ACL tears have become an all-too-familiar sight in women’s soccer, sidelining many of our favourite players. In response to this growing concern, FIFA is funding research to investigate whether hormonal fluctuations during menstrual cycles contribute to these knee injuries.
The research will focus particularly on estrogen and progesterone. As studies suggest these hormones may increase ligament flexibility and slow neuromuscular response times. These factors could leave players more vulnerable to ACL damage (1).
Most sports medicine research is based around the male athlete, whereas females have multiple anatomical and physiological differences that need to be considered.
The Hormonal Connection
Hormones and Ligament Flexibility
Estrogen receptors are found throughout connective tissues, including ligaments and tendons. During certain phases of the menstrual cycle, particularly when estrogen peaks around ovulation, research shows that athletes often experience increased joint laxity. While this flexibility can be beneficial for some movements, it can compromise joint stability during high-impact activities.
Neuromuscular Control
Research supports clinical observations that hormonal fluctuations can affect reaction times and proprioceptive awareness during the follicular phase of the menstrual cycle (2). Female athletes may experience slightly delayed muscle activation patterns during certain phases of their cycle, particularly in the days leading up to ovulation when estrogen levels are highest, potentially increasing injury risk during dynamic movements.
Beyond ACL Injuries
While ACL tears capture a lot of attention due to their devastating impact on athletic careers, hormonal influences and anatomical factors extend to numerous other injury types e.g:
- Stress Fractures: Female athletes with irregular cycles or amenorrhea present with stress fractures at significantly higher rates due to reduced estrogen’s protective effect on bone density.
- Shoulder Instability: Recurrent shoulder dislocations can correlate with hormonal phases, particularly in overhead sports.
- Patellofemoral pain syndrome (PFPS): The female pelvis is often wider than males, creating a larger Q-angle (the angle between the quadriceps muscle and the patellar tendon). This increased angle can pull the kneecap laterally, creating uneven pressure on the cartilage behind the patella.
Why are females at a higher risk?
Female Athlete Triad + REDs (Relative Energy Deficiency in Sports)
The female athlete triad is a well known syndrome comprising three interconnected conditions: low energy availability, menstrual dysfunction, and decreased bone mineral density. This condition specifically affects female athletes and has been recognised as a significant health concern in sports medicine (3).
More recently, they have expanded on this and found it to be a part of a larger syndrome named REDs. The core issue is an energy imbalance where energy expenditure (from training, metabolism, and daily activities) exceeds energy intake from food.
This can happen through restrictive eating, due to poor nutrition knowledge, or from extremely high training loads without adequate fueling. This leaves the athlete without enough energy to fuel the body’s essential functions for maintaining good health and peak performance (4).
Want to know more?
If you’re a female athlete experiencing recurring injuries or have questions about how your cycle might be affecting your performance, let us know! Your hormones aren’t obstacles to overcome—they’re part of your unique physiology that, when properly understood, can inform smarter training and more effective treatment.
References
- Chidi-Ogbolu, N. and Baar, K., 2019. Effect of estrogen on musculoskeletal performance and injury risk. Frontiers in physiology, 9, p.421933.
- Sharma, A., Kaur, S., Kumar, P. and Sharma, N., 2024. Unveiling the menstrual mind: Exploring proprioceptive proficiency, reaction responsiveness, and motor mastery in premenstrual syndrome versus Non-PMS cohorts: A two-arm parallel non-blinded cross-sectional study. Clinical Epidemiology and Global Health, 29, p.101782.
- Nazem, T.G. and Ackerman, K.E., 2012. The female athlete triad. Sports health, 4(4), pp.302-311.
- Mountjoy, M., Sundgot-Borgen, J.K., Burke, L.M., Ackerman, K.E., Blauwet, C., Constantini, N., Lebrun, C., Lundy, B., Melin, A.K. and Meyer, N.L., IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update., 2018, 52. DOI: https://doi. org/10.1136/bjsports-2018-099193, pp.687-697.
