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Acute anabolic response to β-hydroxy-β-methylbutyrate (HMB)-free acid supplementation following heavy resistance exercise

Background

β-hydroxy-β-methylbutyrate (HMB), a metabolite of the amino acid leucine, has been shown to promote strength and lean muscle mass when supplemented in conjunction with resistance training. Recently, a new free-acid form of HMB has been shown to reach higher plasma concentrations in a shorter amount of time compared to the calcium-salt form. This higher bioavailability may rationalize acute supplementation with HMB-FA as a means to enhance the anabolic response resulting from heavy resistance training. The purpose of this study was to examine the effect of acute β-hydroxy-β-methylbutyrate-free acid (HMB-FA) on circulating concentrations of anabolic hormones following a heavy resistance exercise protocol.

Methods

Twenty resistance-trained men (22.8 ± 2.5 yrs, 177.6 ± 6.6cm, 83.4 ± 9.8kg) volunteered to participate in this study and were randomized into two groups [HMB-FA and placebo (PL)] and performed an acute, heavy resistance exercise protocol (four sets of up to 10 repetitions of the squat, dead lift, and split squat exercises). Supplementation included 1 g of HMB-FA or PL consumed 30min prior to exercise. Blood was sampled before (PRE), immediately post (IP), and 30 min post-exercise (30P). Circulating levels of testosterone (TEST), growth hormone (GH) and Insulin (INS) were assayed. A 2 x3 repeated measures ANOVA was used to analyze the data. Consent to publish the results was obtained from all participants.

Results

The resistance exercise protocol produced a significant time effect for an elevation in TEST (p<0.01), GH (p<0.01) and INS (p = 0.05) at IP with GH (p<0.01) and INS (p<0.01) remaining elevated at 30P. A group by time interaction was observed (p=0.05) with plasma GH elevated in HMB-FA compared to PRE values (p < 0.01) at IP and 30P. There were no differences at any other time point with TEST or INS concentrations.

Conclusion

These data indicate that HMB-FA supplementation may augment and prolong the growth hormone elevation associated with heavy resistance exercise.

Acknowledgement

This study was supported by Metabolic Technologies Inc.

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Correspondence to JR Townsend.

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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 (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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Townsend, J., Stout, J., Hoffman, J. et al. Acute anabolic response to β-hydroxy-β-methylbutyrate (HMB)-free acid supplementation following heavy resistance exercise. J Int Soc Sports Nutr 11, P16 (2014). https://doi.org/10.1186/1550-2783-11-S1-P16

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Keywords

  • Growth Hormone
  • Resistance Training
  • Plasma Growth Hormone
  • Significant Time Effect
  • Anabolic Response