As most people know, the human body is mostly made up of water. It just makes sense that we must keep it hydrated. As such, there is a known general rule that one must drink so many cups of water—depending on your size—every day. The average person loses up to 10 cups of water a day (up to 6 cups through urine and up to 4 through breathing, sweating, and bowel movement). So just to keep up with that, the average adult has to drink 8 cups of water a day. This is known as the 8×8 rule (8 ounces of water 8 times in a day).
When you run, your body needs more water primarily because it has to sweat and breath a lot of it out to keep the body temperature cool. When it doesn’t get enough, several things can happen. I’ll list some of the most common ones below, most of which I’ve peronally experienced:
3. Dark urine (blood in urine)
5. Lower level of alertness
There are different levels of dehydration. You might hit mild dehydration (2% fluid loss) once in a while, but hitting severe or extreme dehydration isn’t where you want to be, as you can put your life in danger.
Besides failure to hydrate can severely impact your running performance. So drinking is a must, unless you simply want to pass out or don’t care how you’ll perform.
The distances I run range anywhere from three or more miles. I use a hydration belt pack that can hold 2 bottles of water or Gatorade. Each bottle holds 8 to 10 ounces. One bottle suffices for runs below six miles. I use two bottles for anything beyond six miles.
Before running, I take several big gulps of gatorade or water. Then when I run, I take good sips of water at about the one to two mile intervals. This seems to work out for me (weight: 155 lbs., height: 5’7”).