Prevention of muscle atrophy caused by reduced mechanical loading in microgravity conditions remains a challenge for long-duration spaceflight. To combat leg muscle atrophy, astronauts on the International Space Station (ISS) often perform squat exercise using the Advanced Resistive Exercise Device (ARED). While the ARED is effective at building muscle strength and volume on Earth, NASA researchers do not know how closely ARED squat exercise on the ISS replicates Earth-level squat muscle moments, or how small variations in exercise form affect muscle loading. This study used dynamic simulations of ARED squat exercise on the ISS to address these two questions. A multibody dynamic model of the complete astronaut-ARED system was constructed in OpenSim. With the ARED base locked to ground and gravity set to 9.81 m/s2, we validated the model by reproducing muscle moments, ground reaction forces, and foot center of pressure (CoP) positions for ARED squat exercise on Earth. With the ARED base free to move relative to the ISS and gravity set to zero, we then used the validated model to simulate ARED squat exercise on the ISS for a reference squat motion and eight altered squat motions involving changes in anterior–posterior (AP) foot or CoP position on the ARED footplate. The reference squat motion closely reproduced Earth-level muscle moments for all joints except the ankle. For the altered squat motions, changing the foot position was more effective at altering muscle moments than was changing the CoP position. All CoP adjustments introduced an undesirable shear foot reaction force that could cause the feet to slip on the ARED footplate, while some foot and CoP adjustments introduced an undesirable sagittal plane foot reaction moment that would cause the astronaut to rotate off the ARED footplate without the use of some type of foot fixation. Our results provide potentially useful information for achieving desired increases or decreases in specific muscle moments during ARED squat exercise performed on the ISS.

References

References
1.
Dickey
,
B.
,
2008
, “
Outposts on the Moon, Footprints on Mars: NASA's Future Exploration Plans
,”
NASA 50th Magazine—50 Years of Exploration and Discovery
, http://www.nasa.gov/50th/50th_magazine/futureExploration.html
2.
Gopalakrishnan
,
R.
,
Genc
,
K. O.
,
Rice
,
A. J.
,
Lee
,
S. M. C.
,
Evans
,
H. J.
,
Maender
,
C. C.
,
Ilaslan
,
H.
, and
Cavanagh
,
P. R.
,
2010
, “
Muscle Volume, Strength, Endurance, and Exercise Loads During 6-Month Missions in Space
,”
Aviat. Space Environ. Med.
,
81
(
2
), pp.
91
102
.
3.
Genc
,
K. O.
,
Gopalakrishnan
,
R.
,
Kuklis
,
M. M.
,
Maender
,
C. C.
,
Rice
,
A. J.
,
Bowersox
,
K. D.
, and
Cavanagh
,
P. R.
,
2010
, “
Foot Forces During Exercise on the International Space Station
,”
J. Biomech.
,
43
(
15
), pp.
3020
3027
.
4.
Trappe
,
S.
,
Costill
,
D.
,
Gallagher
,
P.
,
Creer
,
A.
,
Peters
,
J. R.
,
Evans
,
H.
,
Riley
,
D. A.
, and
Fitts
,
R. H.
,
2009
, “
Exercise in Space: Human Skeletal Muscle After 6 Months Aboard the International Space Station
,”
J. Appl. Physiol.
,
106
(
4
), pp.
1159
1168
.
5.
Fitts
,
R. H.
,
Trappe
,
S. W.
,
Costill
,
D. L.
,
Gallagher
,
P. M.
,
Creer
,
A. C.
,
Colloton
,
P. A.
,
Peters
,
J. R.
,
Romatowski
,
J. G.
,
Bain
,
J. L.
, and
Riley
,
D. A.
,
2010
, “
Prolonged Space Flight-Induced Alterations in the Structure and Function of Human Skeletal Muscle Fibres
,”
J. Physiol.
,
588
(
Pt 18
), pp.
3567
3592
.
6.
Loehr
,
J. A.
,
Lee
,
S. M. C.
,
English
,
K. L.
,
Sibonga
,
J.
,
Smith
,
S. M.
,
Spiering
,
B. A.
, and
Hagan
,
R. D.
,
2011
, “
Musculoskeletal Adaptations to Training With the Advanced Resistive Exercise Device
,”
Med. Sci. Sports Exercise
,
43
(
1
), pp.
146
156
.
7.
Davis
,
S. A.
, and
Davis
,
B. L.
,
2012
, “
Exercise Equipment Used in Microgravity: Challenges and Opportunities
,”
Curr. Sports Med. Rep.
,
11
(
3
), pp.
142
147
.
8.
Reed
,
E. B.
,
Hanson
,
A. M.
, and
Cavanagh
,
P. R.
,
2015
, “
Optimising Muscle Parameters in Musculoskeletal Models Using Monte Carlo Simulation
,”
Comput. Methods Biomech. Biomed. Eng.
,
18
(
6
), pp.
607
617
.
9.
Ackermann
,
M.
, and
van den Bogert
,
A. J.
,
2012
, “
Predictive Simulation of Gait at Low Gravity Reveals Skipping as the Preferred Locomotion Strategy
,”
J. Biomech.
,
45
(
7
), pp.
1293
1298
.
10.
Delp
,
S. L.
,
Anderson
,
F. C.
,
Arnold
,
A. S.
,
Loan
,
P.
,
Habib
,
A.
,
John
,
C. T.
,
Guendelman
,
E.
, and
Thelen
,
D. G.
,
2007
, “
OpenSim: Open-Source Software to Create and Analyze Dynamic Simulations of Movement
,”
IEEE Trans. Biomed. Eng.
,
54
(
11
), pp.
1940
1950
.
11.
Kelly
,
S.
,
2010
, “
Working Out Aboard the Space Station
,” NASA Johnson Space Center, Houston, TX, https://www.youtube.com/watch?v=YxImeOomkUk
12.
Hamner
,
S. R.
,
Seth
,
A.
, and
Delp
,
S. L.
,
2010
, “
Muscle Contributions to Propulsion and Support During Running
,”
J. Biomech.
,
43
(
14
), pp.
2709
2716
.
13.
Fregly
,
C. D.
,
Kim
,
B. T.
,
Li
,
Z.
,
De Witt
,
J. K.
, and
Fregly
,
B. J.
,
2012
, “
Estimated Muscle Loads During Squat Exercise on the International Space Station
,”
ASME
Paper No. SBC2012-80785.
14.
Escamilla
,
R. F.
,
Fleisig
,
G. S.
,
Zheng
,
N.
,
Barrentine
,
S. W.
,
Wilk
,
K. E.
, and
Andrews
,
J. R.
,
1998
, “
Biomechanics of the Knee During Closed Kinetic Chain and Open Kinetic Chain Exercises
,”
Med. Sci. Sports Exercise
,
30
(
4
), pp.
556
569
.
15.
Mayhew
,
J. L.
,
Ware
,
J. R.
, and
Prinste.
,
J. L.
,
1993
, “
Using Lift Repetitions to Predict Muscular Strength in Adolescent Males
,”
Natl. Strength Cond. Assoc. J.
,
15
(
6
), pp.
35
38
.
16.
Hedrick
,
T. L.
,
2008
, “
Software Techniques for Two- and Three-Dimensional Kinematic Measurements of Biological and Biomimetic Systems
,”
Bioinspiration Biomimetics
,
3
(
3
), p.
034001
.
17.
De Witt
,
J. K.
, and
Ploutz-Snyder
,
L. L.
,
2014
, “
Ground Reaction Forces During Treadmill Running in Microgravity
,”
J. Biomech.
,
47
(
10
), pp.
2339
2347
.
18.
Clauser
,
C. E.
,
McConville
,
J. T.
, and
Young
,
J. W.
,
1969
, “
Weight, Volume, and Center of Mass of Segments of the Human Body
,”
Aerospace Medical Research Laboratory
,
Wright-Patterson Air Force Base
,
OH
, Report No. AMRL-TR-69-70.
19.
Hartmann
,
H.
,
Wirth
,
K.
, and
Klusemann
,
M.
,
2013
, “
Analysis of the Load on the Knee Joint and Vertebral Column With Changes in Squatting Depth and Weight Load
,”
Sport. Med.
,
43
(
10
), pp.
993
1008
.
20.
Fregly
,
C. D.
,
Kim
,
B. T.
,
De Witt
,
J. K.
, and
Fregly
,
B. J.
,
2013
, “
Dynamic Simulation of Muscle Loading During ARED Squat Exercise on the International Space Station
,”
ASME
Paper No. SBC2013-14792.
21.
Fregly
,
C. D.
,
Kim
,
B. T.
,
De Witt
,
J. K.
, and
Fregly
,
B. J.
,
2014
, “
Model-Based Recommendations for Reducing Back Loads During Squat Exercise on the International Space Station
,”
7th World Congress of Biomechanics
,
Boston, MA
, July 6–11.
You do not currently have access to this content.