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Musculoskeletal Adaptations to Varying Levels of Eccentric Resistance during 8 Weeks of Training (ROI_EccCon)
Principal Investigator
Research Area:
Exercise physiology
Muscle physiology
Skeletal physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

During space flight, significant muscle atrophy, changes in muscle morphology, and reduction in strength have been reported in as short as five to nine days. In addition, increased calcium turnover and reduced bone mineral density (BMD) have been consistently observed following long duration space flights. Activities specifically targeting the musculoskeletal system, such as resistive exercise, may be more effective at protecting against losses in muscle strength as well as muscle and bone mass during space flight.

Muscle strength and bone mass have shown positive adaptations in response to resistive exercise training. Resistive exercise has been shown to be an effective means of increasing muscle strength and mass in ambulatory subjects as well as maintaining muscle strength, mass, and endurance in bed rest. Resistive exercise also has been shown to be effective at increasing BMD in ambulatory subjects and maintaining BMD during bed rest. Resistive exercise usually consists of two discrete actions, concentric (muscle shortening) and eccentric (muscle lengthening). During space flight, past exercise countermeasure hardware has not provided an equal 1:1 ratio of eccentric to concentric load. Eccentric contractions may be important in maintaining muscle mass and strength during space flight, as well as play a role in increasing BMD.

To date, resistance exercise devices used during space flight (i.e. interim Resistive Exercise Device [iRED]) have provided minimal to moderate levels of eccentric loading compared with traditional free weight exercise. The purpose of this study was to determine the relative effectiveness of training with different levels of eccentric to concentric resistance ratios to induce changes in muscle strength, lean tissue mass, BMD, and markers of bone metabolism. Further, these results may aid in the definition of requirements for future exercise hardware to support long duration stays aboard the International Space Station (ISS), on the moon, or in transit to, stays on, and return from Mars. These results also may influence pre-, in- and postflight exercise prescriptions as well as define effective exercise prescriptions for bed rest.

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Bone demineralization, pathologic
Bone density
Comparative study
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Data Information
Data Availability
Archive is complete. Data sets are not publicly available but can be requested.
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Blood pH
Bone metabolism markers
Bone mineral density, hip
Bone mineral density, spine
Bone-specific alkaline phosphatase
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
ROI 01/01/2002 12/31/2012 In Progress

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Jessica Keune
Institutional Support
National Aeronautics and Space Administration (NASA)
Alternate Experiment Name
Eccentric Concentric