The Secret To Triathlon Hydration

INSTRUCTIONS: How to Test Your Own Sweat Rate

NOTE: This is slightly long-winded. You may want to print it and read it later…

A sweat test involves weighing yourself, exercising, then weighing yourself again to see how much weight you lost. This helps you understand how much fluid you lose, as well as how much you may need to drink to replace it. By replicating race conditions during the test you can estimate your sweat rate for upcoming target events. This involves wearing a race day kit, testing in typical race weather conditions and training at race pace during the test.
Before we show you how to conduct your own sweat test, it’s important to understand that the maximal sweat rate of the human body is greater than its ability to re-hydrate. In other words, during tough workouts, you’ll sweat more than you can ever hope to replace at that time. So sometimes you’ll be dehydrated during exercise, no matter how much you drink. You just have to accept that you can’t replace every drop of sweat. So the amount you drink should normally be a little less than the amount you lose through sweat.

7 Steps To Testing Your Sweat Rate

1. Have a good pee, then weigh yourself wearing little or no clothing in order to get the most accurate reading. It is best if no solid food is consumed during the test and that you are hydrated beforehand.
2. After you’ve weighed yourself, exercise for one hour at your target race-day intensity, while keeping track of the amount of water you drink.
3. After exercising, towel yourself dry and step onto the scales again, in exactly what you wore at the initial weigh-in.
4.  Your weight before and after exercise, as well as the amount of fluid that you drank during exercise, will be used to determine your sweat rate. Remember that 500mL of water = 500 grams.
5. Subtract the post-exercise weight from the pre-exercise weight in kilograms. The difference should be what you lost through sweat in grams of fluid loss.
6. Then add to that number the number of millilitres of fluid that were consumed during the exercise. This will determine how much sweat was lost during exercise.
7. Divide the sweat loss by the duration of the exercise to determine total fluid loss per hour.Sweat Rate Calculator
   A. Body Weight pre-exercise
   ___________________ [kg]
   B. Body Weight post exercise
   ___________________ [kg] (A-B)
   C. Change in Body Weight
   ___________________ [grams]
   D. Volume of fluid consumed
   ____________________ [mL]
   E. Sweat Loss
   ____________________ [mL] (C+D)
   F. Exercise time
   ___________________ [mins or hrs]
   G. Sweat Rate
   ___________________ [mL/min or mL/hr] (E/F)
   The final figure (G) is your sweat rate, or the amount of fluid that you lose through sweat (usually expressed as litres per hour). This should help you determine the amount of fluid you should be drinking during and after your workouts.