In the time of Mike Webster, concussions probably were no less frequent than they are today -- it's just that they were not often recognized. Despite thousands and thousands of collisions in his 17-year NFL career, the Hall of Fame center was never diagnosed with a concussion.
Today, the NFL has become, relatively speaking, a place on enlightenment. Quarterbacks Steve Young and Troy Aikman were forced to retire in recent years after they sustained multiple concussions. New York Jets wide receiver Wayne Chrebet, who has suffered at least five concussions in his college and professional career, has been weighing his career options.
"We have a terrifying health emergency here that no one seems to respond to," Leigh Steinberg, agent to Aikman and Young, told the Boston Globe in 2003. "It's one more indication that the danger of concussion needs serious action."
According to a recent study, there were 497 brain injury-related fatalities in American football from 1945-99 -- 75 percent of them to high school players. None occurred on an NFL field, but the impacts in a typical game can register up to 124 times the force of gravity. This explains why, according to the Centers for Disease Control and Prevention, there are approximately 300,000 sports-related concussions sustained each year in the United States.
Dr. Elliot Pellman was a physician on the New York Jets medical staff when wide receiver Al Toon, suffering from post-concussion syndrome, abruptly retired in 1992.
"At the end of the day as a physician, you have to ask yourself, 'Did I do everything I could?' In my original work with Al Toon, I was confused and frustrated that I didn't know as much as I should," Pellman told ESPN.com last year. "My quiet pledge to Al, and myself, was to start getting some answers."
Pellman, the chairman of the NFL's Mild Traumatic Brain Injury Committee, cited a $2 million study that examined brain injuries from 1996-2001. In those six seasons there were 787 reported cases of mild traumatic brain injury, which works out to a rate of 0.41 concussions per game. Defensive backs (18.2 percent) were the players most likely to sustain the injuries, followed by members of the kicking teams (16.6 percent) and wide receivers (11.9 percent). Quarterbacks suffered 7.9 percent of those concussions.
"From my vantage point," Pellman said, "this study was unique for any sports league. The players will be the ones who benefit the most and, hopefully, it will sprinkle down to the colleges and the high schools."
Greg Garber is a senior writer for ESPN.com. He can be reached at Greg.Garber@espn3.com.