(CNN) -- Chris Nowinski's professional wrestling career didn't end with a pink slip or a celebratory sendoff, but with a swift kick to his chin.

Chris Nowinski was a WWE wrestler when he suffered a concussion, but didn't realize how badly he was hurt.

Nowinski played college football at Harvard -- a defensive tackle. He was a promising newcomer to World Wrestling Entertainment. At the time he suffered the injury -- the hit that would cut his career short -- he was performing in a summer 2003 tag-team match as his WWE character, Chris Harvard, a blonde, blue-eyed symbol of Ivy League elitism.

Nowinski didn't know he had suffered a concussion. He didn't know that he shouldn't have been wrestling immediately afterward, and he didn't know that this was probably the sixth concussion of his athletic career. There was a lot Nowinski didn't know about concussions.

Hard hits were nothing new to Nowinski, 28, a tree of a man who had played sports since childhood. Blows to the head punctuated many of the games and matches in his career, he said. Sometimes he blacked out.

"The sky would change colors, or I would see stars, and get really dizzy, and I would just collect myself on the field or in the ring, and continue going, because that's what I thought I was supposed to do," he told CNN in a telephone interview. "I didn't realize that it was a serious brain injury."

Nowinski continued to wrestle, which aggravated the injury, he said. He developed post-concussion syndrome, a condition characterized by prolonged concussion symptoms.

"After my last concussion ... I was stuck with four years of headaches and immediate memory problems and depression and sleep-walking," Nowinski said. He said he still endures migraines and memory loss. "My head just feels differently all the time," he said.

Concussions are common, particularly among athletes in heavy contact sports. The Center for Disease Control and Prevention estimates that at least 300,000 sports-related concussions occur annually in the United States.

Nowinski waited a year and a half for his head to clear so he could return to the ring -- a day that never came. So, the fallen wrestler decided to change what he considers the sports world's biggest liability.

He's now on a mission to eliminate the "damage" from head injuries in athletics. His task is two-fold: To educate coaches, parents and athletes about identifying and treating concussions and to help facilitate research to pin down the injury's long-term effects.

"I knew I had the information that could prevent suffering for a lot of people, a lot of people that I cared about," said Nowinski. "It wouldn't have been right for me to just go on with my life, make money, do whatever, while that information just sat in my head."

He wrote "Head Games: Football's Concussion Crisis from the NFL to Youth Leagues," published in 2006. He's been speaking before youth leagues, sports conferences and other public events for more than three years. And he and a group of top neurologists have recently formed The Sports Legacy Institute.

Part of that organization's purpose will be to study the effects of multiple head injuries, investigating cases of a condition called chronic traumatic encephalopathy, or CTE, Nowinski said. CTE is a dementia-like condition caused by repetitive blows to the head over an extended period of time, according to the National Institute of Health.

Hoping to prove to the rest of the world that multiple concussions have permanent, sometimes ruinous consequences, Nowinski began to work with a University of Pittsburgh neuropathologist, Dr. Bennet Omalu, who found the condition in the brains of two deceased former National Football League players, Terry Long and Mike Webster. With Nowinski's help in obtaining the brain tissue, Omalu diagnosed the condition in two other former players who died, Andre Waters and Justin Strzelczyk.

Both Long and Waters committed suicide. In the case of Waters, Omalu said
Which sport did Chris Nowinski do professionally? How many concussions has Chris Nowinski suffered? What steps is the NFL taking to study the effects of concussions on players? When Chris Nowinski played football at Harvard, what position did he play? Does he have an injuries? Who is taking steps to study the effects of concussion on players? What did Chris Nowinski do?
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question: Which sport did Chris Nowinski do professionally?, answer: wrestling | question: How many concussions has Chris Nowinski suffered?, answer: sixth | question: What steps is the NFL taking to study the effects of concussions on players?, answer: multiple head injuries, | question: When Chris Nowinski played football at Harvard, what position did he play?, answer: defensive tackle. | question: Does he have an injuries?, answer: concussion, | question: Who is taking steps to study the effects of concussion on players?, answer: The Sports Legacy Institute. | question: What did Chris Nowinski do?, answer: played college football at Harvard