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

TY - JOUR

T1 - Whey and casein labeled with L-[1-13C]leucine and muscle protein synthesis

T2 - effect of resistance exercise and protein ingestion

AU - Reitelseder, Søren

AU - Agergaard, Jakob

AU - Doessing, Simon

AU - Helmark, Ida C

AU - Lund, Peter

AU - Kristensen, Niels B

AU - Frystyk, Jan

AU - Flyvbjerg, Allan

AU - Schjerling, Peter

AU - van Hall, Gerrit

AU - Kjaer, Michael

AU - Holm, Lars

PY - 2011/1

Y1 - 2011/1

N2 - 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. Myo-fibrillar 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.

AB - 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. Myo-fibrillar 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.

KW - Adaptor Proteins, Signal Transducing

KW - Adult

KW - Amino Acids

KW - Carbon Isotopes

KW - Caseins

KW - Dietary Proteins

KW - Food, Formulated

KW - Humans

KW - Insulin

KW - Leucine

KW - Male

KW - Milk Proteins

KW - Muscle Proteins

KW - Myofibrils

KW - Phosphoproteins

KW - Phosphorylation

KW - Proto-Oncogene Proteins c-akt

KW - Resistance Training

KW - Ribosomal Protein S6 Kinases, 70-kDa

KW - Signal Transduction

KW - Single-Blind Method

U2 - 10.1152/ajpendo.00513.2010

DO - 10.1152/ajpendo.00513.2010

M3 - Journal article

C2 - 21045172

SN - 0193-1849

VL - 300

SP - E231-42

JO - American Journal of Physiology - Endocrinology and Metabolism

JF - American Journal of Physiology - Endocrinology and Metabolism

IS - 1

ER -