Nearly everyone who has posted on this thread knows more about this topic than I do, so I offer the following questions for the group's consideration:
If you accept, as I do, that:
A) It is generally desirable for training to prepare athletes to perform the functions they will be called upon to perform in competition; and
B) Pitchers are called upon to generate explosive power with their legs every time they throw; and
C) It is possible for too much low intensity distance running to hinder a pitcher's maintenance of muscle mass or development of explosive power, then:
1. How much cardiovascular fitness should a baseball player have and how should it be developed?
2. Does cardiovascular fitness translate into endurance for pitchers?
3. How much running qualifies as excessive distance running, and how does one know?
Many basic fitness plans for adults recommend a half hour or so of aerobic conditioning three or four times per week. Even as a 200+ pounder in my mid-40's, I considered running four miles in a half hour to be only a mildly invigorating workout. Would this sort of running be considered not enough, about right, excessive, or irrelevant for a high school or college pitcher? Is explosive capacity so fragile that this kind of running would degrade it?