One way to determine how much fluid you need to drink during a workout is by measuring your sweat rate. Sweat rate is the amount of fluids that you lose through sweat during a workout session.
How to calculate sweat rate:
Weigh yourself (Kg)
Work out for a specific amount of time (1h/ 2h/ 30min(0.5h)/ etc.)
Measure the amount of beverage you are drinking during the workout (L or Kg)
Do not urinate during the workout (if you have to, measure the amount of urine)
At the end of the workout, weigh yourself again, wearing the same as you wore during the initial weighing
Fill in the following figure and get your sweat rate in Liter per hour
Things to consider:
Sweat rates generally increase after 10-14 days of heat exposure, so sweat rate should be re-calculated following heat acclimatization
Higher sweat rates are generally found in men and those that are highly fit
Temperature plays a role in sweat rate, so calculations should be done for different environments
