The Menstrual Cycle: What Coaches Need to Know

Background

Over recent decades, there has been a remarkable surge in female participation across all levels of sport and exercise, driven by growing interest, investment, and visibility in Women’s sport (McNulty et al., 2024). Despite this, Women are still underrepresented in sport and exercise science research (Cowley et al., 2021). Consequently, performance, training, and recovery-focused research specific to female athletes remains limited, and much of the current understanding and guidance in these areas continues to come from studies on male athletes (Emmonds et al., 2019). Applying male based research directly to female athletes overlooks important sex differences in anatomy, physiology, and hormones (Ansdell et al., 2022) and does not account for individual variation among Women. One key factor for coaches working within Women’s Rugby, is the potential influence of ovarian hormones, particularly their fluctuations across the menstrual cycle, on exercise performance, training adaptation, and recovery.

The Menstrual Cycle

The menstrual cycle refers to the recurring fluctuations in ovarian hormones and structural changes to the endometrial lining that occur approximately monthly in females of reproductive age, from menarche to menopause, with the primary biological function of enabling reproduction (Davis & Hackney, 2017). The length of the menstrual cycle refers to the number of days from the first day of bleeding in the current cycle to the day before the onset of bleeding in the following cycle. While an average menstrual cycle is often cited as 28 days in length, typical menstrual cycle lengths can range from 21 to 35 days (Davis & Hackney, 2017). The menstrual cycle is regulated by hormones released by the hypothalamus (gonadotropin releasing hormone, GnRH), pituitary gland (luteinising hormone [LH] and follicle stimulating hormone [FSH]) and the ovaries (oestrogen and progesterone; Davis & Hackney, 2017). The changes in these hormone concentrations across the menstrual cycle are often used to differentiate between menstrual cycle phases. Specifically, research suggests a four-phase model that reflects key variations in oestrogen and progesterone concentrations (Elliott-Sale et al., 2021): 

1. Phase one (early follicular phase), indicted by the onset of bleeding (commonly referred to as the period) until approximately day five of the cycle, categorised by the lowest oestrogen and progesterone concentrations
2. Phase two (the late follicular phase), occurring until approximately 14 to 16 hours prior to ovulation, classified by peaking oestrogen and low progesterone concentrations
3. Phase three (the ovulatory phase), indicated by a positive urinary ovulation prediction test and lasting approximately 24 to 36 hr, categorised by medium oestrogen concentration and low progesterone concentrations
4. Phase four (the mid-luteal phase), occurring at approximately seven days after ovulation, classified by high oestrogen and the highest progesterone concentrations.

This four-phase framework helps researchers and coaches examine how ovarian hormone patterns may affect exercise performance, training adaptation, and recovery following exercise. It is important to note however, that other timepoints outside these four phases, such as the late luteal (premenstrual) phase are also important to consider for female athletes and those who work with them, such as coaches (Bruinvels et al., 2022).