[polishdude20]

Training properly for long distance runs is different than training properly for high intensity runs. The two forms of exercise cause different adaptations. To get better at running long distances, one must run long distances.

[boyband6666]

I think we are talking cross purposes here. Training for running races, even long distances, involves some long running, lots of medium runs, and a good amount of intense work. Human physiology is complex and to get the most out of it, you have to train it all. If all you do is long runs, you will get nowhere near your potential. Marathon runners will regularly run 400m repeats on the track - speedwork helps in so many ways!