The scientists will then test therapies in retirees who have biological profiles similar to those of the sickest players, to see whether they can forestall serious problems. The treatments might include specialized diets, medications, or exercise regimens.

“We are not trying to change the game,” Nadler said, “We are trying to change the impact of the game.”

He said researchers have already identified “shovel-ready” experimental treatments that are ready to be tested in players, including one that aims to regenerate torn anterior cruciate ligaments. He said research in sheep has shown promise, but it has not yet been tried in humans.

Roughly 42 NFL players tear this critical knee ligament each year, increasing their risk of debilitating joint disease, and current ACL surgery often is not successful, as Foxworth found out.

Also ready for testing is the use of light emitting diodes, better known as LEDs, to treat concussions, in hopes of preventing permanent brain damage. Harvard researchers have reported improved cognitive function is some concussion patients who received this treatment. Also planned is a clinical trial testing whether reductions in strength training after players leave the game will reduce heart problems.

Armed with the biological profiles of specific disease patterns, the researchers also aim to identify 100 college football players headed for the NFL, and another 100 just beginning their college careers, to see whether they can pinpoint in these apparently health players the markers of disease found in the very ill retired players and test intervention therapies.

“Our organization is a role model,” said Foxworth, the NFL players union president. “It’s exciting to believe that whatever improvements we find will trickle down to them.”

One of the many other goals of the project is to focus on the unique mental health problems and needs of players who become millionaires by age 24 and are out of the league with career-ending injuries soon after.

“Players are not all that aggressive with sharing the details about something as fragile as mental health,” Foxworth said. “We are going to try to figure out the best possible way of communicating with our players, to find the best ways to get our players to open up because we find out about it when it’s far too late.”

The players union is still finalizing details of the project with the NFL, because the money set aside for medical research under the collective bargaining agreement is to be jointly administered. But the union said it plans to announce the Harvard-led project at a Thursday news conference in New Orleans, where the Super Bowl will be played Sunday.