Miler or Sprinter is a job description for a RUNNER, typically referring to athletes who specialize in running long distances or short distances, respectively. A miler is a RUNNER who specializes in running races of 1 mile or longer, while a sprinter is a RUNNER who specializes in running races of 400 meters or shorter. Both types of runners require a great deal of physical and mental strength, as well as dedication and discipline to reach their goals.