scholarly journals Leucine-Enriched Amino Acid Ingestion after Resistance Exercise Prolongs Myofibrillar Protein Synthesis and Amino Acid Transporter Expression in Older Men

2014 ◽  
Vol 144 (11) ◽  
pp. 1694-1702 ◽  
Author(s):  
Jared M. Dickinson ◽  
David M. Gundermann ◽  
Dillon K. Walker ◽  
Paul T. Reidy ◽  
Michael S. Borack ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Resistance Exercise ◽  
Older Men ◽  
Amino Acid Transporter ◽  
Myofibrillar Protein ◽  
Acid Transporter ◽  
Transporter Expression ◽  
Myofibrillar Protein Synthesis

scholarly journals Dose-Dependent Increases in Whole-Body Net Protein Balance and Dietary Protein-Derived Amino Acid Incorporation into Myofibrillar Protein During Recovery from Resistance Exercise in Older Men

2019 ◽  
Vol 149 (2) ◽  
pp. 221-230 ◽  
Author(s):  
Andrew M Holwerda ◽  
Kevin J M Paulussen ◽  
Maarten Overkamp ◽  
Joy P B Goessens ◽  
Irene Fleur Kramer ◽  
...  
Keyword(s):  
Amino Acid ◽  
Resistance Exercise ◽  
Dietary Protein ◽  
Older Men ◽  
Myofibrillar Protein ◽  
Whole Body ◽  
Protein Balance ◽  
Dose Dependent ◽  
Net Protein ◽  
Myofibrillar Protein Synthesis

ABSTRACT Background Age-related decline in skeletal muscle mass is at least partly attributed to anabolic resistance to food intake. Resistance exercise sensitizes skeletal muscle tissue to the anabolic properties of amino acids. Objective The present study assessed protein digestion and amino acid absorption kinetics, whole-body protein balance, and the myofibrillar protein synthetic response to ingestion of different amounts of protein during recovery from resistance exercise in older men. Methods Forty-eight healthy older men [mean ± SEM age: 66 ± 1 y; body mass index (kg/m2): 25.4 ± 0.3] were randomly assigned to ingest 0, 15, 30, or 45 g milk protein concentrate after a single bout of resistance exercise consisting of 4 sets of 10 repetitions of leg press and leg extension and 2 sets of 10 repetitions of lateral pulldown and chest press performed at 75–80% 1-repetition maximum. Postprandial protein digestion and amino acid absorption kinetics, whole-body protein metabolism, and myofibrillar protein synthesis rates were assessed using primed, continuous infusions of l-[ring-2H5]-phenylalanine, l-[ring-2H2]-tyrosine, and l-[1-13C]-leucine combined with ingestion of intrinsically l-[1-13C]-phenylalanine and l-[1-13C]-leucine labeled protein. Results Whole-body net protein balance showed a dose-dependent increase after ingestion of 0, 15, 30, or 45 g of protein (0.015 ± 0.002, 0.108 ± 0.004, 0.162 ± 0.008, and 0.215 ± 0.009 μmol Phe · kg−1 · min−1, respectively; P < 0.001). Myofibrillar protein synthesis rates were higher after ingesting 30 (0.0951% ± 0.0062%/h, P = 0.07) or 45 g of protein (0.0970% ± 0.0062%/h, P < 0.05) than after 0 g (0.0746% ± 0.0051%/h). Incorporation of dietary protein–derived amino acids (l-[1-13C]-phenylalanine) into de novo myofibrillar protein showed a dose-dependent increase after ingestion of 15, 30, or 45 g protein (0.0171 ± 0.0017, 0.0296 ± 0.0030, and 0.0397 ± 0.0026 mole percentage excess, respectively; P < 0.05). Conclusions Dietary protein ingested during recovery from resistance exercise is rapidly digested and absorbed. Whole-body net protein balance and dietary protein-derived amino acid incorporation into myofibrillar protein show dose-dependent increases. Ingestion of ≥30 g protein increases postexercise myofibrillar protein synthesis rates in older men. This trial was registered at Nederlands Trial Register as NTR4492.

Influence of nutrient ingestion on amino acid transporters and protein synthesis in human skeletal muscle after sprint exercise

2017 ◽  
Vol 123 (6) ◽  
pp. 1501-1515 ◽  
Author(s):  
Håkan C. Rundqvist ◽  
Mona Esbjörnsson ◽  
Olav Rooyackers ◽  
Ted Österlund ◽  
Marcus Moberg ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Resistance Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Amino Acid Transporter ◽  
Mtor Signaling ◽  
Sprint Exercise ◽  
Phosphorylated Akt ◽  
Acid Transporter

Nutrient ingestion is known to increase the exercise-induced stimulation of muscle protein synthesis following resistance exercise. Less is known about the effect of nutrients on muscle protein synthesis following sprint exercise. At two occasions separated by 1 mo, 12 healthy subjects performed three 30-s sprints with 20-min rest between bouts. In randomized order, they consumed a drink with essential amino acids and maltodextrin (nutrient) or flavored water (placebo). Muscle biopsies were obtained 80 and 200 min after the last sprint, and blood samples were taken repeatedly during the experiment. Fractional synthetic rate (FSR) was measured by continuous infusion of l-[2H5]phenylalanine up to 200 min postexercise. The mRNA expression and protein expression of SNAT2 were both 1.4-fold higher ( P < 0.05) after nutrient intake compared with placebo at 200 min postexercise. Phosphorylated Akt, mammalian target of rapamycin (mTOR), and p70S6k were 1.7- to 3.6-fold higher ( P < 0.01) 80 min after the last sprint with nutrient ingestion as compared with placebo. In addition, FSR was higher ( P < 0.05) with nutrients when plasma phenylalanine (FSRplasma) was used as a precursor but not when intracellular phenylalanine (FSRmuscle) was used. Significant correlations were also found between FSRplasma on the one hand and plasma leucine and serum insulin on the other hand in the nutrient condition. The results show that nutrient ingestion induces the expression of the amino acid transporter SNAT2 stimulates Akt/mTOR signaling and most likely the rate of muscle protein synthesis following sprint exercise. NEW & NOTEWORTHY There is limited knowledge regarding the effect of nutrients on muscle protein synthesis following sprint as compared with resistance exercise. The results demonstrate that nutrient ingestion during repeated 30-s bouts of sprint exercise induces expression of the amino acid transporter SNAT2 and stimulates Akt/mTOR signaling and most likely the rate of muscle protein synthesis. Future studies to explore the chronic effects of nutritional ingestion during sprint exercise sessions on muscle mass accretion are warranted.

scholarly journals Skeletal muscle amino acid transporter expression is increased in young and older adults following resistance exercise

2011 ◽  
Vol 111 (1) ◽  
pp. 135-142 ◽  
Author(s):  
Micah J. Drummond ◽  
Christopher S. Fry ◽  
Erin L. Glynn ◽  
Kyle L. Timmerman ◽  
Jared M. Dickinson ◽  
...  
Keyword(s):  
Older Adults ◽  
Amino Acid ◽  
Resistance Exercise ◽  
Amino Acid Transporter ◽  
Initiation Factor ◽  
Amino Acid Transporters ◽  
Α Subunit ◽  
Mtorc1 Signaling ◽  
Acid Transporter ◽  
Transporter Expression

Amino acid transporters and mammalian target of rapamycin complex 1 (mTORC1) signaling are important contributors to muscle protein anabolism. Aging is associated with reduced mTORC1 signaling following resistance exercise, but the role of amino acid transporters is unknown. Young ( n = 13; 28 ± 2 yr) and older ( n = 13; 68 ± 2 yr) subjects performed a bout of resistance exercise. Skeletal muscle biopsies ( vastus lateralis) were obtained at basal and 3, 6, and 24 h postexercise and were analyzed for amino acid transporter mRNA and protein expression and regulators of amino acid transporter transcription utilizing real-time PCR and Western blotting. We found that basal amino acid transporter expression was similar in young and older adults ( P > 0.05). Exercise increased L-type amino acid transporter 1/solute-linked carrier (SLC) 7A5, CD98/SLC3A2, sodium-coupled neutral amino acid transporter 2/SLC38A2, proton-assisted amino acid transporter 1/SLC36A1, and cationic amino acid transporter 1/SLC7A1 mRNA expression in both young and older adults ( P < 0.05). L-type amino acid transporter 1 and CD98 protein increased only in younger adults ( P < 0.05). eukaryotic initiation factor 2 α-subunit (S52) increased similarly in young and older adults postexercise ( P < 0.05). Ribosomal protein S6 (S240/244) and activating transcription factor 4 nuclear protein expression tended to be higher in the young, while nuclear signal transducer and activator of transcription 3 (STAT3) (Y705) was higher in the older subjects postexercise ( P < 0.05). These results suggest that the rapid upregulation of amino acid transporter expression following resistance exercise may be regulated differently between the age groups, but involves a combination of mTORC1, activating transcription factor 4, eukaryotic initiation factor 2 α-subunit, and STAT3. We propose an increase in amino acid transporter expression may contribute to enhanced amino acid sensitivity following exercise in young and older adults. In older adults, the increased nuclear STAT3 phosphorylation may be indicative of an exercise-induced stress response, perhaps to export amino acids from muscle cells.

scholarly journals Even effect of milk protein and carbohydrate intake but no further effect of heavy resistance exercise on myofibrillar protein synthesis in older men

2018 ◽  
Vol 58 (2) ◽  
pp. 583-595 ◽  
Author(s):  
Søren Reitelseder ◽  
Kasper Dideriksen ◽  
Jakob Agergaard ◽  
Nikolaj M. Malmgaard-Clausen ◽  
Rasmus L. Bechshoeft ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Milk Protein ◽  
Older Men ◽  
Myofibrillar Protein ◽  
Carbohydrate Intake ◽  
Heavy Resistance Exercise ◽  
Myofibrillar Protein Synthesis

scholarly journals Enhanced Amino Acid Sensitivity of Myofibrillar Protein Synthesis Persists for up to 24 h after Resistance Exercise in Young Men

2011 ◽  
Vol 141 (4) ◽  
pp. 568-573 ◽  
Author(s):  
Nicholas A. Burd ◽  
Daniel W. D. West ◽  
Daniel R. Moore ◽  
Philip J. Atherton ◽  
Aaron W. Staples ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Resistance Exercise ◽  
Young Men ◽  
Myofibrillar Protein ◽  
Acid Sensitivity ◽  
Myofibrillar Protein Synthesis

Whey and casein labeled with l-[1-13C]leucine and muscle protein synthesis: effect of resistance exercise and protein ingestion

2011 ◽  
Vol 300 (1) ◽  
pp. E231-E242 ◽  
Author(s):  
Søren Reitelseder ◽  
Jakob Agergaard ◽  
Simon Doessing ◽  
Ida C. Helmark ◽  
Peter Lund ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Resistance Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Myofibrillar Protein ◽  
Western Blots ◽  
Amino Acid Availability ◽  
Amino Acid Concentrations ◽  
Myofibrillar Protein Synthesis

Muscle protein turnover following resistance exercise and amino acid availability are relatively well described. By contrast, the beneficial effects of different sources of intact proteins in relation to exercise need further investigation. Our objective was to compare muscle anabolic responses to a single bolus intake of whey or casein after performance of heavy resistance exercise. Young male individuals were randomly assigned to participate in two protein trials ( n = 9) or one control trial ( n = 8). Infusion of l-[1-13C]leucine was carried out, and either whey, casein (0.3 g/kg lean body mass), or a noncaloric control drink was ingested immediately after exercise. l-[1-13C]leucine-labeled whey and casein were used while muscle protein synthesis (MPS) was assessed. Blood and muscle tissue samples were collected to measure systemic hormone and amino acid concentrations, tracer enrichments, and myofibrillar protein synthesis. Western blots were used to investigate the Akt signaling pathway. Plasma insulin and branched-chain amino acid concentrations increased to a greater extent after ingestion of whey compared with casein. Myofibrillar protein synthesis was equally increased 1–6 h postexercise after whey and casein intake, both of which were higher compared with control ( P < 0.05). Phosphorylation of Akt and p70S6K was increased after exercise and protein intake ( P < 0.05), but no differences were observed between the types of protein except for total 4E-BP1, which was higher after whey intake than after casein intake ( P < 0.05). In conclusion, whey and casein intake immediately after resistance exercise results in an overall equal MPS response despite temporal differences in insulin and amino acid concentrations and 4E-BP1.

scholarly journals An increase in essential amino acid availability upregulates amino acid transporter expression in human skeletal muscle

2010 ◽  
Vol 298 (5) ◽  
pp. E1011-E1018 ◽  
Author(s):  
Micah J. Drummond ◽  
Erin L. Glynn ◽  
Christopher S. Fry ◽  
Kyle L. Timmerman ◽  
Elena Volpi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Protein Expression ◽  
Human Skeletal Muscle ◽  
Amino Acid Transporter ◽  
Dependent Manner ◽  
Mtorc1 Signaling ◽  
Acid Transporter ◽  
Transporter Expression

Essential amino acids (EAA) stimulate skeletal muscle mammalian target of rapamycin complex 1 (mTORC1) signaling and protein synthesis. It has recently been reported that an increase in amino acid (AA) transporter expression during anabolic conditions is rapamycin-sensitive. The purpose of this study was to determine whether an increase in EAA availability increases AA transporter expression in human skeletal muscle. Muscle biopsies were obtained from the vastus lateralis of seven young adult subjects (3 male, 4 female) before and 1–3 h after EAA ingestion (10 g). Blood and muscle samples were analyzed for leucine kinetics using stable isotopic techniques. Quantitative RT-PCR, and immunoblotting were used to determine the mRNA and protein expression, respectively, of AA transporters and members of the general AA control pathway [general control nonrepressed (GCN2), activating transcription factor (ATF4), and eukaryotic initiation factor (eIF2) α-subunit (Ser52)]. EAA ingestion increased blood leucine concentration, delivery of leucine to muscle, transport of leucine from blood into muscle, intracellular muscle leucine concentration, ribosomal protein S6 (Ser240/244) phosphorylation, and muscle protein synthesis. This was followed with increased L-type AA transporter (LAT1), CD98, sodium-coupled neutral AA transporter (SNAT2), and proton-coupled amino acid transporter (PAT1) mRNA expression at 1 h ( P < 0.05) and modest increases in LAT1 protein expression (3 h post-EAA) and SNAT2 protein expression (2 and 3 h post-EAA, P < 0.05). Although there were no changes in GCN2 expression and eIF2α phosphorylation, ATF4 protein expression reached significance by 2 h post-EAA ( P < 0.05). We conclude that an increase in EAA availability upregulates human skeletal muscle AA transporter expression, perhaps in an mTORC1-dependent manner, which may be an adaptive response necessary for improved AA intracellular delivery.

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