Perhaps with a cast on his body, BYU defensive back Scott Johnson more easily could have accepted not being able to play when Florida State came to Provo in September for a high-profile game.

College football players are conditioned to overcoming injuries, dealing with pain and getting back onto the field by the following Saturday.

"You get up to a point where you can pretty much play through anything, with enough tape and enough determination," Johnson said.

This was different. A concussion, defined as a "mild traumatic brain injury," suffered the previous week kept Johnson out of the game.

"With concussions, it's hard," Johnson said recently, "because a lot of times you don't feel like you're injured. ... You can't see it; you can't feel it."

Yet it is there. And while concussions have occurred ever since football was invented and collisions ensued, the awareness of their impact is increasing. Celebrated players including Florida quarterback Tim Tebow have suffered concussions this season and brought attention to the injury and its treatment.

"I played football; I never knew what a concussion was," said BYU trainer Kevin Morris.

In contrast to the days when a player's having his "bell rung" was joked about and coming back to play quickly after even a loss of consciousness was considered a sign of toughness, the science of dealing with brain injuries is being applied much more.

Physical therapist Doug Toole worked with North Summit High School players for some 35 years without the sophisticated testing he uses now, aided by Melinda Roalstad, a former U.S. Ski and Snowboard Association medical director. Having evaluated players by the traditional symptomatic methods, Toole now recognizes how many of them were allowed to come back too soon.

The long-term effects of multiple concussions are only lately being recognized, partly through studies involving retired NFL players. Mike Borich never played in the NFL, but during his career as a receiver for Bingham High School, Snow College and Western Illinois, he suffered 10 or more concussions.

After Borich died in February at age 42, his family donated his brain to a Boston University School of Medicine group that diagnosed his degenerative brain disease, which contributed to struggles with addiction, according to The New York Times .

Anyone who has a concussion becomes more susceptible to another by resuming activities too soon, professionals say, and the potential for damage increases.

"We're trying to protect them from that quick, second concussion," said Byron Horton, a physical therapist who works with South Summit High School athletes.

Pre-testing of cognitive function has become a major component of evaluating concussions. At North Summit, every athlete (other than golfers) takes a 20-minute, computer-based Impact test to measure attention, memory and information processing. Following a concussion, the athlete then must demonstrate similar ability before being cleared for activities.

"It's a real safety net for coaches, and for everybody," said football coach Jerre Holmes. "It allows us to know when they can come back. There's no pressure, one way or another."

For Toole, the testing system is "a relief for me," he said. Coaches "trust us now."

Such testing is prevalent among college programs, and trainers welcome it. "It gives some objectivity to what sometimes can be subjective," said the University of Utah's Paul Silvestri, who hopes it will spread throughout high schools.

"That's where you see a lot of the problems," Silvestri said, because players, coaches and parents all tend to rush the recovery process.

Roalstad and other professionals advocate pre-testing for competitive skiers, soccer players and other athletes. "I'd like to see parents better educated," said Dr. Anthony Morrison, a neuropsychologist in Salt Lake City. "A lot of people, not only kids who play football, are at risk of concussion."

Concerned about the volume of concussions, BYU coach Bronco Mendenhall is campaigning to overturn the recent rule change that moved kickoffs back to the 30-yard line, creating more returns.

Helmet-to-helmet hits are more readily penalized and the helmets themselves are being designed for increased safety, but concussions remain part of the game. As much as he would like to have played against Florida State, Johnson recognizes what he was dealing with.

"When it comes down to it," he said, "you have to consider your future."

kkragthorpe@sltrib.com