Youth Athletes and Sports: Why is there a knee injury epidemic among girls?

By Jeff Miller

Anyone who has a daughter who plays sports has or will at some point see what is called a non-contact knee injury. Whether itʼs their daughter or another player, it will happen.

I say that because there has become an epidemic of non-contact knee injuries in female sports. By non-contact, I mean the player is running down the field or court, goes to change directions and “boom” — blows out the knee. This has become prevalent in what are called cutting sports like soccer, basketball and volleyball. We have to ask ourselves why does this happen, what has changed in female sports to make it more prevalent, and what can be done about it?

While searching for causes, we first must look at anatomy-related components that may contribute to an increased potential for these knee injuries. When we look into female anatomy we see that the knees very often have a lot of valgus motion. Valgus is a term that refers to extreme position or motion, which for our purposes can be thought of as knock knee. If you have ever seen a female basketball player start to jump and their knees collapse toward each other prior to jumping, then you can envision what valgus motion looks like.

In addition, there is often underdevelopment of the hamstrings (muscle group that makes up the back of the thigh from the knee to the glutes ), which limits the ability to balance out the stress put on the knee by the quadriceps (thigh muscle) when running and changing directions. This creates what is known as anteriorly biased tension on the connective tissue of the knee that is due to a lesser stabilizing contribution from the posterior muscles. All of our bodyʼs joints rely on balanced tension from all
muscles that are involved with function, and when we have imbalance the likelihood of injury increases.

The third and final anatomical consideration has to do with knee flexion. Female athletes generally use less knee flexion than their male counterparts. This is evident when jumping, cutting and landing. The reduction in knee flexion at various points of movement results in greater tension on connective tissue. Combine that with valgus position, muscle imbalance and quadricep- dominant sports, and youʼve created a greatly increased potential for knee injuries.

The second part of this is that we have to examine what has changed in female sports that has added to this epidemic. First, female sports is more competitive than ever. The number of female athletes playing today compared to as little as 20 years ago has dramatically increased. This, of course, means the level of competition and talent has also increased. With that increase comes more pressure on performance, more games and more time at practice.

The explosion of select sports programs has added to this as well. With many select sports teams playing 10-plus months out of the year, there is an increased physical toll on the athletes. As a side note, I am not placing the blame on select sports; I’m only saying that it has an additional impact.

Now the reality is the sports scene is not going to go backward. The future will continue to get more competitive with higher expectations and greater demands on athletes. With that in mind, we need to look at what can be done now to reduce the risks to our female athletes. One option would be to place limits on how much time is being dedicated to a sport throughout the year. In my opinion, however, that option is unrealistic due to the popularity and competitiveness of sports in our society.

The more realistic option is that female athletes need to spend some time on a regular basis performing exercises or activities that will help to develop the physical balance and conditioning needed to lower the risk of sustaining a knee injury. Parents and coaches often make the mistake of perceiving this is being done when their athletes do conditioning work at practice. However, upon closer inspection, a lot of times those practice conditioning sessions are just adding to the stress on the knee by working the same muscles that are imbalanced to begin with. The proper program needs to incorporate development of appropriate levels of strength in the hamstrings, ability of the connective tissues to stabilize effectively both statically and dynamically, increased joint mobility, balance and overall flexibility.

In conclusion, the amount of time needed to create this benefit is minimal relative to the amount of time players are already working on developing their games. Yet, the benefits to incorporating a proper program will not only greatly improve performance, but will also greatly reduce the risk for injury. In the long run, players will miss less time due to injuries, have a lower risk of creating long-term chronic issues, and will be stronger and faster athletes. The impact and prevalence of traumatic
knee injuries has become to big to ignore. The choice has become simple: Roll the dice or do the little bit extra that it takes to lower the risk.

Jeff Miller is the owner of Absolute Fitness & Sports Performance. He has a bachelor of science degree in fitness management from Southern Oregon University, an ACSM HFI certification, and an IYCA youth speed and agility certification. Miller has spent the past 20-plus years working in the fitness industry helping athletes of all ages and sports to excel. He also is currently the strength and conditioning coach for the Edmonds-Woodway High School wrestling and basketball teams, and Edmonds Junior Football.

  1. Thanks so much for this article. Having had ACL reconstructive surgery 20+ years ago from a competitive volleyball injury, it explains a lot. Sadly, I am definitely limited in my scope of sports/activities now due to my poor knees. From my perspective, it’s not worth the risk of rolling the dice. Get your athletes to do the extra work to preserve their health in later years!

  2. As the author of They’re Not Boys – Safely Training the Adolescent Female Athlete I must applaud the author for setting the record correctly.

    What I call BNP Training works for all female athletes in all sports and if we are to make a dent in the too high ACL injury rate for female athletes – training to play sports is the next big hurdle for all female athletes to embrace.

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