Muscle and joint pain are a debilitating part of chronic illnesses like fibromyalgia, arthritis, and M.E., among others. Ridiculously ordinary activities can trigger muscle and joint strains and injuries in people with chronic illness, but have no effect on healthy individuals. I recently went to physiotherapy with neck and upper back pain. I could feel the ropey muscle spasm and trigger knots causing the pain, which just wasn’t resolving. My physiotherapist asked whether I had been taking any hormones, and I was surprised by the question, because it just so happened that I was. I decided to do some research, and what I found frustrated me. How was it that after years of seeing doctors and researching online, no one had explained the connection between the menstrual cycle and muscular pain to me? This is the beginning of a series on hormones and flare ups that I hope will make this information, buried in scientific journals, more widely available.

We know that, in general, women experience significantly more pain and injury than men, particularly mid-menstrual cycle, around the time of ovulation, when estrogen is high. One study found that the risk of muscle and tendon injury in women athletes is almost twice as high around ovulation than at other times in the menstrual cycle.[1] These injuries included “muscle ruptures, tears, strains, and cramps, as well as tendon injuries and ruptures.”[2] Other studies have shown that women experience more anterior (front) knee pain, ACL injuries (torn knee ligaments), and plantar fasciitis foot pain around ovulation.[3]

But why?

The surprising answer may lie in the impact of ovarian hormones like estrogen. During ovulation, when estrogen peaks, the elasticity of ligaments, tendons, and muscular tissue increases, heightening the risk of strain, pain, and injury.[4]

Estrogen & Your Monthly Cycle: Back to Health Class

Estrogen is a sex hormone most well-known for regulating the menstrual cycle, although it also has many other functions in the body too. Hormones enable communication between different parts of the body. When hormones are released, they work like keys that fit into receptors on cells, activating or deactivating specific functions.

Let’s go back to high school health class. Your menstrual cycle begins on the first day of your period. Once your period is over, the ovaries begin to produce eggs in small sacs called follicles. The first part of your period, called the follicular phase, lasts about two weeks on average. Estrogen is released from your ovaries, and this stimulates the lining of the uterus to thicken. Estrogen peaks at the end of the follicular phase, triggering a process that results in ovulation, when one mature egg bursts through its follicle.

During the second half of your cycle, called the luteal phase, which lasts about two weeks, estrogen levels are much lower. If the egg does not become fertilized, then this eventually triggers the uterine lining to shed, which is the beginning of your next period, and the start of a new cycle.

The bottom line – estrogen rises during the first half of your cycle, peaking prior to ovulation, and then falls in the second half of your cycle.

Estrogen, Muscles And Connective Tissue

But estrogen also plays an important role in other parts of the body, including connective tissue like muscles, ligaments, fascia, and tendons. The latest research shows that there are estrogen receptors on these connective tissues.[5] Rising or falling estrogen levels communicate messages to these tissues, triggering changes in their form and function.

During ovulation, when estrogen peaks, the elasticity of ligaments, tendons, and muscular tissue increases.[6] This is also true in pregnancy, when the elasticity of your connective tissues increase in order to expand and make space for a growing fetus.[7] When the connective tissue becomes more elastic, it makes joints like the knee, SI joint, and ankle unstable, increasing the risk for injury.[8]

In contrast, when estrogen levels are low, immediately before and during your period (late luteal and early follicular phase), connective tissues become stiffer and more rigid. In turn, joints are stabilized, reducing the risk for injury. Researchers suggest that some biomechanical pain may improve when estrogen is low and connective tissues are less elastic, stabilizing joints .[9] Women who take the pill appear to have fewer injuries, and more consistent pain levels because their hormones do not fluctuate to the same degree.[10]

Fascia, which is a network of connective tissue made mostly of collagen, encases muscles, organs, nerves, and blood vessels, holding them in place. We know that inflammation of the fascia surrounding muscle tissue may drive fibromyalgia pain,[11] and also, possibly, myofascial (muscle and fascial) pain in other chronic illnesses. Fascia also contains estrogen receptors.

When estrogen is high, the consistency of the fascial collagen changes, becoming more elastic, and stiffens when estrogen is low.[12] Researchers explain that “hormonal imbalance damages myfascial tissue, leading to drastic changes in its constitution in collagen and elastic fibers, and thus modifying its biomechanical properties.”[13] In other words, hormone imbalances may play a role in chronic pain in muscles and connective tissue. It is possible that imbalances in hormones like estrogen may contribute to myofascial pain and injury in women with fibromyalgia and other illnesses. More research is needed to determine the effect of hormone imbalances on myofascial pain.

But even if you do not have a hormone imbalance, the increased elasticity of your muscles and connective tissues mid-cycle can increase your flares.

Track Your Period To Reduce Your Strains, Pains, and Injuries

Tracking your period may help you to understand how your cycle impacts flares of muscle and joint pain, strain, and injury. Over the course of several months, you may notice that your bad knee, low back ache, foot pain, wrist pain and other overuse strains, which chronic illness amplifies, cluster around ovulation. If true, avoiding significant activities around this time, or pacing yourself more, could help to reduce pain related to strains, overuse, hypermobility, poor posture, and injury (biomechanical pain)..

A few days after you ovulate may be the perfect time for a physiotherapy (physical therapy) appointment or massage, to treat ovultion related flares. Since knowledge is power, the more you can learn about which variables most affect your pain and strain levels can put you in the driver’s seat for managing more effectively. Tracking your period and ovulation might be the first step.

There are many period tracker apps that can help you to log your cycle. To work out the length of your menstrual cycle, record the first day you start bleeding (first day of your period). This is day 1. The last day of your cycle is the day before your next period begins. Pinpointing ovulation is a bit harder. If your average menstrual cycle is 28 days, you ovulate around day 14. But this varies significantly from woman to woman and even cycle to cycle.

You can use an ovulation calculator like this one to roughly figure out when you ovulate, which is usually 14 days before your period begins. Recording body changes, like temperature, that fluctuate through the month, can be used to predict ovulation. Or, you can purchase ovulation predictor kits at the drugstore that include urine test sticks to pinpoint ovulation. Learning more about your body and how it works is an empowering step women can take to manage their health.

Works Cited

Fede, C. e. (2019). Sensitivity of fasciae to sex hormone levels. PLoS One , 14 (9).

Liptan, G. e. (2010). Fascia: a missing link in our understanding of the pathology of fibromyalgia. Journal of Bodywork Movement Therapy , 14 (one), 3 – 12.

Marcus, J. (2021, April 5). How tracking your period can lower your injury risk. Retrieved April 20, 2021, from Runners World: https://www.runnersworld.com/health-injuries/a35994126/period-tracker-for-runners/

Petrofsky, J. (2016, April). Influence of estrogen on the plantar fascia. Retrieved April 24, 2021, from Lower Extremity Review: https://lermagazine.com/article/influence-of-estrogen-on-the-plantar-fascia#.YIb71wXgmGI.mailto

[1] (Marcus, 2021)

[2] (Marcus, 2021)

[3] (Petrofsky, 2016)

[4] (Fede, 2019) (Petrofsky, 2016)

[5] (Fede, 2019)

[6] (Fede, 2019) (Petrofsky, 2016)

[7] (Fede, 2019)

[8] (Petrofsky, 2016)

[9] (Fede, 2019)

[10] (Petrofsky, 2016)

[11] (Liptan, 2010)