The Sweat Rate TestIt is important to develop an understanding of your sweat rate so that you can develop a thorough understanding of your sweat losses during an event.
The easiest way to measure your sweat rate is to weigh yourself without clothes on before and after exercising for one hour, taking note of the climatic conditions you were exercising in.
ResultsAssuming you did not use the toilet or consume any fluids during exercise, your weight loss is your sweat rate.
1kg of weight lost = 1L of fluid lost
If you drank any fluids or used the rest room between the two weight samples, you will need to include both of these estimated weights in your calculations.
Important ConsiderationsWeather and climatic conditions strongly influence sweat rates. For example, on a cooler overcast morning you will loose less sweat volume than on a hot, humid morning. Therefore, be sure to record the heat, humidity and weather conditions in your sweat test and repeat the test in cool, humid, windy and hot conditions.
Sweat rate also changes with pace and effort increases. For example, if you monitored your sweat rate for a shorter ½ marathon race pace and then want to step up to a 50 or 100km race that requires a lower effort over a prolonged period of time, you will need to conduct the above tests again to highlight the new effort zone.
ConclusionNow that you know your sweat rates, you now need to develop an understanding of how much fluid replacement your stomach can tolerate. For more information on how to rehydrate during events, you may like to read the article Hydration for Endurance Performance
For a comprehensive understanding on sports nutrition & hydration read: Sweat. Think. Go Faster by Darryl Griffiths
See our comprehensive Sports Nutrition range for Trail Runners HERE
These articles are a collection of my writing. If you have feedback or questions, would love to hear from you!