In 1921, the English Football Association banned women’s soccer, declaring the game “unsuitable for females”. The sport has reclaimed its place on the world stage over the subsequent century-plus, but another outdated notion persists; that the players’ menstrual cycles are just an inconvenience rather than a key performance variable worth studying.
Now, a collection of researchers and medical professionals are lending their expertise to what could be the sport’s next big evolution.
“The starting point is that we are women and, ultimately, we go through something very different to men on a monthly basis,” said current USWNT manager Emma Hayes in 2020, when as manager of Chelsea Women she was one of the first major coaches in the women’s game to tailor her team’s training around the players’ cycles. “It comes from a place of wanting to know more about ourselves and understanding how we can improve our performance.”
Each phase’s impact
The menstrual cycle consists of four phases over approximately 28 days: menstrual, follicular, ovulation and luteal. Each phase affects the body differently, influencing optimal training and nutrition strategies.
The menstrual phase (typically days one to five) is when bleeding occurs, and estrogen and progesterone levels are at their lowest. This hormonal dip can lead to fatigue and reduced energy levels. During this time, athletes can support their performance and recovery by prioritizing quality sleep and fueling properly with carbohydrates, protein and healthy fats. Replenishing key nutrients is essential to counteract potential blood loss and maintain overall wellbeing.
Among those nutrients, iron is especially important. Dr Nidia Rodríguez-Sanchez, a sports dietitian and senior lecturer at the University of Sterling, says athletes can lose iron during menstruation, putting them at risk of deficiency if they suffer with heavy bleeding.
“We must make sure women are getting enough iron in their diets, especially at this phase of the cycle to support energy production and a healthy immune system,” Rodriguez-Sanchez said.
During the follicular phase (approximately days six to 14), estrogen levels rise, which is believed to increase strength, endurance and coordination. While more research is needed, existing data suggests the mid-follicular phase is an optimal time for athletes to incorporate additional loading, strength training and high-intensity workouts.
“Athletes could feel more energetic in their mid-follicular phase, so talking to coaches about a stronger resistance training plan at this time is a way to optimize your cycle,” said Dr Sinéad Dufour, a pelvic health physiotherapist and associate clinical professor at McMaster University.
Ovulation is a brief window, typically spanning days 14 to 16 when estrogen and testosterone peak. This surge enhances energy levels and explosive power, making it an ideal time for sprint work or high-intensity intervals.
However, the luteal phase (approximately days 17 to 28) requires greater attention. As progesterone rises, athletes may experience increased fatigue, bloating and muscle soreness. During this phase, focusing on coordination, mobility work, sleep and nutrition can be key to maintaining performance and overall wellbeing.
“The mid-luteal phase can be associated with more sleep disruption and other symptoms like musculoskeletal pain and increased injury risk, so that might be the time to back off a little bit regarding training,” Dufour said.
There’s no one-size-fits-all approach, as every athlete experiences different symptoms and cycles. However, according to a study conducted at the University of Bath, the luteal phase may be linked to a higher risk of muscle injury – potentially six times more than during the menstrual phase.
“The physiology of a woman’s body changes as it gets closer to bleeding and gets more fatigued; this is a time where more injuries seem to happen although the data are inconclusive,” said Dr Charles Pedlar, a sports physiologist and professor of applied sports and exercise science at St Mary’s University. “However, there’s also some evidence that other phases of the cycle are a risk factor, so larger research studies with many more teams need to be done to know.”
Education
For professional female soccer players, understanding menstrual cycle is a potential performance superpower.
“Women have won World Cups and Olympic medals every day of their menstrual cycle, they don’t have a choice but to play on,” said women’s health physiotherapist and Fifa consultant Michelle Lyons. “We need to see periods as a superpower we can tap into to optimize how female athletes fuel, recover and ultimately perform on the pitch.”
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Still, even in an era of personalized nutrition plans and AI trackers, the menstrual cycle remains a footnote in most training programs and research studies. Sports science still operates on studies that do not equally involve men and women.
“Historically, female athletes have been trained like men, who have different hormonal profiles, so we need to think more intelligently about training women,” said Pedlar.
The same goes for nutritional guidelines, which “are based on studies in male athletes, but realistically are different for women at different phases of their cycle,” adds Rodriguez-Sanchez.
When Lyons works with athletes, she encourages them to track their cycle and symptoms for at least three months. Over time, patterns in cycle length and symptoms emerge, allowing for a more personalized and strategic approach to training. Even if this means athletes on the same team follow different training plans, tailoring workouts to individual needs is key.
This is the true power of cycle tracking – understanding how their own body responds to each phase and making informed adjustments to minimize discomfort while maximizing high-energy days. By tapping into the strengths of their hormonal fluctuations, women can train smarter and perform at their best.
“To quote cardiologist Dr Nieca Goldberg, ‘women are not small men,’ and we have to take that into account,” Lyons said. “Women have a 28-day cycle with hormones ebbing and flowing, while men run on a 24-hour testosterone cycle, so why are women still training like men?”
The role of contraceptives
A complicating factor is the use of oral contraceptives and other forms of hormonal birth control. Soccer players may use them for various reasons, such as regulating their cycle, managing bleeding, improving acne, preventing pregnancy or alleviating Endometriosis symptoms.
However, hormonal birth control can affect the body in ways that might negatively influence performance. Dufour reveals that athletic execution tends to be better when you don’t have artificially altered physiology, but cites the need for more research to fully understand how changing hormones affects athletes – both on an individual level and across women’s teams.
According to studies from the University of York and Nottingham Trent University, taking oral contraceptives might lower levels of testosterone, a hormone that helps build lean muscle mass, and could lead to reduced endurance, stagnant muscle growth, mood swings, weight gain, and a change in hunger levels.
“Some women on oral contraceptives have reported feeling hungrier or [have noticed] changes in their energy intake at certain phases compared to athletes not on contraceptives, so that’s where tracking and understanding your cycle comes in handy,” said Rodriguez-Sanchez.
How are things changing?
While more research needs to be done to fully understand the effect of the menstrual cycle on performance, positive change has been made with apps like FitrWoman.
Used by the England Lionesses, Olympic medallists and more, the app and others like it can be used as a tool to understand an athlete’s personal cycle and symptoms, and a way to break down barriers and normalize conversations about periods while providing menstrual health education.
“The menstrual cycle is already stressful, so having a coach or trainer open to discussing it may make it easier and more normalized,” added Pedlar. “Providing resources and creating an open dialogue is a good starting point.”
By working with their bodies rather than against them, professional female soccer players can train more efficiently, recover faster, and unlock new levels of excellence on the pitch.
“Soccer and sports in general are such global unifying forces,” Lyons said. “And we don’t want to let something like a menstrual health problem, that’s avoidable or fixable, become a barrier.”
