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

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]

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
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.

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?

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


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