As far as i know, not all runner wear sunglasses. Some of them wearing sunglasses not just to be cool, but protetc their eyes and provide them better vision. You know, sometimes, runner run in the sun. And the sunlight is really boring to shine that affect them focus on the road. Wearing sunglasses can reduce such intensive sunlight thus give them better vision. Besides, when they run, the qucik speed can create wind and partcles in the air. Wearing sunglasses can prevent those tiny things from damaging to eyes. From this point, wearing sunglasses make them running easier.
