title: Hypothalamic-pituitary-adrenal responses to short-duration high-intensity cycle exercise.
abstract: beta-Endorphin (beta-EP), adrenocorticotropin (ACTH), and cortisol plasma concentrations were examined before and after maximal exercise at four intensities [36, 55, 73, and 100% of maximal leg power (MLP)] by means of a computerized cycle ergometer. All intensities were greater than those eliciting peak O2 uptake for the individual subjects. Blood samples were collected at rest, immediately after exercise, and at 5 and 15 min postexercise. Significant (P less than 0.05) increases were observed at 36% MLP for beta-EP and ACTH immediately after exercise and at 5 and 15 min postexercise. Plasma cortisol increased at 36% MLP at 15 min postexercise. Blood lactate significantly increased at all postexercise collection points for exercise intensities of 36, 55, and 73% MLP and at 5 min postexercise for 100% MLP. beta-EP concentrations at 36% MLP were significantly correlated (r = 0.75) with capillary density (mm-2), and cortisol concentrations at 36% MLP were significantly correlated (r = 0.89) with percentage of type II muscle fibers. No other significant relationships were observed. These data show that brief, high-intensity exercise up to maximal power production results in a nonlinear response pattern in peripheral blood hormone concentrations. Furthermore, blood lactate levels do not appear to be related to hypothalamic-pituitary-adrenal hormone plasma concentrations at high exercise intensities.
authors.affiliation: Exercise Physiology Division, US Army Research Institute of Environmental Medicine, Natick 01760-5007.
authors.forename: W J
authors.initials: WJ
authors.lastname: Kraemer
authors.forename: J F
authors.initials: JF
authors.lastname: Patton
authors.forename: H G
authors.initials: HG
authors.lastname: Knuttgen
authors.forename: L J
authors.initials: LJ
authors.lastname: Marchitelli
authors.forename: C
authors.initials: C
authors.lastname: Cruthirds
authors.forename: A
authors.initials: A
authors.lastname: Damokosh
authors.forename: E
authors.initials: E
authors.lastname: Harman
authors.forename: P
authors.initials: P
authors.lastname: Frykman
authors.forename: J E
authors.initials: JE
authors.lastname: Dziados
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D001642:Bicycling; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology*; D007773:Lactates / Q000097:blood; D008297:Male; D005082:Physical Exertion; D010913:Pituitary-Adrenal System / Q000502:physiology*; D010953:Plasma Volume; D013997:Time Factors; D001615:beta-Endorphin / Q000097:blood
chemical_list: D007773:Lactates; D001615:beta-Endorphin; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone