How much water should I drink? What seems to be a fairly straightforward question usually has a different answer, depending on who you ask. You should drink 8 glasses of water a day. No, that’s an old wives’ tale: you don’t need that much. Or, you could need more. When we exercise, it becomes more complicated, with both water and salt losses to consider. Can’t we just rely on our body’s mechanism to tell us when we need to intake more liquids and drink if we feel thirsty?
According to a study reported in the International Journal of Sports Nutrition and Exercise Metabolism, going by judgment alone may not lead to adequate hydration during our runs. The results of the study suggest that runners underestimate their liquid intake needs and are left dehydrated, even when given the opportunity to drink while they are running.
In the small study performed at the Gatorade Sports Science Institute in Barrington, Il., 18 experienced runners (15 men and 3 women) were offered a sports drink at miles 2, 4, 6, and 8 of a ten-mile run performed at around 20∫C and 76 percent relative humidity. After the run, the participants were asked to estimate their sweat loss and fluid intake. The results suggest that though the runners’ estimations of their fluid intakes were similar to their actual fluid intakes, they were underestimating their sweat losses and not drinking enough to compensate—they were “voluntarily dehydrating.”
The conclusions drawn from the study are that runners need to become better at assessing their sweat losses and that a pre-set hydration schedule might be necessary for runners to stay properly hydrated. One simple way to estimate how much you sweat during a run, as cited in “25 Instant Fixes” in November 2007’s Runner’s World, is to “weigh yourself nude, then run at race pace for one hour, keeping track of how much you drink weight-wise. Strip down, towel off any sweat, and weigh yourself nude again. Tally the difference and convert to grams. Add to that number however many grams of liquid you consumed on your run, and divide that by four—that’s how much you should be drinking every 15 minutes.” If you prefer to play interactively with bubbles and sounds, head over to the Drink More Water page at the UK Web site Wateraid for their hydration calculator. It’s probably not terribly accurate, but it is fun.
Personally, I tend to under-hydrate. On a daily basis, I can go hours without drinking without really realizing it. On my runs it’s even worse. I carry a water bottle, even on short runs so that I am used to carrying it for the longer runs. But, I rarely drink. I usually arrive home with about 75 percent of what I took out, and then proceed to gulp it down during my stretching sessions when I realize how thirsty I am. Part of me knows it’s just laziness. It feels like an awful lot of effort to reach behind my back and grab that bottle. But another part knows it’s because I just don’t think about it, and when I do, I don’t feel thirsty. Maybe it’s time for me to start setting my timer and planning out my hydration a little better, especially now that winter’s approaching and the chillier weather might make me even less inclined to consider knocking back cool liquids. How about you?