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Title: Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis

Author
item PASIAKOS, STEFAN M. - United States Army Medical Research Unit
item MCCLUNG, HOLLY L. - United States Army Medical Research Unit
item MCCLUNG, JAMES P. - United States Army Center For Health Promotion And Preventative Medicine
item MARGOLIS, LEE M. - United States Army Medical Research Unit
item ANDERSEN, NANCY E. - United States Army Medical Research Unit
item CLOUTIER, GREGORY J. - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
item PIKOSKY, MATTHEW A. - Dairy Management, Inc
item ROOD, JENNIFER C. - Pennington Biomedical Research Center
item FIELDING, ROGER A. - Jean Mayer Human Nutrition Research Center On Aging At Tufts University
item YOUNG, ANDREW J. - United States Army Medical Research Unit

Submitted to: American Society for Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2011
Publication Date: 7/20/2011
Citation: Pasiakos, S., Mcclung, H., Mcclung, J., Margolis, L., Andersen, N., Cloutier, G., Pikosky, M., Rood, J., Fielding, R., Young, A. 2011. Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis. American Society for Clinical Nutrition. DOI: 10.3945/ajcn.111.017061. PMID:21775557.

Interpretive Summary: This study was a collaboration between the JM-USDA Human Nutrition Research Center on Aging and the US Army Research Institute of Environmental Medicine. In this study we examined how young soldiers responded to a single session of aerobic (endurance) exercise similar to riding a bicycle for one hour. We found that an amino acid beverage (10 gram of essential amino acids) that was enriched with an 1.6 grams of leucine caused a greater stimulation of muscle protein synthesis following exercise. These results suggest that the leucine content of beverage can modulate the increase in muscle protein synthesis after exercise.

Technical Abstract: BACKGROUND: The effects of essential amino acid (EAA) supplementation during moderate steady state (ie, endurance) exercise on postexercise skeletal muscle metabolism are not well described, and the potential role of supplemental leucine on muscle protein synthesis (MPS) and associated molecular responses remain to be elucidated. OBJECTIVE: This randomized crossover study examined whether EAA supplementation with 2 different concentrations of leucine affected post-steady state exercise MPS, whole-body protein turnover, and mammalian target of rapamycin 1 (mTORC1) intracellular signaling. DESIGN: Eight adults completed 2 separate bouts of cycle ergometry [60 min, 60% VO(2)peak (peak oxygen uptake)]. Isonitrogenous (10 g EAA) drinks with different leucine contents [leucine-enriched (L)-EAA, 3.5 g leucine; EAA, 1.87 g leucine] were consumed during exercise. MPS and whole-body protein turnover were determined by using primed continuous infusions of [(2)H(5)]phenylalanine and [1-(13)C]leucine. Multiplex and immunoblot analyses were used to quantify mTORC1 signaling. RESULTS: MPS was 33% greater (P < 0.05) after consumption of L-EAA (0.08 +/- 0.01%/h) than after consumption of EAA (0.06 +/- 0.01%/h). Whole-body protein breakdown and synthesis were lower (P < 0.05) and oxidation was greater (P < 0.05) after consumption of L-EAA than after consumption of EAA. Regardless of dietary treatment, multiplex analysis indicated that Akt and mammalian target of rapamycin phosphorylation were increased (P < 0.05) 30 min after exercise. Immunoblot analysis indicated that phosphorylation of ribosomal protein S6 and extracellular-signal regulated protein kinase increased (P < 0.05) and phosphorylation of eukaryotic elongation factor 2 decreased (P < 0.05) after exercise but was not affected by dietary treatment. CONCLUSION: These findings suggest that increasing the concentration of leucine in an EAA supplement consumed during steady state exercise elicits a greater MPS response during recovery. This trial is registered at clinicaltrials.gov as NCT01366924.