Here’s what happens when two football players meet in a helmet-to-helmet collision: Their brains bounce around in their skulls like dice in a Yahtzee cup. The health risks posed by these bell-ringing hits have created controversy at the highest level of the sport: In August, the NFL reached a settlement with more than 4,000 former players who had sued the league over alleged negligence in addressing high-impact head injuries. But as concussions hog the spotlight, two researchers at Purdue University have found that even small hits might cause permanent brain damage. And they are pioneering new technology to protect the next generation of football players.
Eric Nauman and Tom Talavage, both biomedical engineers, began their partnership in 2009 as part of the Purdue Neurotrauma Group, an MRI-research program. Talavage had experience reading MRI scans, and Nauman brought a longtime interest in helmet design; together, they decided to take a closer look at how consecutive hits in football and other sports might damage the brain. They received $120,000 in funding from the Indiana State Department of Health’s Spinal Cord and Brain Injury Research Fund for the effort. “We thought everything would be easy after that,” says Nauman.
Not exactly. The two developed a spongy, shock-absorbing material intended for the interior of headgear, creating a protective cocoon that approximates the “crumple zone” concept in cars. But when they brought the idea to Riddell, one of the biggest helmet manufacturers in the country, their play resulted in an incomplete pass. “If you talk to anybody in that business, they’ll tell you that the material [presently in helmets] is the best material, and there is nothing better,” says Nauman. “That’s because they’re doing this crazy test.” The manufacturers’ test involves putting a 20-pound weight (meant to simulate a human head) into a helmet and then slamming it down on an anvil with 1,000 pounds of force to determine whether it will prevent skull fractures. But the procedure can’t show whether the equipment will actually protect the brain inside.
"Right now there's a lot of belief in the way [helmets] should be," says Nauman, "but not a lot of data to support those beliefs."
Nauman and Talavage have taken a more delicate approach. In their underground laboratory in Purdue’s Mechanical Engineering Building, a dummy head lined with sensors rests on a metal stand. The researchers hit the head repeatedly with a small hammer, at forces of anywhere from 5 to 100 g’s—much closer to the kind of routine, play-by-play impacts athletes experience in the course of a game. The two also brought their research onto the field, finding subjects in their own backyard. Starting in 2009, they took MRI brain scans of high-school football players in Lafayette, and then outfitted the teenagers’ helmets with sensors that read the force of head blows they received during games; scans taken from the players at the end of the season showed a noticeable alteration in brain activity—even in those who hadn’t been diagnosed with concussions (see sidebar). This fall, Talavage and Nauman will begin testing Purdue football players to gauge how much the force increases at higher levels of competition, which should lead to even more precise conclusions about the damage caused by different tackling techniques. “The way this used to work was someone would get a bunch of people that were concussed and do one scan on them,” says Nauman. “Now, Tom is doing 12 [different readings] at the same time.”
Nauman and Talavage are currently developing a new helmet that incorporates their shock-absorbing liner. “Right now there’s a lot of belief in the way [helmets] should be, but not a lot of data to support those beliefs,” says Nauman. “I think in 12 to 18 months we could be at a point where we can actually start implementing things.”
Since 2009, researchers from the Purdue Neurotrauma Group (png) have taken force readings from the helmets of high-school footballers in Lafayette using Riddell’s Head Impact Telemetry (HIT) technology. Here’s how the on-field blows measure up:
1 g — Gravity
6 g — Roller coaster
9 g — If sustained, causes pilots and racecar drivers to black out
10 g - Lowest force PNG's helmet sensors were able to detect
22 g - Median point of all helmet readings taken by PNG researchers
30 g - Minor rear-end auto collision
75 g - Force applied to helmets in manufacturer quality testing
90 g - Highest helmet reading taken by PNG researchers during pregame player head-butting
100 g - Head impact in crash that killed Princess Diana
180 g - 1977 F-1 crass of British driver David Purley (he survived)
230 g - Fourth-highest helmet reading from PNG research
289 g - Highest helmet reading from PNG research
300 g - Fall from a height of 35 ft., as measured by Mythbusters TV show
Read "Protected Development," IM's timeline chronicling a century of football-helmet innovation.
This article appeared in the October 2013 issue.