Effects of β-Hydroxy-β-methylbutyrate Free Acid Ingestion and Resistance Exercise on the Acute Endocrine Response.

Jeremy R Townsend,Adam J Wells,David H Fukuda,Maren S Fragala,Edward H Robinson,Jeffrey R Stout,Adam R Jajtner,Jay R Hoffman,Gerald T Mangine,Adam M Gonzalez,Carleigh H Boone

doi:10.1155/2015/856708

Jeremy R Townsend, Adam J Wells + Show 9 more

Open Access

https://doi.org/10.1155/2015/856708

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Abstract

Objective. To examine the endocrine response to a bout of heavy resistance exercise following acute β-hydroxy-β-methylbutyrate free acid (HMB-FA) ingestion. Design. Twenty resistance trained men were randomized and consumed either 1 g of HMB-FA (BetaTor) or placebo (PL) 30 min prior to performing an acute heavy resistance exercise protocol. Blood was obtained before (PRE), immediately after (IP), and 30 min after exercise (30P). Circulating concentrations of testosterone, growth hormone (GH), insulin-like growth factor (IGF-1), and insulin were assayed. Data were analyzed with a repeated measures ANOVA and area under the curve (AUC) was analyzed by the trapezoidal rule. Results. The resistance exercise protocol resulted in significant elevations from PRE in testosterone (P < 0.01), GH (P < 0.01), and insulin (P = 0.05) at IP, with GH (P < 0.01) and insulin (P < 0.01) remaining elevated at 30P. A significant interaction was noted between groups in the plasma GH response at IP, which was significantly higher following HMB-FA compared to PL (P < 0.01). AUC analysis revealed an elevated GH and IGF-1 response in the HMB-FA group compared to PL. Conclusion. HMB-FA prior to resistance exercise augments the GH response to high volume resistance exercise compared to PL. These findings provide further support for the potential anabolic benefits associated with HMB supplementation.

Highlights

Introduction βHydroxy-β-methylbutyrate (HMB), a leucine derived metabolite, has been demonstrated to augment strength and lean muscle gains when supplemented in conjunction with resistance training [1,2,3,4]
Many of the earlier studies used HMB formulated as a calcium salt (HMB-Ca); a new free acid form of HMB (HMBFA) has been shown to yield higher plasma concentrations in a shorter amount of time compared to the calcium salt form [8]
The main findings of this investigation were that hydroxy-β-methylbutyrate free acid (HMB-FA) ingestion prior to resistance exercise can augment both the growth hormone (GH) and insulin-like growth factor-1 (IGF-1) response to a training session

Summary

Introduction

Hydroxy-β-methylbutyrate (HMB), a leucine derived metabolite, has been demonstrated to augment strength and lean muscle gains when supplemented in conjunction with resistance training [1,2,3,4]. An 18% increase in strength gain was demonstrated following 12 weeks of HMB ingestion compared to placebo in experienced resistance trained men [1]. Earlier studies of HMB were not consistent in demonstrating the efficacy of supplementation in regard to performance improvements [2, 5,6,7]. The greater bioavailability of HMB-FA may provide greater benefits regarding its efficacy as a nutrient supplement used to enhance training adaptations. HMB is known to increase muscle protein synthesis through mTOR signaling pathways while concurrently reducing proteolytic processes [10,11,12,13]. Evidence exists demonstrating HMB’s ability to modulate specific cytokines and immune cells responsible for muscle tissue repair [14,15,16]

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