Oral contraception but not menstrual cycle phase is associated with increased free cortisol levels and low hypothalamo-pituitary-adrenal axis reactivity

Background: In females, estrogen is a potential modulator of cortisol response to stressors. The aim of this study was to determine the influence of menstrual cycle phase, oral contraception (OC) use and exercise training on hypothalamo-pituitary-adrenal (HPA) axis activity and reactivity after physical stress. Aim: We investigated the effects of the menstrual cycle and OC use on exhaustive exercise-induced changes in free salivary cortisol concentrations and free urinary cortisol/cortisone excretion in healthy young women. Materials and subjects: Twenty-eight women were allocated to an untrained group (no.=16) or a trained group (no.=12), depending on their physical training background. The untrained group was composed of nine OC users (UNT-OC + ) and seven eumenorrheic women (UNT-OC − ) tested in the follicular and luteal phases, while the trained group was entirely composed of OC + subjects (T-OC + ). Methods: Three laboratory sessions were conducted in a randomised order: a prolonged exercise test, a short-term exercise test, and a control session. For each session, urine and saliva specimens were collected at rest (09: 00 h) and then, 30, 60 and 90 min later. Results: Estradiol fluctuation during the menstrual cycle phase did not alter free cortisol baseline values and responses to exercise. OC use was associated with increased free resting salivary concentrations and urinary cortisol excretion with blunted salivary cortisol response to prolonged exercise stimulation. No training effect was noted. Conclusions: OC but not menstrual cycle phase is associated with increased free cortisol levels and low HPA axis reactivity.