Emma Hayes has turned women’s health from a long-ignored subject into a central part of how elite soccer is coached, researched and organised. Her work began at Chelsea and has since been expanded through U.S. Soccer’s herLENS programme, but the account needs several factual corrections: the defining Chelsea defeat was the 2016 FA Cup final against Arsenal, not a quarterfinal loss to Manchester United, and Hayes did not leave Chelsea in 2022.
The turning point came after Chelsea’s 1-0 defeat to Arsenal in the 2016 FA Cup final at Wembley. Hayes later concluded that several players’ performances may have been affected by different stages of their menstrual cycles, including symptoms such as fatigue, brain fog and inflammation. Rather than treating those experiences as private or incidental, she began building a more informed approach to women’s health in elite football.
Chelsea made that approach public in February 2020. The club said Hayes and her staff used a specialist app, with players’ consent, to tailor individual training and nutrition plans around menstrual-cycle phases. The programme covered menstruation, pre-ovulation, the period between ovulation and premenstrual symptoms, and the premenstrual phase. Its aim was to support performance and reduce injury risk—not to impose a single formula on every player.
Hayes remained Chelsea manager until 2024, when she became head coach of the United States women’s national team. She led the USWNT to Olympic gold at Paris 2024, but the broader legacy she is now pursuing is less about one tournament result than about changing the sport’s underlying assumptions. Her argument is that women’s soccer should not simply replicate a men’s model of training, recovery, facilities and player development.
The 2026 herLENS Conference reflected that ambition. Held near Atlanta and hosted by Hayes and U.S. Soccer, it brought together roughly 300 people from across the sport, including NWSL executives, youth coaches, researchers and former players. Sessions addressed menstruation and hormonal effects on performance, nutrition, sleep, mental health, injury prevention, inclusion, and why girls remain in or leave the game.
The initiative is deliberately individualised. U.S. Soccer’s “Female 360” approach includes player surveys, one-to-one conversations and personalised programmes covering hydration, nutrition, recovery and, where players choose to share it, menstrual-cycle tracking. Participation in cycle tracking is voluntary, which is important: the model is designed around informed consent and individual need, not compulsory disclosure.
The research side has also expanded. U.S. Soccer has partnered with Michele Kang, whose $55 million donation established the Kang Women’s Institute. The institute’s newly launched herLENS Research Consortium is intended to close gaps in women’s soccer research, including a study with the University of North Carolina on how women’s health and performance data are collected and applied. Only about 6% of published athlete-focused research currently examines women exclusively, underscoring why Hayes sees the research gap as structural rather than marginal.
Hayes’ influence is therefore best understood as a shift in culture and method. At Chelsea, she normalised conversations about menstruation and built individualised support around them; with the USWNT, she is trying to extend that approach across coaching, research, facilities and youth development. The Paris gold medal was a major achievement, but the more durable claim is that Hayes has made women’s physiology a legitimate, evidence-based foundation for football planning rather than an afterthought.
