The helmet sensors measure the force of the impact by measuring both the linear and rotational acceleration of the head. The resulting linear acceleration is expressed in g-force, with 1 g being equal to the force of gravity. NFL research has determined that 98 g is a threshold for concussions. But Chris Nowinski, president of the Sports Legacy Institute, a nonprofit organization based in Waltham that studies brain injury in athletes, said the study data indicates that football players are enduring numerous blows that are beneath the concussion threshold but still are serious.
“Ninety percent of concussions on the football field go undiagnosed because the impact was relatively minor and a player was able to play through it,” Nowinski says. “When you line up this data–so hits that are 30 g’s and 40 g’s are next to impacts of 120 g’s–you start to see the damage. It seems insane that football players take repetitive hard hits to the head and this is applauded for making them tougher.”
The data for the study came from a system originally developed by Simbex, which specializes in biomechanical feedback systems, and Joseph Crisco, an engineering professor at Dartmouth. In 2004, Riddell, a sporting-equipment manufacturer based in Rosemont, Illinois, acquired the technology and developed a helmet called Revolution IQ Hit. Individual helmets are $1,000, while the equipment that continuously and wirelessly transmits data to a sideline laptop is sold to teams for roughly $60,000 to $70,000. (A less-expensive version is being developed for high school and youth leagues.)
The alerts on the helmet system can be customized so sideline physicians can be notified when a player exceeds a certain number of hits per practice or game, or when his accumulated g forces are too high. Within a few years, such a system could be used in colleges and high schools for the equivalent of a pitch count for football, says Gunnar Brolinson, the physician for Virginia Tech’s football team and the associate dean for clinical research for the Virginia College of Osteopathic Medicine. “Currently, when a player sustains a high head acceleration and continues to play, we watch him carefully from the sideline. If he is acting confused and not playing appropriately, he can remove him from the game for medical evaluation,” says Brolinson. But once researchers better understand the effects of cumulative head accelerations, a player might be taken out once he has sustained a certain frequency or magnitude of collisions, even if no single blow registered at extreme levels.
Already, he says, Virginia Tech has modified its practices to reduce the number of head impacts players sustain and taught players new ways to tackle that don’t require using their heads as battering rams.