The effect of HMB ingestion on the IGF-I and IGF binding protein response to high intensity military training

Michael J Redd; Jay R Hoffman; Yftach Gepner; Jeffrey R Stout; Mattan W Hoffman; Daniel Ben-Dov; Shany Funk; David D Church; Guy Avital; Yacov Chen; Hagai Frankel; Ishay Ostfeld

doi:10.1016/j.ghir.2016.10.003

The effect of HMB ingestion on the IGF-I and IGF binding protein response to high intensity military training

Growth Horm IGF Res. 2017 Feb;32:55-59. doi: 10.1016/j.ghir.2016.10.003. Epub 2016 Oct 5.

Authors

Affiliations

¹ Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, United States.
² Institute of Exercise Physiology and Wellness, Sport and Exercise Science, University of Central Florida, Orlando, FL, United States. Electronic address: jay.hoffman@ucf.edu.
³ Department of Public Health, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
⁴ Israel Defense Forces, Combat Fitness Branch, Netanya, Israel.
⁵ Israel Defense Force, Medical Corps, Tel Hashomer, Israel.

PMID: 27726925
DOI: 10.1016/j.ghir.2016.10.003

Abstract

Objective: Insulin-like growth factor-I (IGF-I) is a metabolic and anabolic biomarker that has been proposed to reflect physiological adaptations resulting from multistressor environments. The bioactivity of IGF-I is regulated by seven different insulin-like growth factor binding proteins (IGFBPs) which act not only as carriers of IGF-1, but also function as a modulator of IGF-I availability and activity. Supplementing with β-hydroxy-β-methylbutyrate (HMB) has been shown to enhance physiological outcomes associated with intense training, and has been reported to augment the IGF-1 response. The purpose of this study was to examine the effect of 23days of HMB supplementation on circulating levels of IGF-I and IGFBPs in combat soldiers during highly intense military training.

Methods: Thirteen male soldiers from an elite infantry unit volunteered to participate in this double-blind, parallel design study. Soldiers were provided 3g·day^-1 of either HMB (n=6) or placebo (PL; n=7). During the study soldiers performed advanced military training with periods of restricted sleep and severe environmental stressors. Blood samples were obtained prior to (PRE) and approximately 18h following the final supplement consumption (POST).

Results: No significant differences were observed for circulating IGF-1 concentrations between HMB and PL (p=0.568). In addition, no differences were seen between the groups for IGFBP-1 (p=1.000), IGFBP-2 (p=0.855), IGFBP-3 (p=0.520), IGFBP-4 (p=0.103), IGFBP-5 (p=0.886), or IGFBP-6 (p=0.775). A significant difference was noted between HMB (169.9±23.0ng·ml^-1) and PL (207.2±28.0ng·ml^-1) for IGFBP-7 at POST (p=0.042).

Conclusions: Although the results of this study do not support the influence of HMB supplementation on circulating concentrations of IGF-1 or IGFBPs1-6 during high intensity military training, it does present initial evidence that it may lower circulating IGFBP-7 concentrations. This may provide some indication of a reduced stress response, but further investigation on the physiological role of IGFBP-7 and military training is needed.

Keywords: Endocrine; Hormones; Physical stress; Soldiers; Supplements.

Publication types

Randomized Controlled Trial
Research Support, Non-U.S. Gov't

MeSH terms

Adult
Dietary Supplements*
Double-Blind Method
Eating
Exercise / physiology*
Humans
Insulin-Like Growth Factor Binding Proteins / blood*
Insulin-Like Growth Factor I / analysis*
Male
Military Personnel*
Valerates / administration & dosage*
Young Adult

Substances

IGF1 protein, human
Insulin-Like Growth Factor Binding Proteins
Valerates
beta-hydroxyisovaleric acid
Insulin-Like Growth Factor I