High-affinity growth hormone binding protein and acute heavy resistance exercise

Rubin, Martyn, French, Duncan, Kraemer, William, Maresh, Carl, Judelson, Daniel, Silvestre, Ricardo, Sharman, Matthew, Hymer, Wesley, Vanheest, Jaci, Volek, Jeff, Gomez, Ana, Vescovi, Jason and Ratamess, Nicholas (2005) High-affinity growth hormone binding protein and acute heavy resistance exercise. Medicine & Science in Sports & Exercise, 37 (3). pp. 395-403. ISSN 0195-9131

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Abstract

Purpose: The purpose of this investigation was to examine the influence of resistance training on circulating concentrations of growth hormone binding protein (GHBP) in response to acute heavy resistance exercise. Methods: Using a cross-sectional experimental design, a group of resistance-trained men (RT, N = 9, 7.9 ± 1.3 yr resistance training experience) and a group of untrained men (UT, N = 10) performed an acute heavy resistance exercise protocol (AHREP) consisting of 6 sets of 10 repetition maximum parallel squats. Blood samples were obtained 72 h before exercise, immediately before exercise, and 0, 15, 30, 45, and 60 min after exercise. Results: Significant increases (P < 0.05) in GHBP, immunoreactive growth hormone (iGH), and IGF-1 were observed in both subject groups after AHREP. There were no differences (P > 0.05) between groups in GHBP at rest or after AHREP. However, RT exhibited a significantly greater iGH response to AHREP than UT subjects, and significantly higher IGF-1 values at rest and after exercise. Significant positive correlations were found between GHBP and BMI, body fat, and leptin in both groups. A significant positive correlation also was observed between resting leptin and GHBP values in UT but not RT subjects. Conclusions: In summary, these data indicate that resistance training does not increase blood GHBP. Nevertheless, the increases observed with IGF-1 concentrations in the resistance-trained subjects do suggest an apparent adaptation with the regulation of this hormone. If there was in fact an increase in GH sensitivity and GH receptor expression at the liver that was not detected by blood GHBP in this study, it may be possible that factors contributing to the circulating concentration of GHBP other than hepatocytes (e.g., leptin and adipocytes) may serve to mask training-induced increases in circulating GHBP of a hepatic origin, thus masking any detectable increase in GH receptor expression.

Item Type:	Article
Additional Information:	Equal status author. French was a member of the research team that formulated the study design and conducted all data collection activities. This included acting as a team member with the responsibility for coordinating all resistance exercise trials, in addition to laboratory based assessment of circulating growth hormone concentrations from isolated blood samples using ELISA and EIA methodologies.
Subjects:	C600 Sports Science
Department:	Faculties > Health and Life Sciences > Sport, Exercise and Rehabilitation
Depositing User:	EPrint Services
Date Deposited:	12 Nov 2008 10:08
Last Modified:	12 Oct 2019 15:28
URI:	http://nrl.northumbria.ac.uk/id/eprint/1010

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