"To determine how much liquid to take during a run or race, you need to know your sweat rate, and that can vary between 1 to 4 quarts per hour. Weigh yourself nude before a timed training run, and then again after. One pound of weight loss equals 1 pint of water loss. Calculate your sweat rate and use this to determine your fluid needs during a run or race. For example, if you lose 2 pounds during an hour run, that's 2 pints or 32 ounces. Thus, you need 8 ounces of water or sports beverage every 15 minutes."--Christine Luff, About.com Guide to Running/Jogging
During my longer runs on the treadmill I tend to drink a small swallow of Gatorade every two miles, which works well for me; after a Long Run (17 miles or more) I usually lose a total of about two pounds of water weight and don't strive to maintain the exact starting weight after my run...I expect to be a little lighter. During my long runs on the roads I need more fluids due to the weather, but still drink every two miles, but larger swallows. I haven't developed a fluid plan for my upcoming ultra-marathon next April yet.
Today is my last hard run before Recovery Week and decided to give a little extra effort during my Medium-Long Run by adding two marathon pace miles, which is eight minute miles.
10:10 a.m. Medium-Long Run, Progressive. 14 miles. Life Fitness Treadmill set at a 1% grade. 6 miles at 6.4 mph (Pace, 9:22 minute miles), 6.5 mph (Pace, 9:14 minute miles), last two miles at marathon pace, 7.5 mph (Pace, 8:00 minute miles). Average heart rate: 148 bpm. Cardiac drift: 159 bpm. (Note: my maximum heart is 190 bpm). I was surprised how easy those last two marathon paced miles so early in my base building season, I'll have loads of confidence when I start training in September for the Las Vegas Marathon.
