Hormonal responses to a 160-km race across frozen Alaska

W. J. Kraemer, M. S. Fragala, G. Watson, J. S. Volek, M. R. Rubin, D. N. French, C. M. Maresh, J. L. Vingren, D. L. Hatfield, B. A. Spiering, J. Yu-Ho, S. L. Hughes, H. S. Case, K. J. Stuempfle, D. R. Lehmann, S. Bailey, D. S. Evans

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37 Citations (Scopus)

Abstract

Background: Severe physical and environmental stress seems to have a suppressive effect on the hypothalamic-pituitary-gonadal (HPG) axis in men. Examining hormonal responses to an extreme 160-km competition across frozen Alaska provides a unique opportunity to study this intense stress. Objective: To examine hormonal responses to an ultraendurance race. Methods: Blood samples were obtained from 16 men before and after racing and analyzed for testosterone, interleukin-6 (IL-6), growth hormone (GH) and cortisol. Six subjects (mean (SD) age 42 (7) years; body mass 78.9 (7.1) kg; height 1.78 (0.05) m raced by bicycle (cyclists) and 10 subjects (age 35 (9) years; body mass 77.9 (10.6) kg; height, 1.82 (0.05) m) raced by foot (runners). Mean (SD) finish times were 21.83 (6.27) and 33.98 (6.12) h, respectively. Results: In cyclists there were significant (p ≤ 0.05) mean (SD) pre-race to post-race increases in cortisol (254.83 (135.26) to 535.99 (232.22) nmol/l), GH (0.12 (0.23) to 3.21 (3.33) μg/ml) and IL-6 (2.36 (0.42) to 10.15 (3.28) pg/ml), and a significant decrease in testosterone (13.81 (3.19) to 5.59 (3.74) nmol/l). Similarly, in runners there were significant pre-race to post-race increases in cortisol (142.09 (50.74) to 452.21 (163.40) ng/ml), GH (0.12 (0.23) to 3.21 (3.33) μg/ml) and IL-6 (2.42 (0.68) to 12.25 (1.78) pg/ml), and a significant decrease in testosterone (12.32 (4.47) to 6.96 (3.19) nmol/l). There were no significant differences in the hormonal levels between cyclists and runners (p>0.05). Conclusions: These data suggest a suppression of the hypopituitary-gonadal axis potentially mediated by amplification of adrenal stress responses to such an ultra-endurance race in environmentally stressful conditions.

Original languageEnglish
Pages (from-to)116-120
Number of pages5
JournalBritish Journal of Sports Medicine
Volume42
Issue number2
DOIs
Publication statusPublished - 2008 Feb

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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