I think the data presented at ASCO this year showed an increase in adenomas (benign, potential precursors of colon cancer) among marathoners. It’s unknown yet whether the that translates into an increase incidence of colon cancer in this population, though it would be prudent to assume so for now. The study was smallish n=100 IIRC so more research is warranted. Interesting to consider the biological mechanisms if this relationship holds up.
I think about this TED Talk from 2012 a lot.. and he presents some data. It changed some of my goals, and I’m a bit more multi-sport than I used to be.
Run for your life! At a comfortable pace, and not too far: James O'Keefe at TED×UMKC
Given that exercise in moderation reduces cancer risk, I find this take a bit odd. There are plenty of environmental problems that only fit women would be highly exposed to. I.e. due to demographic differences in sport popularity, a fit male is less likely to spend significant time on a synthetic yoga mat in a generally high pollutant indoor environment with a high breathing rate.
Still.. if you asked me why marathon runners had bowel cancer I would say that they eat more low fiber carbs than is possible for a normal person..
The theory that exercise is harmful seems more like a fanciful wish than a probability given other correlation in environment and behavior where much of our environment is poorly tested and probably harmful.
