In collisions, "G" is a unit equal to the force of gravity. A low-speed rear-end crash causes an impact of 10G to 30G. A high-flying soccer ball lands on your head with a force of around 20G. Then there's the high-school football player who, according to a recent evaluation by Purdue researchers, received a blow to the head during a game that carried a force of 289G—nearly 300 times the force of gravity.
The scary thing about the hit was not the size of the impact. It was that the young man had no visible symptoms of a concussion.
Newfound concern about the wellbeing of football players has focused on the tip of a very large iceberg. Parents, schools, and athletes worry that thousands of amateurs each year may be suffering head injuries similar to the ones that make us gasp during NFL games. But there's a worse possibility: The most serious brain injuries at all levels of the sport are going completely undiagnosed and undetected. It gives me no pleasure to say this. I am a fan who eagerly awaits game day and the ultimate redemption of my long-suffering team.
Today we worry more about high-impact strikes to the head than about repetitive blows of moderate intensity. We think the only players who suffer brain injuries during collisions are the ones who later look dazed, or who can't keep their balance, or who suffer from slurred speech and vision.
The Purdue research changes all that. Many brain injuries suffered by football players do not produce the "shell-shock" symptoms we associate with concussions. The damage caused by these hits is just as evident when you study players in brain scanners or give them tests that measure sophisticated aspects of brain functioning, but are not picked up by trainers on the sidelines.
The finding about a new group of brain injuries came about, like many discoveries, by accident. Purdue biomedical engineering professor Eric Nauman and his colleagues were studying garden-variety concussions among high-schoolers—hits similar to this one and this one and this one during NFL games.
Nauman and his colleagues wanted to compare changes in the brains of football players who had suffered concussions with the "normal" brains of football players who were concussion-free. But when they scanned the concussion-free players a few weeks into the season and compared these pictures to the same players' preseason scans, they found that many had long-lasting brain changes.
"At first we thought our scanner was broken," Nauman said during a recent presentation of his findings to a group of journalists. "Then we realized this was a new group of impaired players."
Nauman calculates there are about 1 million high-school football players in any given year in the United States. There are some 67,000 reported concussions, and probably about as many that go unreported because fans, coaches, and parents don't want a star athlete pulled from a game. But among the supposedly injury-free remainder, the Purdue researchers believe tens of thousands of athletes routinely suffer serious brain injuries from high-impact collisions intrinsic to the game.
Some of the high-schoolers Nauman studied suffered about 150 head impacts per week during the season, or about 1,500 impacts per year. On average, the hits carried a force of around 40G. (The force of impacts is measured by sensors within helmets.) These hits did not knock players out, but they caused systematic changes in their brain functioning. Unlike the violent helmet-to-helmet collisions in the open field that have drawn warnings and suspensions from the NFL, these blows usually involved routine blocks and tackles, often along the line of scrimmage.
"Half the population we brought in had no obvious impairment whatsoever," Nauman said. But when the Purdue group compared the in-season scans with the preseason scans, "we saw even more significant neurophysiological changes than in the players diagnosed with concussions."
Nauman and other researchers aren't exactly sure what is happening to these players. But they believe that what we call concussions are only one of several kinds of head injury that affect players' verbal ability, memory, and "vestibular system," which controls spatial orientation and balance. Many of the hits that produce "shell-shock" concussions involve blows to the side of the head, as happens with helmet-to-helmet collisions in the open field. The new group of injured players—the ones without visible injury—had suffered damage to the frontal lobe, the part of the brain that controls high-end "executive functioning."
"These seem to result from repetitive blows to the top-front of the head," Nauman told me in an e-mail. "Most common when players lead with their heads to block or tackle. The challenge is that we don't really have sideline tests that can evaluate visual working memory or impulse control. So it is very hard to find the players in this group. Our fear is that they go undiagnosed, keep playing, and accumulate more and more damage."
To avoid running afoul of physicians who believe that all football concussions can be diagnosed on the sidelines, the Purdue researchers are not calling the new kind of brain injuries concussions. They are calling them impairments. But medical turf wars aside, it seems obvious these injuries are concussions, too.
Nauman thinks that while football helmets are pretty good at protecting against skull fractures, they are not good at protecting against concussions. And overconfidence in the helmets' protective power prompts many NFL athletes to deliver and accept hits that would have killed the helmetless players of previous generations.
"If you have traumatic brain injury and keep playing, you are at enormous risk for really serious damage later on," Nauman said. "Because these kids don't show any symptoms, they keep playing and exposing themselves to neurological trauma."
The neurological changes observed by the Purdue researchers did subside in the postseason. As good as brain scans are, they measure only indirectly what is happening at the neural level. And, as with all science, the findings of the Purdue team need to be expanded and independently verified. So we're likely to remain uncertain about the exact nature of this new class of injuries, their behavioral implications, and how they translate to measurable deficits later in life.
While acknowledging those uncertainties, Nauman told me he would never allow a child of his to play football. And now that I've seen the pictures of brain changes among "concussion-free" players, I would no more let a school-age child of mine play competitive football than I would let him or her start smoking. At least one prominent football commentator has said the sport is not for his own son. What does it say about us that we derive so much enjoyment from watching other people's kids take risks we would never accept for our own?
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