Free leucine supplementation during an 8-week resistance training program does not increase muscle mass and strength in untrained young adult subjects
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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.
KeywordsNutritional supplementation Hypertrophy Cross-sectional area Ergogenic Skeletal muscle
Compliance with ethical standards
Conflict of interest
No conflicts of interest, financial or otherwise, are declared by the author(s).
Human rights statement
This research involved human participants, who were carefully informed of the purpose, procedures, benefits, risks, and discomfort of the investigation, and signed an informed consent document approved by the Institutional Review Board of the University (Protocol No: 44487715.6.0000.0108–CAAE).
- American College of Sports Medicine (2016) American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance. Med Sci Sports Exerc 48:543–568Google Scholar
- Chromiak JA, Smedley B, Carpenter W, Brown R, Koh YS, Lamberth JG, Joe LA, Abadie BR, Altorfer G (2004) Effect of a 10-week strength training program and recovery drink on bodt composition, muscular strength and endurance, and anaerobic power and capacity. Nutrition 20:420–427CrossRefPubMedGoogle Scholar
- Churchward-Venne TA, Burd NA, Mitchell CJ, West DW, Philp A, Marcotte GR, Baker SK, Baar K, Phillips SM (2012) Supplementation of a suboptimal protein dose with leucine or essential amino acids: effects on myofibrillar protein synthesis at rest and following resistance exercise in men. J Physiol 590:2751–2765CrossRefPubMedPubMedCentralGoogle Scholar
- Coburn JW, Housh DJ, Housh TJ, Malek MH, Beck TW, Cramer JT, Johnson GO, Donlin PE (2006) Effects of leucine and whey protein supplementation during eight weeks of unilateral resistance training. J Strength Res 20(2):284–291Google Scholar
- Dickinson JM, Fry CS, Drummond MJ, Gundermann DM, Walker DK, Glynn EL, Timmerman KL, Dhanani S, Volpi E, Rasmussen BB (2011) Mammalian target of rapamycin complex 1 activation is required for the stimulation of human skeletal muscle protein synthesis by essential amino acids. J Nutr 141:856–862CrossRefPubMedPubMedCentralGoogle Scholar
- Dreyer HC, Drummond MJ, Pennings B, Fujita S, Glynn EL, Chinkes DL, Dhanani S, Volpi E, Rasmussen BB (2008) Leucine-enriched essential amino acid and carbohydrate ingestion following resistance exercise enhances mTOR signaling and protein synthesis in human muscle. Am J Physiol Endocrinol Metab 294:E392–E400CrossRefPubMedGoogle Scholar
- Luiking YC, Deutz NE, Memelink RG, Verlaan S, Wolfe RR (2014) Postprandial muscle protein synthesis is higher after a high whey protein, leucine-enriched supplement than after a dairy-like product in healthy older people: a randomized controlled trial. Nutr J 13:9CrossRefPubMedPubMedCentralGoogle Scholar
- Ratamess NA, Kraemer WJ, Volek JS, Rubin MR, Gómez AL, French DN, Sharman MJ, McGuigan MM, Scheett T, Häkkinen K, Newton RU, Dioguardi F (2003) The effects of amino acid supplementation on muscular performance during resistance training over reaching. J Strength Cond Res 17:250–258PubMedGoogle Scholar
- Wilkinson DJ, Hossain T, Hill DS, Phillips BE, Crossland H, Williams J, Loughna P, Churchward-Venne TA, Breen L, Phillips SM, Etheridge T, Rathmacher JA, Smith K, Szewczyk NJ, Atherton PJ (2013) Effects of leucine and its metabolite b-hydroxy-b-methylbutyrate on human skeletal muscle protein metabolism. J Physiol 591:2911e23Google Scholar