Runners versus swimmers: Is there any useful news in this unlikely comparison?

But even now, he says, “an important message is that all of the athletes showed better function than a normal person off the street, which supports the message that exercise is good for hearts.”

https://www.nytimes.com/2019/04/03/well/move/heart-health-swimming-running-exercise.html

So let us read the paper:

"A new study finds that the answer may be yes, and the differences, although slight, could be telling and consequential, even for those of us who swim or run at a much less lofty level."

How it is that slight differences could be useful for you?

First emphasis on the filling LV:

"While presently debated, there is evidence to suggest an association between aerobic exercise training and enhanced early diastolic filling, ..."

1/ why do authors don't include triathletes in their study?

https://www.frontiersin.org/articles/10.3389/fphys.2018.01700/full