Sports Medicine Research: In the Lab & In the Field: Neuromuscular Training to Reduce ACL Injuries may be More Effective in Younger Athletes (Sports Med Res)


Monday, November 5, 2012

Neuromuscular Training to Reduce ACL Injuries may be More Effective in Younger Athletes

The Influence of Age on the Effectiveness of Neuromuscular Training to Reduce Anterior Cruciate Ligament Injury in Female Athletes: A Meta-Analysis

Gregory D. Myer, PhD, FACSM, CSCS, Dai Sugimoto, MS, ATC, CSCS, Staci Thomas, and Timothy E. Hewett, PhD; Am J Sports Med. 2012 Oct 9. [Epub ahead of print]

Anterior cruciate ligament (ACL) injuries early in life may not only have an immediate impact on an athlete’s career but may also have longstanding effects well beyond the years of active athletic participation.  The best way to prevent these long-term consequences is to avoid ACL injuries.  Currently neuromuscular training (NMT) programs are the focus of ongoing research to determine their effectiveness in preventing ACL injuries.  Some investigators theorize that there may be an optimal age to initiate NMT among young female athletes; however, this has yet to be evaluated.  With this meta-analysis the authors assessed the influence of age at the time of implementing NMT on the effectiveness of NMT to reduce the risk of ACL injuries.  They hypothesized that NMT is more effective in younger populations.  Of the available literature, the authors identified 14 studies that met the inclusion criteria. They then extracted data regarding the number of ACL injuries, contact or non-contact mechanism of injury, number of athletes, and age of the participants.  The meta-analysis of these 14 studies showed that NMT reduced the odds of knee injuries among female athletes compared to those in control groups (odds ratio = 0.54).  NMT participants < 18 years of age reduced their risk of knee injury by 72% compared to controls but the >18 years of age group did not experience a similar benefit.  Finally, the authors divided the study population into mid-teens (14-18 years), late teens (18-20 years), and early adults (over 20 years). Meta-analysis of these groups indicated a greater reduction of knee injury risk in the mid-teen category (72% reduction) when compared to late teens who had a trend for less knee injuries (52% reduction) and early adults, who had no reduction in knee injury risk.

The results of Myer’s study suggest that integrated NMT programs have the greatest effect in reducing ACL injuries when initiated between 14 and 18 years of age.  The authors provide two possible explanations for this result:  (1) greater motivation/compliance of younger athletes and (2) the influence of changes in the musculoskeletal system and hormonal changes in the postpubertal athlete.  Further explanations for these results could be that younger athletes have less bad movement habits and can adapt their neuromuscular control better than older athletes.  The findings of this study were also echoed by Feigenbaum, who looked at seven year old students who participated in an integrative NMT program.  The results support that initiating NMT programs at a younger age is beneficial in injury prevention during adolescence.  More research is needed to address the durability of NMT program participation; i.e. is the program effective long after the NMT program is discontinued? Do you incorporate an NMT program in the conditioning programs for your female athletes?

Written by Christian Glaser, DO, and Marc Harwood, MD
Reviewed by: Jeffrey Driban

Related Posts:
Myer GD, Sugimoto D, Thomas S, & Hewett TE (2012). The Influence of Age on the Effectiveness of Neuromuscular Training to Reduce Anterior Cruciate Ligament Injury in Female Athletes: A Meta-Analysis. The American Journal of Sports Medicine PMID: 23048042


Alyson said...

I agree with this article and the explanations to why earlier NMT programs influence the risk of ACL injury in younger athletes, rather than older. I just watched the Wilke videos of ACL rehab, it is a 3 video series, and I have seen the first 2. The major element of rehabilitation for ACL reconstruction is perturbations, unbalanced flooring, and NMT. Now, this is after ACL rehab so doesn't directly correlate to study of trying to prevent first time ACL injuries, but it is in definite agreement with this study, on the basis that the idea is to concentrate on proprioception, kinesthetic awareness, and variability to adjust to unknown movements and contact.

It it shocking that a 72% injury reduction can be seen in athletes who started a NMT program early on in there athletic career. Why haven't we incorporated this into practice each day for these athletes? Education from the AT to the coaches on how we can reduce the change of loosing an athlete to an ACL injury by 72% would probably go over well. The task would be the get it implemented correctly into the daily practice schedule, but doing it at the beginning of practice when the coach is discussing last night's game, or right after their warm-up would be a great time to do so. If we know that it help reduce injury, and we are fairly certain that NMT works, then our task now, is to get our athletes involved in this benefit.

I am currently rehabbing an ACL-R and have used some forms of NMT, but definitely have starting implementing more after watching the Wilke videos, and reading this article.

The idea that the younger athletes have not developed fixed movement patterns, and can adjust and be instructed on how to move correctly is an idea that i agree with. At that age, puberty takes a toll on your body, and it is the most vulnerable stage of change for MS system, and hormonal system, allowing for a window to be used to create correct muscle movement patterns, and movement characteristics for proper adaptation to events, and changes in the environment. Using, NMT during this time period, in theory, should work then. Older athletes have learned muscle patterns, and can't change them as easily as they did before, must like learning a language early in life, rather than later in your school career.

I agree, more studies need to look at the efficacy of NMT programs, but the research shows that this could help prevent ACL injuries in female athletes,and now it is our job it try to get it implemented into daily practice schedules.

Aaron said...

I think that the results of this study have huge implications, however further research is still required. I agree with Alyson, if a NMT program can decrease injuries by 72%, then they of course need to be implemented in our young athletes.

Jeff- I am curious, how were these NMT programs implemented? Were they given to athletic teams or just in a clinic setting? Alyson stated that she believed that they could be implemented during practices, along with coach education. I wonder if the same results could be replicated if the NMT program was performed during PE classes? If still found successful, it provides great support to limit cutting PE programs throughout the country. Also, if these programs were implemented through a child's PE classes from say K-9, would it have even greater reductions than just a specific time point?

Jeffrey Driban said...

Alyson and Aaron: Thanks for the comments. In the meta-analysis they included studies that implemented NMT with various strategies. If you look at the related posts section you'll find several posts that describe research that supports the the idea of training coaches and letting them implement the NMT programs. There's also been suggestions that NMT injury prevention programs could be put forward as potentially performance enhancing which might help encourage the coaches to adopt the programs. I would suspect there would be ways of implementing NMT programs in PE classes (assuming the class size doesn't get to large). It makes you wonder if we are heading down the path of having some kind of certification program for injury prevention programs that coaches could take. The sports medicine community then could help those coaches as needed.

Bethany said...

I agree with Alyson and Aaron that the 72% reduction rate is critical and definitely lends support to initiating prevention programs early. A hard part to this is that while colleges have ATCs, the age groups present in that setting are the ones that are least likely to benefit from a program, while high school athletes seem to have the most gain. Since not all high schools have ATC-coverage, this suggests that there should be some kind of program that coaches could take in order to help prevent injuries in their athletes.

In addition, the type of training performed could be of importance as well. Although the 18+ age group did not respond as well to NMT, what about other types of training - landing, balance, dance, etc? McNitt-Gray (1992) did a study comparing dancers, non-dancers, and individuals who completed a 15 week dance training. Looking at landing biomechanics, both the dancers and "students" landed in positions associated with decreased ACL injury risk (increased knee flexion and decreased hip flexion at initial contact). The study did not look at how long these effects lasted following the conclusion of the dance training, but that is something that future studies could consider.

Christian said...


thank you for your comment. You raise a very valid point that ATC coverage is often not available at the high school level, the level which showed the most promising results for injury prevention. I absolutely agree with you that it would be very beneficial if coaches could get educated in NMT programs. You raise an interesting point of how long an athlete maintains the protective effect of NMT porgrams. Hopefully future research helps answer that question.

Nate said...

This article by Padua et al. sheds some light on how long changes can be seen after intervention programs:

Retention of Movement Pattern Changes After a Lower Extremity Injury Prevention Program Is Affected by Program Duration

This article compared a 3 month and 9 month intervention and showed that only the 9 month intervention retained their changes in movement patterns. If this is true in other populations it would be very difficult to complete a 9 month prevention program on younger populations. It would be difficult for the reasons mentioned above and also younger athletes might only play one season or will switch to multiple teams. I feel like it would be difficult and there would be a high number of drop outs if you tried to complete a 9 month intervention on 14 year olds. Aaron's suggestion on adding prevention in PE class could make it easier to have everyone on the same program but then I think people would ask why aren't we doing other prevention programs too? Like ankle sprain prevention programs, or shoulder prevention programs etc. Interventions for prevention will have to be targeted to the highest risk athletes so coach education on prevention programs I think is the best option similar to how coaches are required to take a concussion education class in some states they would be required to complete a injury prevention class that could give them the tools to implement these programs and prevent injuries.

Christian said...


thank you very much for your comment and on finding the article. I agree with your statement that I would be difficult to integrate a 9 month program and at the same time keep athletes motivated.
I believe that prevention programs should be focused on season ending injuries rather then a broad approach. Since this also could lead to a bigger drop out rate in a younger athlete population. I do agree with you that coaches could benefit from injury prevention courses.

William T. said...

72% reduction is a stat that speaks for itself; it’s hard to argue against the implementation of a prevention program for this reason. I think implementing these programs through coaching/practice and PE are good ideas however I don’t think they’re realistic options. This implementation refers to kids who go to PE to have fun and play dodgeball (actually, maybe not a bad idea for a NMT aspect) I think it’d be tough to keep compliance, effort rather, at a consistent level with a program for any duration. However I do agree that it would be important to use early before they become older and thus making it more difficult to teach “new” correct movement patterns or rather “un learn” what they’ve already developed.. Another concept to consider is that implementing a NMT program for the mid-teen age group may be questionable since performance comes into play. I think drawing a line between reducing injury for performance is a tough subject. For example, let’s say you have a female basketball athlete who is an HS all-American and gets put on an NMT and decreases performance is that really worth it? I think patient values come into play as well. At the end of the day however, it is within our duty as ATC’s to prevent injury and therefore if there is any possibility of doing so we should give it a shot.

Alyssa Grell said...

If proper rehab and treatment is completed, long term issues with injury can be slightly avoided. If surgery is done, and not much effort is put into post surgery rehab, major complications will become apparent in everyday life as well as long term. The scar tissue and adhesion that could build up could be very self limiting, not to mention the muscle atrophy that will not be fully recovered.

Sylvia Thelemaque said...

The 72% of reduction for knee injuries, more specifically knee injuries is just huge. I feel that NMT programs/warms should be incorporated more in sports;specially for female athletes. ITis fact that women are already more prone to tear their ACL more then males.

Simply because of factors such as having a narrow intercondylar notch width, smaller ACL, and lastly because the menstrual cycle. This last factor of a menstrual cycle effects our hormones and in turn mood causing a decrease in performance, reaction time and muscles, posture and etc.

NMT is about balance and if can be incorporated as early as possible it will and can improve biomechanics,posture and even correct bad and incorrect habits before it is to late.

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