The recent Olympic Games in Tokyo were the most equal ever, with nearly 49% female athletes. This reflects the proportion of women who participate in physical activity and sport in the general population. Even so, there is a clear underrepresentation of female participants in sports medicine and exercise physiology research [Citation1–3]. Women have often been excluded from scientific studies due to researchers’ ignorance of the menstrual cycle. When women have been included, hormonal variations and/or women’s well-being during the menstrual cycle have seldom been considered [Citation4]. This also reflects how women’s diseases in general are given attention in health care. The menstrual cycle is still a neglected and taboo area in sports and society [Citation3,Citation5]. Female hormone related symptoms are often considered as a natural part of life and something women must accept even though effective treatment often is available.
Physiological impact
Serum levels of the female sex hormones oestradiol (E2) and progesterone (P4) vary significantly during the menstrual cycle. Although E2 and P4 have several proven physiological effects, they have not been studied in detail in sports and exercise [Citation4]. E2 has been described as an anabolic hormone, while P4 has been referred to have an anti-estrogenic effect [Citation6]. Our research group detected presence and varying levels of E2 (ERα and Erβ) and P4 receptors in skeletal muscle throughout the menstrual cycle [Citation7]. However, there is still conflicting results if and how the varying female sex hormones during the menstrual cycle affect training and performance [Citation8,Citation9].
Menstrual cycle related symptoms
Menstrual cycle related symptoms have been reported to affect physical training and perceived performance [Citation10]. Primary dysmenorrhoea (menstrual related pain) often leads to absence from planned training and perceived impaired performance [Citation10,Citation11]. Premenstrual symptoms (PMS) that are characterised by physical (e.g. bloating, breast tenderness, headache) and psychological (e.g. depression, irritability, fatigue) symptoms have also been reported to negatively influence training, performance, and well-being [Citation10]. Therefore, this also needs to be considered when planning and interpreting results from studies of the menstrual cycle.
Psychosocial impact
Few female athletes feel comfortable to talk to their coach about menstrual cycle related issues and they rarely consider the menstrual cycle when planning training or competition, even if they have pronounced symptoms of dysmenorrhoea or PMS [Citation5,Citation11,Citation12]. However, they are more willing to talk to a female coach. Still, female coaches are underrepresented in most sports. Athletes seem to turn to medical staff instead of the coach [Citation5]. Physiotherapists are the most common profession that athletes have access to. Therefore, knowledge about the menstrual cycle is important for physiotherapists working with female athletes.
In recent years, several sportswomen have openly spoken about menstruation in the media, which has contributed to curiosity, reduced taboos, and more research in the field. Adaptation of exercise in relation to the menstrual cycle has become a debated topic in sports as well as in the fitness industry. This is a positive development. However, a lot of advice, for example about periodized exercise based on the menstrual cycle, has spread even though the evidence is still weak [Citation13]. With the knowledge available today, no general recommendations on periodization can be given. Advice needs to be given on an individual level. Varying levels of motivation to exercise and psychological well-being might be just as important as physiological effects of the varying hormone levels [Citation14].
Methodological recommendations
Studies about the impact of the menstrual cycle on training and performance often have methodological weaknesses and small sample sizes. Methodological recommendations and criteria for menstrual cycle related studies have lately been developed [Citation4,Citation15]. These recommendations should be followed in high quality studies. Well-controlled studies with sufficient power are needed to be able to give female athletes and physical active women in general evidence-based advice and recommendations. The possible physiological impact of female sex hormones on training response as well as perceived effect of women’s menstrual cycle related symptoms and well-being must be considered. The social context in which the athlete operates, the dialogue with coaches and with the medical team is also important aspects. To plan and carry out menstrual cycle related studies with high quality, interprofessional research groups are needed that include expertise in exercise physiology, gynecological endocrinology, and behavioural medicine.
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No potential conflict of interest was reported by the author(s).
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References
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