Some runners do that. Others do not. My cousin is a D1 cc runner. He runs a lot of sprints in his training (mostly 400, 800m), but his shortest race distance is

Some runners do that. Others do not. My cousin is a D1 cc runner. He runs a lot of sprints in his training (mostly 400, 800m), but his shortest race distance is 10k. He is doing a marathon soon and an ironman is in the works. Good football players often go jogging or do other continuous, light cardio for longer periods in general training. It is sorta like how to be a good reader you need to be able to read/comprehend novels and academic articles -- imho.