received +3 Gz withand without a G-suit. Blood pressure andheart rate were monitored. All parameters

increased significantly during accelerationboth before and after BR. G-suit usage

before and after BR resulted in significantlylower heart rate at + 1.5 Gz and +2 Gz and

higher systolic and diastolic blood pressuresat all three G levels. In conclusion, older

individuals have some degree of protectionduring Gz, probably due to loss of vascularelasticity with the aging process.

71. Sandier H, P Webb, J Annis, NPace, BW Grunbaum, DDolkas, B Newsom.Evaluation of a reverse gradientgarment for prevention of bed-restdeconditioning.

26

Aviation, Space, and EnvironmentalMedicine 54: 191-201, 1983.

Authors' Abstract

A reverse gradient garment (RGG) wasused to intermittently induce venous poolingin the extremities of a magnitude similar tothat seen in going from a lying to standingposition during the course of a 15-d period ofhorizontal bed rest. Venous pooling failed to

improve bed-rest-induced losses in +2.5 Gzand +3.0 Gz centrifugation tolerance or to

prevent increased heart-rate responses tolower-body negative pressure (LBNP). Foursubjects served as controls, four weretreated. Tests during the 7-day recovery

period showed fluid/electrolyte and bodycomposition values to have returned to pre-bed-rest levels with continued depression ofacceleration tolerance times (56% decreasedat +2.5 Gz and 74% decreased at +3.0 Gz

compared to pre-bed-rest levels) andexaggerated blood insulin response onglucose tolerance testing (blood insulin fortreated group increased 95% at 1 h before bedrest and 465% during recovery). This studydemonstrates that the physiologic changesafter bed rest persist for significant periods oftime. Acceleration tolerance time proved tobe a sensitive test for the deconditioning

process.

72. Shulzhenko EB, IF Vil-Vilyams,

EA Aleksandrova, KI Gogolev.Prophylactic effects of intermittentacceleration against physiologicaldeconditioning in simulatedweightlessness.

Life Sciences and Space Research17:187-192, 1979.

Authors' Abstract

The prophylactic effect on adult humanmales of intermittent acceleration againstphysiological deconditioning inweightlessness simulated by water immersionwas studied at +0.8, +1.2, and +l.6g.These prophylactic exposures reduced renalexcretion of fluid and plasma volumechanges, and increased venous complianceand the time at which the subjects couldtolerate an acceleration field of +3 g.

73. Shulzhenko EB, IF ViI-Vilyams,MA Khudyakova, AIGrigoryev.Deconditioning during prolongedimmersion and possiblecountermeasures.

Life Sciences and Space Research14:289-294, 1976.

Authors' Abstract

Test subjects, covered with a waterproofhighly elastic cloth, were exposed to 13-daywater immersion up to the neck. They weredivided into two groups. The first (control)group consisting of six persons was exposedto immersion alone and the second

(experimental) group was exposed daily toaccelerations of 0.6-2 Gz for 60-90 min

during the last 6 days of immersion. Beforeand after immersion all the test subjects were

exposed to +3 Gz for 5 min which served asa provocative test. These experiments giveevidence that the use of dry immersion allowsexperimentation during prolonged immersionwithout concomitant complications.Variations in the physiological parameters(cardiovascular system, fluid-electrolytebalance, blood-coagulatory system) areindicative of the preventive effect of periodicaccelerations during 13-day immersion.

74. Shul'zhenko YeB, VG Koziova,KA Kudrin, AS Yarov, VGPiokhova.

G suit of bladderless type as a meansof improving orthostatic stability afterwater immersion hypokinesia andexposure to accelerations.Kosmicheskaya Biologiya i

A viakosmicheskaya Meditsina17:30-33, 1983.

Authors' Abstract

Orthostatic tolerance after 7-day dryimmersion and head-to-feet acceleration was

investigated on test subjects with and withoutan antigravity suit of bladderless type. Withthe suit on, the 20 min tilt test at 70 Uprior toimmersion induced less marked changes thanwithout the suit. When the suit was on,cardiovascular reactions to tilt tests after

immersion and acceleration improved. Themaximum heart rate decreased from 135 + 4

to 101 + 5 beats/min (p<0.01), minimumstroke volume increased from 29 + 2 to 41 +

27

3 ml (p<0.05)andpulsepressuregrew.Thus,anantigravitysuitmayhelpincreaseinitial orthostatictoleranceandmaintainitafterthecombinedeffectof simulatedhypogravityandacceleration.

75. Spence DW.Abdominalmuscleconditioningasameansof increasingtoleranceto +Gzstress.Aerospace Medical AssociationPreprints, 1981. p.148-149.(Abstract).

Annotation

Purpose:To determine the effects of specific

abdominal muscle conditioning on +Gztolerance.Method:

Twenty male volunteers (18-38 yrs) wererandomly assigned to two groups aftercompleting baseline measurements ofanthropometry, body composition, muscularstrength and endurance (MVTC), G-toleranceand heart rate response to G stress.Group 1 consisted of the abdominal muscleconditioning (AMC) subjects, whichfollowed an AMC program 3 times per weekfor 12 weeks (36 workouts). Group 2consisted of the control subjects (C) who didno abdominal conditioning.

During the 12 week experimental periodboth groups underwent a centrifugationprofile of alternating 15 second plateaus at4.5 and 7.0 +Gz until fatigue or visual losscriteria were met ( 100% peripheral or 50%central light loss). The centrifuge protocolfor both groups was followed weekly forfour weeks then bi-weekly for eight weeks.Determinations of abdominal muscle strengthand endurance were made on the AMC groupfour times during the experimental period.Baseline measurements were performed againat the end.

Results:

1) Muscular strength and endurance toincreased significantly (p<0.01) during theconditioning program up to a maximum of177%.

2) However, further centrifuge trainingadaptation had occurred which was notsignificantly affected by the muscleconditioning program as evidenced by the

lack of statistically different tolerancebetween the groups.Conclusion.

The lack of statistical significancebetween groups or trials on heart rate

response to an equal G stress supports thefinding that abdominal muscle conditioningdid not increase G-tolerance.

76. Suvorov PM.

Influence of thirty-day hypokinesia incombination with exposure to LBNPon tolerance to accelerations (+Gz).


Aviakosmicheskya Meditsina 8:65-68, 1971.

Author's Abstract

A study was made of the effect ofhypokinesia combined with LBNP ontolerance to accelerations. Before and after

hypokinesia the subjects were centrifuged at3 g for 30 sec and at 5 g as long as it could betolerated. Two days after exposure to

hypokinesia and LBNP the duration oftolerance to accelerations of 5 g was 24.2-36.5% of the initial level. This may bebrought about by the functional activity of themuscular system and venous tone whichresults in a marked decrease in systolicvolume and cardiac output during exposure toaccelerations and accordingly in the earlydevelopment of optic disturbances.

77. Tesch PA, H Hjort, UI Balldin.Effects of strength training on Gtolerance.


Authors' Abstract

The G tolerance of pilots flying modern,high-performance fighter aircraft is crucial.Therefore, methods to increase G tolerance

are of vital importance. In this study, Gtolerance was studied in a human centrifuge

using simulated aerial combat maneuvers(ACM)--consisting of 15-s periods of 4.5and 7 G until exhaustion--before and after 11

weeks of muscle strength training. TheACM-time in 11 fighter pilots was increasedafter this training by 39%. Gains wereobserved in knee extensor muscle strength

during slow contractions by 17% and inanaerobic power by 14%. Aerobic

28

performanceandvariousmusclehistochemicalindices,asassessedfrommusclebiopsysamplesobtainedfrom m.vastuslateralis,wereunchanged.Neuromuscularadaptationseemsto beresponsiblefor theincreasedmusclestrength,aswell asfor the improvedperformanceoftheM-1 strainingmaneuver.ThismightexplaintheenhancedG tolerance.

78. van Beaumont W, JE Greenleaf,HL Young, L Juhos.Plasma volume and blood constituent

shifts during +Gz acceleration after

bedrest with exercise condition!ng.Aerospace Medicine 45:425-430,1974.

Authors' Abstract

The purpose of the present study was toinvestigate the influence of isometric andisotonic exercise during bedrest on plasmavolume (PV) and blood constituents during+Gz acceleration in seven young men.During bedrest, PV decreased between 8.0%and 11.5%. During centrifugation beforebedrest, the average decrease in PV wasbetween 10.7% and 13.2%, with

concomitant plasma protein losses of 2.6% to3.7%, and albumin losses of 1.2% to 4.6%;

after bedrest, the corresponding changes withcentrifugation were between -6.3% to -7.1%,- 1.1% to -2.0%, and +2.4% to -3.1%,

respectively. The average accelerationtolerance during pre-bedrest control runs was1,129 _SE 27 s, while after bedrest, the

mean tolerance was 817 _SE 31 s (p < 0.05).For comparative purposes, additionalhematological changes with centrifugationwere evaluated from nine different

hypovolemic, ambulatory subjects. During+Gz acceleration there was an isotonic loss of

plasma fluid (8.6% to 11.2%) with respect toserum sodium, potassium, chloride,creatinine, and osmolarity; however, serumglucose concentration increased between6.3% and 19.3%. It is concluded that duringacceleration (a) the mean reduction in PV and

protein contents after bedrest is about half asgreat as during the control runs beforebedrest; (b) isometric and isotonic exercise

during bedrest have no effect on the decreasein PV and protein contents duringcentrifugation; (c) during +Gz acceleration, in

hypohydrated ambulatory subjects, there isan isotonic loss of plasma fluid; (d)centrifugation tolerance was significantlyreduced following bedrest; and (e) the twoexercise regimens had no statisticallysignificant effect upon post-tbedrestcentrifugation tolerance; however, bothisometric and isotonic exercise reduced the

average +Gz tolerance decrement by 85-100s.

79. Vil-Vilyams IF.

Principle approaches to selection ofthe short-arm centrifuge regimens for

extended space flight.Acta Astronautica 33:221-229,

1994.Author's Abstract

Eight +Gz regimens on the SAC varyingin their values (within 0.8 to 1.6 G),

exposures, schedules, etc. were analyzed.Some regimens were combined with water-salt supplements (WSS) or veloergometertraining (VE). Weightlessness was simulatedby 3- to 28-day water immersion. +3 Gzloads on the centrifuge with the radius of7.5m were applied prior to and postimmersion. Regimens for human runs on theSAC as a novel, perspective countermeasurefor interplanetary expeditions should beselected with due regard of the humantolerance, their efficiency, and subsequentverification and specification in orbitalflights. These approaches showed that 3days of exposure to 1.2 G combined withWSS and 6 days of exposure to G-loadsfrom 0.8 to 1.6 G together with VE weremost optimal.

80. Vil-Vilyams IF, YeBShul'zhenko.

Cardiac arrhythmia followingpostimmersion +Gz accelerations.



Authors' Abstract

Cardiac arrhythmia is a common disorderoccurring under the influence of alteredgravity. Thus, under the influence ofaccelerations, extrasystolic arrhythmia, sinusarrhythmia and relative bradycardia are themost typical forms of rhythm disturbances

29

dueto accelerations.Underweightlessconditions,spacecraftcrewsnotuncommonlydevelopedrhythmdisordersintheform of isolatedandsystemicextrasystoles.

Immersionis oneof theground-basedmodelsof weightlessness.However,therehasbeenlittle studyof arrhythmiasoccurringunderthe influenceof immersionfollowedbyexposureto accelerations.Weonly knowthat,in onestudydealingwithhumansubjects,anattackof paroxysmaltachycardiadevelopedin asubject23h afterdroppinginto theimmersionmedium.Post-immersionfunctionalloadtestsrevealedmoremarkedsinustachycardiathanincontrolstudies.

Our objectiveherewasto investigatetheeffectof immersionfollowedbyhead-pelvisaccelerationsondistinctionsof developmentof cardiacarrhythmia.

81. Vil-Vilyams IF, YeBShul'zhenko.Functional state of the cardiovascular

system under the combined effect of28-day immersion, rotation on ashort-arm centrifuge and exercise on abicycle ergometer.



Authors' AbstractThe cardiovascular function of four test

subjects exposed to 28-day "dry" immersionwas examined before and after 6-day cyclesof rotation in a short-arm centrifuge toprovide 1-2 Gz, bicycle ergometer exercise,and their combination. An exposure toacceleration of 3 Gz in a 7.25 m arm

centrifuge was used as a provocative test.The above countermeasures reduced but not

eliminated entirely immersion-inducedcardiovascular deconditioning. From thisstudy a combined use of acceleration of 1-2Gz in a short-arm centrifuge and bicycleergometer exercise can be recommended as acountermeasure against cardiovasculardeconditioning in weightlessness.

82, Wessel JA.

An investigation of the relationbetween man's fitness for strenuous

work and his ability to withstand highheadward acceleration.

University of Southern California,

Los Angeles, CA: Ph.D.

Dissertation, 1950. 109p.Author's Abstract

1. An investigation was made of therelationship between fitness for strenuouswork and G-tolerance in twenty-three healthymale university students.

2. The study was designed to determinethe relationship between the subjects'tolerance to +5 G and their fitness for

strenuous work; to study the effects of atraining program on the subjects' G-tolerance; and to investigate the influence ofcessation of systematic training on G-tolerance.

3. Fitness for strenuous work was

measured by means of performance tests,namely, the Harvard Step and Army AirForce Tests and the hand dynamometerstrength test.

4. Each subject was exposed to +5 Guntil he greyed out or for a maximum run of30 seconds. G-tolerance was measured in

terms of earopacity during acceleration andduring an 8 minute recovery period, andpulse rates during an 8 minute recoveryperiod after acceleration for those subjectswho endured +5 G for 30 seconds; and time

until grey-out for those subjects who greyedout at +5 G.

5. The basic exercises used in the six and

a half weeks' training program were weighttraining and running. These items wereselected because of their high components ofmuscular strength and cardiovascularendurance. Each subject participated at leastthree times weekly in the training program.

6. During the eight weeks' period aftertraining had ended, the subjects wererequested to participate as little as possible inorganized physical activity.

7. Analysis of the fitness measuresrevealed that most of the subjects were in"average" physical condition when theystarted the training program. The level was

raised to "good" after training and droppedsomewhat eight weeks after the programstopped.

8. A statistically significant increase in theHarvard Step Test scores, Army Air Force

30

Testscoresandhanddynamometerstrengthwasfoundaftera six andahalfweeks'of thesystematictrainingprogram.

9. G-tolerancemeasuresshowedasignificantimprovementafterthesix andahalfweeks'of thesystematictrainingprogram.

10.A slightbutconsistentrelationshipwasfoundto existbetweenG-tolerance(earopacityat theendof therunandpulseratesimmediatelyafter+5G)andfitnessforstrenuouswork asmeasuredby theHarvardStepandArmy Air ForceTests.

11.A statisticallysignificantdrop-offinfitnessasmeasuredby theArmy Air ForceTestwasfoundeightweeksaftersystematictraininghadstopped.Only aslightdrop-offin fitnesswasobservedasmeasuredby theHarvardStepTestandhanddynamometerstrengthtest.

12.A statisticallysignificantdrop-offinG-tolerancemeasures(earopacityandpulserates)for thosesubjectswhoendureda+5 Gfor 30secondswasnotedeightweeksafterthetrainingprogramstopped.Groupperformanceon the+5G-testrunsshowednochangein durationof thecentrifugeruns.

83. Whinnery JE.+Gztolerancecorrelationwithclinicalparameters.Aviation, Space, and EnvironmentalMedicine 50:736-741, 1979.

Author's AbstractIncreased +Gz stress demands continue

to be placed on modern high-performancefighter aircraft pilots. Precise definition ofnormal +Gz tolerance along with a fullunderstanding of the physiologic andanatomic factors that influence +Gz tolerance

is therefore of increasing importance. Ifcertain subtle medical abnormalities areassociated with altered +Gz tolerance, it will

be necessary for medical standards torecognize them and to find in what way theyaffect +Gz tolerance. With the cost of fighteraircraft becoming tremendously high, alongwith the associated high cost of trainingaviators to fly them, it will become moreimportant to assure safety by selecting onlythose individuals most suited to tolerate the

multistress environment of the fighteraircraft. If certain parameters are associated

with increased +Gz tolerance, it might be

necessary in the future to establish high-performance fighter aircraft selectionstandards so that a group of aviators with

super-high +Gz tolerance could be selected tomaintain complete air superiority. Initialstudies measuring the +Gz tolerance of 59USAF aircrewmen undergoing aeromedicalevaluation were made on the USAF School

of Aerospace Medicine human centrifuge.

Specific clinically measurable parameterswere found to be associated with +Gz

tolerance. A high +Gz tolerance prototype isdescribed. The parameters associated withhigh +Gz tolerance are not necessarily theoptimum attributes for the high-performancefighter pilot since these parameters do carryincreased risk for cardiovascular disease.

84. Whinnery JE, MJ Parnell.The effects of long-term aerobicconditioning on +Gz tolerance.


Authors' Abstract

Aerobic conditioning programs foraircrews of high performance fighter typeaircraft are very important in assuringoptimum fitness and health. The aerobicconditioning resulting from running alters thephysiologic state of the individual, andwhether or not this alteration affects +Gz

tolerance is unknown. In this study, 27

long-term (2 years of running) aerobicallyconditioned subjects were tested for gradual(1 G • 15 s t) and rapid onset (1 G ' s _) +Gz

tolerance. Maximum 40 2 and percent body

fat measurements were also performed andcorrelated to the +Gz-tolerance

measurements. Although beneficial for

optimum health and fitness, increased aerobic

condition ( %zO2 max) resulting from long-

term running was not found to enhance +Gztolerance. No relationship was observedbetween aerobic condition and +Gz tolerance.

An increased susceptibility to motionsickness was found to be associated with

long-term aerobic conditioning. Certainindividuals were found to be predisposed tocardiac rate and rhythm disturbances (A-Vdissociation and transient asystole) which

could potentially alter +Gz-tolerance.Optimum physical conditioning programs for

31

aircrewof fighteraircrafthaveyetto bedeterminedandimplemented.Specificityofexercisetrainingandassuranceof theabsenceof exaggeratedcardiovascularresponseto+Gzstressresultingfrom physiologicalterationof autonomictonearecriticalto thedesignof optimumconditioningprogramsforfighteraircraftaircrews.

85. White PD, JW Nyberg, LMFinney, WJ White.Influence of periodic centrifugationon cardiovascular function of man

during bed rest.

Santa Monica, CA: Douglas Aircraft

Co. Inc., Report No. DAC-59286,1966. 47p.

Authors' Abstract

A study was made of the influence ofperiodic centrifugation on the physiologicaldisturbances associated with 10 days of bedrest. During bed rest the subjects werescheduled to ride the centrifuge 4 times eachday; the duration of each ride was 20 min;and the magnitude of acceleration was +2.5gz at heart level. Subjects exercised for a 14-day period before the study. The energy costof this exercise was approximately 1,000kcal/day/man.

Functional and diagnostic tests conductedat regular intervals during the experimentrevealed the following:

1. The prescribed regimen of +2.5 gz for20 min exceeded tolerance to positiveacceleration. The modal conditioningregimen was +1.75 gz for 20 min 4 timeseach day. When the magnitude ofacceleration is referenced to foot level, the

integrated g-time is 4.7 g-hours.2. Expected deterioration produced by

recumbency in the ability to tolerate 700 head-

up tilt for 20 min was largely alleviated byperiodic centrifugation, as judged bysyncopal episodes and highest orthostaticheart rates.

3. The conditioning regimen did notappear so effective as shorter g-timeintegrals, as judged by highest orthostaticheart rates and plasma volumes.

4. Step-function acceleration toleranceand tolerance for sustained acceleration are

more sensitive than the standard bioassay

method for measuring cardiovascular changesat bed rest.

5. Tolerance to positive accelerationdeclines during the first 12 hours of bed rest,remains relatively constant during bed rest,and improves during ambulation.

6. Losses in body weight wereprogressive and ranged from 0.98 to 2.35kg. Average weight loss during the I0-dayperiod was 2%.

7. The condition of the experimentresulted in an average loss of 17% in totalblood volume, 26% in plasma volume, and2% in red blood cell volume.

8. No significant changes were seen inserum electrolytes, bilirubin, glucose, orblood urea nitrogen; in red blood cell, whiteblood cell, or reticulocyte counts; inhemoglobin, hematocrit, or in meancorpuscular hemoglobin concentration; inhearing, or in the postural equilibrium; norwas there any change in exercise tolerance asmeasured by the Master's two-step test.

9. No cardiac irregularities orarrhythemias were encountered in the testingof eight subjects during a total of 135 hoursof positive acceleration.

10. Application of negative pressure tothe lower half of the body producescardiovascular changes similar to those seenin 700 head-up tilt. Application of a pressuredifferential of 70 mmHg to subjects after l0days of bed rest produced presyncopalsymptoms in 2 to 4 min. During theprerecumbency period, these two subjectstolerated 20 min of negative pressure withoutsymptoms.

86. White PD, JW Nyberg, LMFinney, WJ White.A comparative study of thephysiological effects of immersionand bed rest.

Santa Monica, CA: Douglas Aircraft

Company Inc., Report No. DAC-

59226, I996. 77p.Authors' Abstract

The purpose of the study was to comparethe physiological responses of 10 subjects,each serving as his own control, duringalternate 10-day periods of immersion andbed rest. Functional, diagnostic, and

monitoring tests conducted before, during,

32

andafterthe 10-daytestingperiodswereusedto follow physiologicalchangesproducedby thesetwo analogsof null gravityandtoquantitativelycomparetheireffects.Fluid siliconewasusedastheimmersionmedium.

Neitherimmersionnorbedrestproducedappreciablechangesin Master'stwo-steptestof exercisetolerance,restingoxygenconsumption,tolerancetoaccelerationin thegzdirection,visualandauditoryacuity,or inECGandheartsoundrecordedduringtilt-tabletesting.Therewerenosignificantchangesin microscopicorqualitativeanalysisof theurinefor sugar,acetone,or protein;restingbloodpressure,temperature,heart,andrespirationrate;bloodandurinechemistriesor kidneyandliver functions.

No seriouscomplicationswerenotedinanyof thesubjectsduringimmersionorbedrest.Neitheranalogproduceda free-waterdiuresis.Theresultsof thestudyconfirmthedetrimentaleffectsof prolongedimmersionandbedrestonorthostatictoleranceandextracellularfluid volume.Both analogsbroughtaboutadeteriorationin themechanismsessentialfor adequatecirculationin theerectposition. Thiswasshownbyincreasedincidenceof presyncopalreactions,by declinesin pulsepressure,andbyincreasedheartrateduringtilt-tabletesting.Experimentalconditionsproducedreductionsinplasma,blood,andextracellularfluidvolumes;declinesin maximumoxygenconsumption;andsomeimpairmentofposturalequilibrium. Lossesin bodyweightwereprogressive,theaveragewasapproximately2%of initial weight. Anegativefree-waterclearancewasobtainedinall subjectsduringimmersionandbedrest.

Differentialeffectof thetwoenvironmentsareseeninorthostatictolerance,fluid compartments,andrenalfunction. Theincidenceof pre-syncopalreactionswashigherandoccurredearlierduring immersionthanduringbedrest.Heartrateswerehigherandpulsepressureswerelowerduring immersionthanduringbedrest. After 5 daysof immersionandbedrest,theextracellularfluid decreasedby 3%and2%,respectively.After 10days,thenetdecreasein fluid was5%duringimmersionand7%duringbedrest. Theconditionsofimmersionproducedalargerlossin plasma

volumeafter5 daysthandid bedrest,but thenetlossafter10dayswasapproximatelythesamefor bothenvironments.Changesinbloodvolumewereparallelto thoseofplasmavolume. Immersionproducedanelevatedurineflow, asevidencedby acomparisonof urineoutputsin thetwoenvironmentsandby higherurineoutputsthanfluid intakesduringimmersion.Duringbedrestthesubjectsproducedamoreconcentratedurine,bothwith respecttoindividualelectrolytesandsoluteload.Duringimmersionthedaily soluteloadexcretedby thekidneywashigher,urineoutputwaslarger,andosmolarclearancewashigher.

Thesiliconefluid, immersiontanks,filtration,andcoolingequipmentmettherequirementsof theexperiment.Exceptfortwo subjects,skinproblemsthatdevelopedduringimmersionweretrivial. An effort torelatetheoccurrenceof skinproblemstobacteria,water,andcontaminationof thesiliconewasinconclusive.Duringa 6-monthperiodfollowing thestudy,thesubjectswerefreeof abnormalphysicalsigns,symptoms,andskinproblems.

87. White PD, JW Nyberg, WJWhite.

A comparative study of thephysiological effects of immersionand recumbency.In: Proceedings of the SecondAnnual Biomedical Research

Conference. Houston, TX: NASA,

Mantled Spacecraft Center, 1966.

p. 117-166.Annotation

Purpose:The purpose of this study was to compare

the physiological effects of immersion andrecumbency. Subjects were immersed insilicone fluid up to neck level for periods upto 30 days.Method:

Each subject was immersed to neck level24 hours per day for 10 days.Simultaneously 3 subjects were at absolutebed rest (and second study reversed

subjects), 8 subjects were at absolute bedrest, 6 subjects rode the short-radiuscentrifuge (SRC) for a 20-min period four

33

timesadayfor 80minperdaypersubject.Subjectsrodeat +3.5- 4 gzat thefeetand2othersubjectsperformeda stepfunctionbioassayrideeveryotherday.Results:

All subjects riding the centrifuge fourtimes per day maintained tilt table tolerance.Changes in acceleration tolerance were seenin deconditioned subjects and it returnedtoward normal with ambulation.

Conclusion:

1. SRC training can largely preventcardiovascular deconditioning from bed rest.2. There is a severe loss of g tolerance insubjects deconditioned with bed rest.

88. White W J, JW Nyberg, PDWhite, RH Grimes, LMFinney.

Biomedical potential of a centrifuge inan orbiting laboratory.

Santa Monica, CA: Douglas AircraftCo. Inc., Los Angeles Air ForceStation, CA No. SSD-TDR-64-209,

Supplement, 1965. 120p.Authors' abstract

The results of several studies pertainingto manned orbital laboratories are reported.

The first of these studies concerns the

consequence of heart-to-foot accelerationgradients for the measurement of tolerance topositive acceleration. A major finding of thisstudy is that two modifications to thestandard bioassay method--a low-intensitycentral light and one gradual onset ofacceleration to blackout--make it possible tomeasure tolerance in the presence of a 219%heart-to-foot gradient with minimalcardiovascular stress.

The second was a parametric study of thepower requirements of a short radiuscentrifuge. The findings here were (1) emptyweight of the centrifuge is 155 lb, (2) peakpower consumption is 436 watts, (3) energyconsumption during a 7.5-min run at 4g is5.85 Whr.

The third study is an analysis of theerrors resulting from use of the centrifuge todetermine body mass. The results of an errorreduction study and the experimentalapparatus for verifying the two-radiusmethod are presented.

34

The salient generalizations derived from aseries of studies in which bed rest was used

as the analog of null gravity are presented.The results of a pilot study to determine

the influence of periodic centrifugation on thephysiological disturbances associated with 41days of bed rest are reported in the fourthstudy. The investigation was carried outduring 20 days of bed rest, and 16 days ofbed rest with periodic rides on the centrifuge,followed by 5 days of bed rest,centrifugation, and physical exercise. Majorfindings of this study were (1) motionsickness is not a problem for the well-trainedindividual when exposed to high angularrates of rotation and modest head or limb

movements, (2) deterioration produced byrecumbency in the ability to tolerate 900 head-up tilt for 20 min was largely alleviated byperiodic centrifugation as judged by syncopalepisodes, (3) the three subjects receiving +4gz four times each day showed less lability inblood pressure and heart rate during the tilt-table tests than did the two subjects exposedto +1 gc

The fifth study extended the results of thefourth study by increasing the integrated g-time from 0.5 and 2 g-hour to 3 g-hour,

added approximately 700 kcal of exercise,and distributed the rides over a 24-hour

period as contrasted with the 8-hour scheduleof the fourth study. A maintenance group of

three subjects began riding the centrifuge ,0nthe first day of bed rest and rode every dayfor 13 days. A therapy group of threesubjects started riding the centrifuge after 17days of bed rest and rode periodically for 6days. A control group of four subjects wastransported to and from the centrifuge, butwas not rotated. The major finding of thisstudy was that the use of periodiccentrifugation and exercise during bed resttended to prevent deterioration, in themaintenance group, of the mechanismsessential for circulatory control on the tilttable. The effects of centrifugation were

indicated by lack of syncope in themaintenance group as compared with threecases of syncope in the noncentrifugedgroup. The effects of exercise were indicatedby heart rate responses during tilt.

As a result of these studies, the potentialof the short-radius centrifuge is presented andrecommendations for future research are

made;andtheimpactonfuturemissionsisexamined.

89. Wiegman JF, LP Krock, RRBurton, EM Forster.

Anaerobic power testing and +Gzendurance.


Authors' Abstract

Introduction:

Performance of the L- 1 and M- 1 strainingmaneuvers, used during high sustained +Gz,has been described as anaerobic work.

Therefore, the present study examines therelationship between anaerobic abilities and+Gz endurance.

Methods:

The Wingate cycle ergometer test (WAT)

was employed to assess upper and lowerbody capacity for short-term exhaustiveexercise in 8 subjects. Performance indices(measured 3 times) include: peak power for a5-sec period; 30-sec mean power (MP, anindex of anaerobic capacity); and percentfatigue. Acceleration was measured byduration in seconds, on 2 occasions, for a

simulated aerial combat maneuver (SACM)

profile which alternates 4.5-7 G (15 sec each)until exhaustion. Heart rate was collected

online and blood lactates sampled at rest and3, 6 and 8 rain post-WAT and post-SACM.Results:

SACM duration is not significantlycorrelated with WAT power outputs or bloodlactates post-SACM in five subjects testedthus far. However, a correlation coefficient

exists between SACM time and highestobserved blood lactates following the lowerbody WAT (r = .93). The 2 subjects withthe highest single SACM times (391 sec),exhibit contrasting lower body WAT MPs of495 and 825 W; max heart rates during

SACM of 158 and 178 bpm; and peak bloodlactates post-SACM of 3.61 and 5.91mmol/L, respectively.Conclusions:

Some individuals may work at asubmaximal intensity, not associated withanaerobic metabolism, during the 4.5-7 GSACM. The role of anaerobic power in +Gzendurance should be further evaluated in a

multifactorial approach which considersindividual +Gz tolerance levels.

90. Wood EH, EF Lindberg, CFCode, EJ Baldes.Effect of partial immersion in water

on response of healthy men toheadward acceleration.


Authors' Abstract

Protection against the effects of headwardacceleration afforded by immersion in waterhas been assayed in the human centrifuge on15 trained subjects. Immersion in water tothe xyphoid afforded an average protection of1.1 + 0.1 G for vision and ear opacity and of1.6 + 0.2 G for ear pulse and heart rate.Deeper immersion, to the level of the third ribat the sternum increased the protection to 1.8+ 0.1 G for vision and ear opacity and to 2.8+ 0.2 G for ear pulse and heart rate. The

protection afforded the various physiologicvariables increased with the magnitude ofacceleration tested. Protection against loss ofconsciousness may be greater than protection

against blackout and is probably similar to theprotection afforded the ear pulse and heartrate. The cardiovascular reactions produced

by headward acceleration are qualitativelysimilar with and without water immersion.

This finding does not support the concept thatimpediment to venous return is the primarydeterminant of man's tolerance to headward

acceleration. Visual symptoms occurred at

greater amplitudes of ear pulse, andpresumably also at greater blood pressures athead level, during water immersion thanduring control runs.

91. Zborovskaya BI.Use of short-arm centrifuge to

prevent deconditioning whenimmersed in water (according to H-reflex).

Kosmicheskaya Biologiya iAviakosmicheskaya Meditsina13:78-79, 1979.

Author's Abstract

A study was made of the possibility ofusing periodic rotation on a short-armcentrifuge (SAC) as a means of preventingthe adverse effects of immersion.

35

Eachsubjectwassubmittedto +3Gzafterpureimmersionandimmersioncombinedwith periodicrotationonaSAC, whereaccelerationsof +0.8Gz,+l.2Gz or 1.6Gzweregeneratedfor 60min twiceaday(firstseries)andfor 40min 3 timesaday (secondseries).

In 76%of thecasestherewasearlyrecoveryof H-reflexamplitude( lS'_3dminof aftereffect)with exposureto +3Gzafterimmersioncombinedwith SACwhenusingG forcesof +1.2Gz for 40min 3 timesaday,and62%for +1.6Gz for 60min twiceaday.

36

ADDITIONAL SELECTED BIBLIOGRAPHY

Antonutto G, C Capeili, PEdiPramperoPedalling in space as acountermeasure to microgravitydeonditioning.Microgravity Q 1:93-101, 1991.

Balldin UI.

Physical training and +Gz tolerance.Aviation, Space, and EnvironmentalMedicine 55:991-992, 1984.

Bjurstedt H, O Eiken.Graded ischemia in exercise humanskeletal muscles: Methods and

applications.

News in Physiological Sciences10:193-197, 1995.

Burton RR.

A human-use centrifuge for spacestations: Proposed ground-basedstudies.


Greenleaf JE.

Importance of fluid homeostasis foroptimal adaptation to exercise andenvironmental stress: Acceleration.

In: Perspectives in Exercise

Science and Sports Medicine. Vol.

3: Fluid Homeostasis During

Exercise, edited by CV Gisolfi, DRLamb. Carmel, IN: Benchmark

Press, Inc., 1990. p. 309-346.

Kotovskaya AR, RA Vartbaronov, SF

Simpura.Izmeneniye perenosimostichelovekom poperechnykhperegruzok posle gipodinamiirazlichnoy prodolzhitel'nosti.(Changes in the tolerance of man totransverse accelerations followinghypodynamia of varying duration).

Proceedings of the 18th Congress ofthe International Astronautical

Federation, edited by M Kung.Warsaw: Pergamon Press & PWN-Polish Scientific Publishers, Vol 4,

Life in Spacecraft, 1968. p. 123-131.(NASA TT F-11,401, 1967).

Meehan JP and HI Jacobs.

Relation of several physiological

parameters to positive G tolerance.Los Angeles, CA: Universi_, of

Southern California, School of

Medicine, Wright Air Development

Center Technical Report No. 58-

665, 1959. lip.

Murthy G, DE Watnepaugh, REBallard, AR Hargens.

Supine exercise during lower bodynegative pressure effectivelysimulates upright exercise in normalgravity.


Norsk eo

Gravitational stress and volume

regulation.

Clinical Physiology 12:505-526,1992.

Nyberg JW, RH Grimes, WJ White.Consequence of heart-to-footacceleration gradient for tolerance topositive acceleration.


Piemme TE, AS Hyde, M McCally, GPotor, Jr.Human tolerance to Gz 100 per cent

gradient spin.Aerospace Medicine 37:16-21,

1996.

Shumate WH, SD Leverett, SJShubrooks, CK LaPinta.Physiological effects of prolongedpositive (+Gz) acceleration followingone and seven days bedrest.

In: Physiological Effects ofProlonged Positive +Gz

Acceleration following One and

Seven Days Bedrest, edited by WHShumate. Houston, TX: NASA

45

MannedSpacecraftCenter,Chapt.1,1971.p.l-13.

von Beckh HJ.

Flight experiments about humanreactions to accelerations which are

followed or preceded byweightlessness.In: Proceedings of the IXInternational Astronautical

Congress, Vol. 2, 1958. p.507-525.

Watenpaugh DE, RE Ballard, MSStout, G Murthy, RT Whalen,AR Hargens.Dynamic leg exercise improvestolerance to lower body negativepressure.


46

(numbers

Akhrem-Akhremovich RM: 35Aleksandrova EA: 72Andersen HT: 3

Andreyeva VG: 37Annis J: 71Antonutto G: 1Armbruster R: 26

Asyamolov BF: 2, 40Augerson WS: 5

Backhausen F: 42,Baldes EJ: 90Balldin UI: 3, 4, 68, 69, 77Baranova BP: 54Beckman MC: 5

Benevolenskaya TV: 60Benson VG: 5

Bernauer EM: 14, 15, 16, 26, 27, 28

Bjurstedt H: 6Bodarenko RA: 2

Boglevskaya NM: 54Boykova OI: 60Brock PJ: 24, 25Brtiner H: 42, 44, 45, 46, 47

Brunjes S: 59Bulbulian R: 7

Burton RR: 12, 14, 15, 16, 89

Chambers RM: 5Chase GA: 8Chelnokova NA: 66

Cherepakhin MA: 9, 35Chertovskikh YeA: 54Clark WG: 10Coburn KR: 5Code CF: 90

Convertino VA: 21, 22, 58

Cooper KH: 11Crisman RP: 12, 63

Davis GL: 27DeForest RE: 5de Vries H: 59

di Prampero PE: 1Dlusskaya IG: 13Dobronravova NN: 61Dolkas D: 71Driscoll TB: 55

Eichhorn J: 42, 44Elizarov SYu: 2Elizondo R: 25Ellis S: 39

Epperson WL: 14, 15 16

Author Indexrefer to abstract number)

Finney LM: 85, 86, 88Forster EM: 17, 89

Gale RR: 18Gardiner IDR: 10Gavrilova LN: 18

Georgiyevskiy VS: 19, 35Gogolev KI: 20, 72Goldenrath WL: 64Goldwater DJ: 21, 22, 58, 70Golovkina OL: 23Grave C: 8Greenleaf JE: 24, 25, 26, 27, 28, 78

Grigoriev AI: (Gregor'yev AI): 29, 30, 73Grimes RH: 88Grunbaum BW: 71

Haines RF: 26, 28Hannah K: 32

Henry JP: 59

Hjort H: 77Hoffler GW: 31

Houghton JO: 32Hyatt KH: 33

Jacobson LB: 33Johnson PC: 55Johnson RL: 31

Jorgenson H: 10Jovy D: 42, 45Juhos L: 78

Kakurin LI: 34, 35Kaliberdin AV: 2Kamenskii YuN: 36, 37

Katkovskiy BS: 35, 38Keil LC: 39

Khapilov NV: 40Khomenko MN: 13

Khudyakova MA: 41, 73Klein KE: 42, 44, 45, 46, 47, 48Kokova NI: 49Kollias J: 27

Korotayev MM: 61Kotovskaya AR: 35, 50, 51, 52, 53Kotov NN: 40Kozar MI: 61Kozlova VG: 74Krauhs JM: 56Krikum IS: 18Krock LP: 89

Krupina TN: 54Kudrin KA: 74

47

KudrovaRV: 66Kuklinski P:48KuronenP:4, 68, 69Kuz'min MP: 60KuznetsovMI: 66

LeachCS: 55,56LeverettJr.SD: 11,62LindbergEF:90LinnarssonD: 1Lobzin PP:66LohrbauerLA: 57Ludwig DA: 58

MatsnevEI: 54McBride DK: 32McCallyM: 57Mclntyre AK: 10MeehanJP:59MeyerLG: 63MikhaylovVM: 19Mikhaylovskiy GP:60,61Miller PB:62MorseJT: 26MukharlyamovNM: 35MurdochDM: 63MyhreK: 3

NewsomBD: 64,71NybergJW: 85, 86, 87,88

OvechkinVG: 18

PaceN: 71PanchenkoVS: 2, 40PanferovaNYe: 35ParnellMJ: 65, 84PetrovaTA: 60PetrovykhVA: 66PetuknovBN: 67PlokhovaVG: 2, 74PoleseA: 25PopovIG: 66PurakhinYuN: 67PushkarYuT: 35

RomanovaIA: 66RosenhamerG: 6RositanoSA: 70RowellLB: 8RuskoH: 4, 68, 69

SaganL: 26

48

SandierH: 21, 26,28, 33, 56, 58,64, 70,71SavilovaAA: 60Schlhalk_iuserKL: 44SchotteJ:42,44SciaraffaD: 24,25SenkevichYuA: 35ShamrovPG:35ShilovVM: 61ShubrooksSJ:57Shul'zhenko,YeB (EB): 30, 36, 37,41, 72,

73, 74,80, 81SimpuraSF:35,51, 52,53Solov'yevaSN: 60SpenceDW: 75StaleyRW: 28StinnettHO:27SundbergCJ: 1SuvorovPM: 76SvenssonE:4SyzrantsevYuK: 66

TerpilovskiyAM: 66TeschPA: 3, 68,69,77TizulAYa:54TsiganovaNI: 61

UdalovYuF:66UlyatovsiyNV: 2UstyushinBV: 18

vanBeaumontW: 26,28,78VanyushinaYuV: 35VarbaronovRA: 35VartbaronovRA: 52,53VartbaronovRV: 51Vernikos-DanellisJ: 56Vil-Vilyams IF: 72,73,79, 80,81VoigtED:44,46VogtL: 42,45,47VoroninLI: 2

WebbP:71WegmannHM: 42,44,45, 46,47, 48WesselJA: 82WhinneryJE: 17,65, 83,84WhitePD: 85,86,87,88WhiteWJ: 85,86,87,88WiegmanJF:89WigertzO: 6Wiley RL: 57WilhelmsenU: 3WinterWR: 64WoodEH: 90

Wolthuis RA: 31

Yakovleva IYa: 60, 61Yarov AS: 2, 74Yelkin PA: 18Yelkina LG: 18

Young HL: 28, 78Yusken JW: 28

Zborovskaya BI: 91

Author Index

(numbers refer to abstract number)

49

Keyword Index(numbers refer to abstract number)

Abdominal muscle training: 3Acceleration tolerance: 2, 5, 7, 9, 10, 11, 12,

13, 14, 15, 17, 19, 21, 22, 24, 25,27, 30, 31, 32, 35, 39, 40, 42, 44,45, 46, 47, 48, 49, 50, 51, 52, 53,54, 55, 56, 57, 58, 60, 61, 62, 64,65, 67, 70, 71, 72, 73, 74, 75, 76,78, 80, 82, 87, 88, 90

Aerobic

fitness: 12, 17, 46

training: 22, 84Age: 56, 58, 70Anaerobic power: 89Antigravity: 2Arterial lactates: 6

Artificial gravity: 1

Bed rest: 7, 9, 19, 21, 26, 27, 28, 31, 34,38, 39,50, 51, 52, 53, 54, 55, 56,59, 60, 61, 62, 67, 70, 71, 78, 85,86, 87, 88

Blood

clotting: 41pressure: 8, 13, 28, 45, 47, 49, 51,57, 58, 70, 90, 91volume: 13

Body weight: 28, 58Breathing: 36, 37

Cardiovascular

deconditioning: 1response: 17, 50, 52, 60, 62, 65, 71,73, 80

Circulation: 19, 40, 60, 80

shifts: 27, 29, 30, 73

supplements: 49Flexor muscles of abdomen and hip: 3Formed elements: 61

Gas exchange: 23Gauer-Henry reflex: 5G-tolerance: 2, 3, 16, 17, 24, 26, 27, 28,

32, 33, 39, 44, 45, 48, 49, 51, 52,53, 55, 57, 59, 60, 62, 63, 64, 65,68, 69, 70, 72, 73, 74, 75, 77, 78,79, 81, 83, 86, 89

H-reflex: 91Head-down tilt: 2Heart rate: 4, 6, 8, 11, 13, 28, 44, 45, 47,

48, 49, 51, 53, 57, 62, 70, 71, 73,74, 79, 80, 81, 82, 84, 85, 87

Hematocrit: 10

Human centrifuge: 1, 3, 8, 18, 23, 37, 41Hypokinesia: 2, 9, 18, 19, 34, 35, 40, 54,

60, 61, 67, 74, 76

Hypoventillation: 8Hypoxia: 44, 46, 47

Immersion: 5, 20, 30, 36, 37, 41, 48, 49,50, 72, 73, 74, 79, 80, 81, 86, 87,90, 91

Immunity: 34, 61Intra-abdominal pressure: 3Isometric training: 3, 26, 68, 69, 75Isotonic exercise: 6, 9, 26

Knee extensor muscles: 3, 77

Diet: 9, 66Diuresis: 5

Dynamic endurance: 3

Lean body mass: 11Lower body negative pressure (LBNP): 31,

33, 48, 56, 71, 76, 85

Electrocardiogram: 2Electrolyte responses: 25, 27, 29, 30Endocrine responses: 25, 56, 71Endurance capacity: 11, 48, 65, 68Environment cool/hot: 24Exercise:

anaerobic: 12heat acclimation: 24

training: 4, 12, 23, 52, 54, 63

Fat: 11, 58, 65, 84Fitness test: 82Fluid:

loss: 10retention: 49

Manned space flights: 29Maximal peak torque: 3Metabolism: 38Muscle:

endurance: 3, 67, 75

strength: 14Musculo-skeletal deconditioning: 1

Myogram: 2

Nervous system: 54, 64Neuromuscular adaptation: 77

Orthostatic tolerance: 31, 35, 45, 47, 48, 58,

79, 87

51

Oxygenuptake:6, 7, 11,14,21, 33,44,45,46, 48, 58, 65, 69, 78, 84, 87

Performancecapacities:8,45,69Peripheralintracranialcirculation:18Photoplethysmography:2Physical:

conditioning:11, 15,42,43,48training:7, 24,45

Plasma:protein:10reninactivity:39vasopressin:39volume:27, 58,78,85

Psychomotorperformance:59Pulmonaryvolumes:5

Rateof perceivedexertion (RPE): 4Rehydration: 28Renal function: 30

Respiration: 50, 51, 52, 53, 71Running: 63, 82

Salt supplements: 49Schneider test: 46

Short-radius centrifuge: 20, 23, 79, 81, 87,88, 91

Shuttle flight: 21, 22, 33Simulated aerial combat maneuver: 4, 7, 14,

15, 16, 77

Specific weight training: 16Static endurance: 3

Strength training: 68, 69, 77Submaximal intensity: 89Syncope: 32, 48, 83

Thyroid function: 55Tilt test: 13, 33, 42, 43, 45, 48, 88

Training: 44, 46Transcapillary exchange: 20Treadmill: 8, 69

Valsalva maneuvers: 51

Veloergometer: 79Vestibular tolerance: 1

Water loading: 13Weight: 11, 45, 85Weight lifting: 63, 82Work:

capacity: 8load: 6

52

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I October 1997 Technical Memorandum4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Acceleration Tolerance: Effect of Exercise and Acceleration Training;

Bed-Rest and Weightlessness Deconditioning

A Compendium of Research (1950-1996)6. AUTHOR(S)

J. L. Chou, M. A. McKenzie, N. J. Stad, P.R. Barnes, C. G. R. Jackson,

F. Ghiasvand, and J. E. Greenleaf

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Ames Research Center

Moffett Field, CA 94035-1000

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National Aeronautics and Space Administration

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199-97-62-13

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13. ABSTRACT (Maximum 200 words)

This compendium includes abstracts and annotations of clinical observations and of more basic studies

involving physiological mechanisms concerning interaction of acceleration, training and deconditioning. If the

author's abstract or summary was appropriate, it was included. In other cases a more detailed annotation of the

paper was prepared under the subheadings Purpose, Methods, Results, and Conclusions. Author and keywordindices are provided, plus an additional selected bibliography of related work and of those papers received after

the volume was prepared for publication. This volume includes material published from 1950-1996.

t4. SUBJECT TERMS

Acceleration, Exercise, Deconditioning

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