MINNEAPOLIS (WCCO) — It has been seven years since Brett Favre’s career-ending concussion — and he is still feeling the effects.

Now, the former Packer turned Viking is telling his story in a very public way.

READ MORE: Eli Hart Killing: Mother Accused Of Murdering 6-Year-Old Son To Appear In Court Tuesday

He is an executive producer of the new documentary, “Shocked: A Hidden Factor in the Sports Concussion Crisis.”

Favre says there is something people simply do not understand about concussions.

The roof of the Metrodome collapsed on Dec. 12, 2010, forcing the Vikings to play their Dec. 20 matchup with the Chicago Bears at TCF Bank Stadium.

Quarterback Brett Favre #4 of the Minnesota Vikings is sacked by the Chicago Bears at TCF Bank Stadium on December 20, 2010 in Minneapolis, Minnesota. (credit: Matthew Stockman/Getty Images)

READ MORE: Chemical Spill Prompts Hotel Evacuation In Bloomington

Farve was taken down by defensive end Corey Wootton in the second quarter, hitting his head on the cold, hard ground.

His new documentary exposes a lesser-known type of concussion that happens when athlete’s heads hit the ground.

“A lot of the research for concussion has gone into helmet technology, equipment technology, mouth guards,” said Dr. Alex Null of TRIA in Bloomington. “Not a lot of research has been developed for concussion risk and artificial turf.”

He said artificial turf can easily wear thin over time, and natural grass — like Favre played on — can freeze or dry out.

“The question is if we add more padding, can that reduce impact-related forces as the head strikes the ground and reduce those potential concussion injuries?” Null said.

MORE NEWS: Mosquitoes Mostly Missing, But Twin Cities Thick With Ticks

Favre also said he will not encourage or discourage his young grandsons to play football, but he said he would prefer they play a safer sport, like golf.

Susan-Elizabeth Littlefield