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Bed Rest Standard Measures: Tendon Reflex (BRSMTReflex)
Principal Investigator
Research Area:
Muscle physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

The Tendon Reflex (T-Reflex) is a feedback mechanism that controls increasing muscle tension by causing muscle relaxation before tension force becomes so great it may damage the muscle. The investigators hypothesized that the amplitude of the T-Reflex will decrease throughout the bed rest period while the latency of the reflex will increase. It is believed that these alterations will be due to two primary changes. First, the compliance of the primary postural muscles is reduced, and second, there is a reduction or atrophy of motor synapse to muscle. Compensation for these changes results in a potential and inappropriate hyper-motor response following a return to the upright position that returns to normal within a few days.

A second hypothesis dealt with a change in otolith bias from the six-degree head down bed rest position, and the influence of descending otolith modulation of spinal interneuron's following a return to the upright position. The specific aims of this experiment were to compare the effects of weightlessness on the amplitude and latency of the torque reflex, with those subjects participating in head down bed rest studies.

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J. M. Cerisano, M. F. Reschke, I. S. Kofman, E. A. Fisher, and D. L. Harm. Stretch Reflex as a simple Measure to Evaluate the Efficacy of Potential Flight Countermeasures Using the Bed Rest Environment. Presented at the 18th IAA Humans in Space Symposium, Houston, TX, April 11-12, 2011.

Motor neurons
Motor activity
Reflex, stretch

Photo Gallery
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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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Acceleration, latency
Acceleration, peak
Amplitude, fifty percent
Amplitude, peak
Amplitude, start
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Campaign 11 05/11/2011 12/15/2014 3 years, 7 months, 4 days
Campaign 17 05/11/2011 02/12/2012 278 days
Campaign 3 02/20/2005 04/14/2010 5 years, 1 month, 25 days
DBLS 05/03/2010 05/23/2010 Discontinued
HDT30 10/13/2009 05/13/2010 213 days

Additional Information
Other Key People
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Pamela A. Bieri
Institutional Support
National Aeronautics and Space Administration (NASA)