Who hasn’t had them? Seeing no hands, I will continue.
Most runners have experienced, “I’ve got to go NOW!” while running. We are talking about having a bowel movement here, so for those faint of heart, turn back now.
What is happening down there to cause all of the trouble?
Blood is shunted to your working muscles and skin (too keep you cool) rather than your intestinal track. The more strenuous your workout the more blood that is diverted to supply your muscles with oxygen and nutrients
Another factor that contributes to GI issues is dehydration. At some point during a long run, you are probably going to become a bit dehydrated and your electrolytes will be out of balance. This can stress your GI as can the jostling and bouncing of running.
Other things that can negatively impact your GI when you run are your diet, your running experience, and the strength of the muscles of your pelvic floor.
There are some things you can do to reduce and prevent yourself from having diarrhea while you’re running. First, you need to track what you eat, how much you are running, and how much time is between eating and running.
If you see a pattern with what you eat and your GI issues, fix it. Try to eat different things with less fiber. Make sure you are not increasing your miles by more than ten percent a week. Your body needs time to adjust to using both the digestive system and your running muscles at the same time.
Anxiety and caffeine contribute to GI issues for many runners too. The caffeine problem can be fixed through the diet and activity log. As for the anxiety, try some visualization and make sure you pack your gear the night before. Double and triple check it if you need to and if you have crazy superstitions go ahead and keep them if it is going to calm you down.
Make sure and plan your route around a few restrooms, just in case. If you’re out on the trail, take the necessary supplies to do your business like the bears.
And remember pine needles are better than frozen wet wipes (just ask spongebunny).
ultrarunningmom 
Great Blog! That photo is classic!
Thanks! Have you had any GI issues?
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If you don’t know the cause of a pain, tap on the image of that pain and you’ll probably get a measure of
relief.