Stress Hormone Responses Following Heat Acclimation And Physical Training In Young Women Using Different Contraceptives

PURPOSE: With the current prevalence of female contraceptive use as well as increasing trends in physical activity among women, which often occurs in hot environments, it is important to understand the mitigating effects of different forms and formulations of reversible contraceptives. METHODS: This investigation evaluated the effects of oral (ORAL, n = 15), injectable Depo-Provera (DEPO, n = 7), and no hormonal contraception (EU-OV, n = 14, control) use on circulating levels of epinephrine (EPI), norepinephrine (NOREPI), and cortisol (CORT) in healthy, inactive women (age 21 ± 3 yr) before and after a standardized exercise-heat tolerance test (EHT), performed before and after an 8 week program (HAPT) of indoor heat acclimation (90 min/day, 3 days/wk) and outdoor physical training (3 days/wk). RESULTS: The standardized physical fitness and EHT tests (36.5oC, 37% rh) conducted after HAPT demonstrated that the three groups successfully (p < 0.05) acclimated to heat (i.e., rectal temperature, heart rate) and improved muscular endurance (i.e., sit-ups, push-ups, 4.6-km run time) and body composition parameters. Menstrual cycle length and phase characteristics, ovulation, and reproductive hormone levels were not changed (p > 0.05) in the EU-OV group following HAPT. There were no differences (p > 0.05) in EPI, in any groups, in response to the EHT test pre-HAPT, but EPI was increased (p < 0.02) with exercise in EU-OV subjects post-HAPT. In contrast, NOREPI was increased (p < 0.05) with exercise, both pre- and post-HAPT, in all groups. CORT decreased (p < 0.05) in ORAL and increased (p < 0.05) in DEPO in response to exercise pre-HAPT but did not change in EU-OV. Following HAPT, CORT increased (p < 0.02) from pre- to post-EHT in the EU-OV group only. There were no pre- to post-EHT differences among the groups in the % change in EPI and NOREPI, from pre- to post- HAPT, whereas this % change in CORT in both ORAL and EU-OV was increased (p < 0.05) pre- to post HAPT. CONCLUSION: In summary, the overall effects of EHT testing on these stress hormones, and in response to HAPT, were generally similar among the ORAL, DEPO and EU-OV groups. The differences that did exist between EU-OV and both ORAL and DEPO, and between ORAL and DEPO, were attributed to the different formulations of the contraceptives examined.