This post will provide a summary of the menstrual cycle, the role of the key hormones and our top tips for understanding your bodies’ responses & staying active throughout.
There is currently no known clinical evidence to say that women experiencing a normal menstrual cycle can not exercise and train optimally at any stage of their cycle. However, optimal performance can be better supported with a better understanding of an individual’s responses to different stages of the menstrual cycle. First of all, let’s discuss the menstrual cycle... The menstrual cycle is driven by fluctuations in hormones: luteinising hormone (LH) & follicle-stimulating hormone (FSH). These hormones are secreted by the pituitary gland and stimulate the secretion of progesterone and oestrogen from the ovaries. The menstrual cycle is typically categorised into 4 phases based on hormonal profiles. The phases are divided as follicular (1 and 2) and luteal (3 and 4) phases
Phases 1 & 2 make up the follicular phase: Phase 1 is menstruation (period): the shedding of blood & endometrium (lining of the uterus) through the cervix & vagina. Phase 2 occurs as menstruation is ending. At this stage, one of the follicles (fluid filled sacs containing eggs) within the ovaries becomes the dominant follicle & prepares to be released in ovulation. This stage sees an increase in the hormone oestrogen, when levels of oestrogen peak this signals an increase in luteinising hormone & the subsequent release of an egg (ovulation). Phase 3 marks the start of the luteal phase. Luteinising hormone is active, & both progesterone & oestrogen levels are high. The corpus luteum (a mass of cells responsible for making progesterone to support early pregnancy) forms where the egg was released from. The role of progesterone (under the influence of oestrogen) is to ripen the lining of the womb ready to receive a fertilised egg. If the egg is not fertilised, the cycle progresses to Phase 4: the pre-menstrual phase. Here, the corpus luteum shrivels, progesterone & oestrogen levels fall & menstruation occurs again. What does this have to do with exercise? Hormones circulate within our blood, therefore they travel all over our bodies & effect a vast range of functions including the way muscles & connective tissue behave. This article focuses on oestrogen & its relationship with connective tissue. What is connective tissue?
Connective tissue is our internal scaffolding support system: it binds structures together, provides a framework and support for organs & structures & is found throughout our whole body. Collagens form the main structural component of connective tissue & they resist tensile (stretching) forces. Tendons (the connections between muscle & bone) are made up of 60-80% collagen & their job is to transmit muscle forces & withstand tension during muscle contractions. Ligaments provide support for joints & are made up of 70% collagen. Fascia is the 3D matrix of structural support which both separates & connects our organs & body parts internally, allowing force transmission from one area to another. Oestrogen & connective tissue Oestrogen receptors are present in all musculoskeletal connective tissue including bone, muscles, ligaments and tendons. There are oestrogen & progesterone receptors within the skeletal muscles & connective tissue of the pelvic floor & within the smooth muscle cells of the vagina. Oestrogen has a known positive effect on bone density as well as muscle & tendon function. Oestrogen also has an important role in ligament laxity via decreased connective tissue stiffness. So why does this matter? By improving the understanding of what happens throughout a normal cycle & how an individual’s body responds to the normal fluctuations of hormones that occur every month, we can listen and tune in to individual responses so we are able to continue exercising / training / functioning optimally. Each individual’s response is unique, this article hopes to help you better understand why you may find a fluctuation in your exercise experience throughout your menstrual cycle to then guide you to plan your exercise so you have maximal enjoyment & ultimately gain most benefit from your individual regime. Commonly, individuals complain of an exacerbation of niggling injuries or a feeling of perceived weakness at stages of the cycle when oestrogen levels are high. There have been many associations in clinical research between female hormone fluctuations & ACL (anterior cruciate ligament) injuries. We therefore often recommend individuals focus on targeting specific asymmetries or imbalances during these phases. Commonly we work on pelvic floor, core & posterior chain activating exercises to counterbalance typical female muscle dominances & weaknesses. We know that during these phases of peak oestrogen we have an opportunity to capitalise on the anabolic (building) function of oestrogen within muscle tissue therefore we should focus on targeted strengthening regimes. We also know that there can be some increase in ligament laxity, so a respect for this must be applied with the type of training that is completed with some individuals. Take home message Whilst there is no clear evidence or clinical need to make blanket recommendations about exercise modifications during the menstrual cycle, a clear understanding of the fluctuations of hormones and their role on the musculoskeletal system allows us to make individual recommendations for women who exercise. If you don't already, consider tracking your menstrual cycle & any symptoms you might have so you can determine how best to exercise throughout your cycle.
Book an appointment to learn how we can support you & your individual exercise goals throughout each phase of your menstrual cycle.