Also, if you're wondering about stuff like bananas, or aren't super versed in hydration, here's the basic idea: you need water, yes, but if you just chug a bunch of water, you're not doing yourself any favors. The main components of hydration are water (obvious), salt, and potassium. When anybody says "electrolytes", wanting to sound fancy, they're basically talking about those two things - potassium and salt. Let's say you're going to run in an hour, and you eat some peanut butter crackers and drink a good sized cup of water (~12 oz, whatever). As long as you weren't peeing dark yellow at some point before that, you should be good to go hydration-wise for your run. At that point, if you still get a side stitch, it's probably either your body adjusting to the effort of the run, or something dumb we're not going to be able to tell you about since we don't see you 24/7.