Title

Adrenal and autonomic hormone responses to aerobic training and heat acclimation: Influence of oral and injectable contraceptives

Date of Completion

January 2000

Keywords

Health Sciences, Obstetrics and Gynecology|Health Sciences, Pharmacology|Health Sciences, Recreation

Degree

Ph.D.

Abstract

The present study examined the stress hormone and fluid-regulating hormone responses of women who ingested oral contraceptives (ORAL, n = 15), women who received injections of steroid contraceptives (DEPO, n = 7), and women who were eumenorrheic and ovulatory (EU-OV n = 14). Participants performed exercise heat tolerance (EHT) tests during designated menses, before and after eight weeks of physical training and heat acclimation (PTHA). The PTHA program involved three days of exercise-heat exposure in an environmental chamber and three days of outdoor group running, calisthenics, sit-ups and push-ups. The results of this research demonstrated that changes in physical and exercise-related characteristics were similar among groups (p > 0.05) from pre- to post-PTHA. At rest, plasma epinephrine levels were higher in ORAL (p < 0.03) after PTHA, and were significantly different only in EU-OV from pre- to post-PTHA (p < 0.05). Resting plasma norepinephrine levels were significantly lower after PTHA (p < 0.001) and from pre- to post-PTHA (p < 0.05), and resting plasma cortisol levels were significantly higher both before and after PTHA (p < 0.001) in ORAL. Resting aldosterone levels were higher before PTHA (p = 0.008) in ORAL, while they significantly decreased (p < 0.03) and increased (p = 0.007) in ORAL and DEPO, respectively, from pre- to post-PTHA. The percent change in plasma norepinephrine levels was significantly different in EU-OV vs. ORAL, while the percent change in plasma aldosterone levels was different in DEPO vs. ORAL (p < 0.02). With exercise, plasma epinephrine levels increased in EU-OV (p < 0.02) after PTHA. Plasma norepinephrine levels increased with exercise both before and after PTHA in all groups (p < 0.003). With exercise, plasma cortisol levels were changed in ORAL and DEPO (p < 0.002) with a significant percent change in DEPO (p = 0.005) before PTHA. After PTHA plasma cortisol levels increased in EU-OV with exercise (p < 0.02), while the percent changes in ORAL and EU-OV were significantly different from pre- to post-PTHA (p < 0.05). It was concluded that the overall effects of PTHA on stress hormone and fluid-regulating hormone responses were similar among groups, but that differences between the two contraceptive groups and the eumenorrheic and ovulatory group were related to the effects of estrogen and progestin, while differences between the two contraceptive groups were attributed to the effects of estrogen. ^