Eating in Space: Does Nutrition Matter?
Protocol for Wolfe et al. 28-day Bed Rest Study
This slide shows the protocol for the Wolfe bed rest study. Days 1-5 were the diet stabilization period in which initial measurements were made: lean leg mass (by DEXA* – Dual Energy X-Ray Absorptiometry); calf volume (by MRI); and a series of strength tests. On Day 6, the first tracer study** was done with a stable isotope to measure muscle protein synthesis. During days 7-33, subjects were in bed rest (with other samples collected and food intake controlled). Day 34 was a repeat of the tracer study done on Day 6, and Days 35-38 provided time for re-ambulation and repeats of measurements made on days 1-5. There were two groups, a placebo group and the group receiving the essential amino acid supplement.
* DEXA: a precise instrument that uses energy in the form of very small doses of X-rays to determine bone mineral density.
** Tracer studies: harmless radio isotopes are attached to specific amino acids that travel through the bloodstream. Blood samples are taken to determine the amount of amino acids that enter and leave the muscle.
- Paddon-Jones, D., Sheffield-Moore, M., Urban, E. J., Sanford, A. P., Aarsland, A., Wolfe, R.R., Ferrando, A.A. (2004). Essential amino acid and carbohydrate supplementation ameliorates muscle protein loss in humans during 28 days bedrest. J Clin Endocrinol Metab, 89, 4351-4358. Unpublished image, by permission of D. Paddon-Jones.
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Funded by the following grant(s)
This work was supported by National Space Biomedical Research Institute through NASA cooperative agreement NCC 9-58.