My brain and my ACL

My life, though generally fortunate, has been peppered by a small number of somewhat serious injuries: broken hand, broken collarbone, broken wrist, torn meniscus, ruptured anterior cruciate ligament (ACL). The hand and collarbone were consequences of my big sister tripping and crushing me, respectively, but the rest I managed to accrue on my own. (Even though I sustained these latter injuries on the soccer field, I was unaccompanied by the touch of another player).

My mom always insisted that my proclivity for injury was due to the intrinsic grace of my bones and joints—"elegant and delicate, like a bird!"—but a recent study in the June edition of the American Journal of Sports Medicine suggests something different is to blame: my brain.

From the University of Delaware News:

A torn anterior cruciate ligament (ACL) is among an athlete's most-dreaded injuries, often requiring surgery and months of rehab, as has been the case with Philadelphia Eagles quarterback Donovan McNabb. While being tackled in football or hurtling into an embankment on an icy ski course can tear this major knee ligament, most athletes actually “do themselves in”--they don't collide with a person or object, they end up injuring themselves when they land off-balance during a jump or run.

“We had some data from previous research which suggested that these noncontact 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. 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.

Based on my personal experiences, the connection between sport-induced injury and distraction is not surprising. Both my wrist and my ACL/meniscus injuries (the latter being a simultaneous double-whammy) occurred while I wasn't particularly focused on the games. In both situations, I was slightly anxious because these were the only two soccer games my dad had attended since I was 10 (one in high school (wrist), one in college (knee)). Further, I was not involved in the plays that immediately preceded my injuries; it was precisely when ball unexpectedly approached, summoning my mildly reluctant participation, that my "delicate" limbs met with disaster.

But Swanik believes these momentary lapses in attention are indicative of more extensive deficiencies.

“This made me wonder if we could measure whether these individuals had different mental characteristics that made them injury-prone,” Swanik said.

To identify subjects for their study, the researchers administered neurocognitive 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, Swanik said.

Visual memory, verbal memory, processing speed, and reaction time all were assessed.

...

In analyzing the data, the scientists found that the athletes who ended up with noncontact 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.

As Swanik writes in his report, "physical activity requires situational awareness of a broad attentional field to continuously monitor the surrounding environment, filter irrelevant information, and simultaneously execute complex motor programs. Increased arousal or anxiety changes an athlete's concentration, narrows their attentional field, and alters muscle activity, which has been associated with poor coordination and inferior performance."

These conclusions remind me of one of David Foster Wallace's essays in Consider the Lobster, "How Tracy Austin Broke My Heart." Wallace devotes this essay to the devastating contrast between Tracy Austin's brilliance on the tennis court (both physical and mental) and her abominable ability to intellectualize her experiences in her memoir. He ultimately concludes that the vacuity and lack of insight of sports memoirs, such as hers, is inextricably linked to the qualities that lead to great athletes in the first place.

Their ability to maintain exceptional focus under the scrutiny of thousands of viewers (including their parents), makes them incapable of an appreciation of their athletic genius, and thus of significant insight into its nature. During games that are crucial to the careers to which they have been devoted since childhood, they manage to "invoke for themselves a cliché as trite as 'One ball at a time' or 'Gotta concentrate here,' and mean it and then do it." Meanwhile, if the rest of us were under such circumstances, we would founder and crumple and fail precisely because we think too much about matters that have nothing to do with the direction and velocity of the ball, or the appropriate bending of the knee during complicated, high-velocity movements.

As Wallace writes, "those who receive and act out the gift of athletic genius must, perforce, be blind and dumb about it—and not because blindness and dumbness are the price of the gift, but because they are its essence." (Their vastly superior speed, strength, and visual acuity probably isn't trivial).

Another major risk factor for ACL injuries is gender. Girls are four to eight times more likely to tear or rupture their ACLs than men, with female soccer and basketball players at the highest risk. There are a few theories as to why this gender difference exists: 1) bone alignment of the pelvis/femur/tibia create excess stress on the ACL; 2) female hormones relax ligaments, muscles and joints, making joints more flexible and prone to injury; 3) as girls pass through adolescence, their muscular control of the knee may not keep up with their skeletal growth.

To incorporate Swanik's conclusion with the gender discrepancy, female hormones can also result in concentration deficits, which may result in a sub-optimal state of arousal in a given athletic situation. In any case, this study has interesting implications for injury prevention. Not only should female athletes stop running like girls, but perhaps cognitive exercises that train processing speed and reaction time may also benefit the accident prone.