Colin Kaepernick’s simple act of taking a knee during the national anthem in an act of protest against racism and police violence has set off an earthquake in the world of sports, and the reverberations show no sign of stopping any time soon.

Why did this protest appear now? How does it compare to sports protests of the past? And should we expect to hear more of sports players’ political views? Danny Katch talked to Dave Zirin, a sports columnist for the Nation and the author of Game Over: How Politics Has Turned the Sports World Upside Down to answer those questions.

First of all, there’s always been this intersection of politics and sports and antiracism because sports was one of the few avenues for black men in particular to show excellence and have standing.