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Characteristics and Preliminary Observations of the Influence of Electromyostimulation on the Size and Function of Human Skeletal Muscle During 30 Days of Simulated MicrogravityDuring 30 days (d) of bedrest, the practicality of using Elec- troMyoStimulation (EMS) as a deterrent to atrophy and strength loss of lower limb musculature was examined. An EMS system was developed that provided variable but quantifiable levels of EMS, and measured torque. The dominant log of three male subjects was stimulated twice daily in a 3-d on/1-d off cycle during bedrest. The non-dominant leg of each subject acted as a control. A stimulator, using a 0.3 ms monophasic 60 Hz pulse waveform, activated muscle tissue for 4 s. The output waveform from the stimulator was sequenced to the Knee Extensors (KE), Knee Flex- ors (KF), Ankle Extensors (AE), and Ankle Flexors (AF), and caused three isometric contractions of each muscle group per minute. Subject tolerance determined EMS Intensity. Each muscle group received four 5-min bouts of EMS each session with a 10 -min rest between bouts. EMS and torque levels for each muscle action were recorded directly an a computer. Overall average EMS Intensity was 197, 197, 195, and 188 mA for the KE, KF, AF, and AE, respectively. Overall average torque development for these muscle groups was 70, 16, 12, and 27 Nm, respectively. EMS intensity doubled during the study, and average torque increased 2.5 times. Average maximum torque throughout a session reached 54% of maximal voluntary for the KE and 29% for the KF. Reductions in leg volume, muscle compartment size, cross-sectional area of slow and fast-twitch fibers, strength, and aerobic enzyme activities, and increased log compliance were attenuated in the legs which received EMS during bedrest. These results indicate that similar EMS levels induce different torques among different muscle groups and that repeated exposure to EMS increases tolerance and torque development. Longer orien- tation periods, therefore, may enhance its effectiveness. Our preliminary data suggest that the efficacy of EMS as an effective countermeasure for muscle atrophy and strength loss during long duration space travel warrants further investigation.
Document ID
19970022011
Acquisition Source
Kennedy Space Center
Document Type
Reprint (Version printed in journal)
Authors
Duvoisin, Marc R.
(NASA Kennedy Space Center Cocoa Beach, FL United States)
Convertino, Victor A
(NASA Kennedy Space Center Cocoa Beach, FL United States)
Buchanan, Paul
(NASA Kennedy Space Center Cocoa Beach, FL United States)
Gollinick, Philip D.
(Washington State Univ. Pullman, WA United States)
Dudley, Gary A.
(Bionetics Corp. Cocoa Beach, FL United States)
Date Acquired
August 17, 2013
Publication Date
July 1, 1989
Publication Information
Publication: Aviation, Space, and Environmental Medicine
Publisher: Aerospace Medical Association
Subject Category
Aerospace Medicine
Report/Patent Number
NASA-CR-204453
NAS 1.26:204453
Meeting Information
Meeting: Aerospace Medical Association Scientific Meeting
Location: New Orleans, LA
Country: United States
Start Date: January 1, 1988
Accession Number
97N72070
Funding Number(s)
CONTRACT_GRANT: NAS10-10285
Distribution Limits
Public
Copyright
Public Use Permitted.
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