I cheated a little by mentioning that person B was a runner; I’ve seen those statistics, and they mysteriously don’t apply to runners. Likewise, footballers (both gridiron and the real kind) have very high rates of arthritis, but runners do not. It seems to be a difference between what we were evolved to do and what we can do. Analogous to this discussion? Very likely :-)
One not-so-mysterious difference is muscle mass; long-distance runners don’t develop much, whereas many other athletes do. Muscle is even harder to pump blood through than fat, so an extra 20kg of muscle is harder on the heart than 20kg of fat, which is sometimes cited as the reason that body builders so often have serious cardiac health problems (other reasons include large amounts of protein and cholesterol consumed, but I suspect you don’t buy those explanations).
EDIT: I shouldn’t stress my claim so much. I posted quickly because I’m busy with other things, but post-posting Googling seems to disagree with what I said; I haven’t actually found anything I trust yet, but it does seem that moving from long-distance running to ultra-long-distance running may move athletes back into a risk category.
I cheated a little by mentioning that person B was a runner; I’ve seen those statistics, and they mysteriously don’t apply to runners. Likewise, footballers (both gridiron and the real kind) have very high rates of arthritis, but runners do not. It seems to be a difference between what we were evolved to do and what we can do. Analogous to this discussion? Very likely :-)
One not-so-mysterious difference is muscle mass; long-distance runners don’t develop much, whereas many other athletes do. Muscle is even harder to pump blood through than fat, so an extra 20kg of muscle is harder on the heart than 20kg of fat, which is sometimes cited as the reason that body builders so often have serious cardiac health problems (other reasons include large amounts of protein and cholesterol consumed, but I suspect you don’t buy those explanations).
EDIT: I shouldn’t stress my claim so much. I posted quickly because I’m busy with other things, but post-posting Googling seems to disagree with what I said; I haven’t actually found anything I trust yet, but it does seem that moving from long-distance running to ultra-long-distance running may move athletes back into a risk category.