Head injuries have always been a part of football. But people at all levels of the game are trying to minimize future injuries and protect players from themselves.

FOX News Radio's Rich Johnson reports in the sixth installment of our ten-part series investigating the growing concern about concussions in the sport:

(Announcer) "Personal foul"

Fans may love those big hits, but former players have always paid the price, even as they turned a blind eye to the problem during their playing days.

(Dunn) "My clients, particularly my quarterback clients, are the worst obstacles to changing the culture."

Veteran agent David Dunn found himself sometimes confronting his clients, telling them to step away. Hall of Fame quarterback Warren Moon knows the feeling.

(Moon) "A lot of players have this gladiator mentality that they never want to admit that they have a weakness."

The NFL points to several new rules of the past four years designed to protect players: banning blindside blocks, limiting hits on defenseless recievers, limiting low hits. And this year: Protecting defensive players from crackback blocks. Also, a new analysis on moving up kickoffs from the 30 to the 35, which started last year, produced some good news.

(Kheyfets) "It reduced the number of returns, obviously, because you had more touchbacks. And correspondingly there was a pretty significant drop in the number of concussions."

From 35 in 2010 to just 20 kickoff concussions last season, according to Mike Kheyfets with Edgeworth Economics.

Rich Johnson, FOX News Radio.

CLICK HERE for more of the FOX News Radio series "Head Games: The Dark Side of Football".

CLICK HERE to listen to the full FOX News Radio special "Head Games: The Dark Side of Football".