An interesting article in the Florida (Jacksonville) Times-Union today 2001-08-21, page C-1. The two measurement relevant parts (quoted below) were virtually all metric, with the one reference to the non-SI "pound" being handled by telling how to convert it to kilograms so that the rest of the discussion could remain purely in SI. For quote #1, you should know that the article is discussing the body's need for water when exercising and how that water works its way through the digestive tract. Part of the discussion revolves around the relative merits of pure water compared to other drinks. Quote #2 concerns how to measure or calculate how much fluid is lost during exercising and therefore how much to drink afterward. ---------- quote #1 ---------- The water then moves from the stomache to the small intestine, to be absorbed into the blood. Carbohydrates make the water hang around longer in the stomache. A drink with more than 6 to 8 grams per 100 milliliters can make a person feel bloated or nauseated. (Sugared sodas, with about 12 grams of carbohydrates per 100 milliliters, are too carbo-heavy to be useful to an athlete.) ---------- quote #2 ---------- To find out how much water you lose during a workout, weigh yourself without clothes before exercising. If you drink during the workout, keep tack of the amount; for instance, drink from a one-liter bottle, then measure how much is left. Afterward, dry off and weigh yourself without clothes again. Facts (which) you will need (in order) to do the math: One liter of water weighs 1 kilogram. One pound equals 0.45 kilogram. Example: Suppose a woman weighs 150 pounds (67.5 kilograms) before exercising. During an intense one-hour workout, she drinks half a liter of water. After the workout, whe weighs 148 pounds (66.6 kilograms). 67.5 kilograms plus 0.5 kilogram water minus 66.6 kilograms equals 1.4 kilograms water loss per hour, which equals 1.4 liters per hour. So our hypothetical athlete has sweated off 1.4 liters of water. Drinking 1.4 liters should fix her up, right? Unfortunately, it's not quite so simple ... After you've been working, you continue to sweat and lose water as your body cools down. So a rule of thumb is to drink 1.5 times what you've lost in the hours after a workout. That would mean our athlete needs to drink a bit more than 2 liters (over the next few hours, not all at once). ---------- end quotes Although I was happy with the use of SI, I am a bit unhappy with the uncertain precision of the results in quote #2. Starting with weights in pounds measured to three digits (to the nearest one pound) and then converting to kilograms with only a two digit conversion factor and reporting the kilogram result to three digits (to the nearest 0.1 kg) is not accurate. Then subtracting two nearly equal quantities (weight before and after exercising) which are not very precise leads to a result that is even less precise. (This is a problem that ALWAYS arises when subtracting two similar quantities.) The resulting value of 1.5 litres probably is more likely to be "anything between 0.5 L and 2.0 L". I don't think that tells the average person very clearly how much to drink. If you want to find the whole article in other newspapers, the following may help: The article was written by Aline McKenzie of the Dallas Morning News. The headline in the Jacksonville paper was "Water needs aren't the same for everyone". However, as you may know, headlines are usually written locally and probably would be different in the Dallas paper or other newspapers that ran the article. The article is a health and excercise type article which, I think, may be printed in the sports section of some other papers. The Jacksonville paper carried it in their "Lifestyles" section whose special theme today was health. This article was one of several health related articles. Regards, Bill Hooper ============ Keep It Simple! Make It Metric! ============
