The range of motion in your shoulders influence your stride length.
Have you ever noticed that sprinters pump their arms far forwards and backwards? They are driving their arms and the legs are following, creating powerful strides that get them across the finish line. Now watch the elite distance runners arms. The quick smooth swinging of their arms keep their strides efficient and quick. Your legs follow your arms. It is all about range of motion in the shoulders.
Touchdowns -- Dynamic and static rotator cuff or shoulder stretches will enhance your running stride.