Protein and amino acid supplementation does not alter proteolytic gene expression following immobilization

Abstract

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- and NF-B. Results. All genes of interest increased over time (P