How to Determine Your Sweat Rate
Here’s the basic formula to determine your sweat rate:
Step 1: Weigh yourself before you ride. For example, let’s say you weigh 155 pounds before you start exercising. (Just like I do, if I’m at my race weight…)
Step 2: Exercise for an hour in the weather conditions and at the same intensity you expect to face in an upcoming race or long ride.
Step 3: After your workout, remove your dripping wet shoes, shorts, jersey, etc. Dry yourself off and weigh yourself again. Let’s say you weigh 151 pounds after your workout.
Step 4: To calculate your sweat rate per hour of exercise, subtract your ending exercise weight of 151 pounds from your beginning weight of 155 pounds. The difference of 4 pounds represents your fluid loss during exercise.
Since you should drink 16 ounces of fluid for every pound of fluid you sweat out during exercise, multiply the number of pounds lost by 16. In this example, you should drink 64 ounces of fluid to counteract the symptoms of dehydration and return your body weight to normal.
Step 5: If you drank any fluid during your 60 minutes of exercise, you’ll need to add that number to the total amount of fluid lost during exercise that you calculated in Step 4.
There you go. Those five simple steps will tell you how much fluid you need to consume. But remember, you can’t truly reproduce a race in a training ride. And weather conditions are always uncertain.
Once you know your personal sweat rate per hour, you can take fluid breaks so that every 15 minutes you consume 10 to 12 ounces of fluid.
By the end of your 60-minute ride, you won’t be so dehydrated, your performance won’t slow as dramatically, your body temperature won’t be as high, and you won’t have to drink as much fluid the rest of the day.