Dr. Julia Iafrate, DO, practices sports medicine, and physical medicine and rehabilitation.She's a former competitive skier who tore her ACL.She says hormones increase the risk of an ACL injury but aren't the only factor.This as-told-to essay is based on a conversation with Julia Iafrate, DO, a physician with the Center for Women's Sports Medicine at NYU Langone. It has been edited for length and clarity.I first started skiing when I was about 6. I grew up in Canada, where skiing was a way of life. I used to race until I tore my ACL, a major ligament in the knee joint, at 18. Once that was surgically repaired, I had two more back-to-back knee injuries that required surgery. That ended my competitive ski career but kicked off my interest in medicine.Now, I'm a double-board-certifieddoctor in sports medicineand physical medicine and rehabilitation. I'm one of the doctors who treat the US Ski Team. In my work, I'm seeing more discussion about the impact of hormones on sports injuries for women. Here's what we know about the role of hormones in injury and how to prevent getting hurt on the slopes.Women are more prone to ACL injuryWomen are twice as likely to tear their ACLs than men are in fact, some research puts the risk much higher, at eight times the risk men have. There are a few reasons for this. Women tend to have wider hips than men, which impacts the knee angle. Anatomically, this can increase the risk of ACL injury.In addition, broadly speaking, women have less neuromuscular control than men. Boys are often encouraged into sports like weightlifting and biologically have more muscle mass. Women tend toward sports like figure skating or dancing, where strength isn't the priority. Since muscle strength provides stability, many women have less stability in their ACLs compared to men.Hormones play a role tooHormones are also at play. We need more research on this, but a few studies suggest that women are more likely to injure their ACLs when they're ovulating.This is the time of the menstrual cycle when estrogen is highest. Estrogen can make ligaments less stiff, increasing the risk for injury. This is the same reason women might experience ligament injuries during pregnancy. Since body temperature also increases during ovulation, the body may be more prone to inflammation and injury.To be clear, we would never blame an ACL injury purely on hormones. But, increased estrogen combined with fatigue, lack of muscle control, and biomechanical strains on the ligament can have an impact.However, women aren't the only ones with a correlation between hormone changes and injury. For males, increased testosterone can increase competitiveness or risk-taking behavior, creating more risk for injury.Dynamic exercises can helpFlexibility is often celebrated, but without stability, it's not great. Women and everyone else need flexibility and stability to protect their ligaments. Building strength is a great way to increase stability.Focus on exercises that mimic the real world and use multiple muscle groups simultaneously. Squats and leg presses are great examples. These exercises train multiple muscle groups to work together and respond to different stimuli. That will help on the slopes when you need to suddenly navigate around other skiers, stay steady on a patch of ice, or land a jump.Quit while you're aheadWhen you notice you're tired during an exercise, your muscles are already fatigued. That reduces your performance, and it's one of the reasons so many injuries happen on the last run of the day.Remember, no bear is chasing you. You can always ski another day, so don't push it once you begin to feel tired. Head to the lodge and enjoy aprs instead.Be mindful of whole-body changesWhether you're on the national ski team or hitting the slopes as a casual hobby, it's important to be aware of changes to the whole body during your menstrual cycle, pregnancy, and menopause.I had my first baby 15 months ago, and I still can't run with the same biomechanics I had before. I've had to understand that and give myself grace in getting back into exercise. By listening to your body and acknowledging the changes that hormones can bring, you can prevent an injury, which is much easier than trying to repair one after it happens.