By not performing the traditional gesture of placing the hand on their hearts and singing the anthem, these two athletes knew the kind of retaliation that they would likely experience from their expression. A fist raised in the air has long been associated with worker solidarity movements, linking race and class in America (Cushing)
Another "truth" the image conveys is related to the Black Power movement itself. The Black Power movement began in 1966, "in the wake of massive civil rights demonstrations and new civil rights laws," but it was not the first time that phrase had been used (Hamilton and Ture 201)
Carlos and Smith wanted to point out the context in which they raised their fists: it was a context in which black children did not have access to the same training facilities as their white counterparts. After all, Carlos wanted to become a swimmer before he wanted to be a runner, but his father had to eventually tell his son that "the training facilities he needed were in private clubs for the white and the wealthy," (Younge 1)