The purpose of a sweat test is to determine how much sweat (water & minerals) an individual looses during exercise.
This is a moving target; weather conditions, effort level, and even ones diet leading up to the exercise session will change how much you perspire.
For these reasons you should test often, under different circumstances and strive to replicate anticipated race day/competition conditions.
- Weigh yourself, in the buff, before session. Make note of the weight.
- Perform an hour of activity. If racing/competing try to do so under the same conditions.
- Immediately strip down to the buff and weigh yourself again.
- Subtract post exercise weight from pre exercise weight.
- Convert to ounces (multiply by 16).
- Add any fluids consumed (in ounces).
- The final answer is the amount of fluid lost during that hour of exercise.
Each 16oz of fluid loss also represents an estimated loss of the following mineral amounts.
- 220mg of Sodium
- 63mg of Potassium
- 8mg of Magnesium
- 16mg of Calcium
Your hydration protocol needs to include replacing both your water and electrolytes.