Hypoxia and training-induced adaptation of hormonal responses to exercise in humans

Kim Engfred, Michael Kjær, Niels H. Secher, Daniel B. Friedman, Birgitte Hanel, Ove Juel Nielsen, Flemming W. Bach, Henrik Galbo, Benjamin D. Levine

Research output: Contribution to journalArticlepeer-review

51 Scopus citations


To establish whether or not hypoxia influences the training-induced adaptation of hormonal responses to exercise, 21 healthy, untrained subjects [26 (2) years, mean (SE)] were studied in three groups before and after 5 weeks' training (cycle ergometer, 45 min· day-1, 5 days· week-1). Group 1 trained at sea level at 70% maximal oxygen uptake ( {Mathematical expression}O2max), group 2 in a hypobaric chamber at a simulated altitude of 2500 m at 70% of altitude {Mathematical expression}O2max, and group 3 at a simulated altitude of 2500 m at the same absolute work rate as group 1. Arterial blood was sampled before, during and at the end of exhaustive cycling at sea level (85% of pretraining of {Mathematical expression}O2max). {Mathematical expression}O2 increased by 12 (2)% with no significant difference between groups, whereas endurance improved most in group 1 (P < 0.05). Training-induced changes in response to exercise of noradrenaline, adrenaline, growth hormone, β-endorphin, glucagon, and insulin were similar in the three groups. Concentrations of erythropoietin and 2,3-diphosphoglycerate at rest did not change over the training period. In conclusion, within 5 weeks of training, no further adaptation of hormonal exercise responses takes place if intensity is increased above 70% {Mathematical expression}O2max. Furthermore, hypoxia per se does not add to the training-induced hormonal responses to exercise.

Original languageEnglish (US)
Pages (from-to)303-309
Number of pages7
JournalEuropean Journal of Applied Physiology and Occupational Physiology
Issue number4
StatePublished - Jul 1 1994


  • ACTH
  • Catecholamines
  • Erythropoietin
  • Growth hormone
  • Insulin

ASJC Scopus subject areas

  • Physiology
  • Public Health, Environmental and Occupational Health


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