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

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 100/1/120    most recent 01415.2004v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted 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 Nindl, B. C. Articles by Montain, S. J. Search for Related Content PubMed PubMed Citation Articles by Nindl, B. C. Articles by Montain, S. J.

Altered secretion of growth hormone and luteinizing hormone after 84 h of sustained physical exertion superimposed on caloric and sleep restriction

¹Military Performance Division, ²Thermal and Mountain Medicine Division, and ³Military Nutrition Division, United States Army Research Institute of Environmental Medicine, Natick, Massachusetts

Submitted 23 December 2004 ; accepted in final form 24 August 2005

The pulsatile release of growth hormone (GH) and luteinizing hormone (LH) from the anterior pituitary gland is integral for signaling secretion of insulin-like growth factor (IGF)-I and testosterone, respectively. This study examined the hypothesis that 84 h of sustained physical exertion with caloric and sleep restriction alters the secretion of GH and LH. Ten male soldiers [22 yr (SD 3), 183 cm (SD 7), 87 kg (SD 8)] had blood drawn overnight from 1800 to 0600 every 20 min for GH, LH, and leptin and every 2 h for IGF-I (total and free), IGF binding proteins-1 and -3, testosterone (total and free), glucose, and free fatty acids during a control week and after 84 h of military operational stress. Time-series cluster and deconvolution analyses assessed the secretion parameters of GH and LH. Significant results (P 0.05) were as follows: body mass (–3%), fat-free mass (–2.3%), and fat mass (–7.3%) declined after military operational stress. GH and LH secretion burst amplitude (50%) and overnight pulsatile secretion (50%), IGF binding protein-1 (+67%), and free fatty acids (+33%) increased, whereas leptin (–47%), total (–27%) and free IGF-I (–32%), total (–24%) and free testosterone (–30%), and IGF binding protein-3 (–6%) decreased. GH and LH pulse number were unaffected. Because GH and LH positively regulate IGF-I and testosterone, these data imply that the physiological strain induced a certain degree of peripheral resistance. During periods of energy deficiency, amplitude modulation of GH and LH pulses may precede alterations in pulse numbers.

hormone pulsatility; insulin-like growth factor-I; soldiers; leptin; testosterone

This article has been cited by other articles:

				J. A. Alemany, B. C. Nindl, M. D. Kellogg, W. J. Tharion, A. J. Young, and S. J. Montain Effects of dietary protein content on IGF-I, testosterone, and body composition during 8 days of severe energy deficit and arduous physical activity J Appl Physiol, July 1, 2008; 105(1): 58 - 64. [Abstract] [Full Text] [PDF]