Elite cyclists have a high abundance of methane-producing archaea, potentially augmenting carbohydrate metabolism, which can lead to constipation if not exercising frequently.

“in the highest level cyclists they had a high amount of methane up over bats and it's probably because it helps augment their carbohydrate metabolism but you probably know of a lot of endurance athletes who can't poop unless they run and so the gut microbiota definitely shifts to help them before but then if you're not exercising then it has a downside”