Neuromuscular Coordination Training for Athletes at Higher Risk of ACL Injury
When we talk about the knee joint the Anterior Cruciate Ligament (ACL) as well with the Posterior Cruciate Ligament (PCL) is one of the most crucial (no pun intended) ligaments in the knee. The knee joint and the ACL are some of my favorites to talk about. This is possibly because I'm a soccer player by trade and have experienced ACL injuries second hand from teammates or possibly due to the fact that I train a fair amount of soccer players with the majority of them being females. My strength and conditioning programs at OPZ aim to help prevent the chance of any injury including ACL injuries, especially in high risk athletes. Before jumping into what the sum of this article is about, it is important to understand what the ACL is and what role it plays in the knee.
The ACL is a ligament that helps attach the tibia (shin bone) with the femur bone (thigh bone) and plays a crucial role in keeping stability via passive restraints throughout the knee joint. Unfortunately, out of the four ligaments in the knee the ACL is the one of the most frequently injured. An ACL tear can lead to many problems and roadblocks even well after an ACL reconstruction surgery. So why not try and reduce the chance of it from happening in the first place? The role of the ACL is to prevent and control anterior translation of the tibia, tibial rotation and varus and valgus knee stress (the typical knocked knee)(1). Injuries to the ACL can either happen by contact or non-contact mechanisms with about 72% of them happening via non-contact mechanisms(2). The fact that most ACL injuries happen due to non-contact mechanisms drives me to better understand why and how to reduce the chance of this happening to athletes. Athletes that play any sport that involves high-intensity cutting and deceleration will have a greater chance of tearing an ACL compared to those athletes in different sports. Let's also get the elephant in the room out, yes, females do have a greater chance of experiencing a non-contact ACL injury compared to their male counterparts. I wrote an article on Assessing the Female Soccer Player that talks more about why.
There are many factors that contribute to a possible ACL tear which can include, but are not limited to gender, age, biomechanical factors, genetics; experience, training, sport position, dominant leg, sport and shoe-surface and previous ACL injury(3). So basically, there are a lot of reasons why someone might injure their ACL, with some of them being more controllable than others. Overall, when the foot is fixed or stuck on the ground and then the knee joint is hyperextended it will most likely result in some kind of ACL injury. The quads also play a large role in this. Some research has also suggested that the lack of force produced by the hips and lack of range of motion may be a contributing factor to ACL injuries as well(4,5). Mike Boyle mentions in his Joint-By-Joint Approach that if there is a decrease in mobility at the ankle joint and hip joint it can cause instability at the knee joint. To keep things simple we will stick to the scenario that when a foot strike occurs and the knee is close to full extension the ACL is compromised.
With all this being said, what's the deal with ACL prevention? Is it a waste of time or is it beneficial? I will be the first to say that a lot of ACL prevention programs and/or exercises are so gimmicky and probably a waste of time. Put the Bosu ball away and do something better. At the end of the day, injury prevention programs have shown to be effective. Beneficial ACL prevention exercises and programs have focused on biomechanical features and have shown to reduce the chance of injury by 52% in female athletes and 85% in male athletes(6,7). When training athletes it is important to consider the individual athlete, biomechanics or technique, compliance, frequency/volume, feedback and variety of exercises(8). This is where proper assessing, programming and exercise selection comes into play. Personally, I use three main methods; strength training, plyometric training and neuromuscular coordination training to help prevent the chance of any ACL injuries.
Also, before I get started it is important to note that the knee needs increased stability, as Mike Boyle explains in his Joint-by-Joint Approach. I say again, the knee needs to be stable. If you haven’t taken a look at the Joint-by-Joint Approach I highly recommend looking at it.
In this article I will briefly go over the concept of neuromuscular coordination training (NCT) and why and how I use it.
NCT helps with neuromuscular control which is described as the unconscious trained response of a muscle to a signal regarding functional joint stability(9). Functional or dynamic joint stability refers to being able to keep proper technique through movements while performing high intensity movements. It’s basically doing certain movements without having that “giving out” feeling. The knee joint and even the ankle joint is controlled through neuromuscular control, which is why NCT plays such a large role in my ACL prevention programming. NCT method uses biomechanical and neuromuscular principles to improve sensorimotor control and functional stability(9). Sensorimotor can simply be referred to as using both our sensory system and motor system together. Overall, the goal of NCT is to train both nerves and muscle together so they can communicate quickly, correctly and efficiently. This is important because research shows that a decrease in neuromuscular reaction time can result in a certain level of functional joint instability, remember the knee joint needs stability(9)! Another positive is that NCT will improve overall movement quality, strength, balance and technique.
The important part with NCT is to make sure that quality of the movement with adequate control is the main focus. NCT has to be controlled in all three planes of motion (sagittal, frontal, transverse) in order to be effective. With that being said, when I utilize NCT I make sure that the quality of the movement is correct and I pay close attention to make sure proper alignment of the upper trunk and lower limb joints are maintained. The underlying goal of NCT is to obtain equilibrium of loaded segments in both static and functional situations to be able to control certain demands of the game(9).
I like to use two different drills; 1-Leg Reactive Neuromuscular Coordination (Mirror Drill) Training and a simple 1-leg Medial/Lateral Line Hop Neuromuscular Coordination Training. This training method is great for athletes that have a high risk of ACL injury, such as female soccer players and/or athletes that have had a past ACL injury. I like to use this training either in the pre-training program (warm-up) or at the end of a full training session or even sometimes both. When performed earlier in the warm-up it allows for proper technique and ideal quality of the movement. This is where I would program the first training drill as it is more difficult. When NCT is performed at the end of a training session it is more challenging due to the onset of fatigue, but because ACL injuries often occur in fatigued states it is beneficial to expose an athlete to these certain movements similar to what the game demands. Oftentimes I will even add extra movements or exercises prior to the NCT to enhance more fatigue in the athlete. When NCT is performed after training sessions I usually use the second exercise as it's less difficult, but I will possibly use the first exercise as well for higher level athletes.
Here is an example of 1-Leg Neuromuscular Coordination (Mirror Drill) Training:
I program about 2 sets of 8-12 seconds on each leg.
Here is an example of controlled 1-Leg Medial/Lateral Line Hop Neuromuscular Coordination Training:
I program about 2-3 sets of 10 seconds of each leg.
Overall, as strength and conditioning coaches it is our responsibility to use proven methods to help keep athletes healthy. NTC is just one method I tend to gravitate towards when training high risk ACL injury athletes as other methods should also be considered. Each athlete is different so taking an individualized approach will make a big difference.
References
Friedberg MD. Anterior cruciate ligament injury. Post TW, ed. UpToDate. Waltham, MA: UpToDate Inc, https://www.uptodate.com (Accessed on April 13, 2019.)
Alghamdi W, Alzahrani A, Alsuwaydi A et al. Prevalence of Cruciate Ligaments Injury among Physical Education Students of Umm Al-Qura University and the Relation between the Dominant Body Side and Ligament Injury Side in Non-Contact Injury Type. American Journal of Medicine and Medical Sciences. 2017;7(1):14-19.
Volpi P. Risk factors of anterior cruciate ligament injury in football players: a systematic review of the literature. Muscles Ligaments Tendons J. 2016.
Nguyen A, Zuk E, Baellow A, Pfile K, DiStefano L, Boling M. Longitudinal Changes in Hip Strength and Range of Motion in Female Youth Soccer Players: Implications for ACL Injury, A Pilot Study. J Sport Rehabil. 2017;26(5):358-364.
Gomes J, Palma H, Ruthner R. Influence of hip restriction on noncontact ACL rerupture. Knee Surgery Sports Traumatology Arthroscopy. 2014;22(1):188-191.
Nessler T, Denney L, Sampley J. ACL Injury Prevention: What Does Research Tell Us?. Curr Rev Musculoskelet Med. 2017;10(3):281-288.
Sadoghi P, von Keudell A, Vavken P. Effectiveness of Anterior Cruciate Ligament Injury Prevention Training Programs. The Journal of Bone and Joint Surgery-American Volume. 2012;94(9):769-776.
Sugimoto D, Myer GD, Micheli LJ, et al. ABCs of evidence-based anterior cruciate ligament injury prevention strategies in female athletes. Curr Phys Med Rehabil Rep. 2015;3(1):43–49. doi: 10.1007/s40141-014-0076-8.
Neuromuscular Exercise Program. (2020, October 17). Physiopedia, . Retrieved 16:33, November 5, 2020
