It is no secret that running tends to "get things moving" in our digestive tracts. It is actually quite a healthy benefit of running, but we understand that it is not always the most convenient thing in the world. Here are some tips to help make sure you go before your run, so you do not have to stop mid workout!
First, up the fiber in your diet. This might seem counterintuitive, as many professionals say they eliminate heavily fibrous foods from their diet in the days and hours before their race, but you can not (and should not) completely throw out these nutrient-rich foods on a day-to-day basis. The best option is to get in a good source of fiber right after your run. So if you run in the evenings, make sure you have got fibrous veggies, legumes, or whole grains incorporated into your post-run dinner. This will help make sure you digest the fiber and let it "do its thing" within the next 12 to 15 hours, so that you can have a bowel movement BEFORE your next run.
Pay attention to your fluid intake too. Being well-hydrated helps your colon process stuff more efficiently and coffee is a known diuretic. One or two cups in the morning will not only put a pep in your step to start your day, but helps jump start your bowel movements so that you can get in the go long before you set off for your afternoon run.
Finally, timing is everything. Try not to eat anything with too much fiber within two to three hours of your afternoon workout - and that includes coffee. Also, try not to stress too much! Anxiety and stress can lead to a lot of nervousness, which may increase the amount of times you poop during the day. So stressing about pooping might actually MAKE you poop! Relax, and try instead to focus more on how much you enjoy your evening runs.
Sources:
https://www.active.com/running/articles/how-to-poop-before-a-race
https://www.runnersworld.com/health/how-to-make-yourself-poop/slide/1