Anterior Cruciate Ligament (ACL) tears are seven times more common in women than men. Seven times! That’s a lot.
And the disparities between male and female ACL injury rates are more exaggerated in youth sports compared to adults. ACL tears are especially common for young girls in soccer, basketball, and volleyball.
Why are girls so much more likely to have a serious knee injury? Is there anything you can do to protect your knee? Or maybe you’re reading this to help protect your daughter’s knee?? Either way, we hope you learn something valuable to add to your or your daughter’s training routine in this blog post!
There are several factors the research points to as possible explanations as to why girls are predisposed to ACL tears when boys in the same sports tear at a much lower rate.
Anatomy:
The typical female has wider hips than the typical male proportionally to their bodies.
This means that girls are relatively more “knocked kneed” than boys. Since this angle, called the Q angle, is wider it increases the forces going through the ACL and makes girls more prone to knees collapsing inward during sport when jumping and cutting.
When the knee caves in excessively it puts a great amount of strain on the ACL and pushes its limits.
Women also tend to have smaller ACLs compared to men. But when you consider the extraordinary athleticism, many female athletes are displaying, their ACLs are no longer
equipped to handle their athleticism to some extent which leads to higher rates as well.
Hypermobile joint:
Ligaments connect bone to bone typically across the joint line. Their job is to help stabilize the joint. Compared to men, women tend to have more laxity in their joints i.e., the ligaments have more give. Because of this female theoretically needs more strength in order to stabilize the joint during cutting and jumping movements. This lack of stability also leads to a lesser proprioceptive awareness. Since the ligament is more lax, it has more difficulty relaying information to the brain about the amount of stress going through the joint. Without this information the brain cannot react and activate the right muscles to stabilize and protect the knee.
Additionally, increased amounts of progesterone in a female’s system during certain times of their menstrual cycling further makes their ligaments more lax for a few days each month!
Quad Dominance
For an unknown reason, girls tend have what we call quad dominance. This is when the ratio between quad and hamstring is significantly unequal in favor of the quads. This imbalance pulls your tibia, the shin bone, forward putting increased stress on the ACL especially during sport.
Over time, this repeated increase stress causes wear and tear leading to degradation of the ligamentous tissue and eventually it can tear.
What can we do to decrease the risk of ACL tears?
So, with all this information and such a high prevalence rate of ACL tears in young women, what can we do to reduce the risk of injury?
How to address wider Q angle
You can’t change the anatomy; however, you can reduce the caving inward of the knees. The glutes, specifically the glute medius and minimus, are super important in terms of helping to prevent the knees collapsing in during cutting and jumping. We need to improve strength, endurance, and reaction time of these muscles to protect the knee.
Here are a few examples of exercises where the glute medius and minimus muscles are extremely active. These are staples in a well-rounded ACL prevention program.
How to stabilize the knee joint
Along with strengthening the muscles all around the knee like the quad, hamstring, and calf, we need to improve proprioception and balance. Ligaments have little sensors within them that feed information to the brain when they are stretched and pulled in different directions during movement. If overly stretched one way, the brain sends a signal to the corresponding muscle that needs to respond to help fight excessive movement of the joint that is occurring. This happens within milliseconds. Because of the hypermobility, we need to improve this reaction time. How? Balance drills! Variations of balance drills should be in every athlete’s training regimen.
Here are some examples of how to train your balance!
How to fix quad dominance
Briefly mentioned above, we need quad and hamstring strength to stabilize the joint. But when designing our strength training program, we need to keep in mind that hamstrings should be a primary focus for most girls. Following an individual assessment, customization of the strength program to address the athlete’s individual needs for her knee and her sport is paramount.
In this video we demonstrate how a simple tweak in your form is able to change which muscle, quad vs glute, you're targeting. You can take this concept to any squat and lunge variation and adjust it to recruit less quad and more glute if you're someone who is quad dominant.
Make sure you're isolating the hamstrings! Deadlifts and Nordic curls are a must!
Here's an effective way to perform hamstring curls with a physio ball! A great way for young athletes to begin to focus on hamstring strength if they haven't done so in the past!
Any well-rounded strength training program will have a positive impact on reducing the risk of ACL tears, but we need to make sure girls are trained for their specific needs of their sports and are trained slightly differently than boys because of the aforementioned biological differences. If you’re a female athlete, make sure your trainer is knowledgeable of these differences and are mindful of them when programming your strength and conditioning routine.