Branched-chain amino acid supplementation during bed rest: effect on recovery

1 Department of Surgery, School of Osteopathic Medicine, University of Medicine and Dentistry of New Jersey, Stratford, New Jersey 08084; and 2 Department of Medicine and the General Clinical Research Center, Temple University Health Sciences Center, Philadelphia, Pennsylvania 19140 Bed rest is associated with a loss of protein from the weight-bearing muscle. The objectives of this study are to determine whether increasing dietary branched-chain amino acids (BCAAs) during bed rest improves the anabolic response after bed rest. The study consisted of a 1-day ambulatory period, 14 days of bed rest, and a 4-day recovery period. During bed rest, dietary intake was supplemented with either 30 mmol/day each of glycine, serine, and alanine ( group 1 ) or with 30 mmol/day each of the three BCAAs ( group 2 ). Whole body protein synthesis was determined with U- 15 N-labeled amino acids, muscle, and selected plasma protein synthesis with L -[ 2 H 5 ]phenylalanine. Total glucose production and gluconeogenesis from alanine were determined with L -[U- 13 C 3 ]alanine and [6,6- 2 H 2 ]glucose. During bed rest, nitrogen (N) retention was greater with BCAA feeding (56 ± 6 vs. 26 ± 12 mg N · kg 1 · day 1 , P