The ball is snapped and Virginia Tech’s junior varsity football team slams into Hargrave Military Academy’s offensive line in a crunch of plastic helmets and face masks that sounds like a 10-car pileup.

Somewhere in the mix, a Hokies defensive lineman gets cracked on the head at 80 times the force of gravity–about as hard as head butting a brick wall. It’s one of the heavier knocks of the 100 or so he’ll endure in the game.

On the sidelines, mechanical engineer Stefan Duma records the hit on a laptop linked to sensors in the lineman’s helmet. Duma, who specializes in collisions and the physics of safety equipment, is trying to learn how much trauma the brain can take.

“Football is the best for this kind of research,” Duma said. “You know people are going to get their heads knocked around.”

Scientists are still foggy about how concussions happen. Crash tests on humans always posed ethical problems, and previous studies with dummies or animals don’t translate well to the unique size and weight of the human brain.

With football, however, Duma realized there was a unique opportunity to see thousands of hits without worrying about the volunteers.

“They’re going to do what they’re going to do anyway,” Duma said. “We’re just measuring.”

His research team at Virginia Tech began monitoring the Hokies’ practices and home games this season. They record every hit–measured in multiples of “G,” the force of gravity–experienced by four players wearing helmets fitted with the same kind of acceleration sensors that trigger air bags in cars.

By comparing the impacts with routine health exams the players take throughout the season, Duma hopes to determine a player’s chances of concussion after every hit.

“We really don’t know” how much a player can take, Hokies team physician Dr. P. Gunnar Brolinson said. “Is it a 50 G impact or a 70 G impact that is serious? How about multiple hits over a period of time?”

Concussions are the result of an electrical discharge that sweeps through the brain after a heavy blow to the head. The region that’s injured will quickly try to repair itself, rerouting functions in a hypermetabolic state that temporarily impairs memory and the ability to make calculations.

“Sometimes you hit somebody, and you don’t know where you’re at for a couple of seconds,” said Hokies defensive tackle Nathaniel Adibi. “Sometimes you almost knock yourself out.”

It can take more than a week to heal from a concussion, and a particularly bad hit can permanently damage brain tissue. Studies of World War II veterans and retired pro football players also show that concussions can increase the risk of clinical depression later in life.

Unlike other sports injuries, concussions might not be immediately apparent. Many football players have learned to pick themselves up after a major hit and trot back to the huddle for the next play.

“With athletes, 90 percent of the time they’re still walking around after a concussion,” said Dr. Julian Bailes, a neurological consultant with the NFL Players Association and former team physician for the Pittsburgh Steelers.

Players regularly re-enter games when they shouldn’t. St. Louis quarterback Kurt Warner, for example, continued to play after suffering a concussion Sept. 7 in the first quarter of the Rams’ 23-13 loss to the New York Giants. Warner appeared well enough to continue, but coach Mike Martz said afterward Warner didn’t seem to understand plays called from the sidelines.

“Often, the one making the decision whether to return the player back into the game did not actually see the hit,” Bailes said. “Your view is blocked–some physicians are in the stands. Or sometimes you just don’t see it.”

College football is the same, Brolinson said.

“One of our receivers sustained a concussion two games ago … and nobody knew,” Brolinson said. “He continued to play, and he can’t remember what he did.”

Americans suffer about 300,000 sports-related head injuries each year, according to the Centers for Disease Control and Prevention. In football, which injures more college players than any other sport, the NCAA estimates Division I, II, and III teams treated about two concussions each in 2002.

Tech, which prides itself on hard-nosed defense, sees more than that: about six to 10 concussions each year, Brolinson said.

With 8:07 left in the second quarter of the Hargrave game, the Tech defensive lineman gets hit for the 39th time. This one isn’t so bad–a 30 G slap just above his left ear. Duma’s research team sees the collision on the laptop as a yellow arrow pointing to a 3-dimensional portrait of the lineman’s head.

To the right, another computer portrait is surrounded by a crown of arrows where the other 38 hits landed.

After the game, the team will compare the data with the game video to determine the exact angle of the hit and to filter out phantom hits recorded if the player dropped his helmet or knocked it into something while he wasn’t wearing it.

So far, the hits Duma has recorded stay around 10 to 80 times the force of gravity. “But we have seen hits exceeding 100 Gs,” Duma said.

Tech’s Edward Via Virginia College of Osteopathic Medicine bought the helmet system for $20,000 from SIMBEX, a Lebanon, N.H., company that develops safety equipment. SIMBEX president Rick Greenwald said he is developing similar equipment for a few other universities, but the helmets are currently not commercially available.

In the future, Greenwald said he hopes to create similar crash monitoring systems for every sport where head injuries are possible, from soccer to wrestling to hockey.

“Nothing is going to replace qualified medical staff,” Greenwald said. “But I think this will be another tool in their belt.”

Links:

Virginia Tech Center for Injury Biomechanics
http://www.ibl.vt.edu

SIMBEX
http://www.simbex.com