TY - JOUR
T1 - Branched-chain amino acid supplementation during bed rest
T2 - Effect on recovery
AU - Stein, T. P.
AU - Donaldson, M. R.
AU - Leskiw, M. J.
AU - Schluter, M. D.
AU - Baggett, D. W.
AU - Boden, G.
PY - 2003/4/1
Y1 - 2003/4/1
N2 - Bed rest is associated with a loss of protein from the weightbearing 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-15N-labeled amino acids, muscle, and selected plasma protein synthesis with L-[2H5]phenylalanine. Total glucose production and gluconeogenesis from alanine were determined with L-[U-13C3]alanine and [6,6-2H2]glucose. During bed rest, nitrogen (N) retention was greater with BCAA feeding (56 ± 6 vs. 26 ± 12 mg N·kg-1·day-1, P < 0.05). There was no effect of BCAA supplementation on either whole body, muscle, or plasma protein synthesis or the rate of 3-MeH excretion. Muscle tissue free amino acid concentrations were increased during bed rest with BCAA (0.214 ± 0.066 vs. 0.088 ± 0.12 nmol/mg protein, P < 0.05). Total glucose production and gluconeogenesis from alanine were unchanged with bed rest but were significantly reduced (P < 0.05) with the BCAA group in the recovery phase. In conclusion, the improved N retention during bed rest is due, at least in part, to accretion of amino acids in the tissue free amino acid pools. The amount accreted is not enough to impact protein kinetics in the recovery phase but does improve N retention by providing additional essential amino acids in the early recovery phase.
AB - Bed rest is associated with a loss of protein from the weightbearing 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-15N-labeled amino acids, muscle, and selected plasma protein synthesis with L-[2H5]phenylalanine. Total glucose production and gluconeogenesis from alanine were determined with L-[U-13C3]alanine and [6,6-2H2]glucose. During bed rest, nitrogen (N) retention was greater with BCAA feeding (56 ± 6 vs. 26 ± 12 mg N·kg-1·day-1, P < 0.05). There was no effect of BCAA supplementation on either whole body, muscle, or plasma protein synthesis or the rate of 3-MeH excretion. Muscle tissue free amino acid concentrations were increased during bed rest with BCAA (0.214 ± 0.066 vs. 0.088 ± 0.12 nmol/mg protein, P < 0.05). Total glucose production and gluconeogenesis from alanine were unchanged with bed rest but were significantly reduced (P < 0.05) with the BCAA group in the recovery phase. In conclusion, the improved N retention during bed rest is due, at least in part, to accretion of amino acids in the tissue free amino acid pools. The amount accreted is not enough to impact protein kinetics in the recovery phase but does improve N retention by providing additional essential amino acids in the early recovery phase.
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U2 - 10.1152/japplphysiol.00481.2002
DO - 10.1152/japplphysiol.00481.2002
M3 - Article
C2 - 12471043
AN - SCOPUS:0037378442
VL - 94
SP - 1345
EP - 1352
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 4
ER -