What Is The ACL?

There are three bones that meet to form the knee. The thigh bone (femur), shin bone (tibia), and kneecap (patella). The ACL (anterior cruciate ligament) is a ligament (connect bones together) in the knee, which help create stability in the knee joint. Injuries to the ACL are often times not in isolation. Many times other ligaments, cartilage, and meniscus are also damaged. Injury to ligament are called “sprains”, which can be graded on their severity below.

Grade 1 Sprains. The ligament is mildly damaged in a Grade 1 Sprain. It has been slightly stretched, but is still able to help keep the knee joint stable.

Grade 2 Sprains. A Grade 2 Sprain stretches the ligament to the point where it becomes loose. This is often referred to as a partial tear of the ligament.

Grade 3 Sprains. This type of sprain is most commonly referred to as a complete tear of the ligament. The ligament has been split into two pieces, and the knee joint is unstable.

Roughly 70% of ACL injuries occur in the form of “non contact injuries”. Meaning, the athlete wasn’t hit or rolled into by another player (the injury occurred in isolation from other players). In addition, of those that are non contact, they occur while the athlete is:

• Decelerating

• pivoting or cutting

• landing

• Suddenly stopping

• Wearing the inappropriate foot wear

*note*

There are very specific movements that occur when an athlete injuries their knee. The majority of the time it doesn’t happen when an athlete is accelerating, but rather deceleration. It happens much more with the athlete is landing, not jumping. ETC.

Who’s At Risk For ACL Injuries?

While knee injuries aren’t specific to one sports, they are more common in field/court sport athletes. Any sport that requires an athlete to: plant, pivot, cut, decelerate, land, etc. will be at an increased risk of knee injuries.

The Female Athlete

Female athletes are particularly susceptible to ACL injuries. In fact, reports show that female athletes are 9 times MORE LIKELY to experience an ACL injury than their male counterparts. It’s been observed that there are over 15,000 debilitating knee injuries occurring in women’s intercollegiate sports alone! So why are female athletes more susceptible to knee injuries than males, and what can we do to help mitigate the risk of knee injuries?

Understanding why female athletes are more susceptible to knee injuries is the first step to putting into place measures to help mitigate the risk of knee injuries.

Intrinsic risk factors for female athletes include the following: Muscular imbalances, poor neuromuscular patterning (firing pattern), hormonal fluctuation, increased body mass index (BMI), increase ligament laxity, wider pelvis in relation to the rest of the body, increase Q angle, smaller ACL, narrower intercondylar notch.

These risk factors put female athletes into higher risk category than their male counterparts. Most of these risk factors are innate in female athletes, some of which, can’t be changed or improved. For example, an athlete’s Q angle is pretty set, same with a narrower intercondylar notch. One can’t train to have narrower hips, nor would it be a good idea (females are designed with wider hips relative to their body for birthing children).

However, some risk factors can be training and improved; such as muscular imbalances and neuromuscular firing patterns.

Extrinsic risk factors are risk factors outside of the athlete. Most of which cannot be controlled. For example, the weather and playing surface are both extrinsic risk factors that cannot be controlled by the athlete.

However, shoe surface interface is. How the shoe, whether a cleat or sneaker, interfaces with it’s surface can have a negative/positive affect on the athlete.

For example, running shoes are designed to go forward. They have very poor lateral support, and generally, have thick soles. Knowing this, one can easily see why they’d be an incredibly poor choice of footwear in the weight room (where solid connection to the ground in necessary) and during speed and agility drills (especially lateral change of direction).

Understanding these intrinsic/extrinsic risk factors, which can be trained and improved, will help greatly reduce the risk for non contact knee injuries in the future.

4 Main Categories of ACL Risk Factors

Once we understand the intrinsic/extrinsic risk factors that are innate to the female athlete, it’s next important to detail the categories which some athletes may fall into: Leg dominance, trunk dominance (dysfunctional core), quadriceps dominance and ligament dominance.

Leg Dominance

Chances are you’re reading this on your phone. Chances are you’re holding this in one hand. Chances are that you’re hold that device in your dominant hand. Now just like everyone has a dominant hand, athletes have a dominant leg. This dominant leg will be used for: planting, cutting, jumping, kicking, etc.

Nothing wrong with that.

However, the issue rears it’s ugly head when the athlete is called to use their non dominant leg. See, until this point, if a coach or athlete hasn’t gone out of the way to make sure that the opposing leg gets equal to, or more work than the dominant leg, it’ll not only be much weak, but also have an increased risk of injury. The greater the imbalance, the greater the risk of injury.

Athletes can help mitigate these asymmetry by performing single leg strength work, single leg jump training and plyometrics. In addition, any type of change of direction work or agility work MUST be done with both legs receiving equal treatment. If coaches and athletes don’t make an effort to work both legs equally, the athlete will naturally chose their dominant leg for all planting, cutting, jumping, kicking, etc.

Trunk Dominance (dysfunction)

Trunk dominance, or core dysfunction is the inability to control one’s center of mass through space. Like a race car who’s horsepower exceeds it’s braking ability, an athlete that has core dysfunction will find it difficult to change levels, drop their center of mass, and change direction.

You see this happen often. An athlete gets going and has issues braking, slowing their body down, putting their foot into the ground and has excessive side-to-side trunk movement that translates to medial/lateral forces on the knee. Or maybe you’ve seen an athlete look “top heavy” suddenly needing to change direction.

So why does this seem to suddenly happen?

Young athletes that moved great as children tend to still operate using the same neuromuscular patterns and systems of operation. We’ve all seen this. The kids that experience tremendous growth during puberty and are now all the sudden clumsy.

So while puberty is not unique to females athletes, what does seem to be disproportionate to the female athletes is the increase rate of body mass compared to lean muscle mass.

This increase in “none functional mass” increases the percent of body fat, which may result in the athlete playing “higher”, which will be more difficult to control and balance.

Aside for participating in a general strength and conditioning program, coaches and athletes need to make sure they’re activating and working all the stabilizing muscles in the trunk (core). This doesn’t mean do endless sit-ups and crunches. But rather makes sure to implement a program that takes into consideration: anti-extension, anti-lateral flexion, anti-rotation, etc.

In addition to a solid strength program, athletes need a multidirectional speed and agility program that provides feedback to the athlete while they are learning to stay balanced over their center of mass.

Quadriceps Dominance

Quad dominance is a term given to an athlete who primarily uses the quad to stabilize the knee joint. Biomechanically, stability should come from a combination of quad/hamstring. The quad is not only the knee extensor, but also helps with hip flexion. However, from a neurological stand point, if an athlete’s firing patterns are off, and their quad now become the primary source of knee extension, hip flexion and knee stabilization; we can see how under a little fatigue, this can be a recipe for disaster.

From a mechanical standpoint, it’s been shown that female athletes tend to land from a jump with more knee extension than males (or those struggling with a visual, these athletes land with straighter legs). So if an athlete lacks the eccentric strength to withstand the additional responsibility placed on the knee, once fatigued, the athlete will now be placed in a compromised state.

So whether it’s due to improper firing patterns or a poor hamstring:quad strength ratio that causes an athlete to be quad dominant, athletes should take all the necessary precautions to help mitigate injury. Primarily, participating in a speed and agility program that offers multidirectional speed development, neuromuscular control drills, such as jump and plyometric program. In addition time should also be spent in the weight room developing the posterior chain (glutes, hamstrings, and calves). Preferably a full spectrum strength and conditioning program written by a Certified Strength and Conditioning Specialist and ideally by a Master Sports Performance Coach.

Ligament Dominance

Ligament dominance takes place when the athlete’s muscles aren’t capable of withstanding the stress placed on them during an activity.

Simply put, the forces either from momentum or gravity are too great for the athletes muscles to absorb, thus those forces are transferred to the ligaments instead.

Similarly to the quad dominant athlete, these athletes should take extra care of neuromuscular development, as well as the development of the posterior chain.

What Can Female Athletes Do To Help Reduce The Risk of an ACL Injury?

*Assuming the athlete has already been screen by a sports medicine physician*

• Understand why females are more susceptible in the first place.

• Start from the bottom up, wearing proper foot wear during weight training/ practice. For example, running shoes are only great for running. Running shoes are made to go forward, they offer incredibly poor lateral support (thus increasing the risk of knee injuries).

• Begin each weight training session/ practice with a general dynamic warm-up. A proper warm-up will help prime key muscle groups that are the prime movers for the forthcoming activity.

• Female athletes should participate in year round: Weight training, multidirectional speed & agility training, jump & plyometric training. Participating in such a program allows the athlete to progressively adapt to the stimulus of the program. If training ceases, so do adaptions (benefits) of the program.

• Female athletes should be able to demonstrate the proper biomechanics of not only the movements required by their sport, but also those during a resistance training program.

For more information on the sports performance program offered at The FIT Facility, click HERE!

Sources

https://orthonc.com/your-health/preventing-acl-tears-why-are-acl-tears-more-common-in-female-athletes

https://www.sportsmed.org/aossmimis/STOP/Prevent_Injuries/Revised/Injury/ACL%20in%20Youth%20Athletes.pdf

Brooks, T., & Wentworth, S. (2018). Complete sports training: speed, strength & conditioning for todays athlete. North Attleboro, MA: Athletes Acceleration, Inc.

Zatsiorsky, V. M., Kraemer, W. J., & Fry, A. C. (2021). Science and practice of strength training. Champaign, IL: Human Kinetics.

Baechle, T. R. (2016). Essentials of strength training and conditioning. Champaign, IL: Human Kinetics.