Players’ cycles, once deemed to be a minor inconvenience, are now seen as potential keys to unlock big gains in performance. 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 The sport has reclaimed its place on the world stage over the subsequent century-plus, but another outdated notion persists; that the players’ menstrual cycles are just an inconvenience rather than a key performance variable worth studying.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.”.
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.”.
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.”.
