Blood, Sweat, and Tears: The Link Between The Menstrual Cycle and Injury Risk

In the past 2 years, the trajectory of female athletics has grown immensely with increased viewership and support paving the way for growth and development. August 30th, 2023 marked the most attended women’s sporting event in history, with over 92,000 fans crowding the court to view the Nebraska Cornhuskers beat the Omaha Mavericks in a record-breaking volleyball game. The 2024 Summer Olympics became the first games in which an equal number of male and female athletes attended. In January, a professional Women’s Hockey League will begin its inaugural season in the United States. With such great progress, Deloitte predicts that women’s elite athletics will generate “a revenue that surpasses $1 billion dollars” in 2024, almost a 300% increase since 2021.

However, the increasing size of female athletics has led to new fears, as injuries grow at unprecedented rates. This is coupled with higher incidences of bone stress injuries, ACL tears, and concussions in female athletes, especially in comparison to male counterparts. Thus, the sports medicine world has begun to investigate this phenomena, hoping to find root causes of such susceptibility. This has led to evidence of a positive correlation between certain phases of the menstrual cycle and injury risk. Research is currently being conducted, meaning the extent to which the menstrual cycle impacts injury risk is still uncertain. However, the link is definitely present, meaning knowledge on phases of high risk and means of prevention are incredibly useful to female athletes. Therefore, the main questions for professional, collegiate, or high school athletes are when one is at high risk and what can be done about it?

Firstly, an athlete needs to understand the menstrual cycle and the unique characteristics of all 4 phases. The menstrual cycle is the monthly hormonal cycle that prepares a female for pregnancy, typically measured in a 28 day span although the length depends heavily on the individual. The first phase is the menstrual phase, which restarts the cycle and lasts an average of 3 to 7 days according to Better Health. During this time the lining of the uterine wall is shed, leading to the release of blood, tissue and mucus from the uterus. This is coupled with drops in estrogen and progesterone levels as well as symptoms like cramps, tenderness, mood swings alongside others. This is followed by the follicular phase, in which the release of follicle-stimulating hormones (FSH) cause the ovaries to produce follicles, each of which contains an immature egg. Follicles with the healthiest eggs will mature, leading to a surge of estrogen. This hormonal rise triggers the ovulation phase, in which the pituitary gland will release luteinizing hormone (LH) to begin the process of ovulation. This entails the release of a mature egg from the ovary through the fallopian tube towards the uterus for fertilization by the sperm. Release of the egg occurs regardless of the presence of sperm. The luteal phase follows, finishing the cycle. It occurs after the egg is released, as the empty follicle changes into a structure known as the corpus luteum. This structure releases hormones, keeping the uterine lining thick in cases where a fertilized egg should implant. If pregnancy does not occur, the corpus luteum will shrink away, leading to decreases in progesterone and estrogen levels. These comprise the 4 phases of the cycle, each accompanied by unique processes and hormonal levels.

The complexity of this process makes it an understudied research topic, especially in relation to the field of sports. However, a study published in Medicine & Science in Sports surrounding the Women’s Super League, the professional women’s soccer league in the UK, attempted to fill this gap. It followed 26 players over 13,390 days in which 593 cycles were tracked and 74 injuries were reported. The results revealed that players were 6 times more likely to get injured in phase 4, or the luteal phase. It is important to note that no ACL injuries occurred during the study, meaning it is not indicative of the impacts of menstruation on that specific issue. Additionally, muscle injuries showed the greatest variation throughout the study, with the majority present in both the ovulation and luteal phase.

This alongside several other studies reveals the high prevalence of injuries in both the luteal phase and the ovulatory phase. Ligament and joint injuries are largely caused by the increased progesterone production of the luteal phase, which can hinder muscle strength and increase ligament laxity. However, the high estrogen levels associated with the ovulatory phase also impact laxity and neuromuscular control which thereby increases susceptibility to muscular injuries, like strains, and ligament injuries, like ACL tears. While more research needs to be conducted to conclusively corroborate these studies, the risks of the luteal and ovulatory phases already exposed should be considered by female athletes, especially while in season. Ultimately, one’s cycle and hormonal production cannot be prevented. However, there are several ways to lessen injury risk. The first of which is to track your cycle. This does not necessarily mean on an app, as simply journaling to find basic trends in your cycle can be effective. However, period tracking apps provide multiple benefits as they make the tracking process easier. If an athlete does decide to use one, practicing responsibility by ensuring your data is stored locally, limiting location sharing and protecting search data are incredibly important steps. Specifically, tracking can give knowledge into one’s general beginning of the ovulatory and luteal phases. This knowledge can be used to adjust the scope and difficulty of your training regimen, ensuring proper measures are taken to reduce injury risk.

Another key factor is not over exercising. Increased progesterone and estrogen production leads to a higher likelihood of overuse injuries, meaning managing your activity load and taking note of energy levels is crucial. This does not mean not exercising, it simply means adjusting the length, difficulty, and type of workouts in response to your natural cycle.

Lastly, one of the most important means of injury prevention for female athletes, strength training. Women have less muscle mass genetically, meaning that ligament and tendon tears, such as ACL injuries, are much more common. Strength training can help remedy this deficit, thereby limiting the prevalence of injuries due to pure muscle inefficiencies. This positive impact can also extend to all age groups, with positive correlations between weight lifting and a smoother aging process. Overall, the link between injuries in female athletes and the menstrual cycle is definitive. The extent to which this is a leading factor is still to be determined. However, it is still something to consider, especially by coaches or teams looking to protect the health of their athletes. Athletic organizations should take inspiration from Chelsea’s Women Football Club, who have adjusted the training cycles of each individual player to accommodate for their cycle. This forward-thinking approach can protect the careers of countless athletes without severely disrupting practice and training schedules. It should ultimately be a widespread practice, as blood and sweat should not accompany tears.

References

Barlow A, Blodgett JM, Williams S, Pedlar CR, Bruinvels G. Injury incidence, severity and type across the menstrual cycle in female footballers: a prospective three season cohort study. Med Sci Sports Exerc. 2024. doi: 10.1249/MSS.0000000000003391

"Chelsea Women Tailor Training to Players' Menstrual Cycles." Chelsea F.C., 14 Feb. 2020, www.chelseafc.com/en/news/article/chelsea-women-tailor-training-to-players-menstrual-cycles. Accessed 11 Nov. 2024.

Ernst, Holly, editor. "Stages of the Menstrual Cycle." Healthline, 13 Mar. 2023,www.healthline.com/health/womens-health/stages-of-menstrual-cycle. Accessed 5 Nov. 2024.

Martínez-Fortuny, Núria et al. "Menstrual Cycle and Sport Injuries: A Systematic Review." International journal of environmental research and public health vol. 20,4 3264. 13 Feb. 2023, doi:10.3390/ijerph20043264

"The Menstrual Cycle." Better Health Channel, Victoria State Government, 8 Feb. 2024, www.betterhealth.vic.gov.au /health/conditionsandtreatments/menstrual-cycle. Accessed 10 Nov. 2024.

Smith, Rhianna-Lily. "Female Athletes Six Times More Likely to Get Injured in the Days Leading up to Their Period." Technology Networks, 5 May 2024,www.technologynetworks.com/proteomics/news/female-athletes-six-times-more-likely-to-get-injured-in-the-days-leading-up-to-their-period-386458. Accessed 5 Nov. 2024.