But that hasn’t been the case historically, and still isn’t true across the board. Compared to their equivalents on the men’s side, women’s squads and leagues at every level are often at a disadvantage when it comes to everything from appropriate gear to playing surface to access to medical resources and coaches who will implement prevention programs and training—disparities that could increase the danger, Dr. Silvers-Granelli says.
Hormones
Fun fact: Women’s monthly hormonal fluctuations are one reason why women (and even female mice) haven’t always been included in medical or exercise science research. Menstrual cycles might confound the results, researchers worried—never mind that the approximately half of the population who have them might be interested in how the shifts influence their health.
Indeed, it turns out those ebbs and flows may make a difference in susceptibility to tendon injuries. Unlike men, women’s ACLs have relaxin receptors, a hormone that’s released at high levels just after ovulation and breaks down collagen, loosening ligaments.
That’s likely a good thing during pregnancy, but less useful during quick pivots on the court or pitch. And hormones also influence how women feel and recover, potentially leading to excess fatigue at some points that can add to injury risk, Dr. Ode says.
To explore this issue, Dr. Trentacosta and her colleagues compared injury rates between 32 athletes taking hormonal contraceptives—which modulate those monthly shifts and prevent ovulation, keeping relaxin levels low—and 40 who weren’t. Those who were on birth control had fewer ACL tears and other injuries, and also different biomechanics when landing from a jump.
This doesn’t mean athletes should take the pill to prevent ACL tears, Dr. Trentacosta says (although it’s one factor they might consider if they’re deciding between contraceptive methods). But it does confirm a correlation between hormones and risk that deserves further exploration.
Genetics
Like many other medical problems, ACL tears can run in families, and some of the genes linked to a higher risk may have a bigger impact on women than men. In fact, one 2020 study in the British Journal of Sports Medicine estimated that about 69% of the risk is heritable, meaning that if you looked at a group of athletes, about 69% of the difference in the rate of ACL tears between them would be due to genetics rather than environmental factors.
Anatomy
On average, women have shorter femurs in relation to the width of their hips. That means their Q angle—the angle formed between the quadriceps and kneecap, when viewed from the front—is wider, placing more stress across the knee joint, Dr. Ode says. Plus, the notch where the ACL sits tends to be a bit more narrow in women than men, potentially increasing the risk for tearing.
But even football players with dramatically different bodies from female soccer players, including larger notches, still tear their ACLs, as do people with no family history of such injuries. And no athlete can fundamentally alter their anatomy, or their genes, anyway. So rather than dwelling on these differences and instilling fear—which, paradoxically, actually further increases the risk of injury—it makes a lot more sense to focus on prevention methods that are known to work, Dr. Silvers-Granelli says.
So what can women do to protect themselves?
If there’s one message women’s sports medicine experts have for athletes, it’s that their bodies aren’t fragile and injuries aren’t inevitable. Everything from proper nutrition and recovery to specific prevention programs can go a long way toward mitigating the risk of ACL tears and other injuries. Here are some other prevention strategies to keep in mind:
1. Follow the program.
Pinpointing the neuromuscular and biomechanical risk factors that increase the risk of ACL tears has allowed researchers like Dr. Silvers-Granelli to develop exercise programs specifically to address them. Most are 10- to 15-minute sessions involving elements like running drills, plyometrics, strength moves, and stretching, which can double as a dynamic warm-up. Not only do they strengthen muscles and improve mobility, they also increase body awareness and proprioception, or the sense of where your body is in space, which is important for pivoting and landing, Dr. Ode says.