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Amino Acids. 2017 Jul;49(7):1255-1262. doi: 10.1007/s00726-017-2427-0. Epub 2017 Apr 25.

Free leucine supplementation during an 8-week resistance training program does not increase muscle mass and strength in untrained young adult subjects.

Author information

1
Center of Research in Health Sciences, North University of Paraná (UNOPAR), Avenue Paris, 675, Jardim Piza, Londrina, PR, 86041-120, Brazil. afaguiarunesp@gmail.com.
2
Center of Research in Health Sciences, North University of Paraná (UNOPAR), Avenue Paris, 675, Jardim Piza, Londrina, PR, 86041-120, Brazil.
3
Department of Physiotherapy, University of Western São Paulo (UNOESTE), Presidente Prudente, São Paulo, Brazil.

Abstract

The purpose of this study was to examine the effects of free leucine supplementation on changes in skeletal muscle mass and strength during a resistance training (RT) program in previously untrained, young subjects. In a double-blind, randomized, placebo-controlled study, 20 healthy young (22 ± 2 years) participants were assigned to two groups: a placebo-supplement group (PLA, N = 10) or a leucine-supplement group (LEU, N = 10). Both groups underwent an 8-week hypertrophic RT program (2 days/week), consuming an equivalent amount of leucine (3.0 g/day in a single post-training dose) or placebo (cornstarch). Quadriceps muscle strength, cross-sectional area (CSA) of the vastus lateralis (VL), and rectus femoris (RF), as well as the habitual dietary intake were assessed before and after the 8-week intervention period. There was a similar improvement in muscle strength (Leg press, LEU: +33% vs. PLA: +37%; P > 0.05, and knee extension, LEU: +31% vs. PLA: 34%; P > 0.05) and CSA (VL, LEU: 8.9% vs. PLA: 9.6%; P > 0.05, and RF, LEU: +21.6% vs. PLA: + 16.4%; P > 0.05) in the both groups from pre- to post-training. In addition, there was no significant (P > 0.05) difference in daily dietary intake between the LEU and PLA groups before and after the intervention period. Free leucine supplementation (3.0 g/day post-training) does not increase muscle strength or CSA during RT in healthy young subjects consuming adequate dietary protein intake.

KEYWORDS:

Cross-sectional area; Ergogenic; Hypertrophy; Nutritional supplementation; Skeletal muscle

PMID:
28444456
DOI:
10.1007/s00726-017-2427-0
[Indexed for MEDLINE]

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