Growth hormone responses to continuous and intermittent exercise in females under oral contraceptive therapy

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Authors
  1. Bernades, R.P.
  2. Radomski, M.W.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN)
Abstract
In this study we investigated the effect of oral contraceptive (OC) use (OCU) and non-use (OCNU) on growth hormone (GH) responses to exercise in the same females (n = 7, age 22-31 years) during the normal course of OC therapy. Continuous (60% maximum oxygen consumption,, VO2mar for 20 min) and intermittent exercise (>80% VO2max) protocols of equal total duration, and similar external work were performed during phases of OCNU (days 3-5 of the menstrual cycle) and OCU (days 7-11). Levels of GH, lactate, 17 beta-estradiol, and progesterone were measured. Lactate responses were significantly greater (P < 0.05) during intermittent than continuous exercise, with no effect of OC use. However, significantly greater GH responses were found during the OCU phase than the OCNU phase in both the continuous (+94%) and intermittent (+250%) exercise protocols. Estradiol and progesterone levels increased significantly during exercise in all four conditions. We suggest that the increased GH responses observed during the OCU-phase were potentiated by the elevated levels levels of total estrogens (endogenous 17 beta-estradiol and exogenous ethinyl estradiol). TRUNCATED
Keywords
Growth hormones;Oral contraceptives;Estradiol;Progesterone;Intermittent and continuous exercise
Report Number
DCIEM-97-P-15 — Paper; Reprint
Date of publication
13 Jul 1998
Number of Pages
9
Reprinted from
Eur J Appl Physiol, vol 79, 1998, p 24-29
DSTKIM No
CA010589
CANDIS No
515443
Format(s):
Hardcopy;Document Image stored on Optical Disk

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