Distilling the water myth: experts now say the eight-glasses-a-day rule is wrong. Here, new guidelines to determine how much you really should be drinking

Shape, May, 2004 by Richard Laliberte

RELATED ARTICLE: what to drink for a hot-weather workout

Summer is the time to move your exercise outside. But when the temperature is hotter and/or more humid than you're accustomed to, you'll need to pay special attention to your fluid intake to replace what you sweat out (and to prevent heat cramps, heat exhaustion or heatstroke). The American College of Sports Medicine offers these general recommendations for working out on a hot day:

* Down 20 ounces of water (about 2 1/2 cups) or a sports drink two or three hours before exercising.

* Consume another 10 ounces of water or a sports drink about 15 minutes before starting.

* During your workout, swig 10 ounces about every 15 minutes.

* After exercising, drink 20 ounces for every pound you lose working out. (As noted on page 140, to calculate your needs, weigh yourself before and after a workout.)

Richard Laliberte is a health writer living in eastern Pennsylvania.