How the Menstrual Cycle Affects Female Athlete Performance: Why This Topic Is Important

Personal Connection

In the past 20 years, woman's sports and female athletics has skyrocketed - the industry has only been growing, and all across the world more and more girls get to play sports! This is truly amazing and is a testament to female empowerment, as now young girls like me get to watch our athletic role models on TV. I've played club soccer since I was 5 years old, which allowed me to experience the competitive but exciting environment that girls youth soccer has created in the Bay Area.

For the past year, though, I’ve found myself struggling both physically and emotionally. I’ve been falling in and out of love with a sport that’s always been such an important part of my life. While I don’t have concrete data to prove it, I feel a part of this shift comes from going through puberty and dealing with hormone imbalances. On top of that, there is a lot of pressure that comes with being a young athlete playing competitive club sports wether it be from coaches, parents, or even team mates. My mom has always told me that one shouldn't play during menstruation, but club coaches aren't that understanding or cognizant of this factor when it comes to young female athletes. It's struggles like these that have gotten me more curious about the affect of the menstrual cycle on a females ability to exercise and perform well.

Background: The Menstrual Cycle

Diagram of uterus during 4 phases of cycle

Graph of hormone activity during cycle

Before we can dive into the different studies, it's very important to actually understand the

phases of a woman's menstrual cycle. The menstrual cycle is the monthly process that prepares the body for a potential pregnancy, and it happens in four main phases: the menstrual phase, the follicular phase, ovulation, and the luteal phase.

During the menstrual phase, the uterine lining sheds, which is why bleeding occurs; this phase usually lasts about 3–5 days, and hormone levels (especially estrogen and progesterone) are at their lowest. Technically the menstrual phase is also part of follicular phase, but really after the period is when the follicular phase begins. In this stage, FSH (follicle-stimulating hormone) is released by the pituitary (a part of your brain that regulates your bodies hormones) to help ovarian follicles mature, estrogen levels rise, and the uterine lining starts to thicken again in preparation for a possible pregnancy.

Next is ovulation, a short 24-hour window when a mature egg is released from the ovary into the fallopian tube. This is the only time in the cycle when pregnancy is possible, and it’s triggered by a surge of luteinizing hormone (LH).

After ovulation, the luteal phase begins. The corpus luteum forms and releases progesterone, which stabilizes and thickens the uterine lining. If pregnancy doesn’t occur, hormone levels drop, the corpus luteum breaks down, and the cycle starts over with menstruation.

This was just a summary, and if you're still confused (I was!), this youtube video is very helpful as it goes through each phase with a 3-D diagram and alongside it discusses the patterns of the hormones. Also, it's important to recognize that all woman have slightly different cycles, and slightly different balanced hormones - every woman experiences menstruation and its side effects differently. Now that you have the necessary background, we can move on to examining the different research papers.

It is known that while menstruating most women do feel symptoms like fatigue, nausea, and mood changes, and that this does affect their physical performance. While multiple studies have been done to identify correlations, the exact science is still unclear.

Female Soccer Players & Injuries

The paper that I'm reviewing is titled:"Injury Incidence, Severity, and Type Across the Menstrual Cycle in Female Footballers: A Prospective Three Season Cohort Study", authored by Ally Barlow, Joanna M. Blodgett, and others from the University of Bath, UK. It goes over the three year study they conducted with professional female footballers (soccer players), and their findings from it. Their goal was to assess the influence of menstrual cycle phases on incidence, severity, and type of injury.

In the study, they worked with 26 soccer players and prospectively tracked 593 cycles over the course of 3 professional seasons (13,390 days). Prior to the study, each footballer was examined and declared eligible for the study, the biggest criteria being that they had to be off any hormone medications, and eumenorrheic (have a "normal" and regular cycle). Their period's were tracked through an app and an algorithm was applied to distinguish the different phases based on the time between menstruation. They broke up the cycle into four phases which they defined as:

1. Menstruation phase: actively having your period

2. Remainder of the estimated follicular phase (until peak ovulation)

3. Majority of luteal phase

4. Pre-menstruation, the 5 days before next period

Before we go into their findings, it important to understand how they measured data. They used three main values, person-days, IIR, and IIRR to explain injury risk and compare them between phases. Person-days was their unit to measure time, this was generated by totaling the number of days of training and game days for each player - all of the data was simplified to be shown over 1000 person-days rather than 13,390 because it's easier to see the percentages. Next, IIR stands for Injury Incidence Rates. This is the rate of injury per phase, which helps you understand the injury risk during that phase as well. IIRR stands for injury incidence rate ratios, and this value comes from comparing the IIR from different phases to each other with a percentage. To use the real data as an example, per 1000 person-days, the IIR in phase 4 was 14, and the IIR in phase 3 was 10.9. Now, to calculate the IIRR you divide them to get the IIRR: roughly 1.284. This means that injury is 28.4% more likely to occur in phase 4 than 3.

Table of data collected from study

Now that you understand the units and phases they used to collect data, we can move on to their findings. There was a total of 74 eligible injuries across all players. The most common type was a muscle injury, followed by joint & ligament, fracture & bone stress, and lastly central/peripheral nervous system. The rest of their findings were somewhat scattered, so here is a direct summary (pulled from data table above):

1. Injury rate was least common in phase 1 and kept increasing as cycle continued, with 4 having the highest IIR value (14 injuries per 1000 person-days).

2. IIRR value showed that injuries occurred 230% more in phase 4 than in phase 1.

3. Muscle injuries were more common in phases 3 and 4 then in 1 and 2.

4. Compare to phase 1, muscle injuries were 6.07 times higher in phase 4.

5. IIR values were similar for joint & ligament injuries across all phases.

6. No ACL tears were recorded.

These were all the connections they found within data, but they argued that the only significant ones were:

• Total injuries were more common in phase 4 (pre-menstrual) than the other phases.

• Muscle injury was the most common type of injury and also most common in phase 4.

• Majority of the 74 injuries were non-contact.

Researchers suggest several explanations for these findings.

First, during the second half of the menstrual cycle, progesterone levels are higher. Progesterone has been linked to increased breakdown of amino acids, which are the building blocks of muscle. Because skeletal muscle stores many of these amino acids, breaking them down more quickly can reduce the body’s ability to rebuild and strengthen muscle. Over time, especially with repeated training and physical stress, this may increase the risk of muscle injury. However, the researchers note that this explanation should be viewed cautiously, since progesterone levels were not directly measured in the study (1, 2).

Second, in the premenstrual phase (phase 4), hormone levels - especially estrogen and progesterone - drop rapidly. This hormonal withdrawal activates inflammatory processes in the body. During this time, the body increases production of inflammatory substances such as prostaglandins, which are necessary for shedding the uterine lining. This increase in inflammation is not limited to the uterus; studies show that inflammation markers rise throughout the body during this phase. Higher inflammation can slow recovery, weaken tissue integrity, and create a state of physical overload, all of which may raise the risk of muscle injury (3, 2-6).

Third, the premenstrual phase is also when many negative menstrual symptoms occur. Common symptoms include disrupted sleep, mood changes, decreased coordination, and lower back pain. These symptoms can reduce an athlete’s readiness to perform, alter movement patterns, and interfere with proper recovery. In addition, hormonal changes can affect how soft tissues such as muscles and tendons function, potentially leading to changes in movement that increase injury risk. Together, these factors suggest that the drop in hormones during phase 4 may play a significant role in increasing muscle injury risk (7-9).

Non-contact injuries were also found to be about three times more likely to occur during phase 4 compared to phase 1. This increase may be linked to the sudden hormonal withdrawal that happens before menstruation. This finding is especially important because non-contact injuries are generally considered more preventable than contact injuries. The same mechanisms discussed above - such as inflammation, reduced recovery, altered movement, and hormonal decline - may help explain why non-contact injuries are more common during this phase. Since phase 4 involves a sharp drop in hormones to trigger the breakdown of the uterine lining, this period may be particularly critical for injury prevention (2).

Overall, the authors emphasize that more research is needed to better track inflammation, menstrual symptoms, sleep, and individual differences among athletes across the menstrual cycle. Developing a more complete profile of female athletes - including medical, physical, physiological, and lifestyle factors - could improve understanding of injury risk and lead to better, more personalized athlete care.

As you can see, their findings were kind of all over the place, and no true/obvious scientific correlations were found. But that was not the point of highlighting this article. My point was to show that there are connections, we just have to look deeper to figure it out!

My Conclusions

After dissecting this article in depth and reading multiple other papers done on this topic, I have come to three main conclusions:

1. There is no clear/well done research that proves the direct correlation between physical performance and the menstrual cycle. It is known that female athletes do perform differently than male athletes. In fact, females are reported to have 21% less availability than males, primarily due to a greater incidence of severe ankle and knee ligament problems (2). We know they have higher injury rates during different phases, but we haven't done enough research to say that a certain phase, hormone, or factor is contributing to a worse athletic performance or higher injury risk. Every paper claims a different thing. For example, multiple studies have shown a "greater incidence of ACL injury in the late follicular phase when estrogen concentrations are at their peak" (10–12) due to increased ACL laxity from higher levels of estrogen, but others have claimed that "greater ACL injury incidence in the early follicular or late-luteal phases" (13,14). This partly is because it is difficult to conduct this type of research, since it is something that can't be generally measured - it varies from person to person. For example, some people face extreme nausea, cramping, and fatigue when on their period while others feel nothing. In that sense, it's hard to pull accurate findings from labs because it could be an actually correlation, it could be a coincidence, or it could just be specific to that person. It's very gray, and that's not good for the lab.

   
   

   Barlow's article explained it well: "Research around the menstrual cycle has been limited by a lack of a standardized approach to prospective data collection and analysis. Some studies are confounded by the inclusion of combined hormonal contraceptive users, where exogenous hormones down-regulate the natural hormonal. Another issue is that the definition of menstrual cycle phases varies between studies from the most simplistic (two phases) to the highly detailed (seven phases)" (Article). Essentially this is stating that the main reason research around this topic hasn't been done/is not very accurate is because there isn't a good way to conduct it - on top of the usual challenges of executing an accurate study, many female athletes take some form of hormone medication, altering the lab, and there isn't a clear definition of the 4 phases of menstruation. While conducting this type of research is challenging, a greater effort must be made given the amount of people this effects.

2. The general public is not educated enough on women's physical health. For example, a woman's sex hormones can change by over 100% just in 24 hours (15), and that these fluctuations can have larger systemic affects by influencing musculoskeletal tissue which includes muscle, skin, and bones (7, 17)? It seems complex, but I would argue this is knowledge people should possess, especially woman and even more specifically female athletes because this could very well be affecting your performance, and rather than understanding why, you just blame yourself. I know that I, and my teammates have done that - its natural to blame yourself if you don't understand why your body is slowing down, getting fatigued, and cramping. A huge rising problem within sports in general but specifically women's sports is struggles with mental health, and I think more awareness around physical health would allow for athletes, coaches, and even fans to give them more grace.

   
   

3. This topic is so multifaceted, there are so many different factors that go into the relationship between the cycle and performance, some that will probably never be figured out. However, even though this research is often in the gray area in terms of accuracy, the more it is conducted, the more doors we open to learning about new correlations. For example, anterior cruciate ligament (ACL) injuries are up to eight times more prevalent in females than in their male counterparts. This topic was what originally interested and led the University of Bath to conduct their study. They didn't record any ACL injuries, so they pulled no findings around that, but they did learn that there is also a correlation between female biology and muscle injuries, which is something they now argue needs to be further researched. By looking into one thing, new discoveries and connections can be made!

   
   

This research is challenging and time-consuming, but it would help encourage young girls hesitant to participate in sports and professional athletes coping with menstruation-related challenges. The good news is that as female athletics gain more traction, larger studies are planned. For example, FIFA has approved funding for a study to investigate links between ACL injuries and the menstrual cycle. My hope would be that this awareness and knowledge becomes common information that all coaches, clubs, teams, and people understand - so that next time their star player has a cramp, feels muscle/joint pain, or just can't perform well, they aren't scrutinized but are given understanding, empathy, and the support they need to grow!

Articles Referenced

Main Article: Barlow, A., Blodgett, J. M., Williams, S., Pedlar, C. R., & Bruinvels, G. (2024). Injury Incidence, Severity, and Type Across the Menstrual Cycle in Female Footballers: A Prospective Three Season Cohort Study. Medicine and science in sports and exercise, 56(6), 1151–1158. https://doi.org/10.1249/MSS.0000000000003391

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