Women are between two and six times more likely to suffer an ACL tear than men. That number alone should have triggered a serious research response years ago. The NWSL is now joining the WSL, Fifpro, and a coalition of researchers and stakeholders in a three-year initiative — Project ACL x NWSL — to finally start building that evidence base.
This is an expansion of the project launched in 2024, which brought together the WSL, Fifpro, England's Professional Footballers' Association, Nike and Leeds Beckett University. The addition of the NWSL's 16 clubs extends the reach significantly and makes Project ACL what Fifpro describes as the first initiative of its kind to span multiple professional leagues.
Why this matters now
The scale of the problem has been in plain sight for years. Leah Williamson. Beth Mead. Vivianne Miedema. Catarina Macario. All missed the 2023 World Cup with ACL tears. Sam Kerr and Lena Oberdorf were both absent from the 2024 Paris Olympics — and of the 20 US gold medalists at those Games, seven had suffered the injury at some point in their careers. Oberdorf then tore hers again in October 2025, just eight matches into her return. Kerr's own recovery ran nearly 20 months.
The injury is no longer career-ending. But that's a low bar.
What the research is starting to confirm is that biology alone doesn't explain the disparity. Yes, anatomical factors — wider hips, narrower knee structure, quad-hamstring strength imbalances, flat-footed landing patterns — create real additional risk. Some studies point to the menstrual cycle as a contributing factor, though that research is still early. But environmental conditions matter too: pitch quality, access to weight rooms, cleat design built around male feet, schedule congestion, artificial turf. These are things leagues and clubs can actually control.
What Project ACL is actually doing
Since its 2024 launch, the project has interviewed more than 30 players and completed surveys across all 12 WSL clubs on resources and injury prevention. The same process will now run through the NWSL's 16 clubs. Players will also be able to log workload, travel and recovery data through Fifpro's monitoring tool — building the kind of granular, professional-level dataset that barely exists right now.
Less than 10% of sports science research focuses on women. Most of what does exist is centred on amateur athletes, not professionals competing at the top of the game. That gap is precisely why this project has teeth — if it produces standardised injury-prevention protocols that leagues and clubs are actually required to implement, similar to existing concussion frameworks, it could shift how women's football operates structurally.
- Project ACL x NWSL covers 16 NWSL clubs alongside all 12 WSL clubs
- Roughly 70% of ACL injuries in women occur in non-contact situations
- Players will track workload and recovery via Fifpro's monitoring system
- Findings could lead to regulated club and league-level prevention protocols
"That understanding requires looking beyond the individual and examining the conditions players compete and train in every day," said Tori Huster, deputy executive director of the NWSL Players' Association. The NWSL's VP of sporting, Sarah Gregorius, was more direct: "Player health and performance are fundamental to the future of our league, and this is an area where we intend to lead."
The research has three years to produce something actionable. Given the injury toll the women's game has absorbed over the past three seasons alone, that timeline can't move fast enough.
