The effect of intensive physical training on hormonal regulation and the menstrual cycle in women: metabolic, functional and clinical implications

Abstract

The menstrual cycle is one of the most neuroendocrine controlled processes closely involved with the body’s response to exercise and metabolism regulation. Menstrual problems and hypothalamic-pituitary-gonadal (HPG) axis dysfunction are linked to increased exercise intensity in women. The purpose of this study was to examine the impact of physical exercise on hormone control in women and secondary alterations in the menstrual cycle, with particular emphasis on molecular mechanisms, metabolic repercussions, and clinical implications. A literature review was conducted covering experimental and observational studies on physically active women,including intervention studies (HIIT), population-based studies, analyses of high-intensity training such as military training, and data on hormonal contraception use. Hepcidin concentrations are elevated and iron bioavailability is reduced when the HPA axis is activated and inflammatory mediators are increased in response to exercise. Overt training load suppress GnRH, thus reduce LH, FSH and sex steroids, specifically in the low energy availability state. Among population-based studies, up to 86% women experienced menstrual disorders when subjected to heavy training load. Hormonal contraceptives may prevent variability in the hormonal milieu, but they may cover a HPG axis dysfunction. The menstrual cycle may be less susceptible to training load than to the energetic status and the neuroendocrine response. Amenorrhoea and other menstrual dysfunction are indicators of clinical importance for metabolic abnormality, and there is the need for a tailored training prescription and treatment.