Something All Coaches/Trainers Should Know Regarding ACL Tears in Female Athletes

It is fairly common knowledge that female athletes are more likely to tear their anterior cruciate ligament (ACL) than males. But do you know why? And more importantly, what can you do to help prevent it?


Multiple factors contribute to women being at a greater risk than men. They include musculature, hormonal, mechanical, and structural differences. Some of these are difficult, if not impossible to change (hormonal and structural) while other can be worked on (musculature and mechanical). I won't go into a lot of depth on the differences that may be impossible to change, but I will give a short run-down on each of the four differences mentioned above.

Hormonal: The research shows that the menstrual cycle potentially plays a role in a female's increased likelihood of a torn ACL. Hormones that affect tissues and systems include estrogen, progesterone, and relaxin (relaxin has been found to significantly decrease collagen tension). "Estrogen appears to affect the strength of soft tissue, the function of muscle, and the central nervous system. (1)"

Another interesting thing of note here comes from Dr. Kim Templeton (senior editor and co-author of "Women's Sports Injuries"). She states that, after puberty, men and women land from a jump and stop from a sprint differently. After puberty, women tend to land feet planted with their knees straight or locked out, whereas men tend to land more lightly, on their toes. (2)

Structural: One of the major differences here is the Q-angle. The Q-angle is naturally smaller in men than in women (due to women having wider hips for child bearing, among other things). Don't know what the Q-angle is? Look at the picture below:

Another structural difference that continues to be studied is the differences in the femoral notch between men and women. Basically, the smaller the notch, the less room for the ACL. Here is another picture:
Musculature & Mechanical: Several differences appear here as well. I'll just hit on a couple of the major ones. First, muscle strength. Stability of your knee relies heavily on the muscles surrounding the joint, namely, the quadriceps and hamstrings. Men, in general, are stronger in both of these areas (one reason being that men are just bigger) and are typically hamstring dominant. Women, on the other hand, tend to be quad dominant. Why is this a problem? Muscle recruitment.

Non-contact ACL tears occur most frequently with anterior tibial translation. In other words, the bone below your knee (tibia) is moving forward while the bone above your knee (femur) is relatively stationary. The ACL is the ligament that stops this movement, but it needs help from the hamstrings to stabilize the knee as well (with the quadriceps playing a smaller role). Men have shown to be quicker at recruiting these muscles to fire, especially the hamstrings, resulting in less non-contact tears. Women, who are quad dominant, fire their quads first to stabilize the knee, which is not as effective as using the hamstrings to control the movement. Studies have also shown that the quads produce so much force, that they can alone produce enough power to tear an ACL (1).

Another reason that women tear their ACL more frequently is that they stand more erect and with less flexion in their legs when cutting and pivoting in athletic situations. This posture forces their quads to fire more so than their hamstrings, re-enforcing their reliance on (and development of) their quadriceps vs. hamstrings.

Prevention: So what can we (as trainers, coaches, parents, etc.) do to help prevent our female athletes from a non-contact ACL injury?

In my opinion, we should focus on correcting these movement patterns that predispose females to potential injury. Specifically, we need to work on strengthening their hamstrings. There are numerous exercises that can be done to improve hamstring strength, but I only list a couple of my favorites.

Kettlebell deadlift: It is important to cue the athlete that they should be feeling their hamstrings/glutes working (NOT THEIR LOW BACK). Typically, if an athlete feels more of a pull in their low back, that means they aren't loading their hips enough. Their body weight should almost solely be on their heels when reaching for the kettlebell. Take a look:
Bridges: These are less complicated and also work well. There are different variations depending on your the athletes strength and proprioception that you may try with them as well. The first picture is a basic bridge. The athlete lays supine with knees flexed and feet flat on the floor. They then lift their bottom off the ground (try holding for 5-10 seconds for added benefit). You may also have them try doing this single leg (second picture) or with an exercise ball, which can also be done either double or single leg (third picture):

Thanks for reading! Again, if you have any questions or something to add, comment below!

Sources:  
(1)  Hirst,HE.,Armeau, E.,Parish, T.Recognizinganteriorcruciateligament tearsinfemaleathletes:What everyprimarycare practitionershouldknow. TheInternetJournal ofAlliedHealthSciencesandPractice. Jan2007,Volume5Number1.
(2) Templeton, Kimberly J. Women's Sports Injuries. Rosemont, IL: American Academy of Orthopaedic Surgeons, 2013. Print.