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Ten weeks of branched chain amino acid supplementation improves select performance and immunological variables in trained cyclists

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Journal of the International Society of Sports Nutrition201512 (Suppl 1) :P20

  • Published:


We examined if supplementing trained cyclists (32 ± 2 yr, 77.8 ± 2.6 kg, and 7.4 ± 1.2 yr training) with 12g/d (6g/d L-Leucine, 2g/d L-Isoleucine and 4g/d L-Valine) of either branched chain amino acids (BCAAs, n = 9) or a maltodextrin placebo (PLA, n = 9) over a 10-week training season affected select body composition, performance, and/or immune variables.


Before and after the 10-week study, the following was assessed: a) 4-h fasting blood draws; b) dual X-ray absorptiometry body composition; c) Wingate peak power tests; and d) 4km time-trials.


No group*time interactions existed for total lean mass (p = 0.27) or dual-leg lean mass (p = 0.96). A significant interaction existed for body mass-normalized relative peak power (19% increase in the BCAA group pre- to post-study, p = 0.01), and relative mean power (4% increase in the BCAA group pre- to post-study, p = 0.01). 4km time-trial time to completion approached a significant interaction (p = 0.08), as the BCAA group improved in this measure by 11% pre- to post-study, though this was not significant (p = 0.15). There was a tendency for the BCAA group to present a greater post-study serum BCAA: L-Tryptophan ratio compared to the PLA group (p = 0.08). A significant interaction for neutrophil number existed (p = 0.04), as there was a significant 18% increase within the PLA group from the pre- to post-study time point (p = 0.01).


Chronic BCAA supplementation improves sprint performance variables in endurance cyclists. Additionally, given that BCAA supplementation blunted the neutrophil response to intense cycling training, BCAAs may benefit immune function during a prolonged cycling season.

Authors’ Affiliations

School of Kinesiology, Auburn University, Auburn, AL, USA
Edward Via College of Osteopathic Medicine, Auburn Campus, Auburn, AL, USA
Harrison School of Pharmacy, Auburn University, Auburn, AL, USA
Endurance Company, LLC, Bloomington, IL, USA
MusclePharm Sports Science Institute, Denver, CO, USA


© Kephart et al. 2015

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.