Triathlon Training Education

Sweat Testing Protocol

Sweat testing assessments are based on the premise that body mass losses during exercise are reflective of fluid loss. As such, the change in body mass after exercise can be used to estimate whole body sweat loss during exercise, whereby a 1 g body mass loss represents 1 mL of sweat loss.

Prior to Exercise

Immediately before exercise, void your bladder and have body mass measured to the nearest 0.10 kg (0.22 lb). Ideally, to avoid weighing sweat trapped in clothing, weigh yourself nude or with minimal clothing.

During Exercise

The type and duration of exercise will be discussed with an athlete prior to testing.
Avoid spitting, spilling, or pouring fluids from bottles to ensure accurate estimation. If you need to urinate during exercise, have a pre-weighed container available and collect all urine within this container for measurement.

Post Exercise

After the completion of sweat test exercise towel yourself dry before weighing yourself. Use the same scale as you used for your pre-exercise assessment.


Whole body sweat losses can be calculated using the following equations:

Equation 1: Sweat loss (L) = (Pre-exercise BM – (Post-exercise BM – fluid intake + urine output)

Equation 2: Sweat rate (L/h) = Sweat loss (from equation 1) / exercise duration

Notify Coach Kat of your pre-exercise body mass, your fluid intake and urine output if any.