In the midst of the NFL's weeklong product placement extravaganza that culminated with Sunday's Super Bowl at U.S. Bank Stadium, a recurring theme kept putting a damper on the party.

Among the many folks who had something to sell or promote, more than a few were trying to raise awareness for products or research related to the pain and suffering NFL players often experience after their careers are over.

Marvin Washington, a longtime former player who won a Super Bowl ring with the Broncos in 1998, talked at length about the dangers of prescription painkillers. He's involved in a lawsuit against U.S. Attorney General Jeff Sessions as part of a campaign to legalize marijuana as a safer medicinal remedy for the pain and anxiety former players are suffering.

Ricardo Lockette, the former Seahawks player who was the intended receiver on the infamous interception against the Patriots at the 1-yard line just four years ago in the Super Bowl, made the rounds this week with a Harvard doctor promoting awareness of concussions and the quality of life of former players.

"There are a lot of people dealing with worse issues than myself," said Lockette, who has two titanium plates in his neck from a hit that ended his career in 2015. "I use myself as a poster child for the greater cause for those guys who don't have a voice."

Former Vikings quarterback Gus Frerotte is working for RC21X, a company that is touting an app that monitors brain performance on a mobile device. Frerotte was a featured speaker at a Brain Health Summit held a day before the Super Bowl.

And let's not forget: One of the Patriots' best players, Rob Gronkowski, was in concussion protocol until Thursday after a vicious hit in the AFC Championship Game.

In the long term, though, there's plenty of evidence that many of the players who suited up Sunday will have challenges down the road.

"Being at the Super Bowl is like being at a family reunion," Washington said. "But there are a lot of [former NFL players] who are completely off the grid that are suffering from head trauma or opioid addiction. This is something the NFL is very aware of."

Back on the field Sunday, though, those concerns did not seem to be at the forefront. Former Eagles running back Brian Westbrook talked on the pregame show broadcast in the stadium about the need for players to "hit someone in the mouth."

In the second quarter, Patriots receiver Brandin Cooks was leveled by a hard and high hit by the Eagles' Malcolm Jenkins. No replay was shown in the stadium, and the complicated dance between a violent sport's present and future continued.

Staff writer Megan Ryan contributed to this story.