ISSN:
1439-6327
Keywords:
Key words Growth hormone
;
Oral contraceptives
;
Estradiol
;
Progesterone
;
Intermittent and continuous exercise
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
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, V˙O 2max for 20 min) and intermittent exercise (〉80% V˙O 2max) 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 β-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␣β-estradiol and exogenous ethinyl estradiol). It is suggested that training programs for female athletes could be timed in accordance with the menstrual cycle to benefit from an increased GH response to exercise during phases of OC use or the luteal phase of women not on OC therapy.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004210050468
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