DAVENPORT-- Known for hard hits and powerful tackles, it's football.
"Football is the greatest teacher I've ever had," says former NFL player Julian Vandervelde.
He speaks from experience. Vandervelde was a Davenport Central standout, moved on to make his mark at the University of Iowa, then he played for the Philadelphia Eagles in the NFL.
"I'm fortunate that I got out before anything critical happened to me," says Vandervelde.
The game is also known for the wear and tear it puts on those who play. Some more than others.
A new study from the American Medical Association tested the brains of deceased football players. 87-percent of the brains tested positive for CTE — a degenerative brain disease that is caused by blows to the head and can lead to depression, impulsivity, rage and memory.
Out of the 111 brains of former NFL players tested, 110 of them were positive for CTE.
"I've had ringers, sure. I think every guy who's played the game in my generation has," says Vandervelde.
The disease is likely caused by repeated hits to the head, things like concussions.
"Once upon a time, you hear old guys tell stories about one eye's looking this way, one eye's looking that way. Coach tells him to get back out there, the team needs you," says Vandervelde.
Now Vandervelde is a coach himself, carefully watching the health of the next generations of football players.
"When a guy mentions something, oh my neck hurts, I can't see straight, it's immediately, what can we do for this guy," says Vandervelde.
The study showed some good news. There was less sign of brain damage in younger players.
"So if we can incorporate in the high school level the safety training, the emphasis on technique and basics...that will bleed into the higher levels of the game and ultimately make the game safer for everybody," says Vandervelde.
Critics of the study say the way researchers chose which brains to study could produce bias. They used a convenience sample. That means the brains tested weren't random. They were the ones most available and convenient for scientists to choose.