Examining the role of oral contraceptive users as an experimental and/or control group in athletic performance studies.

Background: This study was conducted to examine the effect of oral contraceptives on endogenous reproductive hormone levels in order to assess the suitability of oral contraceptive users as experimental and/or control groups in human performance studies.

Study Design: Ninety-five females who were taking a variety of oral contraceptives (2 types and 11 brands) were recruited. A single blood sample was analysed for endogenous concentrations of oestradiol and progesterone.