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Recruitment of the Rhesus soleus and medial gastrocnemius before, during and after spaceflightElectromyograms were recorded from the soleus and medial gastrocnemius muscles and tendon force from the medial gastrocnemius muscle of 2 juvenile Rhesus monkeys before, during and after Cosmos flight 2229 and of ground control animals. Recording sessions were made while the Rhesus were performing a foot pedal motor task. Preflight testing indicated normal patterns of recruitment between the soleus and medial gastrocnemius, i.e. a higher level of recruitment of the soleus compared to the medial gastrocnemius during the task. Recording began two days into the spaceflight and showed that the media gastrocnemius was recruited preferentially over the soleus. This observation persisted throughout the flight and for the 2 week period of postflight testing. These data indicate a significant change in the relative recruitment of slow and fast extensor muscles under microgravity conditions. The appearance of clonic-like activity in one muscle of each Rhesus during flight further suggests a reorganization in the neuromotor system in a microgravity environment.
Document ID
Document Type
Reprint (Version printed in journal)
Roy, R. R. (Brain Research Institute, University of California Los Angeles, 90095-1761, United States)
Hodgson, J. A.
Aragon, J.
Day, M. K.
Kozlovskaya, I.
Edgerton, V. R.
Date Acquired
August 21, 2013
Publication Date
April 1, 1996
Publication Information
Publication: Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology
Volume: 3
Issue: 1
ISSN: 1077-9248
Subject Category
Life Sciences (General)
Funding Number(s)
Distribution Limits
NASA Discipline Musculoskeletal
NASA Program Flight
Cosmos 2044 Project
Flight Experiment
NASA Discipline Number 00-00
Cosmos 2229 Project
Non-NASA Center
short duration