The National Women's Soccer League (NWSL) has announced its participation in a groundbreaking three-year research project aimed at addressing the disproportionately high rates of anterior cruciate ligament (ACL) injuries in women's football. This initiative, known as Project ACL x NWSL, involves all 16 NWSL clubs, including the defending champion Gotham FC, and expands upon a similar effort launched in 2024 between the Women's Super League (WSL), Fifpro, England's Professional Footballers' Association, Nike, and Leeds Beckett University.
Holistic Approach to Injury Prevention
ACL injuries are between two and six times more likely to occur in female athletes compared to their male counterparts. While biological differences have often been cited as a primary cause, Project ACL adopts a comprehensive perspective that considers environmental and societal factors. These include pitch standards, access to weight-room facilities, schedule congestion, and the quality of cleats designed for women.
Tori Huster, deputy executive director of the NWSL Players Association, emphasized the importance of this broader view in a recent statement. "Project ACL brings together players, leagues, and researchers to better understand ACL injuries," she said. "This requires looking beyond the individual and examining the daily conditions players face. It's an opportunity to build player-centric evidence that can drive meaningful changes across women's professional soccer."
High-Profile Cases and Research Gaps
The urgency for such research intensified ahead of the 2023 World Cup, where several star players, including England's Leah Williamson and Beth Mead, the Netherlands' Vivianne Miedema, and the United States' Catarina Macario, missed the tournament due to ACL tears. More recently, Australia's Sam Kerr and Germany's Lena Oberdorf were sidelined from the 2024 Paris Olympics with similar injuries. Notably, seven of the 20 gold medalists for the United States at that event had experienced an ACL injury at some point in their careers.
Although ACL injuries are no longer typically career-ending, recovery times can vary significantly. For instance, Kerr returned to play nearly 20 months after her injury in January 2024, while Oberdorf suffered a re-tear just eight matches into her comeback in October 2025.
Biological and Environmental Factors
Existing studies indicate that biological factors contribute to the higher risk for women, with about 70% of ACL injuries occurring in noncontact situations. Women often have wider hips, narrower knee bone structures, and different muscle strength distributions, such as stronger quadriceps compared to hamstrings. Some preliminary research also suggests a potential link to menstrual cycles, though this area requires further investigation.
However, researchers are increasingly calling for an examination of societal and environmental influences. Girls and women generally engage in strength-building resistance training less frequently than men. Additionally, playing on artificial turf or using cleats designed for male feet has been linked to increased injury rates. Fifpro has also highlighted the impact of fatigue from crowded match schedules on player performance.
Collaborative Efforts and Future Goals
Fifpro describes Project ACL as the first initiative of its kind to span multiple professional leagues. This is crucial given that less than 10% of sports science research focuses on women, with most studies centered on amateur rather than professional athletes. The collaboration aims to develop injury-prevention programs and protocols that could be standardized across clubs and leagues, similar to existing frameworks for concussions and brain injuries.
Since its 2024 launch, the Project ACL team has conducted interviews with over 30 players and surveyed all 12 WSL clubs regarding resources and prevention strategies. Similar efforts are planned for the NWSL's 16 clubs. Players will also utilize Fifpro's workload monitoring tool to track training, travel, and recovery schedules.
Dr. Alex Culvin, director of women's football at Fifpro, stated, "We believe that player-centricity and collaboration with key stakeholders are central to establishing meaningful change in the soccer ecosystem. Players, organizers, and stakeholders worldwide will benefit from Project ACL's outputs and outcomes."
Sarah Gregorius, the NWSL's vice-president of sporting, added, "Player health and performance are fundamental to the future of our league, and this is an area where we intend to lead. By continuing to invest in this work, we can help build environments where our players are better supported and able to perform at their best."
