To prepare yourself correctly for a run you must take extra care with what you drink pre-run.
How you hydrate before your run has a huge impact on your performance. Some of the worst things a runner should avoid drinking before a run are listed in the following Runner’s World article.
http://www.runnersworld.com/hydration-dehydration/6-things-to-never-drink-before-a-run/slide/6
Be smart! Don’t let your pre-run hydration choices sabotage your training workout, or for that matter, your big race day!