[header] How to prepare for running [title] Drink plenty of water to stay hydrated. [step] While there is no specific amount of water that is recommended by fitness experts before a run, you will want to hydrate before and during your run. [substeps] It is not a good idea to do a long run without having a substantial drink of water beforehand. 
It is certainly possible to run without hydrating first, but this will make your run more difficult and you risk severe dehydration. Fitness experts do recommend that you make sure your urine is a light yellow color before heading out for a run.