Why Are We Seeing An Increase In ACL Tears Each Year If Our Training Has Improved??

Why Are We Seeing An Increase In ACL Tears Each Year??

So what exactly is the ACL? We all have heard of it and we know it is a ligament in the knee. We know you never want to hear someone say, “You tore your ACL”. We also know that it normally requires surgery to fix and involves a long rehabilitation though physical therapy. But why does this injury occur and why are we hearing more about them every year?

First, I think we need to take a moment to get a little more understanding of knee function and what supporting structures help stabilize the knee joint. The primary function of the muscles surrounding the knee is to provide flexion and extension of the joint; it also has the capability for slight rotation, but this is very minimal and normally not discussed in most text.

Muscle is defined as a band or bundle of fibrous tissue in a human or animal body that has the ability to contract to produce a particular movement. There are 4 main muscles in the front thigh area, called the quads, which are responsible for extending the knee. They attach at the kneecap to form a tendon that then attaches to the front portion of the shin bone (tibia). A tendon is defined as a flexible but inelastic cord of strong fibrous collagen tissue attaching a muscle to a bone.

There are three main muscles called the hamstrings that flex the knee. These three muscles are located on the back of the upper leg and extend down to their tendons on the backside of the knee. There are other smaller muscles, tendons, and connective tissue that collectively surround and make up the knee joint but are not relevant for this article to discuss; just be aware of them if you would like to do more extensive research.

There are four main stabilizing ligaments in the knee joint. A ligament is defined as a short band of tough, flexible, fibrous connective tissue that connects two bones or cartilages or holds together a joint. The ACL or Anterior Cruciate Ligaments (also called the cranial cruciate ligament) main function is to stabilize the shin bone (tibia) from going forward. The PCL or Posterior Cruciate Ligaments main function is to keep the tibia from gliding backward. Both of these ligaments are found in the middle of the knee joint and form an “X”like pattern in the joint.


There is also a ligament on each side of the knee joint. The LCL or Lateral Collateral Ligament is located on the outer side of the knee joint. The MCL or Medial Collateral Ligament is located on the inner side of the knee joint. Each of these help prevent the knee from either caving in or out while performing movement. All of the ligaments, tendons, and muscles work too not only create movement but to stabilize the knee.

The bones of the knee joint are made up of the Femur (upper Thigh Bone), Tibia (Lower Shin Bone), Fibula (Lower leg bone positioned laterally to the tibia), and the patella (knee cap). Between the bones are menisci (plural for meniscus).   The meniscus are small “c” shaped pieces of cartilage that act as a cushions in the knee joint. They sit between the femur and the tibia, one on the outside (lateral meniscus) and one on the inside of the knee (medial meniscus).

It is important to know and understand these structures, how they work, and their functions if you truly want to learn how to prevent injuries. I have always thought that if you do not educate yourself about the body, how can you prescribe a training regimen to prevent injuries to the various areas of the body. If you do not know, then you should always seek out the trained professionals with a proven track record for advice and guidance.

In todays training society, being as advanced as it is, with more strength coaches training athletes with weights than ever before. Why is the number of ACL tears increasing every year? Yes, there are many hypotheses for this and I really have not come across any that I would completely rule out; maybe it is combination of reasons? However there is one thought process I have had for a few years now. One I have not heard anyone discuss before as a possible contributor. As the number of ACL tears increase each year, so does the belief that my thoughts on the issue may be correct.

I truly want to share my thoughts with as many individuals as I can so we can try to change some training thoughts to turn this whole thing around and save some knees in the process!

What is the one thing we see our youth of today doing more than ever before in the history of mankind. Wow, that is a bold statement; but when I tell you, I think you will agree right away.


Our youth today SIT more than ever before!!


Our youth today SIT more than ever before. Think about it, they go to school and sit most of the day, maybe go to practice after school and then come home and sit-talking on the phone, texting, watching TV, playing video games, or face booking on the computer all night.

It is my belief that because of this we are seeing our young peoples hip flexors starting to shorten.   Ten years ago, the biggest muscle weakness or imbalance I would access on incoming freshmen athletes to college was hamstring weakness compared to their quad strength. Today that is not the case. I now see more glute weaknesses or even the inability to adequately fire their glutes during exercise or movement and their hip flexors are extremely tight. Most of them cannot lie on their stomach and lift a leg off the floor without their pelvis rotating.

This is sad, because the most powerful muscles in the lower body for an athlete should be their glutes. So what does this have to do with tearing their ACL? It is my belief that if the hip flexor is shortening over time that there is a direct relationship of the glutes being inhibited resulting in less excitation or lack of stimulation during movements when the glutes should be more of a dominate or prime mover. Again, what does this have to do with ACL tears?

If the glutes are not a dominant muscle going into and out of athletic movements then the dominance will be on the quads. The majority of non-contact ACL tears occur when an athlete is sprinting forward, they go to change direction and the dreaded “POP” occurs.

Lets use this example, a lacrosse player is sprinting down the field and quickly has to head to the left, he/she will normally plant on the right foot and drive towards the left. Understand that in any movement there will be a level of deceleration to acceleration properties that take place. If the athlete is Quad dominate and we know that the quads and their tendons (patellar tendon) attach to the front of the tibia, then those quads will be firing and pulling on that tibia to continue forward as slight rotation will occur to change the direction. These two factors will place that direct stress right on the ACL to keep the tibia from gliding forward. This overload can potentially be too much causing something to give.


 Now take that same scenario with an athlete who has good glute activation. If the glutes are the primary decelerator to accelerator (which they should be!) there will be minimal pull to the front of the tibia, which will result in less overload being placed directly on the ACL to manage. The forward translation (angle) of the knee will also be decreased; as a result, the athlete will be faster and move into an accelerated position much more fluidly and with greater speed.

The best way to acquire this is by re-educating the glutes to be primary movers in the lower body. The ultimate way to do this is through deceleration training. Many strength coaches will agree that in order to maximize acceleration you must first master deceleration. The key is learning how to do this systematically with the entire emphasis being placed on the glutes with the expectation that once athletes are trained properly, this firing process with the glutes will come automatically during sport.

I have spent years trying to perfect a simple solution to deceleration training techniques for coaches to implement into their teams current training programs. What I came up with is “Deceleration Training To Prevent ACL Tears.”With the help from Jedd Johnson (Diesel Crew), we were able to make this information attainable to everyone. This systematic approach has been used for 8+ years with outstanding results. I really believe this is a crucial step in reducing and many times preventing ACL tears in athletic programs.

Get This Proven System Today By Clicking On The Image or click HERE!!

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Hope this helps!

To your health,


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About Jerry Shreck

Division 1 Head Strength Coach at Bucknell University, Specialize In The Art of Injury Prevention Training Techniques God Loving Family Man (Wife-Trina & 2 daughters-Alexis & Aleyda)

3 Responses to “Why Are We Seeing An Increase In ACL Tears Each Year If Our Training Has Improved??”

  1. Interesting subject, Jerry. As a labor negotiator for over 31 years, I frequently stated the mantra, “In God we trust – all others bring data!” First, I wonder what the data show for increases in ACL tears over time; what was a “normal” incidence of ACL injury, when did an increasing trend begin and to what extent has there been a statistical analysis of the data. Second, what other possible factors are there in addition to a more sedentary lifestyle and are there any metrics to quantify their effects. I’ve wondered whether there is a statistically demonstrable increase in the height and weight of athletes. I’ve seen some data documenting increases for football players and I’m sure that it’s true for basketball players as well, certainly over the 50 years since I played, but I haven’t been able to find data. I believe that would be significant because the ground reaction forces would be greater with heavier athletes and the “levers” will be longer with greater forces and moments applied to the joints. Given the increased length, it presumably would take greater control forces to allow the hips to stabilize the forces occurring at the knees. I also wonder whether there are any metrics that would track hip strength for flexion, extension, abduction and adduction in a population of athletes over time. Since the advent of Title IX and the research that clearly shows a higher incidence of knee injury in female athletes, especially in basketball, soccer and volleyball that require cutting, jumping and landing, I wonder if any data showing increased ACL tears is disaggregated by gender. If there’s a significant increase in the number of female athletes included in the aggregate data over time, that could skew the data. There was a tremendous article in the NSCA Strength and Conditioning Journal a few months ago focusing on the incidence of ACL injuries in female athletes. It noted among other things, that female athletes tended to cut and land at shallower knee flexion angles than their male counterparts; cut and land in a valgus knee position which is predictive of knee injury and makes the knee more vulnerable; strength imbalance between quadriceps and hamstrings; lag in co-activation between quadriceps and hamstrings, with the hamstrings “firing” significantly slower in female athletes. The article discussed the effect of multi-faceted programs to remedy the deficits, including plyometrics; strengthening the core and legs, especially the hamstrings; balance training; and technique development to promote greater knee flexion on cutting and landing, as well as proper alignment of the hip, knee and ankle. I wonder if strength and movement screening to identify and correct relative strength deficits and movement issues would be effective in reducing the incidence of ACL injuries in the entire athletic population, including those tall guys with the long levers!

    • Rex,
      GREAT comments and points to consider. All the research I have found over the years is normally general to a certain sport and doesn’t date back that far. I have other generalized numbers showing increases each year but again they don’t date back to far either. Professional sports seem to have the best numbers and data but they normally don’t release much of this type of information and you need to contact people directly for it.
      I agree there needs to be more studies on some of the things you have stated and personally have looked into doing my own study about 3 years ago but honestly I just don’t think I can devote the time towards it with my busy schedule.
      What I have always found interesting is talking with older individuals in their 80’s,70’s and even some in their 60’s that played sports even on the professional level about how many ACL tears they saw when they played and many of them say “none”.

      • Rex Trobridge, CSCS*D Reply June 27, 2014 at 2:06 PM

        As one who’s pushing 70 (in September) and played basketball in the early to mid-60’s, I don’t recall seeing or hearing much about knee injuries during that time. I think most of the information from that era will be anecdotal and subject to the vicissitudes of distant recollections because sport and exercise science wasn’t even in its infancy back then and my guess is that there was little data collected. Unlike today, knee injuries were pretty devastating in the days before arthroscopic surgery and resulted in long zippers on both sides of the knee and lengthy recovery and rehab. As a result, my guess is that many injuries that would be easily “scoped” today and the athlete would be back on the field or court relatively quickly, back then would be career-ending. When I blew my knee playing semi-pro ball in Buffalo in 1967 or ’68, since I wasn’t playing in the NBA and didn’t have easy access to PT it was never surgically repaired. I also suspect that the pressure on young athletes to specialize in one sport early on creates the potential for overuse injuries and limits the development of movement skills and balanced muscle strength that also creates the potential for injuries later on. I hear conflicting information regarding strength training experience for current athletes. Fifty years ago, athletes, especially basketball players were actively discouraged from “lifting weights.” “You’ll get muscle-bound,” and, “It will throw your shot off” were generally the prevailing wisdom. Holding my Syracuse team picture next to the TV screen while watching basketball today suggests not only different demographics but also far different anthropometrics – the athletes today are taller, bigger, stronger, faster and jump higher than those of my era. While I believe part of the reason for this is that athletes of both genders are actively working-out much earlier, giving rise to substantially greater physical development and capacity at earlier ages, I’ve also read that not all the athletes arrive at college with strength training experience. For example, Ryan Cabiles, Head S&C Coach for basketball at SU had an article published in Training & Conditioning magazine several years ago noting that point and detailing their progression of young athletes starting with body weight training and moving through an array of progressions to bring them along. In addition, I’ve seen a number of high school training rooms that are filled with an array of machines that will develop strength in prime movers but have no effect on the collateral muscles and stabilizers, especially around the hip, that will help to reduce the incidence of injuries. So perhaps one hypothesis might be that many of today’s young athletes are bigger, stronger and faster but without the full array of movement skills that might have been developed by playing multiple sports and without the stability and control that might have been developed by an appropriate and balanced training program that concurrently developed stability and mobility to go along with the explosive power required in contemporary sports. Interesting topic and I appreciate your information, even though I’m not training athletes and my interest is now fundamentally on seeing my grandsons perform safely and at a high level in their chosen sports and for that, we’ve got my older grandson training with Ron Greenfield, an outstanding trainer of scholastic and collegiate athletes. Thanks again, Jerry!

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