A new study by University of Delaware scientists has revealed that 'non-contact' knee injuries are the results of differences in brain functions.
At UD's Human Performance Lab, researchers are exploring injury proneness by measuring how people mentally prepare and react to unanticipated events.
To identify subjects for their study, the researchers administered neuro-cognitive tests to nearly 1,500 athletes at 18 universities during the preseason. This testing also provided baseline data for athletes who might sustain a concussion after the season started.
"We had some data from previous research which suggested that these non-contact knee injuries occur when a person gets distracted or is 'caught off guard,'" Charles Buz Swanik, the UD assistant professor of health sciences who led the study, said.
"This made me wonder if we could measure whether these individuals had different mental characteristics that made them injury-prone," Swanik said.
These awkward movements have the biomechanical appearance of a knee buckling, but can be reproduced safely in the lab to study how people mentally prepare and react to unanticipated events. Visual memory, verbal memory, processing speed, and reaction time all were assessed.
After the season started, a number of the tested athletes ended up sustaining non-contact ACL injuries. These athletes were identified, and 80 of them were matched up to a control group of 80 non-injured athletes according to height, weight, age, gender, sport, position and years of experience at the college level.
Male and female athletes in 10 intercollegiate sports were represented, including football, soccer, lacrosse, basketball, volleyball, field hockey, gymnastics, wrestling, fencing and softball.
Then the preseason test results from the two groups of athletes were compared. In analyzing the data, the scientists found that the athletes who ended up with non-contact ACL injuries demonstrated significantly slower reaction time and processing speed and performed worse on visual and verbal memory tests when compared to the control group.
"These results suggest that slower processing speed and reaction time, as well as lower visual and verbal memory performance may predispose certain individuals to errors in coordination during physical activity that can lead to injury," Swanik said. But can we do anything to improve our brain function and protect ourselves from injury?
"This study means that there may be an alternative application for neurocognitive testing in the area of injury prevention. It's hard to say at this point how much we can alter these characteristics with training, but certainly the brain has great potential for learning and adaptation. Controlling stress and anxiety must be considered, as both cause changes in muscle tone and concentration and the narrowing of our attentional field," Swanik noted.
"There is likely an optimal state of arousal for each individual to maximize performance and injury avoidance, but future studies will have to determine the relationship between our results and anxiety," Swanik added.
A follow-up study is now under way in UD's state-of-the-art Human Performance Laboratory with support from the University of Delaware Research Foundation.
"We're trying to identify people who are or are not 'caught off guard' during different landing tasks. Then we'd like to match the neuro-cognitive characteristics of people who are easily distracted or have awkward landings. This would allow us to search for injury-prone or perhaps accident-resistant people," Swanik said.
So what light might this study shed on Donovan McNabb's ACL injury in that ill-fated game with the Tennessee Titans last November? "It's a challenge to explain how such a highly conditioned, muscular and coordinated athlete is injured, unless we consider that he was momentarily distracted the instant before his foot contacted the ground, resulting in an awkward landing," Swanik said.
But McNabb is not alone. An estimated 200,000 anterior cruciate ligament injuries occur annually in the United States, mostly in young, healthy, active individuals.
According to Swanik, it is not uncommon to have one or two ACL injuries every season on a football team, and the incidence is likely even greater on women's sports teams. "Young women are actually at the highest risk for these injuries, particularly in soccer and basketball," Swanik said.
The study is reported in the June edition of the American Journal of Sports Medicine.