TY - JOUR
T1 - Leucine-enriched Amino acid ingestion after resistance exercise prolongs myofibrillar protein synthesis and amino acid transporter expression in older men
AU - Dickinson, Jared M.
AU - Gundermann, David M.
AU - Walker, Dillon K.
AU - Reidy, Paul T.
AU - Borack, Michael S.
AU - Drummond, Micah J.
AU - Arora, Mohit
AU - Volpi, Elena
AU - Rasmussen, Blake B.
N1 - Publisher Copyright:
© 2014 American Society for Nutrition.
PY - 2014
Y1 - 2014
N2 - Background: Postexercise protein or amino acid ingestion restores muscle protein synthesis in older adults and represents an important therapeutic strategy for aging muscle. However, the precise nutritional factors involved are unknown. Objective: The purpose of this study was to determine the role of increased postexercise Leu ingestion on skeletal muscle myofibrillar protein synthesis (MyoPS), mammalian/mechanistic target of rapamycin complex 1 signaling, and amino acid transporter (AAT) mRNA expression in older men over a 24-h post-resistance exercise (RE) time course. Methods: During a stable isotope infusion trial (L-[ring-13C6]Phe; L-[1-13C]Leu), older men performed RE and, at 1 h after exercise, ingested 10 g of essential amino acids (EAAs) containing either a Leu content similar to quality protein (control, 1.85 g of Leu, n=7) or enriched Leu (LEU; 3.5 g of Leu, n = 8). Muscle biopsies (vastus lateralis) were obtained at rest and 2, 5, and 24 h after exercise. Results: p70 S6 kinase 1 phosphorylation was increased in each group at 2 h (P > 0.05), whereas 4E binding protein 1 phosphorylation increased only in the LEU group (P > 0.05).MyoPS was similarly increased (~90%) above basal in each group at 5 h (P >0.05) and remained elevated (~90%) at 24 h only in the LEU group (P > 0.05). The mRNA expression of select AATs was increased at 2 and 5 h in each group (P > 0.05), but AAT expression was increased at 24 h only in the LEU group (P < 0.05). Conclusions: Leu-enriched EAA ingestion after RE may prolong the anabolic response and sensitivity of skeletal muscle to amino acids in older adults. These data emphasize the potential importance of adequate postexercise Leu ingestion to enhance the response of aging muscle to preventive or therapeutic exercise-based rehabilitation programs.
AB - Background: Postexercise protein or amino acid ingestion restores muscle protein synthesis in older adults and represents an important therapeutic strategy for aging muscle. However, the precise nutritional factors involved are unknown. Objective: The purpose of this study was to determine the role of increased postexercise Leu ingestion on skeletal muscle myofibrillar protein synthesis (MyoPS), mammalian/mechanistic target of rapamycin complex 1 signaling, and amino acid transporter (AAT) mRNA expression in older men over a 24-h post-resistance exercise (RE) time course. Methods: During a stable isotope infusion trial (L-[ring-13C6]Phe; L-[1-13C]Leu), older men performed RE and, at 1 h after exercise, ingested 10 g of essential amino acids (EAAs) containing either a Leu content similar to quality protein (control, 1.85 g of Leu, n=7) or enriched Leu (LEU; 3.5 g of Leu, n = 8). Muscle biopsies (vastus lateralis) were obtained at rest and 2, 5, and 24 h after exercise. Results: p70 S6 kinase 1 phosphorylation was increased in each group at 2 h (P > 0.05), whereas 4E binding protein 1 phosphorylation increased only in the LEU group (P > 0.05).MyoPS was similarly increased (~90%) above basal in each group at 5 h (P >0.05) and remained elevated (~90%) at 24 h only in the LEU group (P > 0.05). The mRNA expression of select AATs was increased at 2 and 5 h in each group (P > 0.05), but AAT expression was increased at 24 h only in the LEU group (P < 0.05). Conclusions: Leu-enriched EAA ingestion after RE may prolong the anabolic response and sensitivity of skeletal muscle to amino acids in older adults. These data emphasize the potential importance of adequate postexercise Leu ingestion to enhance the response of aging muscle to preventive or therapeutic exercise-based rehabilitation programs.
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U2 - 10.3945/jn.114.198671
DO - 10.3945/jn.114.198671
M3 - Article
C2 - 25332468
AN - SCOPUS:84916882308
SN - 0022-3166
VL - 144
SP - 1694
EP - 1702
JO - Journal of Nutrition
JF - Journal of Nutrition
IS - 11
ER -