2

3

Paul Gibson

NASAPat Rawlings.

Gravity on a mission to mars

NASANASA

Turner Graphic

Design

3 / 8 G( m o n t h s )

M a r s

++G(min ute s)

++G(min ute s)

+ +G( min ute s)

+ +G ( min ute s)

1 G( y e a r s )E a r t h

0Gi nte r pl a en t ar y p has e

(6- 12 m on t hs )

0 Gi nte r pl a en t ar y p hase

(6 -1 2 m ont hs)

4Effects of G

• liquids and soft tissue> blood volume, red blood-cells> cardiovascular deconditioning

• muscles (no antigravity support)> muscle atrophy, change of m-type

• bones (reduced impact loading)> demineralization

• vestibular system (no g-stimulation)> motion sickness > adaptation: tilt as translation

5Effects of G

• Cardiovascular- blood volume, red blood-cells, heart mass and pumping abilities - Peripheral deconditioning

• Orthostatic intolerance problem re-entering gravity field

Pre-flight Post-flight

Long-duration flight

Early Flight

6Effects of G• Musculoskeletal loss

– Mostly lost in lower limbs– Calf muscle and power generation

significantly less post-flight• Even with exercise regiment

– Bone loss - strength• Might not be fully recoverable

Normal Ageing

Effects of G

• vestibular system (no g-stimulation)> motion sickness > adaptation: tilt as translation

7

Cross-system effect of G 8

• New space-normal for all systems– Except bone and radiation effects

• Problems for re-entering a gravity field

9

Traditional countermeasures against G-deconditioning are inadequate.

(esp. against bone density and calf muscle losses)

Traditional countermeasures• exercise on ISS against deconditioning:

- 90 minutes / day• electrical muscle stimulation• impact loading against bone

demineralization • lower body negative pressure • diet and drugs

(against calcium excretion)• pre-flight training

10Traditional Countermeasure Examples

Russian LBNP suit – “Chibis” Cycle Ergometer

Advanced Resistiive Exercise Device (ARED)Interim Resistive Exercise

Device (iRED)

11I. History of Mars Planet exploration I. History of Mars Planet exploration First dreams of humans on Mars

1952

12The new old countermeasure...Short Radius Centrifuge• high rotation rate• intermittent• high g-gradient

Large Radius Centrifuge• low rotation rate• continuous• low g-gradient

or

13Moving in a rotating environment

When moving against-rotation the ‘Artificial Gravity’ pulls toward the floor is reduced.

When moving with-rotation the ‘Artificial Gravity’ presses you more strongly to the floor.

: angular velocity a : Artificial Gravity

rt : Subject tangential velocity

changes the angular velocity

14Physics of AG• GIF: centripetal acceleration + gravity

– FR= m r ωC 2 – static loads -> otolith, fluid shift

• Coriolis: rotation + radial motion– FC= - 2 m ωC v– dynamic loads -> otolith, movements

• CCS: rotation + rotation– FCC = ωC ωH (stimulus ωC sin H )– dynamic loads -> canal stimulation

15

from Shipov, 1996

G = r2

r=radius (m)

=

angu

lar

velo

city

(r

pm)

max

1g

Gmin

Setting AG Requirements

operating point

16MIT Short Radius Centrifuge

back slider

exercisestepper +forceplatesfootplate

electronic driveon board power supply

axis of rotation

axis of head turn

17Adaptation to AG• Adaptation is essential for successful

intermittent AG– Otherwise motion sickness would be an issue

• The adaptation must: – Be easy and rapid to acquire– Minimize motion sickness– Be able to cover all head movements– Enable rapid switching between rotating and non-rotating

states• Results – We CAN adapt people

– Studies at MIT• Incremental adaptation to 30 rpm• Rotation rate, amount and number of head turns allow to control

the side effects of AG by modeling the sensory conflict• What about the effectiveness of AG?

18

IMAG - Pilot Study of Artificial Gravity as a Multi-System Countermeasure to Bed Rest Deconditioning

Principal Investigator:W. Paloski, Ph.D., NASA JSC

Co-Principal Investigator:L. Young, Sc.D., MIT MVL

19

resistive exercise device

aerobic exercise device

IMAG Phase 2 Centrifuge

20How do we test AG?• No human centrifuge has been flown in space• Terrestrial analog to space effects on humans

– 6°head-down bed-rest– Dry-immersion, wet-immersion– 24 hours / day

• Except during countermeasure treatment• Length of study dependent on physiological system

being studied– ~7 days for most

cardiovascular measures– ~21 days for muscle– ~60 days for bone

(DXA/pQCT)

21

AG as a Countermeasure

Microgravity

22AG is NOT = Real Gravity

23IMAG - Earth based G-model

6°head-down bed-rest > 24h per day > 21 days or more

result > reduction of blood-cells & volume > cardiovascular deconditioning > demineralization of bone > muscle atrophy

bed-rest can be used as model for

G-effects

24IMAG - Goal

• validate intermittent AG as an effective countermeasure

• How much AG is needed?– the physiological thresholds for AG?– minimum and/or optimum g-force?– is AG required Moon or Mars?

• What AG is needed?– optimal radius and angular velocity?– untoward consequences and limits of AG?

25Results of Ground-based AG Studies• Cardiovascular system - AG compares well to

traditional countermeasures• Maximum oxygen uptake, orthostatic tolerance time,

plasma volume, exercise time• Cycling coupled to AG for aerobic exercise

• Musculoskeletal system• Very few AG studies exist to compare• Many parameters are trending to support AG

• Relatively short duration of studies an issue

• Space-based AG study would be ultimate test of countermeasure efficacy

26IMAG Pilot StudySummary and Recommendations

• Comparing the centrifuged subjects to the controls in a 21 day head down bed-rest study:

• Good stuff happened• Bad stuff didn’t happen• Lot’s more to do

27The Good Stuff Happened

• Cardiovascular system protected– Orthostatic Tolerance Increased with AG– No decrease in VO2peak with AG

• Muscle loss reduced– Knee Extensor and Plantar Flexor Muscle Groups Maintain

Mass and Strength• Bone loss possibly lowered

– Duration too short to show Density Loss– Awaiting Further Bone Biochemistry Results

28The Bad Stuff Avoided

• Minimal motion sickness• No negative after-effects of spinning• Minimal pre-syncope during spins• Minimal vestibular alterations

– Possible visual vertical variability

• Minimal human factors issues – Possible cognitive effects

29A Critical Benefit Analysis of Artificial Gravity as a

Microgravity CountermeasureJustin Kaderka Laurence Young William Paloski

This study was supported by the NASA Human Research Facility

30Study Definition

• Scope of the study– Literature review – published and unpublished data – of ground based

studied• Artificial gravity

– Studies from the 1960s through present day– Human, bed rest only

• Current space-qualified countermeasures– Aerobic exercise (cycling ergometer, treadmill)– Resistive exercise– Lower Body Negative Pressure (LBNP)

• New, ground-tested, traditional countermeasures– LBNP with vertical treadmill

• Analysis– Statistical analysis performed on parameters where a sufficient number of

AG studies exist (n >=3)– Insufficient number of AG studies

• Individual studies compared using percent change graphs

• A work in progress– Study continually refined as more data is obtained

31Artificial Gravity Examples

UTMB two-arm centrifuge

The Human Powered Centrifuge – NASA Ames (Greenleaf 2001)

University of Nagoya centrifuge with cycle ergometer (Katayama 2004)

32Cardiovascular System - Conclusions

• AG-based countermeasures offer a measure of protection against deconditioning of important cardiovascular parameters

– Exercise capability• VO2 max (exercise capacity) a very important parameter• Resting heart rate is useful parameter for exercise endurance• AG-based countermeasure has same effectiveness as traditional countermeasures

evaluated

– Orthostatic intolerance• Plasma volume thought to be triggering mechanism for further orthostatic dysfunction

– Not necessarily predicts orthostatic intolerance• Orthostatic tolerance time a direct measurement of orthostatic intolerance• AG-based countermeasures preserved orthostatic tolerance time and exercising with

gravity or AG attenuated plasma volume loss

– Resting heart rate• Moderate parameter to fitness level• AG-based countermeasure has same effectiveness as traditional countermeasures

evaluated

33Skeletal Muscle - Conclusions

• For all parameters, AG effective at maintaining soleus fiber CSA

• Length of study– Most traditional countermeasure studies are of a significantly

longer duration than the AG studies– In all parameters, AG studies trending to counteract deconditioning– AG may prove to be significant in longer duration studies

• Number of AG studies– Very few AG muscle studies (n=2)– No staining performed on fibers

• Important parameters cannot be analyzed (e.g. slow to fast fiber transition)

34Bone - Conclusions

• No conclusions can be made on AG effectiveness in preventing bone loss– AG study (Smith 2009) was a pilot study and protocol did NOT

specifically address bone• Pilot study to get a starting point for comprehensive AG protocol

– Protocol of Resistive Exercise studies did aim to counteract bone loss, among other physiological systems

• Length of study– All traditional countermeasure studies are of a longer duration

than the AG studies– In all parameters, AG studies trending to counteract

deconditioning– Longer AG studies will allow bone changes to become more

apparent

35General Conclusions

• Maturity as a countermeasure– AG in its infancy

• Though first researched in the 1960s, very few AG studies have been performed• Protocol still widely undetermined

– AG not ready for flight evaluation– Traditional Countermeasures mature in design

• Many more studies performed than AG• Investigators are tweaking protocols

• Longer, comprehensive, ground studies needed for AG countermeasure– Longer studies needed to allow changes to manifest especially in bone,

and to some extent, skeletal muscle

• AG has the potential to be a single countermeasure for all physiological systems

36The AG Bottom Line

•AG has the potential to be a single countermeasure for all physiological systems

THE ISS AFFORDS A UNIQUE OPPORTUNITY TO TEST AG IN ORBIT

• An International Team has proposed a flight experiment using a human centrifuge on board ISS

37

38AG on the International Space Station• JAXA proposal

– Short-arm centrifuge• Couple AG with cycling

– Selected for one-year feasibility study through mid-2011– International team of investigators

• Many implementation issues– Volume envelope available centrifuge radius– Subject posture?– Centrifuge velocity?– Transmission of vibration?– Power?

39

Artificial Gravity with Ergometric Exercise on International Space Station as the Countermeasure for Space Deconditioning in Humans Iwase, S.1; Sugenoya, J.1; Nishimura, N.1; Paloski, W.H.2; Young, L.R.3; van Loon, J.J.W.A.4; Wuyts, F.5; Clément, G.6; Rittweger, J.7; Gerzer, R.7; Lackner, J.81Aichi Medical University, JAPAN; 2University of Houston, UNITED STATES; 3Massachusetts Institute of Technology, UNITED STATES; 4Dutch Experiment Support Center, Free University of Amsterdam, the NETHERLANDS; 5Antwerp University Research Center for Equilibrium and Aerospace, BELGIUM; 6International Space University, FRANCE; 7DLR, GERMANY; 8Brandeis University, UNITED STATES

Placement of Centrifuge• Pressurized Multi-Purpose Module (PMM) good candidate

location• Dedicated Japanese ATV also possible

40

PMM

41Acknowledgements

• John Charles, PhD

• Vince Caiozzo, PhD

• Alan Hargens, PhD

• Malcolm Cohen, PhD

• Li-Fan Zhang, PhD

• Alan Natapoff, PhD

• Stuart Lee

42

“Artificial gravity is an idea whose time has come around…and around…and around…”

Larry Young (1999)

IThank you for listening

QUESTIONS?

BACKUP SLIDES

ARTIFICIAL GRAVITYPROF. L YOUNG, MIT

43

44Cardiovascular System – Bed Rest Studies Used

• Artificial Gravity Studies– White et al. 1965 first to perform centrifugation studies– Represents an exhaustive literature review of human studies

• Traditional Countermeasure Studies– Not an exhaustive review of human studies, but a representative cross-section

45Cardiovascular System – Bed Rest Studies Used (Expanded)

46Cardiovascular System – Bed Rest Studies Used (Expanded)

47

Watenpaugh 2000Suzuki 1994Maillet 1996Lee 2009Lee 2007Lee 1997Greenleaf 1989a

0 5 10 15 20 25 30 35Days

-0.15

0.00

0.15

0.30

0.45

0.60

0.75

Trea

tmen

t min

us C

ontro

l (L/

min

)

Cardiovascular System – VO2 max

• VO2 max– Subjects taken to volitional fatigue

with graded upright treadmill, ergometer, and/or LBNP

– Measured as maximum VO2 uptake during exercise

• VO2 max degrades with time– Generally, treatment group

degrades less than control group• Produces POSITIVE treatment effect

– Treatment [Post – Pre ≈ 0] minus Control [Post – Pre = (-)]

• Linear regression over time– Trend of both groups to increase

with time (not significant)– AG

– Traditional Countermeasures

Artificial Gravity

Traditional Countermeasures

 Linear Regression Slope SE t value p valueDays  0.014  0.007  1.993  0.093

Vernikos 1996Moore (Unpublished)Lee 1997Katayama 2004Iwasaki 2001

0 5 10 15 20 25Days

-0.15

0.00

0.15

0.30

0.45

0.60

0.75

Trea

tmen

t min

us C

ontro

l (L/

min

)Linear Regression Slope SE t value p value

Days 0.012 0.006 1.987  0.094

48Cardiovascular System – VO2 max

• All countermeasure groups effective (p<0.05)– Answers question: ‘Is the group

significantly different from zero?’

• No difference between groups– Two-sample t-test– AG vs. Traditional

Countermeasures (p>0.05)– AG vs. LBNP w/ Treadmill (p>0.05)

• Cycling– AG outlier - Katayama 2004

(intensive cycling) – Traditional Countermeasures

upper whisker – Greenleaf 1989a (intensive cycling)

VO2 max

1 2 3-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Trea

tmen

t min

us C

ontro

l (L/

min

)

AG Traditional Countermeasures

LBNP w/ Treadmill

Median

25th Percentile

75th Percentile

Range of DataOutlier

49Cardiovascular System – Resting Heart Rate

• Resting HR– Measured in a supine position

• Resting HR increases with time– Treatment group increases less

than control group• Produces NEGATIVE treatment

effect– Treatment [Post – Pre ≈ 0] minus

Control [Post – Pre = (+)]

• Linear regression over time– AG

– Traditional Countermeasures

Artificial Gravity

Traditional CountermeasuresLinear Regression slope SE t value p valueDays -0.034 0.04 -0.836  0.491

Linear Regression slope SE t value p valueDays  -0.045  0.141 -0.316  0.759

Stenger (Unpublished)Katayama 2004Iwasaki 2005Iwasaki 2001

0 5 10 15 20 25Days

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

Trea

tmen

t min

us C

ontro

l (bp

m)

Suzuki 1994Sun 2002Schneider 2002Maillet 1996Lee 2009Lee 2007Guinet 2009Guell 1995 Series 2Guell 1995 Series 1Greenleaf 1989a

0 10 20 30 40 50 60 70Days

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

Trea

tmen

t min

us C

ontro

l (bp

m)

50Cardiovascular System – Resting Heart Rate

• All countermeasures effective (p<0.05)

• No difference between groups– AG vs. Traditional

Countermeasures (p>0.05)– AG vs. LBNP w/ Treadmill

(p=0.126)

• Cycling– Traditional Countermeasures

outlier – Maillet 1996 (moderate cycling)

• LBNP w/ Treadmill – Lee 2007 and Lee 2009 (twin

studies) both have treatment effect of –19 bpm

1 2 3-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

Trea

tmen

t min

us C

ontro

l (bp

m)

AG Traditional Countermeasures

LBNP w/ Treadmill

Resting Heart Rate

51Cardiovascular System – Orthostatic Tolerance Time

• Orthostatic Tolerance Time– Measured as time elapsed to

presyncope or a preset time limit

– Cardiovascular stressors used• Various tilt angles, +Gz overloads, graded LBNP

• All AG studies– Marked improvement of

tolerance time• Significant difference in groups

– Stenger (unpublished) and Vil-Viliams 1980a

• Significant Post vs. Pre Treatment group

– Iwase 2005 – Iwase 2005

• Only study to take subjects to presyncope

• Unclear to cause of Control group to increase tolerance time

-70.00

-60.00

-50.00

-40.00

-30.00

-20.00

-10.00

0.00

10.00

20.00

30.00

40.00

Stenger2009

Vil-Viliams1980a

Shulzhenko1979

Vil-Viliams1980b

Iwase 2005

Per

cent

Cha

nge

from

Pre

-Bed

Res

t

Control

AG

AG with Cycling

a b b b

c

*

$$

a – 80˚ tilt for 30 minutesb – +3Gz overloadc – Graded +3Gz overload – All subjects taken to presyncope* - Post-Pre significance$ - Group effect significance

Artificial Gravity

52Cardiovascular System – Orthostatic Tolerance Time

a – 60˚ tilt for 60 minutesb – Graded LBNPc – 80˚ tilt for 10 minutes – All subjects taken to presyncope

Traditional Countermeasures

• Traditional Countermeasures– Largely ineffective at

maintaining orthostatic tolerance

– LBNP-based• All subjects taken to

presyncope • Only Watenpaugh 2007 had

significant group effect– Treatment group still significantly

different from – Cycling

• Slightly attenuated deconditioning

– Still significantly different from Pre Bed Rest

– Resistive exercise only• Not effective against

orthostatic tolerance

-60

-50

-40

-30

-20

-10

0Watenpaugh

2007 Guinet 2009 Schneider

2002 Greenleaf

1989a Belin de

Chantemele2004

Perc

ent C

hang

e fr

om P

re-B

ed R

est

Control

LBNP-based

Resistive Exercise

Cycling

cb

b

b a

*

*

*

*

*

*

*

**

$

53Cardiovascular System – Plasma Volume

• Plasma Volume– Measured in many ways

• CO Rebreathing Method• Estimated from hematocrit

measurement• Evan’s blue dye

• AG with cycling– Significant group effect

• AG only– Not effective at preventing loss

of plasma volume

• Upright Exercise– Significant group effect in

Vernikos 1996 (4hr walking / day)

Artificial Gravity

-25.00

-20.00

-15.00

-10.00

-5.00

0.00Stenger

(Unpublished) Shulzhenko

1979 Iwasaki 2005 Vernikos 1996 Lee 1997

Control

AG

AG with Cycling

Upright Exercising

*

$

*

*

*

$

54Cardiovascular System – Plasma Volume

• LBNP-based– Mostly effective at

maintaining plasma volume

• Cycling– Also effective at

preventing loss of plasma volume -20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0Maillet 1996 Watenpaugh

2000 Lee 1997 Lee 2007 Lee 2009 Greenleaf

1989a

Control

LBNP-based

Cycling

*

**

*

Traditional Countermeasures

55Cardiovascular System – Exercise Time

• Exercise Time– Measured as time to volitional

fatigue in a graded exercise (upright treadmill or ergometer)

• All studies– Drastic attenuation of degradation

in exercise time in treatment groups

• No treatment group significantly different from Zero

• All control groups significantly different Post vs. Pre

• AG with cycling (Katayama 2004) and upright walking (Lee 1997) – As effective as LBNP w/ Treadmill

countermeasure

-25

-20

-15

-10

-5

0Katayama

2004 Lee 1997 Lee 2007 Lee 2009 Watenpaugh

2000

Perc

ent C

hang

e fr

om P

re-B

ed R

est

Control

AG or Upright Ex.

LBNP w/ Treadmill

*

$ *

$

*

$

**

Exercise Time

56Skeletal Muscle – Bed Rest Studies Used

• Artificial Gravity Studies– Represents an exhaustive literature review of human studies

• Traditional Countermeasure Studies– Not an exhaustive review of human studies, but a representative cross-section

57Skeletal Muscle – Bed Rest Studies Used (Expanded)

58Skeletal Muscle – Fiber Cross-Sectional Area (CSA)

• AG Study– No staining performed to determine

fiber type

• Resistive Exercise– Calculated CSA from published data

• Staining performed – Fiber diameter per muscle type given with

distribution percentage of muscle type– Unable to calculate statistical

significance

• Soleus CSA– AG eliminates decrease in CSA– Resistive exercise trends to lessen

deconditioning• Not significant

• Vastus Lateralis CSA– AG trends to lessen VL deconditioning

• Not Significant– Resistive Exercise trends to attenuate

deconditioning-35

-30

-25

-20

-15

-10

-5

0

5

10

15

20

Caiozzo 2009 Trappe 2007a Trappe 2004 Bamman 1998

Perc

ent C

hang

e fro

m P

re-B

ed R

est

Control

AG

Resistive Exercise

a

[Zero]

aa

Soleus CSA

Vastus Lateralis CSA

a – calculated from published data

a – calculated from published data

-30

-25

-20

-15

-10

-5

0

5

10

Caiozzo 2009 Trappe 2008

Perc

ent C

hang

e fro

m P

re-B

ed R

est

Control

AG

Resistive Exercise

a

*

59Skeletal Muscle – Muscle Volume and Strength

• Muscle Volume– AG

• Trend to eliminate degradation– No significance

– Resistive Exercise• Effective elimination of

deconditioning

• Maximum Voluntary Contraction (MVC)– AG

• Trend to attenuate loss of MVC– No significance

– Cycling (moderate)• Not beneficial to MVC

– Resistive exercise• Eliminates loss of MVC

-25.0

-20.0

-15.0

-10.0

-5.0

0.0

5.0

Akima 2005 Shackelford2004

Alkner 2004 Trappe2007b

Trappe 2004

Perc

ent C

hang

e fro

m P

re-B

ed R

est

Control

AG

Resistive Exercise

*

$ *

*

*

$

-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0Akima 2005 Suzuki 1994 Trappe 2004 Tesch 2004

Perc

ent C

hang

e fro

m P

re-B

ed R

est

Control

AG

Cycling

Resistive Exercise

*

*

Muscle Volume – Knee Extensor

Maximum Voluntary Contraction – Knee Extensor (90°)

60Bone – Bed Rest Studies Used

Artificial Gravity Studies Represents an exhaustive literature review of human studies

Traditional Countermeasure Studies Not an exhaustive review of human studies, but a representative cross-section

61Bone – Bed Rest Studies Used (Expanded)

62Bone – Bone Mineral Density (BMD)

• BMD measured by DEXA scans

• Femoral Neck BMD– All treatment groups

trending to counteract bone loss

• No significance in any group

• Trochanter BMD– AG

• No effect seen– Resistive Exercise

(Shackelford 2004)• Effectively eliminated bone

loss in trochanter

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

Smith 2009 Zwart 2007 Shackelford2004

Smith 2008

Perc

ent C

hang

e fr

om P

re-B

ed R

est

Control

AG

LBNP w/ Treadmill

Resistive Exercise

Femoral Neck BMD

Trochanter BMD

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0Smith 2009 Shackelford 2004 Smith 2008

Perc

ent C

hang

e fro

m P

re-B

ed R

est

Control

AG

Resistive Exercise

* *

*

63Bone – Bone Mineral Density (BMD)

• BMD measured by DEXA scans

• Total Hip BMD– AG

• Did not lessen bone loss– Traditional countermeasures

• LBNP w/ Treadmill and Resistive Exercise (Shackelford 2004)

– Protected against bone loss

• Lumbar Spine BMD– AG

• Slightly lessened bone loss– Not significant

– Resistive exercise (Shackelford 2004)

• Significantly stimulated increase in BMD

-4.5

-4

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0.5

1

Smith 2009 Zwart 2007 Shackelford2004

Smith 2008

Perc

ent C

hang

e fro

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re-B

ed R

est

Control

AGLBNP w/ Treadmill

Resistive Exercise*

*

*

*

$

-2

-1

0

1

2

3

4

Smith 2009 Shackelford 2004 Smith 2008

Perc

ent C

hang

e fro

m P

re-B

ed R

est

Control

AG

Resistive Exercise

$

*

*

Lumbar Spine BMD

Total Hip BMD

64Bone – Resorption Markers

• Urinary Calcium– Measured over 24-hour sampling period– AG

• Upright walking 4hr/d largely eliminated increase

– Not significance– Traditional Countermeasures

• Mostly effective in eliminating increase

• Serum Calcium– AG

• Unclear why depressed in Treatment group– Traditional Countermeasures

• Mostly effective in eliminating increase

• Diet– ~1 g/d Calcium for all studies– Shackelford 2004

• All subjects took vitamin pill – Included 400IU Vitamin D– Could account for the depressed % change for

Control group– Could account for decrease in Ca for

Treatment group-2

-1

0

1

2

3

4

5

6

7

Smith 2009 Smith 2003 Zwart 2007 Shackelford2004

Smith 2008

Perc

ent C

hang

e fr

om P

re-B

ed R

est

ControlAG

LBNP w/ TreadmillResistive Exercise

[Zero]

*

**

$

Serum Calcium

Urinary Calcium

-20

-10

0

10

20

30

40

50

60

70

80

90

Vernikos1996

Smith 2009 Smith 2003 Zwart 2007 Shackelford2004

Smith 2008

Perc

ent C

hang

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est

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AG or Upright Ex.

LBNP w/ Treadmill

Resistive Exercise

**

*

*

$

[Zero]

65Artist’s Concept

Courtesy of NASA