My stomach can take almost anything I throw in. However when I run long distances my stomach goes crazy and remains upset for the rest of the day. Since I don't really change my eating habits I can’t understand what is going on. During the run I drink water and use some power gels. After I finish the race I take some fruit smoothie and some kind of sandwich. I also had Gatorade few times. What is interesting that during the run I don't have any problems. I would appreciate any suggestion.
You are not alone in this. There are runners who have the same problem. Personally, I have never had any problems like that. You shouldn’t eat at least two hours before the race. During the race you can have a carb drink and once it is finished a post workout formula. One hour after that you should have a normal meal with complex carbs, protein and veggies. Try to get plenty of rest. If running a long race is too much stress for the body it is possible that this is a reaction to it. Drinking a carb drink before, during and after the race may keep stress hormones low and thus prevent this reaction.