TY - JOUR
T1 - Branched-chain amino acid ingestion stimulates muscle myofibrillar protein synthesis following resistance exercise in humans
AU - Jackman, Sarah R.
AU - Witard, Oliver C.
AU - Philp, Andrew
AU - Wallis, Gareth A.
AU - Baar, Keith
AU - Tipton, Kevin D.
PY - 2017/6/7
Y1 - 2017/6/7
N2 - The ingestion of intact protein or essential amino acids (EAA) stimulates mechanistic target of rapamycin complex-1 (mTORC1) signaling and muscle protein synthesis (MPS) following resistance exercise. The purpose of this study was to investigate the response of myofibrillar-MPS to ingestion of branched-chain amino acids (BCAAs) only (i.e., without concurrent ingestion of other EAA, intact protein, or other macronutrients) following resistance exercise in humans. Ten young (20.1 ± 1.3 years), resistance-trained men completed two trials, ingesting either 5.6 g BCAA or a placebo (PLA) drink immediately after resistance exercise. Myofibrillar-MPS was measured during exercise recovery with a primed, constant infusion of L-[ring13C6] phenylalanine and collection of muscle biopsies pre and 4 h-post drink ingestion. Blood samples were collected at time-points before and after drink ingestion. Western blotting was used to measure the phosphorylation status of mTORC1 signaling proteins in biopsies collected pre, 1-, and 4 h-post drink. The percentage increase from baseline in plasma leucine (300 ± 96%), isoleucine (300 ± 88%), and valine (144 ± 59%) concentrations peaked 0.5 h-post drink in BCAA. A greater phosphorylation status of S6K1Thr389 (P = 0.017) and PRAS40 (P = 0.037) was observed in BCAA than PLA at 1 h-post drink ingestion. Myofibrillar-MPS was 22% higher (P = 0.012) in BCAA (0.110 ± 0.009%/h) than PLA (0.090 ± 0.006%/h). Phenylalanine Ra was ~6% lower in BCAA (18.00 ± 4.31 μmol·kgBM-1) than PLA (21.75 ± 4.89 μmol·kgBM-1; P = 0.028) after drink ingestion. We conclude that ingesting BCAAs alone increases the post-exercise stimulation of myofibrillar-MPS and phosphorylation status mTORC1 signaling.
AB - The ingestion of intact protein or essential amino acids (EAA) stimulates mechanistic target of rapamycin complex-1 (mTORC1) signaling and muscle protein synthesis (MPS) following resistance exercise. The purpose of this study was to investigate the response of myofibrillar-MPS to ingestion of branched-chain amino acids (BCAAs) only (i.e., without concurrent ingestion of other EAA, intact protein, or other macronutrients) following resistance exercise in humans. Ten young (20.1 ± 1.3 years), resistance-trained men completed two trials, ingesting either 5.6 g BCAA or a placebo (PLA) drink immediately after resistance exercise. Myofibrillar-MPS was measured during exercise recovery with a primed, constant infusion of L-[ring13C6] phenylalanine and collection of muscle biopsies pre and 4 h-post drink ingestion. Blood samples were collected at time-points before and after drink ingestion. Western blotting was used to measure the phosphorylation status of mTORC1 signaling proteins in biopsies collected pre, 1-, and 4 h-post drink. The percentage increase from baseline in plasma leucine (300 ± 96%), isoleucine (300 ± 88%), and valine (144 ± 59%) concentrations peaked 0.5 h-post drink in BCAA. A greater phosphorylation status of S6K1Thr389 (P = 0.017) and PRAS40 (P = 0.037) was observed in BCAA than PLA at 1 h-post drink ingestion. Myofibrillar-MPS was 22% higher (P = 0.012) in BCAA (0.110 ± 0.009%/h) than PLA (0.090 ± 0.006%/h). Phenylalanine Ra was ~6% lower in BCAA (18.00 ± 4.31 μmol·kgBM-1) than PLA (21.75 ± 4.89 μmol·kgBM-1; P = 0.028) after drink ingestion. We conclude that ingesting BCAAs alone increases the post-exercise stimulation of myofibrillar-MPS and phosphorylation status mTORC1 signaling.
KW - Amino acid ingestion
KW - Fractional synthesis rate
KW - Intracellular signaling proteins
KW - Leucine
KW - Muscle anabolism
UR - http://www.scopus.com/inward/record.url?scp=85020819682&partnerID=8YFLogxK
U2 - 10.3389/fphys.2017.00390
DO - 10.3389/fphys.2017.00390
M3 - Article
AN - SCOPUS:85020819682
SN - 1664-042X
VL - 8
JO - Frontiers in Physiology
JF - Frontiers in Physiology
IS - JUN
M1 - 390
ER -