Campaign 3A
This bed rest campaign continued NASA's multi-discipline
approach to understanding the physiologic effects of a
simulated microgravity environment on humans. Campaign
3A began in the spring of 2005 and was conducted under
standard conditions with controlled diet. This campaign
consisted of an 11- to 13-day ambulatory phase immediately
followed by a 90-day period of strict 6-degree
head-down tilt and a 14-day period of post-bed
rest reconditioning and testing. As part of this multi-discipline
approach, 5 new NASA-approved bed rest investigations
were selected to be performed, in addition to the Standard
Measures test protocols, as a means to compare spaceflight
and bed rest responses. Four of these investigations proposed
countermeasures, and Campaign 3A was the platform for
collecting control data for 4 investigations and evaluated
a potential countermeasure of 1 investigation.
Standard Measures data were collected on the 4 subjects,
2 male and 2 female, in Campaign 3A. Similar to the
first campaign, the results from these assessments became
part of the medical monitoring of the subjects, increased
the amount of data on which to base a description of
the physiologic responses to bed rest in humans, provided
a basis to compare bed rest results with results from
flight investigations, served as control data for the
countermeasure studies and provided ancillary data to
individual investigators. The following investigations
were included in Campaign 3A:
Maintenance of Skeletal Muscle Mass and Function during
Bed Rest.
PI: Arny A. Ferrando, PhD, Professor, Department of Surgery, University of Texas Medical Branch, Galveston, Texas
Campaign 3A represented the Control Group for this investigation for the evaluation of the use of essential amino acids supplementation and resistive exercise as countermeasures against changes in muscle protein synthesis, insulin resistance, and changes in lean and fat body mass.
Investigator-specific tests included the collection
of dual-energy X-ray absorptiometry (DEXA) data to determine
the effect of bed rest on lean and fat body mass of
the whole body and leg. Magnetic resonance spectroscopy
was used as a noninvasive means for measuring muscle
oxidative capacity and lipid content. Glucose and insulin
levels were measured during the oral glucose tolerance
test. Resting energy expenditure was measured to predict
total caloric requirements, and nitrogen balance was
calculated from 24-hour urine collection. Muscle
biopsies of the vastus lateralis were obtained to calculate
muscle fractional synthetic rate.
Gender Differences in Bedrest:
Autonomic and Neuroendocrine Changes and Vascular Responses
in Lower and Upper Extremities.
PI: Jan Meck, PhD, NASA Johnson Space Center, Houston, Texas
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