OXFORD, Miss. — As the news began to percolate that pro-Confederate and white supremacist groups were planning to march at the University of Mississippi last Saturday, Devontae Shuler was becoming increasingly anxious. The violence that had unfolded at similar events in Charlottesville, Va., in 2017 had crossed his mind, a menacing video was circulating on social media and Shuler wondered if he and other African-Americans might somehow become targets of physical attacks.

So, last Friday, he did what he often does when something troubles him: He called his mother.

Linda Shuler patched in her oldest son, D.J., and they listened as Devontae, a sophomore guard on the Ole Miss basketball team, relayed the depths of his feelings. Troubled by the mood on campus, he was considering sitting out his team’s game against Georgia. His brother, though, noted an action like that was more likely to punish his team, and himself.

Perhaps, D.J. Shuler suggested, he could take a knee during the national anthem instead. Devontae said he would think it over. The next afternoon, shortly before the game, Linda’s phone rang.

“He said, ‘Momma, I’m going to do it,’” Linda said.

Since Colin Kaepernick first knelt for the national anthem during an N.F.L. exhibition game more than two years ago, his calibrated gesture — meant to call attention to racism, social injustice and police brutality against people of color — has evolved into a broader distress signal. High school teams have used the gesture to show support for their minority peers. Notre Dame students invoked it as an expression of faith. And Jewish students in South Africa even did it during Israel’s national anthem to show support for Palestinians.