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Amino acids and protein synthesis
Med Sci Sports Exerc. 2011 May 20. [Epub ahead of print]
Exercise, Amino Acids and Aging in the Control of Human Muscle Protein Synthesis.
Walker DK, Dickinson JM, Timmerman KL, Drummond MJ, Reidy PT, Fry CS, Gundermann DM, Rasmussen BB.
Source
1Department of Nutrition & Metabolism, 2Division of Rehabilitation Sciences, and the 3Sealy Center on Aging, University of Texas Medical Branch, Galveston, Texas, U.S.A.
Abstract
In this review we discuss recent research in the field of human skeletal muscle protein metabolism characterizing the acute regulation of mammalian target of rapamycin complex (mTORC) 1 signaling and muscle protein synthesis (MPS) by exercise, amino acid nutrition and aging. Resistance exercise performed in the fasted state stimulates mixed MPS within 1 h post-exercise, which can remain elevated for 48 h. We demonstrate that the activation of mTORC1 signaling (and subsequently enhanced translation initiation) is required for the contraction-induced increase in MPS. In comparison, low-intensity blood flow restriction (BFR) exercise stimulates MPS and mTORC1 signaling to an extent similar to traditional, high-intensity resistance exercise. We also show that mTORC1 signaling is required for the essential amino acid (EAA) induced increase in MPS. Ingestion of EAAs (or protein) shortly following resistance exercise enhances MPS and mTORC1 signaling as compared to resistance exercise or EAAs alone. In older adults, the ability of skeletal muscle to respond to anabolic stimuli is impaired. For example, in response to an acute bout of resistance exercise, older adults are less able to activate mTORC1 or increase MPS during the first 24h of post-exercise recovery. However, BFR exercise can overcome this impairment. Aging is not associated with a reduced response to EAAs provided the EAA content is sufficient. Therefore, we propose that exercise combined with EAA should be effective not only in improving muscle repair and growth in response to training in athletes, but that strategies such as EAA combined with resistance exercise (or BFR exercise) may be very useful as a countermeasure for sarcopenia and other clinical conditions associated with muscle wasting.
Amino acids and protein synthesis
Med Sci Sports Exerc. 2011 May 20. [Epub ahead of print]
Exercise, Amino Acids and Aging in the Control of Human Muscle Protein Synthesis.
Walker DK, Dickinson JM, Timmerman KL, Drummond MJ, Reidy PT, Fry CS, Gundermann DM, Rasmussen BB.
Source
1Department of Nutrition & Metabolism, 2Division of Rehabilitation Sciences, and the 3Sealy Center on Aging, University of Texas Medical Branch, Galveston, Texas, U.S.A.
Abstract
In this review we discuss recent research in the field of human skeletal muscle protein metabolism characterizing the acute regulation of mammalian target of rapamycin complex (mTORC) 1 signaling and muscle protein synthesis (MPS) by exercise, amino acid nutrition and aging. Resistance exercise performed in the fasted state stimulates mixed MPS within 1 h post-exercise, which can remain elevated for 48 h. We demonstrate that the activation of mTORC1 signaling (and subsequently enhanced translation initiation) is required for the contraction-induced increase in MPS. In comparison, low-intensity blood flow restriction (BFR) exercise stimulates MPS and mTORC1 signaling to an extent similar to traditional, high-intensity resistance exercise. We also show that mTORC1 signaling is required for the essential amino acid (EAA) induced increase in MPS. Ingestion of EAAs (or protein) shortly following resistance exercise enhances MPS and mTORC1 signaling as compared to resistance exercise or EAAs alone. In older adults, the ability of skeletal muscle to respond to anabolic stimuli is impaired. For example, in response to an acute bout of resistance exercise, older adults are less able to activate mTORC1 or increase MPS during the first 24h of post-exercise recovery. However, BFR exercise can overcome this impairment. Aging is not associated with a reduced response to EAAs provided the EAA content is sufficient. Therefore, we propose that exercise combined with EAA should be effective not only in improving muscle repair and growth in response to training in athletes, but that strategies such as EAA combined with resistance exercise (or BFR exercise) may be very useful as a countermeasure for sarcopenia and other clinical conditions associated with muscle wasting.
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