The Effect of Menstrual Cycle and Oral Contraceptive Pill Phase on Aspects of Exercise Physiology

Participation Requirements

• Sex:

  FEMALE

• Eligible Ages:

  18 to 40

Participation Criteria

Inclusion Criteria:

* Cis gender women
* 18-40 years of age
* Body mass index ≥ 19.5 and ≤ 25 kg∙-2; an exception can be made in the case of some athletes where they have a higher BMI, but are considered more lean/muscular than fat.
* Must be defined as healthy, i.e., not having any medical condition or taking any medication known to affect any of the outcome measures. Examples include diagnosed hyperandrogenism from polycystic ovary syndrome, congenital adrenal hyperplasia, or other differences in sexual development.
* Cannot smoke
* Considered to be physically active. Participants training status will be classified using the criteria outlined by McKay et al. (In press). For this study, participants must be Tier 2 athletes or above (Table 1). In addition, participants will be considered on the basis of relative maximal oxygen consumption (Decroix et al., 2016); needing to be Performance Level 2 or above (Table 2). Participants must provide details on gravidity and parity and must not be in the postpartum period (i.e., within 12 months of childbirth), currently breastfeeding, or pregnant. Participants will be recruited based on their endogenous hormonal profile (i.e., eumenorrheic or OCP users) and these profiles (including inclusion/exclusion criteria) are described below in detail.

Group Specific Inclusion Criteria:

Group 1. Eumenorrheic \[EUM\]

* Must have menstrual cycle lengths ≥ 21 days and ≤ 35 days resulting in 9 or more consecutive periods per year
* Must provide evidence of a luteinising hormone (LH) surge
* Must demonstrate the required hormonal profile as defined in Table 3
* Cannot have used any type of hormonal contraceptives (HC) for a minimum of 3 months, but ideally 6 months, prior to enrolment

Group 2. Oral contraceptive pill \[OCP\] users

* Must have been taking their OCP ≥ 3 months prior to recruitment
* Must be taking a combined, monophasic, second generation OCP (see Table 4 for permitted brands)
* Must demonstrate the correct hormonal profile as defined in Table 5

Exclusion Criteria:

-Cannot speak, read and understand English