If you need to drink water throughout the day to stay hydrated, then how often do you suppose you should drink water during exercise?  The answer is that you need more water more often during exercise.  How much you drink and how often are going to be a result of 4 factors:

1) Type of exercise-for instance, basketball makes you sweat more (need more water) than croquet.

2) Intensity of exercise-the harder and faster you exercise, generating more sweat, the more you need hydration to replace the lost water.

3) Duration of exercise-If you workout longer, you will need more water over the course of the activity.

4) Temperature/humidity of environment-I once went running for 12 minutes in 110° weather.  By the time I was done I was a little dizzy and had a sore throat from which I suffered for several days after.  Needless to say I didn’t take water with me.  I have also gone running for about an hour in 70° weather (with no water) and had no problem.  Temperature and humidity can make a tremendous difference on your hydration needs.

Drinking during exercise

During a typical cardio workout that lasts 20 minutes or less, taking water with you is usually unnecessary (unless it’s particularly hot).  I like to prepare myself by drinking plenty (but not too much) water during the 2 hours prior to my workout.  This ensures I will be hydrated when I exercise.  Make sure though that if you don’t take water, that you take a big drink as soon as you’re done.

The same idea goes for weight lifting.  You want to drink frequently to keep your level of hydration, and therefore performance, at its maximum.  I find it most convenient to drink in between exercises.  So I do my curls (for 8 minutes) and then take a drink before I begin bench press.  I continue this throughout my workout so that I always have enough water in my system, but not so much that it bogs me down.

In other activities such as basketball, soccer, tennis, etc, take a drink as often as you can.  If it’s basketball, drink a little each time you come off the court.  If it’s tennis, take a drink each time you switch sides.  Frequent small drinks are always better than larger, more infrequent ones.  The point here is to be a healthy person, so make sure you don’t defeat the purpose of exercising by not getting enough water!