Hydration is essential for athletes, and dehydration can occur at any time in any climate. Even the smallest amount of dehydration can negatively impact athletic performance.
A method to determining how much fluid you need to drink during a workout is by measuring your sweat rate. Sweat rate is typically higher in men and in those that are at a high level of physical fitness.
Calculating your sweat rate is actually quite easy, it just requires some planning. I’d also recommend checking your sweat rate in different temperatures and seasons. Your sweat rate can also change as you increase your physical fitness, or after 10-14 days of heat exposure due to your body acclimating to the heat. Knowing how it varies can also help you prepare for race day. Looking at the weather forecast and your average sweat rate for that type of weather will give you a better idea of how much fluids you need to be taking in each hour to keep up your hydration levels.
To accurately measure your sweat rate, you’ll want to follow this procedure:
Warm up to the point that you just begin to sweat.
Urinate, if needed.
Using an accurate scale, weight yourself. Weighing yourself nude is best practice.
Work out for a specific time. A one hour workout is easiest to calculating sweat rate per hour.
Do not urinate during the workout.
Drink a measured amount of fluids during the workout.
Weigh yourself again. Using the same scale that you used prior to the workout, and wearing exactly the same clothing (or lack of clothing if you chose to weigh nude).