SAN DIEGO, CA - SEPTEMBER 01: Colin Kaepernick #7 of the San Francisco 49ers poses for photos with fans after a 31-21 win over the San Diego Chargers during a preseason game at Qualcomm Stadium on September 1, 2016 in San Diego, California. (Photo by Harry How/Getty Images)

Colin Kaepernick's boycott of the national anthem is spreading to other sports

His support is growing.

In addition to military veterans supporting Colin Kaepernick's decision to sit out the national anthem, other professional athletes are standing (or should we say kneeling) next to the San Francisco 49ers quarterback.

Related: Cops who patrol the 49ers stadium threaten to not show up if Kaepernick doesn't stand for anthem

United States women's soccer star Megan Rapinoe is the latest to join Kaepernick in kneeling during the national anthem. Her reasoning mimics Kaepernick's as she explained:

Kaepernick's response after his decision to sit drew criticism was swift:

"I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color," he said. "To me, this is bigger than football and it would be selfish on my part to look the other way. There are bodies in the street and people getting paid leave and getting away with murder."

The NFL replied to the controversy with a statement, saying ""Players are encouraged but not required to stand during the playing of the National Anthem."

Other high-profile athletes like LeBron James and Carmelo Anthony have spoken out against what they perceive as racial and social injustice. Following the police shooting deaths of Alton Sterling and Philando Castile in July, which were captured on video resulting in nationwide protests and demonstrations, Anthony reached out to fellow athletes on social media, urging them to "step up and take charge" of the political environment. As has NBA star Dwayne Wade, whose cousin was fatally shot by a stray bullet Friday as she pushed a baby stroller near a school on Chicago's South Side.