Does anyone else have this problem? Lately it has been somewhat of an issue, and the other 6 days of the week I feel fine. This includes interval days. I eat a lot of fiber in general, but do not get diarrhea on my other runs. The only thing I do differently on tempo days is drink slightly more coffee in the morning to supposedly "enhance" my workout through the extra caffeine boost. Do you guys think this may be the cause?