Knowing your sweat rate should not be dismissed by athletes as being over rated since even a minor level of dehydration causes a measurable decline in performance and endurance. Injury rates increase and your training doesn't yield the biggest bang for the buck. Calculating your sweat rate is fast and easy. All you need to do is:
1. Write down what time it is just before you begin exercising.
2. Write down your body weight in pounds (preferably unclothed).
3. Perform your activity and track the total amount of fluid consumed.
4. Write down what time you ended.
5. Write down your body weight in pounds after the activity (preferably unclothed and sweat towel dried)
6. Calculate the total minutes you spent in the activity.
7. Calculate your weight change.
8. Calculate the additional amount of fluid that must be consumed to prevent weight loss. Know that 1 pound of weight loss = 2 cups of fluid. You should be drinking every 10-20 minutes for activities lasting >1 hour.
Remember sweating is a good sign that the body is effectively cooling itself during an activity.