Relative Energy Deficiency in Sport (RED-S) and factors for runners to be aware of
Having a regular menstrual cycle can be used to indicate that the body is in a happy, healthy state, and not subject to excess stress meaning the body is able to carry out all its functions appropriately as well as day to day activities and exercise. As an athlete this is a key indicator that the body is ready to train and improve performance from that training.
Disruption of this process is often a result of a number of things combined, collectively causing a reduction or absence in the release of sex hormones from the hypothalamic pituitary axis. Some irregularities can include anovulation (no ovulation) or changes in length of the cycle (shortening or increasing) or your period stopping altogether (known as hypothalamic amenorrhea)4,15.
Lack of energy availability
The major cause of menstrual cycle irregularities (particularly amongst runners) is due to a lack of energy availability, so not enough energy is being put into the body in comparison to the amount that is being used up. When the body does not have enough energy, it tries to conserve as much as possible, which means the menstrual cycle happens less frequently or not at all.
The female athlete triad
Consequently, there is a lack of oestrogen within the body, impacting upon bone health. This triad of consequences is known as the female athlete triad, more recently scientists have depicted the term Relative Energy Deficiency in Sport (RED-S) to encompass the female athlete triad, as there is now a wider understanding that low energy availability can also influence other systems of the body such as the digestive system, immune function, hormonal function and musculoskeletal health.
You can listen to co-host and marathon runner Jess Piasecki’s story of how she was affected by RED-S and the work she does in this area in Series 1, Episode 5 of the Female Athlete Podcast.
However, energy is not the sole influencer of menstrual cycle regularity, other causes have been reported, such as sleep disturbances, lifestyle stress and alterations in circadian timing systems16.
Other causes and symptoms
Psychological stress has frequently been associated with alterations to menstrual cycle duration and the number and severity of symptoms17,18; which has been illustrated in research by the increase in the prevalence of amenorrhea (the absence of periods) during wartime19,20. Recent research has reported that students under a high amount of perceived stress were four times more likely to be amenorrhoeic21. Furthermore, women with stressful jobs were twice as likely to experience a decreased cycle length22, often as a consequence of decreased follicular phase length, with little variation in the length of the luteal phase23. Women should definitely bear this in mind as we try to muddle our way through the stressful environments that the current pandemic brings on a daily basis.
Up to 90% of women of a reproductive age also experience menstrual cycle symptoms24, and severe symptoms have consistently been shown to affect quality of life25, 26 as well as negatively impacting exercise performance7, 27. Premenstrual symptoms are positively associated with poor diet, lack of exercise and insufficient sleep quantity and quality 28, 29, as well as increased alcohol intake30.
A recent study evaluating symptoms in exercising women found the most common symptoms include mood changes, fatigue, menstrual cramps, lower back pain and cravings31. For more information about menstrual cycle symptoms, understanding why we get them and how to help ease them, head to Series 1, Episode 3 of the Female Athlete Podcast.
In previous episodes we’ve spoken to a variety of guests including sports scientists, doctors, breast health experts, athletes and women suffering with menstrual dysfunctions such as endometriosis and premenstrual dysphoric disorder (PMDD). We’ve also interviewed real women about the impact of long-term oral contraceptive pill use on their bodies and personal experiences of female puberty, menopause and peri-menopause.
1. Chen, F.P., K.C. Wang, and J.D. Huang, Effect of estrogen on the activity and growth of human osteoclasts in vitro. Taiwan J Obstet Gynecol, 2009. 48(4): p. 350-5. 2. Iorga, A., et al., The protective role of estrogen and estrogen receptors in cardiovascular disease and the controversial use of estrogen therapy. Biol Sex Differ, 2017. 8(1): p. 33. 3. Vincent, K. and I. Tracey, Hormones and their Interaction with the Pain Experience. Rev Pain, 2008. 2(2): p. 20-4. 4. Bae, J., S. Park, and J.W. Kwon, Factors associated with menstrual cycle irregularity and menopause. BMC Womens Health, 2018. 18(1): p. 36. 5. Mumford, S.L., et al., The utility of menstrual cycle length as an indicator of cumulative hormonal exposure. J Clin Endocrinol Metab, 2012. 97(10): p. E1871-9. 6. Martin, D., et al., Period Prevalence and Perceived Side Effects of Hormonal Contraceptive Use and the Menstrual Cycle in Elite Athletes. Int J Sports Physiol Perform, 2017: p. 1-22. 7. Findlay, R.J., et al., How the menstrual cycle and menstruation affect sporting performance: experiences and perceptions of elite female rugby players. Br J Sports Med, 2020. 8. Bruinvels, G., et al., The Prevalence and Impact of Heavy Menstrual Bleeding (Menorrhagia) in Elite and Non-Elite Athletes. PLoS One, 2016. 11(2): p. e0149881. 9. Pallavi, L.C., U.J. D Souza, and G. Shivaprakash, Assessment of Musculoskeletal Strength and Levels of Fatigue during Different Phases of Menstrual Cycle in Young Adults. J Clin Diagn Res, 2017. 11(2): p. CC11-CC13. 10. Herzberg, S.D., et al., The Effect of Menstrual Cycle and Contraceptives on ACL Injuries and Laxity: A Systematic Review and Meta-analysis. Orthop J Sports Med, 2017. 5(7): p. 2325967117718781. 11. Chidi-Ogbolu, N. and K. Baar, Effect of Estrogen on Musculoskeletal Performance and Injury Risk. Front Physiol, 2018. 9: p. 1834. 12. Tornberg, Å., et al., Reduced Neuromuscular Performance in Amenorrheic Elite Endurance Athletes. Med Sci Sports Exerc, 2017. 49(12): p. 2478-2485. 13. Sung, E., et al., Effects of follicular versus luteal phase-based strength training in young women. Springerplus, 2014. 3: p. 668. 14. McNulty, K.L., et al., The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis. Sports Med, 2020. 50(10): p. 1813-1827. 15. Kato, I., et al., Epidemiologic correlates with menstrual cycle length in middle aged women. Eur J Epidemiol, 1999. 15(9): p. 809-14. 16. Lateef, O.M. and M.O. Akintubosun, Sleep and Reproductive Health. J Circadian Rhythms, 2020. 18: p. 1. 17. Nagma, S., et al., To evaluate the effect of perceived stress on menstrual function. J Clin Diagn Res, 2015. 9(3): p. QC01-3. 18. Palm-Fischbacher, S. and U. Ehlert, Dispositional resilience as a moderator of the relationship between chronic stress and irregular menstrual cycle. J Psychosom Obstet Gynaecol, 2014. 35(2): p. 42-50. 19. DREW, F.L., The epidemiology of secondary amenorrhea. J Chronic Dis, 1961. 14: p. 396-407. 20. Barsom, S.H., et al., Association between psychological stress and menstrual cycle characteristics in perimenopausal women. Womens Health Issues, 2004. 14(6): p. 235-41. 21. Rafique, N. and M.H. Al-Sheikh, Prevalence of menstrual problems and their association with psychological stress in young female students studying health sciences. Saudi Med J, 2018. 39(1): p. 67-73. 22. Fenster, L., et al., Psychological stress in the workplace and menstrual function. Am J Epidemiol, 1999. 149(2): p. 127-34. 23. McIntosh, J.E., et al., Predicting the luteinizing hormone surge: relationship between the duration of the follicular and luteal phases and the length of the human menstrual cycle. Fertil Steril, 1980. 34(2): p. 125-30. 24. Halbreich, U., The etiology, biology, and evolving pathology of premenstrual syndromes. Psychoneuroendocrinology, 2003. 28 Suppl 3: p. 55-99. 25. Choi, D., et al., The impact of premenstrual symptoms on activities of daily life in Korean women. J Psychosom Obstet Gynaecol, 2010. 31(1): p. 10-5. 26. Kahyaoglu Sut, H. and E. Mestogullari, Effect of Premenstrual Syndrome on Work-Related Quality of Life in Turkish Nurses. Saf Health Work, 2016. 7(1): p. 78-82. 27. Chantler, I., D. Mitchell, and A. Fuller, Diclofenac potassium attenuates dysmenorrhea and restores exercise performance in women with primary dysmenorrhea. J Pain, 2009. 10(2): p. 191-200. 28. Rad, M., M.T. Sabzevary, and Z.M. Dehnavi, Factors associated with premenstrual syndrome in Female High School Students. J Educ Health Promot, 2018. 7: p. 64. 29. Cheng, S.H., et al., Factors associated with premenstrual syndrome – a survey of new female university students. Kaohsiung J Med Sci, 2013. 29(2): p. 100-5. 30. Fernández, M.D.M., et al., Premenstrual syndrome and alcohol consumption: a systematic review and meta-analysis. BMJ Open, 2018. 8(3): p. e019490. 31. Bruinvels, G., et al., Prevalence and frequency of menstrual cycle symptoms are associated with women’s availability to train and compete: a study of 6812 exercising women recruited using the Strava exercise app. British Journal of Sports Medicine, 2020.