ACL Injuries & Female Soccer Athletes-Research & Findings

by CoachZ on December 30, 2008

“Why Women Suffer More Knee Injuries”

Female athletes are up to eight times more likely to suffer knee injuries during their careers than males, and now researchers may be closer to understanding why….A recent study of 10 female and 10 male NCAA athletes completed within the Department of Biomedical Engineering at the Cleveland Clinic found that female athletes tend to land from a jump with a more flexed ankle, the foot rolling outward with an elevated arch, and more knee abduction and knee internal rotation compared to male athletes. When fatigued, differences between women and men in these movements and loads were even larger, possibly explaining why females may be at greater risk of non-contact anterior cruciate ligament (ACL) injury during landing.  The study’s lead researcher, Scott McLean, was previously at Cleveland Clinic and is now an assistant professor with the Division of Kinesiology at the University of Michigan. The study will be published in the March issue of Medicine and Science in Sports and Exercise. The abstract of the article by McLean et. al., can be viewed below and may be accessed in its entirety at www.lww.com. 

To continue: “According to the NCAA, female athletes are at least twice as likely to suffer an ACL injury as male athletes and in some cases up to eight times more likely. Research shows that one in 10 female athletes will experience an ACL injury at some point in their career. “Before we can even consider trying to successfully prevent ACL injuries in both men and women, we need to clearly identify their underlying causes or mechanisms,” McLean said. “This study presents an important step in achieving these ultimate research goals. It seems that when fatigued, the potential for an athlete to execute poor decisions, reactions and thus movement responses is greatly increased. Our next step is to determine how we can effectively combat these effects. Fatigue affects individuals differently. As we begin to pinpoint how fatigue relates to joint motion during sports movements, we hope to gain a better understanding of how ACL injuries occur and how to prevent them.” said Dr. Susan Joy, director of Woman’s Sports Health at Cleveland Clinic and study co-author.” Doctor Joy has worked on many female soccer athletes from Northern Ohio. In fact, Dr. Joy has worked on variety of athletes from throughout the Midwest, including Coach Z’s daughter. “During the study, athletes were observed drop-jumping in the Cleveland Clinic Lerner Research Center’s Biomechanics lab. The athletes had their movement recorded using three dimensional high-speed motion analysis techniques to examine lower-limb-joint kinematics and kinetics during 10 drop jumps, both before and after fatigue. Gary Calabrese, director, Cleveland Clinic Sports Health Rehabilitation and the study’s co-author said the findings open the door for further research and clinical application.

“Understanding when and why athletes suffer debilitating knee injuries helps us develop more successful and personalized treatment and prevention programs for at-risk individuals,” Calabrese said.  This article was adapted, in part, from materials provided by the University of Michigan, via EurekAlet!, a service of Advanced Science, Serving Society (AAAS). 

Additional research into landing strategies was inspired and conducted as a result of the Cleveland Clinic studies, those studies and their explanations will be discussed in the future, as not everyone agrees with the methodology or the findings. Several research studies focus on why there is such a pronounced difference from an anatomical point of view.  

The abstract for the scientific publication of the Cleveland Clinic study follows:

Impact of Fatigue on Gender-Based High-Risk Landing Strategies. Applied SciencesMedicine & Science in Sports & Exercise. 39(3):502-514, March 2007.  MCLEAN, SCOTT G. 1,2,3; FELIN, REBECCA E. 1; SUEDEKUM, NATALIE 2; CALABRESE, GARY 2; PASSERALLO, ALLEN 2; JOY, SUSAN 2 

Abstract: Purpose: Noncontact anterior cruciate ligament (ACL) injuries carry significant short- and long-term morbidity, particularly in females. To combat this epidemic, neuromuscular training has evolved aimed at modifying high-risk lower-limb biomechanics. However, injury rates and the gender disparity in these rates remain, suggesting that key components of the injury mechanism continue to be ignored. This study examined the potential contributions of neuromuscular fatigue to noncontact ACL injuries. Methods: Ten male and 10 female NCAA athletes had 3D lower-limb-joint kinematics and kinetics recorded during 10 drop jumps, both before and after fatigue. Mean subject-based initial-contact (N = 9) and peak stance-phase kinematic (N = 9) and normalized (mass x height) kinetic (N = 9) parameters were quantified before and after fatigue and submitted to a three-way ANOVA to determine for the main effects of leg, gender, and fatigue. A Bonferroni corrected alpha level of 0.002 was adopted for all statistical comparisons.  

Results: Females landed with more initial ankle plantar flexion and peak-stance ankle supination, knee abduction, and knee internal rotation compared with men. They also had larger knee adduction, abduction, and internal rotation, and smaller ankle dorsiflexion moments. Fatigue increased initial and peak knee abduction and internal rotation motions and peak knee internal rotation, adduction, and abduction moments, with the latter being more pronounced in females. 

Conclusions: Fatigue-induced modifications in lower-limb control may increase the risk of noncontact ACL injury during landings. Gender dimorphic abduction loading in the presence of fatigue also may explain the increased injury risk in women. Understanding fatigue effects at both the central and peripheral levels will further afford elucidation of the ACL injury mechanism and, hence, more successful prevention strategies. 

In other words, as female athletes grow tired during the course of training or during match play, they land differently, their ankles tend to roll outward and and as they do, the knee’ abduction and internal rotation is more pronounced. As one basketball player was heard saying, “I knew it was gone as soon as I heard that dreaded POP!” Anyone who has experienced or witnessed an ACL injury knows that POP! all to well.

So why did I spend so much time and take up so much space on medical research and a very technical abstract? Because it brings home the whole point of this blog. It’s all about the training! Yes, there are anatomical differences. And yes, the disparity between male and female athletes remains and, while several theories are considered, the bottom line is that fatigue, and thus training, are vital in at least attempting to offset the likelihood of a catastrophic ACL injury during competition when fatigue is at its most pronounced level.

We will go into a little more depth as far as the etiology or cause of this injury because it is so important to what we are trying to achieve here. In order to completely understand the dominant points of view concerning this injury we must consider anatomy, neuromuscular interaction, physiology, kinesiology, and biomechanics. While beyond the scope of this blog, we will at least summarize next time and then start to get in to training strategies.

I hope you weren’t all bored to tears and will stay with me. There really is a method to my madness. And, anyone who has had an ACL injury or  knows someone who has had one, will understand where it is I am coming from even if it is not entirely clear where I am going with this yet.  

Stay with me and see you next time!

{ 0 comments… add one now }

Leave a Comment

Previous post:

Next post: