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Effects of free leucine supplementation and resistance training on muscle strength and functional status in older adults: a randomized controlled trial

Authors Trabal J, Forga M, Leyes P, Torres F, Rubio J, Prieto E, Farran-Codina A

Received 2 October 2014

Accepted for publication 20 January 2015

Published 13 April 2015 Volume 2015:10 Pages 713—723


Checked for plagiarism Yes

Review by Single anonymous peer review

Peer reviewer comments 5

Editor who approved publication: Dr Richard Walker

Joan Trabal,1 Maria Forga,1 Pere Leyes,1 Ferran Torres,2,3 Jordi Rubio,4 Esther Prieto,5 Andreu Farran-Codina6

1Department of Endocrinology and Nutrition, Hospital Clínic Universitari de Barcelona, Barcelona, Catalonia, Spain; 2Biostatistics and Data Management Core Facility, IDIBAPS, Hospital Clinic Universitari de Barcelona, Barcelona, Catalonia, Spain; 3Biostatistics Unit, School of Medicine, Universitat Autònoma de Barcelona, Barcelona, Catalonia, Spain; 4Residencia Ballesol Almogavers, Grupo Ballesol, Barcelona, Catalonia, Spain; 5Centre de Rehabilitacio, Fundació Amiba, Badalona, Catalonia, Spain; 6Department of Nutrition and Food Science, Faculty of Pharmacy, Universitat de Barcelona, Barcelona, Catalonia, Spain

Objective: To assess the effect of free leucine supplementation combined with resistance training versus resistance training only on muscle strength and functional status in older adults.
Methods: This was a randomized, double-blind, placebo-controlled, parallel study with two intervention groups. Thirty older adults were randomly assigned to receive either 10 g leucine/day (leucine group [LG], n=15) or a placebo (control group [CG], n=15), plus resistance training over a 12-week period. Maximal overcoming isometric leg strength, functional status, nutritional status, body composition, health-related quality of life, depression, and dietary intake were assessed at 4 and 12 weeks. Missing data at 12 weeks were handled using mixed models for repeated measurements for data imputation.
Results: Twenty-four subjects completed the 4-week assessment and eleven completed the 12-week intervention. Clinically significant gains were found in isometric leg strength at both assessment time points. Analysis of the effect size also showed how participants in LG outperformed those in CG for chair stands and the timed up and go test. No significant changes were observed for the rest of the outcomes.
Conclusion: Our combined analysis showed moderate changes in isometric leg muscle strength and certain components of functional status. The magnitude of changes found on these outcomes should be qualified as a positive effect of the concomitant intervention.

Keywords: aged, elderly, strength training, amino acid, functionality

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