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REVIEW

HIGHLIGHTED TOPIC
Regulation of Protein Metabolism in Exercise and Recovery

Nutritional and contractile regulation of human skeletal muscle protein synthesis and mTORC1 signaling

¹Department of Physical Therapy, ²Division of Rehabilitation Sciences, and ³Sealy Center on Aging, University of Texas Medical Branch, Galveston, Texas

Submitted 21 October 2008 ; accepted in final form 13 January 2009

ABSTRACT

In this review we discuss current findings in the human skeletal muscle literature describing the acute influence of nutrients (leucine-enriched essential amino acids in particular) and resistance exercise on muscle protein synthesis and mammalian target of rapamycin complex 1 (mTORC1) signaling. We show that essential amino acids and an acute bout of resistance exercise independently stimulate human skeletal muscle protein synthesis. It also appears that ingestion of essential amino acids following resistance exercise leads to an even larger increase in the rate of muscle protein synthesis compared with the independent effects of nutrients or muscle contraction. Until recently the cellular mechanisms responsible for controlling the rate of muscle protein synthesis in humans were unknown. In this review, we highlight new studies in humans that have clearly shown the mTORC1 signaling pathway is playing an important regulatory role in controlling muscle protein synthesis in response to nutrients and/or muscle contraction. We propose that essential amino acid ingestion shortly following a bout of resistance exercise is beneficial in promoting skeletal muscle growth and may be useful in counteracting muscle wasting in a variety of conditions such as aging, cancer cachexia, physical inactivity, and perhaps during rehabilitation following trauma or surgery.

essential amino acids; contraction; translation initiation; leucine

This article has been cited by other articles:

				B. B. Rasmussen and E. A. Richter The balancing act between the cellular processes of protein synthesis and breakdown: exercise as a model to understand the molecular mechanisms regulating muscle mass J Appl Physiol, April 1, 2009; 106(4): 1365 - 1366. [Full Text] [PDF]