What you are describing is the difference between acute and chronic stress placed on the body. There is a term for this: "the hormetic effect" https://en.m.wikipedia.org/wiki/Hormesis
People who undergo acute bouts of physical exercise with adequate recovery improve the well known blood markers and vital signs associated with the chronic diseases currently plaguing the modern world (cardiovascular disease, diabetes, stroke, etc). Long bouts, like ultra marathons or doing intense exercise for days on end without a rest day, is probably going to be deleterious to health because you never give your body a chance to recover and adapt.
People who undergo acute bouts of physical exercise with adequate recovery improve the well known blood markers and vital signs associated with the chronic diseases currently plaguing the modern world (cardiovascular disease, diabetes, stroke, etc). Long bouts, like ultra marathons or doing intense exercise for days on end without a rest day, is probably going to be deleterious to health because you never give your body a chance to recover and adapt.
edit wording