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

J Appl Physiol (1985). 2006 Jan;100(1):120-8. doi: 10.1152/japplphysiol.01415.2004. Epub 2005 Sep 1.


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 < or = 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 (approximately 50%) and overnight pulsatile secretion (approximately 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.

Publication types

  • Clinical Trial

MeSH terms

  • Adaptation, Physiological
  • Adult
  • Exercise Test
  • Growth Hormone / blood*
  • Growth Hormone / metabolism
  • Humans
  • Insulin-Like Growth Factor I / metabolism*
  • Luteinizing Hormone / blood*
  • Luteinizing Hormone / metabolism
  • Male
  • Military Personnel
  • Physical Endurance*
  • Physical Exertion*
  • Sleep Deprivation / blood*
  • Sleep Deprivation / physiopathology*


  • Insulin-Like Growth Factor I
  • Luteinizing Hormone
  • Growth Hormone