Document Detail

Whey and casein labeled with L-[1-13C]leucine and muscle protein synthesis: effect of resistance exercise and protein ingestion.
MedLine Citation:
PMID:  21045172     Owner:  NLM     Status:  MEDLINE    
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-(13)C]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-(13)C]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 p70(S6K) 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.
Søren Reitelseder; Jakob Agergaard; Simon Doessing; Ida C Helmark; Peter Lund; Niels B Kristensen; Jan Frystyk; Allan Flyvbjerg; Peter Schjerling; Gerrit van Hall; Michael Kjaer; Lars Holm
Publication Detail:
Type:  Comparative Study; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't     Date:  2010-11-02
Journal Detail:
Title:  American journal of physiology. Endocrinology and metabolism     Volume:  300     ISSN:  1522-1555     ISO Abbreviation:  Am. J. Physiol. Endocrinol. Metab.     Publication Date:  2011 Jan 
Date Detail:
Created Date:  2010-12-29     Completed Date:  2011-01-31     Revised Date:  2011-04-05    
Medline Journal Info:
Nlm Unique ID:  100901226     Medline TA:  Am J Physiol Endocrinol Metab     Country:  United States    
Other Details:
Languages:  eng     Pagination:  E231-42     Citation Subset:  IM    
Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery M, Bispebjerg Hospital and Center for Healthy Aging, University of Copenhagen, Copenhagen NV, Denmark.
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MeSH Terms
Adaptor Proteins, Signal Transducing / metabolism
Amino Acids / blood,  metabolism
Carbon Isotopes
Caseins / chemistry,  metabolism*
Dietary Proteins / metabolism*
Food, Formulated / analysis*
Insulin / blood
Leucine / blood,  chemistry,  metabolism*
Milk Proteins / chemistry,  metabolism*
Muscle Proteins / biosynthesis*
Myofibrils / metabolism
Phosphoproteins / metabolism
Proto-Oncogene Proteins c-akt / metabolism
Resistance Training*
Ribosomal Protein S6 Kinases, 70-kDa / metabolism
Signal Transduction
Single-Blind Method
Reg. No./Substance:
0/Adaptor Proteins, Signal Transducing; 0/Amino Acids; 0/Carbon Isotopes; 0/Caseins; 0/Dietary Proteins; 0/EIF4EBP1 protein, human; 0/Milk Proteins; 0/Muscle Proteins; 0/Phosphoproteins; 0/whey protein; 11061-68-0/Insulin; 61-90-5/Leucine; EC Proteins c-akt; EC Protein S6 Kinases, 70-kDa
Comment In:
Am J Physiol Endocrinol Metab. 2011 Mar;300(3):E610; author reply E611-2   [PMID:  21357461 ]

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