HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 291/6/E1177    most recent 00042.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Kraemer, W. J. Articles by Hymer, W. C. Search for Related Content PubMed PubMed Citation Articles by Kraemer, W. J. Articles by Hymer, W. C.

Chronic resistance training in women potentiates growth hormone in vivo bioactivity: characterization of molecular mass variants

¹Human Performance Laboratory, Department of Kinesiology and Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut; ²Military Performance Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts; ³Department of Biology, The University of Pennsylvania, Philadelphia, Pennsylvania; ⁴Department of Health and Physical Education, University of Hawaii at Hilo, Hilo, Hawaii; ⁵Laboratory of Integrated Physiology, Department of Health and Human Performance, University of Houston, Houston, Texas; and ⁶Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania

Submitted 27 January 2006 ; accepted in final form 27 June 2006

This investigation determined the influence of acute and chronic resistance exercise on responses of growth hormone (GH) molecular variants in women. Seventy-four healthy young women (23 ± 3 yr, 167 ± 7 cm, 63.8 ± 9.3 kg, 26.3 ± 4.0% body fat) performed an acute bout of resistance exercise (6 sets of 10 repetition maximum squat). Blood samples were obtained pre- and postexercise. Resulting plasma was fractionated by molecular mass (fraction A, >60 kDa; fraction B, 30–60 kDa; and fraction C, <30 kDa) using chromatography. Fractionated and unfractionated (UF) plasma was then assayed for GH using three different detection systems (monoclonal immunoassay, polyclonal immunoassay, and rat tibial line in vivo bioassay). Subjects were then matched and randomly placed into one of four resistance exercise training groups or a control group for 24 wk. All experimental procedures were repeated on completion of the 24-wk resistance training programs. After acute exercise, immunoassays showed consistent increases in UF GH samples and fractions B and C; increases in fraction A using immunoassay were seen only in the monoclonal assay. No consistent changes in bioactive GH were found following acute exercise. Conversely, chronic exercise induced no consistent changes in immunoassayable GH of various molecular masses, whereas, in general, bioassayable GH increased. In summary, although acute exercise increased only immunoactive GH, chronic physical training increased the biological activity of circulating GH molecular variants. Increased bioactive GH was observed across all fractions and training regimens, suggesting that chronic resistance exercise increased a spectrum of GH molecules that may be necessary for the multitude of somatogenic and metabolic actions of GH.

hormones; isoforms; somatotrophs; strength training

This article has been cited by other articles:

				J. L. Vingren, W. J. Kraemer, D. L. Hatfield, J. M. Anderson, J. S. Volek, N. A. Ratamess, G. A. Thomas, J.-Y. Ho, M. S. Fragala, and C. M. Maresh Effect of resistance exercise on muscle steroidogenesis J Appl Physiol, December 1, 2008; 105(6): 1754 - 1760. [Abstract] [Full Text] [PDF]