The Effect of Leucine-Enriched Essential Amino Acid Supplementation on Anabolic and Catabolic Signaling in Human Skeletal Muscle after Acute Resistance Exercise: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group Comparison Trial

Resistance exercise transiently activates anabolic and catabolic systems in skeletal muscle. Leucine-enriched essential amino acids (LEAAs) are reported to stimulate the muscle anabolic response at a lower dose than whey protein. However, little is known regarding the effect of LEAA supplementation...

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Bibliographic Details
Main Authors: Junya Takegaki, Kohei Sase, Jun Yasuda, Daichi Shindo, Hiroyuki Kato, Sakiko Toyoda, Toshiyuki Yamada, Yasushi Shinohara, Satoshi Fujita
Format: Article
Language:English
Published: MDPI AG 2020-08-01
Series:Nutrients
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Online Access:https://www.mdpi.com/2072-6643/12/8/2421
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Summary:Resistance exercise transiently activates anabolic and catabolic systems in skeletal muscle. Leucine-enriched essential amino acids (LEAAs) are reported to stimulate the muscle anabolic response at a lower dose than whey protein. However, little is known regarding the effect of LEAA supplementation on the resistance exercise-induced responses of the anabolic and catabolic systems. Here, we conducted a randomized, double-blind, placebo-controlled, parallel-group comparison trial to investigate the effect of LEAA supplementation on mechanistic target of rapamycin complex 1 (mTORC1), the ubiquitin–proteasome system and inflammatory cytokines after a single bout of resistance exercise in young men. A total of 20 healthy young male subjects were supplemented with either 5 g of LEAA or placebo, and then they performed 10 reps in three sets of leg extensions and leg curls (70% one-repetition maximum). LEAA supplementation augmented the phosphorylation of mTOR<sup>Ser2448</sup> (+77.1%, <i>p</i> < 0.05), p70S6K<sup>Thr389</sup> (+1067.4%, <i>p</i> < 0.05), rpS6<sup>Ser240/244</sup> (+171.3%, <i>p</i> < 0.05) and 4EBP1<sup>Thr37/46</sup> (+33.4%, <i>p</i> < 0.05) after resistance exercise. However, LEAA supplementation did not change the response of the ubiquitinated proteins, MuRF-1 and Atrogin-1 expression. Additionally, the mRNA expression of IL-1β and IL-6 did not change. These data indicated that LEAA supplementation augments the effect of resistance exercise by enhancing mTORC1 signal activation after exercise.
ISSN:2072-6643