Plasma changes in beta-endorphin to acute hypobaric hypoxia and high intensity exercise

W. J. Kraemer, A. J. Hamilton, S. E. Gordon, L. A. Trad, J. T. Reeves, D. W. Zahn, A. Cymerman

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

The purpose of this study was to examine the immediate post-exercise effects of acute exposure to a simulated altitude of 4,300 m on plasma concentrations of beta-endorphin (β-EP) and associated changes of adrenocorticotropin (ACTH), and cortisol to high intensity cycle exercise (i.e., stages of 90 and 100% peak V̇O2). Exercise intensities were assigned relative to peak O2 uptak both under sea level conditions and under acute hypobaric hypoxic conditions. Plasma β-EP concentrations significantly increased from pre- to immediately post-exercise at both 90 and 100% peak V̇o2 in both the sea level and acute hypobaric hypoxic trials. No associated exercise-induced changes were observed for ACTH or cortisol pre- to immediately post-exercise at either sea level or during hypoxic conditions. Exercise at acute hypobaric hypoxia elicited no significantly different responses in plasma β-EP, ACTH, or cortisol than those elicited by the same relative exercise intensities under normobaric normoxic conditions. Additionally, no changes in the β-EP/ACTH molar ratio for exercise or between conditions were observed. These data indicate that acute simulated high altitude exposure neither diminishes nor augments the physiological stimuli involved with high relative exercise intensity activation mechanisms of these hormones.

Original languageEnglish (US)
Pages (from-to)754-758
Number of pages5
JournalAviation Space and Environmental Medicine
Volume62
Issue number8
StatePublished - Sep 13 1991
Externally publishedYes

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health

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