Tuesday, 26 February 2013

ACL article for the sporting athlete.

Training to minimise the sporting knee complaint.
Learning Objectives:

  1. To create an awareness in the reader and general trainer population in what activities and ‘events’ are high-risk for non-contact ACL injuries.
  2. To raise the awareness on the importance of a well-designed, multi-pronged training program designed to address the several components contributing to non-contact ACL injury prevention.
  3. To challenge the reader to continue study and research in this oft-overlooked, but extremely important aspect of athletic training – particularly for female athletes.

An athlete makes a sharp cut on the soccer field as she approaches the ball, or lands after grabbing a rebound in basketball. Suddenly there’s a loud popping sound from her knee that any athlete dreads hearing, and she crumbles to the ground – she has torn her ACL! Every year, the press has several news reports of high-profile professional athletes, such as NBA Most Valuable Player Derrick Rose or perennial Major League Baseball All-Star Mariano Rivera, suffering one of these potentially career-changing non-contact ACL injuries. These injuries seem to be all too prevalent in the sports world today. Though perhaps not as prominently displayed, but just as devastating, is the same injury to our College-level athletes; here’s one such example as reported in the Washington Post on December 1, 2012, “The 11th ranked Maryland women’s basketball team will be without starting guard Laurin Mincy for the rest of the season after the junior tore the anterior cruciate ligament in her right knee during Wednesday night’s …[A]n MRI exam on Thursday revealed the tear, which is the second of her career and the third to befall a member of the women’s basketball team.” But what often flies under the radar of media coverage and public attention is the literally thousands of these injuries that occur each year at the Middle School, and High School level as well – those injuries to our typical training client.

The Big Three

While a select few sports – soccer, basketball and volleyball – are recognized and reported as being the primary culprits for this type of injury and have become known as ‘The Big Three,’ the truth is that an athlete playing any sport requiring quick stops, cuts or changes in direction, or landings can be at risk for this injury. According to the American Orthopaedic Society for Sports Medicine (AOSSM), 70 percent of all ACL tears are non-contact in nature, and most of those occur during a landing or quick deceleration such as cutting or stopping (AOSSM, 2008). These injuries can have a devastating negative impact not only in terms of medical costs (it has been reported that the annual medical cost associated with these types of injuries exceed $650 million per year), but can also have a long-lasting impact on the specific athlete’s ability to perform in their sport, and on their quality of life outside of sport.

With literally hundreds of thousands of these injuries occurring each year, and with statistics revealing that female athletes suffer this type of injury at a rate that’s between 2-10 times higher than their male counterparts, the need for more attention focused on helping our athletes --- particularly females --- reduce their risk for these injuries could not be more apparent.

The ‘Typical’ ACL Injury

So, what does a ‘typical’ non-contact ACL injury look like? And how can we help our athletes avoid or at least reduce their risk for these terrible injuries? While there may not be a ‘typical’ non-contact knee injury per se, here are some of the common elements for this type of injury, as noted by several researchers:

The Quadriceps versus the Hamstrings

According to some researchers, many non-contact ACL injuries appear to be associated with multi-plane knee loadings where the ACL is excessively loaded due to strong quadriceps muscle forces (Myer, Ford, Jensen & Hewett, 2007). These strong forces are combined with frontal-plane and/or transverse-plane knee loading, and insufficient hamstring muscle co-contraction forces. A fairly typical example of this type of scenario would be where an athlete lands from a jump in a stiff legged and valgus (knees collapsing inward) position resulting in strong contractions of their quads coupled with a much lesser involvement of their hamstrings.

Many researchers consider the quadriceps muscles as one of the major forces producing an anterior force on the tibia, and it’s this anterior tibia force that loads the ACL – sometimes to excess and failure (Barber-Westin, Noyes, Tutalo-Smith, & Campbell, 2009). Conversely, the hamstring muscles exert a force that is associated with protecting the knee from this type of injury by leading to knee stability when they co-contract with the quadriceps. This is because of the hamstrings’ function of exerting a counter – posterior-shear force at the tibiofemoral joint. Knowing how these two muscle groups function, leads to the simple conclusion that teaching our athletes proper techniques for landing, cutting and stopping would be instrumental in helping to reduce their risk of this injury.

By training our athletes on proper muscle recruitment patterns that involve contraction of their hamstrings; and by helping our athletes to improve their hamstrings-to-quadriceps strength ratio so that the hamstrings are strong enough to serve their protective function – we can take some important steps to help our athletes reduce their risk of non-contact knee injury.

There are many components to a well-designed training program targeted to reducing the risk of non-contact knee injuries. A cursory online review of research reveals that there are a number of ACL-injury prevention programs out there. While a review of each of these programs and the training techniques that they espouse is beyond the scope of this paper, I would highly recommend that the reader conduct their own research in this area to determine which, if any, of these programs satisfies their needs.

There are a few components that are common to most, if not all, of these programs and the remainder of this article will review 3 components you may wish to include in your training program designed to help your athletes.

Common Components of an Injury Prevention Program

Training and drills targeted at teaching and training our athletes to become safer on the field of play by reducing their risk of non-contact ACL knee injuries fall under several categories:

  • Strength Development,
  • Deceleration Technique, and
  • Kinesthetic Awareness Training or Controlling the Center of gravity (COG).

As trainers and coaches, we can have a positive impact in each of these areas.

Strength Development

Research findings indicate that by improving the athlete’s hamstring strength in relation to the quadriceps, we can better prepare those muscles to perform their protective co-contraction function when our athletes decelerate, and thus help them protect their knees from these types of injuries. By improving or maintaining the athlete’s hamstring strength we can have a positive effect on reducing their risk of these injuries. Additionally, improving the strength of the entire lower body posterior chain musculature will help reduce the occurrence of contributing factors such as valgus - which is often cited as being exacerbated by having weak gluteus medius muscles.

Exercise suggestions: Russian hamstring curls, Single-Leg Deadlifts, Squats, Lunges, Ankle Cuff Lateral Walks and Leg Curls can each be effective in improving strength for these muscles.

Figure 1(a): Ankle Cuff Lateral Walk

Figure 1(a) above shows the athlete in the starting position before performing an Ankle Cuff Lateral Walk. This exercise is used to strengthen the glutes – specifically the gluteus medius, a muscle that is instrumental to helping reduce the risk of non-contact knee injury.

Figure 1(b): Ankle Cuff Lateral Walk

In Figure 1(b) the athlete has taken a lateral step against the resistance of the ankle cuff band. Although not reflected in this photo, have the athlete point their toes straight-ahead throughout the exercise, which will help focus the tube resistance work onto the gluteus medius as intended.

Deceleration Technique Training

The primary focus for many speed coaches and trainers is on improving speed and acceleration. Yet, it’s in teaching properdeceleration techniques where we as trainers can have a positive impact on non-contact knee injuries. Deceleration training is an important, and often overlooked, part of speed training and injury prevention. Not only will teaching our athletes how to decelerate properly have a positive impact on their risk of injury, but also this will help our athletes become effectively fast by teaching them to control their speed in a way that allows them to perform an athletic skill in conjunction with their speed.

The skill-sets of acceleration and deceleration are mirror images of each other and are not, and should not, be treated the same. For example, in the case of jumping and landing (i.e. vertical speed and power), jumping or vertical acceleration is about improving ground-force production, while landing or deceleration training is all about improving ground-force reduction. These two abilities go hand-in-hand and are opposite sides of the training coin. Yet much of what we do as coaches and trainers is spent on theproduction side of this equation.

Reducing our athletes’ risk of non-contact knee injury relies to a great extent on developing the ability to reduce the forces of landing or stopping. From a deceleration perspective, this means using exercises and cueing tips that raise our athlete’s awareness during deceleration. Cueing the athlete to produce a “soft landing,” or a “quiet landing,” while incorporating triple-flexion (flexed ankles, knees and hips) on their landings is just one example of this type of training tip or cue used to improve our athlete’s vertical deceleration technique. Figure 2(a) and Figure 2(b) below show one exercise that I use to teach triple flexion from a stationary position. Once the athlete has adequate experience with triple flexion from this position, I introduce a more dynamic exercise requiring the athlete to jump and land into triple flexion with the cueing for a “soft landing” (see Figure 2(c)).

Figure 2(a):
Deceleration Training Technique – Step 1
Figure 2(a) shows Step 1 of a drill I use to teach athletes soft landing into ‘triple flexion.’ Here I stand on a 12 inch platform holding a light medicine ball. I instruct the athlete to ‘catch the ball when I drop it,’ and as she catches it to ‘drop into triple flexion.’

Figure 2(b):
Deceleration Training Technique – Step 2
Triple Flexion

Figure 2(b) shows the athlete after she catches the ball while simultaneously dropping into triple flexion from her stationary position. While admittedly this final position is not one that the athlete may normally use in a sport competition, this exercise teaches the athlete what triple flexion is and feels like, and gives her the biomechanical feedback necessary to recreate this feeling during athletic competition.

Figure 2(c):
Deceleration Training Technique
Jump prior to Triple Flexion

Figure 2(c) shows the athlete jumping – as if she has just grabbed a rebound – from her position in Figure 2(b). From this jump, the athlete will land again into triple flexion and with a soft landing.

Kinesthetic Awareness and Control of COG

Researchers have cited landing with stiff legs, and decelerating either vertically or horizontally in a valgus knee position, as two main contributors to non-contact knee injuries. Also, studies have shown that many of these types of injuries occur during what researchers call a perturbation event. This is where the athlete decelerates in an uneventful way, but then is suddenly or simultaneously perturbed or disturbed – meaning bumped or otherwise contacted physically in a way that throws them off balance.

Teaching our athletes to become more kinesthetically aware of what their bodies are doing and where their various body parts are in relation to one another during these types of athletic skills is vitally important to the safety of our athletes (Fitzgerald, Axe, & Snyder-Mackler, 2000).

Exercise suggestions: Chair Stand-ups (while looking for signs of valgus), Drop-landings with triple flexion (ankles, knees and hips), Single-leg Squats, Stork Stands with perturbations, and Speed Skaters, are a few of the exercises intended to teach the athlete this type of kinesthetic awareness. During these exercises, the athlete should be required to stop after each repetition and bring their center of gravity under control (i.e. not toppling over laterally).

Figure 3(a): Speed Skater exercise

Here’s an example of the Speed Skater exercise. In Figure 3(a) above, the athlete has performed the Speed Skater exercise with ‘controlled deceleration.’ By controlling her body position and center of gravity the athlete reinforces her ability to dynamically decelerate from a lateral acceleration --- a sport skill that oftentimes leads to non-contact knee injury.


ACL injuries of all types are devastating injuries when they occur. While little can be done in the way of preventing or reducing the risk of the contact ACL injuries typical to such sports as football, trainers can have a significant positive impact on reducing the risk of noncontact ACL injuries when using proper program design and planning. This article highlighted some of the components of effective non-contact ACL Injury Reduction Programs as a way to stimulate thinking in this important direction for any trainers working with athletes.

By designing a training program that incorporates these and other important components, we as trainers can play a significant role in helping to reduce the epidemic of non-contact knee injuries, and thus become instrumental in helping our athletes improve the quality of their athletic and everyday lives.


Hewett, T. E., Shultz, S. J., & Griffin, L. Y. (2007). Understanding and Preventing Noncontact ACL Injuries. Champaign, IL: Human Kinetics.

Dintiman, G., & Ward, B. (2003). Sports Speed. Champaign, IL: Human Kinetics.

Noyes, F. R. and Barber Westin, S. D. (2011). Anterior Cruciate Ligament Injury Prevention Training in Female Athletes: A Systematic Review of Injury Reduction and Results of Athletic Performance Tests, Sports Health: A Multidisciplinary Approach, 4(1), 36-46.

Cross, M. (1998). Anterior Cruciate Ligament Injuries: Treatment and Rehabilitation. Retrieved May 6, 2010, from http://www.sportsci.org/encyc/aclinj/aclinj.html/

Meyer, G. D., Ford, K. R., Jensen, B. L., and Hewett, T. E. (2007). Differential Neuromuscular training Effects on ACL Injury Risk Factors in “high-Risk” Versus “Low-Risk” Athletes, BMC Muscular Disorders, 8(39).

Barber-Westin, S. D., Noyes, F. R., Tutalo Smith, S. and Campbell, T. (2009). Reducing the Risk of Noncontact Anterior Cruciate Ligament Injuries in the Female Athlete, The Physician and Sportsmedicine, 3(37), 1-13.

Fleming, B.C., Oksendahl, H., Beynnon, B. D. (2005). Open or Closed-Kinetic Chain Exercises After Anterior Cruciate Ligament Reconstruction, Exercise Sport Science Review, American College of Sports Medicine, 33(3), 134-140.

Lephart, S. M., Pincivero, D. M., Giraido, J. L. and Fu, F. H. (1997). The Role of Proprioception in the Management and Rehabilitation of Athletic Injuries, American Journal of Sports Medicine, 25, 130-137.

Fitzgerald, G. K., Axe, M. J. and Snyder-Mackler, L., (2000). Proposed Practice Guidelines for Nonoperative Anterior Cruciate Ligament Rehabilitation of Physically Active Individuals, Journal of Orthopaedic & Sports Physical Therapy, 30(4), 194-203.

American Orthopaedic Society for Sports Medicine, Anterior Cruciate Ligament (ACL) Injury Prevention, (2008).
COMMENTS Add Comment
 De Veirman, Lieven | 13 Feb 2013, 08:42 AM
Not sure if we should teach our athletes to consciously avoid a valgus knee position. Pronation is the most natural movement and I would prefer teaching my athlete's muscles how to get into pronation/valgus, decelerate the movement and explode back to the other direction.
 Cook, LaRue | 12 Feb 2013, 04:09 AM
Hi Brian. Thanks for your comment. I agree that “discovering a pattern of weakness” is a key element of developing an effective program here. One such weakness is (or can be) the strength ratio gap between the quads and posterior chain musculature – a weakness that has been shown to be a potential contributing factor to non-contact knee injuries in sports.
“Cleaning up movement patterns” (where such defective patterns exist) is necessary as well, and oftentimes one of the primary movement pattern defects in this area – improper deceleration - is related to this muscular imbalance. Learning proper deceleration technique is a key to reducing the risk of non-contact knee injuries in sports movement, and obtaining or maintaining the requisite strength to properly decelerate goes hand-in-hand with this technique. The article speaks of three components to the training program --- strength development, deceleration technique and kinesthetic awareness. Each of these components is an important part of the program, and forms an integral part of the whole. Thanks again for your comment and I hope that you found the article somewhat helpful.
 Strachan, Gary | 11 Feb 2013, 01:57 AM
I think training for function may be the best place to start. Replicate all the possibilities of where the knee may go, and train at different tempos, ROMs, under load, no load, different drivers etc. And look for mobility or lack of to structure.
 Thurston, Brian | 08 Feb 2013, 18:36 PM
My belief is that there seems to be a great value in discovering a pattern of weakness or tightness and then exploring how to improve this pattern of weakness or tightness. I think to say that targeting the glute medius as a stamped out program for all athletes may not be the best way to go. Additionally, hamstring strength (as co-contrators) may not be as important to preventing sheer on the tibia-femoral region as we think. By strengthening the hamstrings without first cleaning up movement patterns, we may be doing what Gray Cook calls "adding fitness to imbalance".

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