Question

How does the digestive system change during exercise?

Answer 1

During exercise it basically competes for the blood supply, which is why exercise should not be done immediately after eating. You can't really digest food well while exercising.

Explanation:

Different types of exercise have different effects on the body. For example, exercise such as riding a bike can help to reduce heartburn. Light exercise that increases breathing and heart rate can help to produce more efficient bowel movements. However, extreme exercise can have negative effects on the digestive system.
http://www.ghpsi.com/articles/exercise_article.html

and
https://draxe.com/how-your-digestive-system-works/