Ask the Expert Dave Musnick Dave Musnick text here . Ask Dr. Dave a question Meet Dr. Dave Previous Answers Diarrhea and stomach problems in runners are not necessarily from dehydration. Of course you should make sure you are well hydrated. During your workouts or races, drink 6 to 8 ounces of fluid every 20 minutes.
Some people develop diarrhea and cramps if they drink sugary solutions like sports drinks.
Try to stick with pure water unless you are in a race situation. Some runners need to change their running posture to alleviate cramping. This may mean extending your low back and lifting up your chest a little to decrease the compression on your abdomen. Consider eating more than 2 hours before a run and experimenting with the type of foods you eat. Avoid milk products or fruit or sugar before a run.