Energy expenditure during antiorthostatic bed rest (simulated
microgravity).
Gretebeck, Randall J., Dale A. Schoeller, Everett K. Gibson, Helen W.
Lane.
Nutritional Biochemistry and Stable Isotope Laboratories, Space and
Life Sciences Directorate, NASA-Johnson Space Center, Houston, TX and
University of Chicago, Department of Medicine, Chicago, IL
APStracts 2:0109A, 1995.
Few studies have addressed the interaction between energy balance and
lean body mass in healthy subjects during space flight or its
simulations. We used doubly labeled water to measure total energy
expenditure (TEE) in 9 healthy adult men during two 7-day periods,
once before and once during a 10-day head-down bed-rest period. Mean
TEE was 21 percent less during bed rest than before; however, neither
basal (BEE) nor resting energy expenditure (REE) changed, implying
that the lesser TEE resulted from reduction in physical activity.
During the bed-rest period, energy intake was 563 +/- 280 kcal/day
higher than TEE (p<0.05), but neither body weight, fluid balance,
BEE, nor REE changed relative to before. However, the small but
statistically significant increase in body fat (0.44 +/- 0.67 kg,
p<0.05) during the bed-rest period suggests that body weight alone
does not accurately reflect changes in energy balance during
antiorthostatic bed rest.
Received 29 September 1994; accepted in final form 13 February
1995.
APS Manuscript Number A1004-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 21 March 1995.