[adaml_623]

I'd love to know the causation for that correlation

[elric]

There was some discussion about this on HN recently. Supposedly something to do with less blood going to the bowels during prolonged exercise. Apparently the risk was largest in people who ran 5+ marathons.

[saladdays]

Perhaps higher sugar consumption from fueling techniques?

[nradov]

No one knows for sure. One hypothesis is chronic inflammation, perhaps linked to diet or mechanical stress.

[array_key_first]

My understanding is that exercise lowers chronic inflammation. Basically, you trade off acute inflammation during the exercise itself for less inflammation when you're not exercising. But, maybe long distance running is too long or something.