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Journal of Nutrition and Metabolism
Volume 2011, Article ID 539690, 9 pages
Research Article

Protein and Amino Acid Supplementation Does Not Alter Proteolytic Gene Expression following Immobilization

1Exercise and Biochemical Nutritional Laboratory, Department of Health, Human Performance, and Recreation, Baylor University, Waco, TX 76798, USA
2University of Florida College of Medicine, Gainesville, FL 32611, USA
3Education and Clinical Center of the Baltimore Veterans Affairs Medical Center, University of Maryland School of Medicine and the Geriatric Research, Baltimore, MD 21201, USA
4Texas A & M University, College Station, TX 77843, USA

Received 1 November 2010; Revised 28 January 2011; Accepted 13 June 2011

Academic Editor: Maurizio Muscaritoli

Copyright © 2011 Jennifer A. Bunn et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Objective. To determine if supplementation of protein and amino acids (PAA) decreases skeletal muscle expression of atrophy-related genes, muscle mass, and strength during immobilization in humans. Methods. Twenty males wore a lower-limb immobilization boot for 28 days and consumed either a PAA supplement (28 g protein) or carbohydrate placebo (28 g maltodextrose), while consuming their normal daily diet. Testing sessions included dietary analysis, lower-leg girth and body composition measurements, strength testing, and gastrocnemius muscle biopsies. Muscle was analyzed for mRNA expression of markers in the ubiquitin and calpain systems, myostatin, TNF-α, and NF-κB. Results. All genes of interest increased over time ( ), but there was no difference between groups. Lower-leg girth decreased over time ( ); however, there were no significant changes in body composition or strength. Conclusion. Short-term lower-limb disuse, despite the absence of significant muscle atrophy, is associated with increases in skeletal muscle gene expression of several proteolysis-related genes. These changes do not appear to be altered by oral PAA supplementation.