It is a sentiment shared by NFL players.

The killing of mostly unarmed black men by mostly white police officers sparked the Black Lives Matter movement, which has again drawn black athletes into the national conversation on race . The sideline protests in the NFL — started in August 2016 by Kaepernick — have been the most prominent display of players’ engagement, though black athletes in baseball and basketball have also had smaller displays of activism.

Because sports are such a prominent aspect of American life, they remain an effective way to bring attention to issues of racial injustice.

“This is our inheritance,” said Howard Bryant, senior writer at ESPN and author of the forthcoming book “The Heritage: Black Athletes, A Divided America, and the Politics of Patriotism.”

“You’re not allowed to check out,” Bryant said. “This is going to continue until the United States respects the black brain more than the black body. Then sports can go back to what it was supposed to be — just a game.”

Media — and social media in particular — has helped in recruiting athletes to the cause, explained Color of Change Executive Director Rashad Robinson, whose online civil rights organization has joined with athletes in addressing systemic racism and mobilized its membership to boycott the NFL and its corporate sponsors.

Such stands have often come at a cost, even for today’s players, who are far more prominent and wealthy than their predecessors. Like players who spoke out before them, they have been met with violence and vitriol, described as unpatriotic, ungrateful and disrespectful.

“The public is used to black guys selling sneakers and making jump shots,” said Bryant. “Do white people want to hear what black people have to say? No, they don’t. Does it need to be said? Yes.”

In this Sept. 25, 2016, file photo, San Francisco 49ers’ Colin Kaepernick kneels during the national anthem before an NFL football game against the Seattle Seahawks, in Seattle. (AP Photo/Ted S. Warren, File)

Abdul-Jabbar agreed, tying Ali’s fate to Kaepernick’s as two athletes who sacrificed their livelihoods at the height of their careers for a greater cause.

“Anybody that knows anything about football will tell you that he is a talented athlete and should be on somebody’s team,” Abdul-Jabbar, author of “Becoming Kareem: Growing Up On and Off the Court,” said of Kaepernick. “I think he’s being blackballed.”

But with the cost are also benefits. Using the universal language of sports as a platform to discuss race reveals racism and galvanizes support to end it, Robinson said.

“Part of why people are paying attention is because of exactly who they are,” he said. “Throughout time, it has been the people with reputations and something to lose whose risk-taking has helped result in change.”

Thanks to Associated Press for contributing to this article.