Despite all the hype in advertising sports drinks and supplements, anyone doing less than 45-60 minutes of moderate exercise probably does not benefit from a sugary drink.
Staying well hydrated is important of course. On the hottest of days probably 8 oz of fluid every 20 minutes is plenty. For cooler days, substantially less is OK. Rather than carrying water I usually route my hot-afternoon runs around known water fountains every couple of miles. Most of us have pretty good internal thirst sensor - drink when you are thirsty, plus a little.
Yes, you CAN drink too much water. The New England Journal of Medicine showed that 13% of Boston Marathon finishers had water poisoning (or had drank too much). Boston Marathoners are a well trained and smart bunch. No doubt the runners in the Peachtree 10K who are offered gallons of water starting at the 1/2 mile marker are at even more risk...
Once you hit the one hour mark it is probably time to start supplementing with electrolytes and (maybe) calories. For races I usually take a sports gel about every 45 minutes. For training runs I personally like to avoid calories. The jury is out on how much good sugar does for your weight loss/exercise, but it definitely can give you short term boost for the race. The new low calorie sports drinks are what I prefer for long training runs.
Briefly,
-For cool-weather runs, 8oz water first hour, 8oz sports drink thereafter
-For hot weather runs, 8oz water every 20 minutes, replace with sports drink after 60 minutes
-May replace "sports drink" with water + Gel pack
-For most of our cooler 6am runs,
prehydrating with water only will suffice. There are plenty of fountains along the way anyway. You can leave your CamelBack behind...
