(04-10-11) Leucine-enriched essential amino acid supplementation during moderate steady state exercise

Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis1,2,3,4,5
1. Stefan M Pasiakos,
2. Holly L McClung,
3. James P McClung,
4. Lee M Margolis,
5. Nancy E Andersen,
6. Gregory J Cloutier,
7. Matthew A Pikosky,
8. Jennifer C Rood,
9. Roger A Fielding, and
10. Andrew J Young
+ Author Affiliations
1. 1From the Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, MA (SMP, HLM, JPM, LMM, NEA, MAP, and AJY); the Nutrition, Exercise Physiology and Sarcopenia Laboratory, Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA (GJC and RAF); and Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA (JCR).
+ Author Notes
↵2 The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the US Army or the Department of Defense. Any citations of commercial organizations and trade names in this report do not constitute an official Department of the Army endorsement of approval of the products or services of these organizations.
↵3 This material is based on work supported by the US Department of Agriculture, Agricultural Research Service, under agreement no. 58-1950-7-707. Any opinions, findings, conclusion, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the US Department of Agriculture.
↵4 Supported by the US Army Medical Research and Material Command.
↵5 Address reprint requests and correspondence to SM Pasiakos, Military Nutrition Division, US Army Research Institute of Environmental Medicine, Kansas Street, Building 42, Natick, MA 01760. E-mail: [email protected].
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 remains 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% VO2peak (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 [2H5]phenylalanine and [1-13C]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.

Source: Am J Clin Nutr September 2011 vol. 94 no. 3 809-818

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