HOUSTON -- WEARING BLACK Crocs accented with two Fast U buttons, Pittsburgh Steelers running back Najee Harris shuffles through the doors of O Athletik just after 9 a.m. Muhammad Ali's likeness stretches across the back of his black T-shirt. A black Nike boxing backpack is slung over a shoulder.
Inside the cavernous downtown Houston gym -- co-owned by NFL players Adrian Peterson and Trent Williams with trainer James Cooper -- Harris fist-bumps his way to the back, where a small group of NFL players, boxers and local athletes have gathered to stretch before the morning workout.