Reducing ACL Injury in Female Athletes with Neuromuscular Training:
Summary of Recent Research
John Baur PT, DPT, OCS, CSCS, OMPT1
Girls are More Likely than Boys to Injure a Knee
Girls participating in lacrosse, soccer, basketball, and other sports that involve cutting, pivoting, and jumping are four to six more times likely to seriously injure a knee than boys playing the same sport. Additionally, sports-related injuries to the anterior cruciate ligament (ACL) increase during adolescence and peak in incidence during the mid- to late teens, right when serious athletes are considering competing at the college level.
An ACL injury not only takes the athlete off the field temporarily, but it also impacts their quality of life as they age. Regardless of whether they chose surgery or non-operative management, they are ten times more likely to suffer from osteoarthritis (OA) and almost always develop OA 20 years after the injury.
Playing Like a Girl
Three separate theories seek to explain why teenage girls are more prone to ACL injuries than teenage boys; 1) hormonal variances, 2) anatomic differences and 3) sex disparities in neuromuscular abilities – the ability to coordinate the movements of multiple muscle groups. There have been many investigations into the connection between hormonal involvement and injury; however, the results have not been conclusive on exactly how hormones play a role in the increased risk of injury in women. Anatomic differences between men and women have also been explored, to see if they explain the increased prevalence of knee injuries in women and here again the results are equivocal. However, when comparing the neuromuscular abilities of girls and boys playing similar sports, researchers identified altered neuromuscular strategies during play in female athletes that likely explain the increased risk of ACL injury. From a different perspective, power/strength and coordination have been s hown to increase with puberty in boys; however, the same changes have not been observed in girls.
Altered mechanics and different landing strategies associated with increased risk of injury in female athletes appear after the pubertal growth spurt. This coincides with peak prevalence of ACL injury. Different landing strategies include landing with the knee in a more valgus or turned in position and with less overall control of the lower extremity, putting the ACL at high risk for being injured. This misalignment and not having control over the entire leg may be the underlying cause of increased risk of injury in teenage female athletes. Moreover, the reason that female athletes lack the ability to maintain proper landing alignment may be linked to hip abductor strength and trunk stability, both of which can be improved with proper intervention.
Neuromuscular Training Programs Can Prevent Knee Injury
Neuromuscular training (NMT) programs that focus on increasing hip strength and core muscle strength can decrease lateral trunk motion and improve how females land when cutting, pivoting, and jumping. Several NMT protocols have emerged in the literature that target ACL injury prevention in female athletes. Research suggests the best time for implementing an NMT program is before the onset of puberty where it has been shown to be more effective in reducing ACL injury risk compared with interventions implemented in late adolescents and early adult-aged female athletes.
The training modalities employed in the design of NMT to prevent serious knee and ACL injury have been varied. Balance and strength-focused exercises combined with biomechanical feedback appear to be key elements for injury prevention. Programs that used only isolated plyometric exercises without feedback-driven instruction were not as effective. Similarly, balance training alone did not appear to provide the needed stimulus to reduce ACL injury risk and in fact appeared to be the least effective approach.
Finding the Right Program
A well-designed NMT program for athletes that addresses specific physical deficits and includes sport specific NMT is likely to be most effective in ACL injury prevention. Consumers should be cautious of programs that make outrageous promises. One-size-fits-all-fitness and injury prevention programs are not always successful due to individual physical differences. Furthermore, since no two athletes are physically or anatomically identical it is valuable to have a physical therapist involved in the physical assessment and design of the injury program.
A physical therapist that is well versed in biomechanical / movement analysis, orthopedics and sports physical therapy would be best able to evaluate the athlete’s movements as a whole system and identify specific components of weakness that need to be addressed. These components would include muscle strength, endurance, coordination, balance/agility, joint stability/mobility, muscle flexibility and screen of the nervous system. Baseline measurement for all these elements can be established and later follow up assessments can properly evaluate an athlete’s physical progress. Any identified deficits can be addressed in an off-season conditioning program.
The physical therapist can help athletes, parents and coaches monitor factors that influence physical recovery time. Proper nutrition, sufficient sleep, overtraining, psychological stresses influence on stress hormones, the absence of the athletic off-season, and lack of cross training (or single sport athletes) are all elements that can be manipulated. Even though the exact influence of these factors on non-traumatic ACL injury is unknown, by knowing the warning signs, coaches, strength coaches, athletic trainers and parents should be able to intervene with appropriate action.
John Baur, PT is a physical therapist in the Greater Baltimore area specializing in advanced orthopedic therapy techniques and physical therapy following ACL injuries. Call 410-662-7977 for more information about physical therapy or to arrange an appointment with John Baur, PT.
1. Myer, Gregory D., Sugimoto, Dai, Thomas, Staci, & Hewett, Timothy E. (2013). 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, 41: 203, originally published online October 9, 2012 DOI 10.1177/0363546512460637. The online version of this article can be found at http://ajs.sagepub.com/content/41/1/203
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