Legions of Harvard specialists from across its many schools and affiliated hospitals will team up with the NFL Players Association in an unprecedented study of 1,000 retired players. The researchers will look at everything from their repetitive brain traumas, torn knee ligaments, and arthritic joints to the gnawing effects of long-term exposure to acute pain and chronic use of painkillers.

The 10-year collaboration carries an ambitious goal: Begin to transform the health of active and retired players within five years.

The stakes are high—for the players and for the NFL.

More than 100 concussion-related lawsuits have been filed against the league, with thousands of players claiming the NFL did not do enough to inform them of the long-term dangers from repeat brain injuries and protect them.

Public attention has focused on an Alzheimer’s-like condition, called chronic traumatic encephalopathy, that is thought to be caused by repeated blows to the head. It has been linked to the erratic behavior, depression, and deaths of several former players, including Junior Seau, a linebacker for the New England Patriots and other teams who committed suicide in May.

But the health problems are much more wide-ranging. Countless former players struggle with searing and debilitating joint pain and rely heavily on anti-inflammatory medications and painkillers, say union officials. Many others grapple with heart disorders linked to extreme strength training common in the NFL.

The result is a dramatically shortened life span: While white men in the United States on average live to age 78 and African-American men to about 70, “it appears that professional football players in both the United States and Canada have life expectancies in the mid- to late-50s,” Harvard researchers wrote in a summary of their project.

Domonique Foxworth, the 29-year-old players association president, understands chronic pain. A torn knee ligament ended his career prematurely, forcing the cornerback to retire last year from the Baltimore Ravens. “There is a constant discomfort in my knee and hip,” he said in an interview.

“You get used to it,” he added. “I hope this project gets us to a place where players some day don’t have to get used to it.”

Foxworth said there hasn’t been a concerted effort to understand “how this game affects our players in the long run.”

Frustrated by the inattention, the union opted to give up some salary in the 10-year collective bargaining agreement signed with the NFL in 2011 and earmark the money, $11 million annually, for medical research.

Last July, it sought applications from top research centers. Roughly two dozen applied, including Boston University School of Medicine, which has led the research on chronic traumatic encephalopathy and received $1 million for the research from the NFL. The finalists were the University of Michigan, Duke University’s Health System, and Harvard.

Harvard’s winning proposal involves an unusual degree of cooperation among the university’s many parts, tapping expertise from across its 10 schools and 16 academic medical centers. It also draws on about 20 research centers nationally that specialize in minority health issues.

“In order to make real breakthroughs in the complexity of today’s medicine, you need to create teams,” said Dr. Lee Nadler, director of the football project and dean for Clinical and Translational Research at Harvard Medical School. “We have created teams and that’s not natural at Harvard.”

The project builds on a major National Institutes of Health grant Harvard received in 2008 to hasten the time it takes to bring ideas from the laboratory to the public, and the new undertaking is the most extensive collaboration the university has attempted. Nadler, however, said the aggressive timetable was not too ambitious: “Remember, this is Harvard,” he quipped.

Nadler said the Harvard team, with help from NFL players, will recruit a geographically, racially, and ethnically diverse pool of 1,000 retired players to be screened with blood and other health tests and questionnaires.