Sweat Rate Test (nutrition assessment, ~75 min)

What this assessment is

The Sweat Rate Test is the seeded nutrition assessment that pairs with the Sweat rate calculator. It produces your sweat rate in litres per hour at the tested intensity and conditions, plus total fluid loss across the session.

Domain: nutrition. Estimated duration: 75 minutes. Linked calculator: sweat_rate.

Inputs the form asks for

Weight before the workout (kg).
Fluid consumed during the workout (L).
Exercise duration (HH:MM or minutes).
Weight after the workout (kg).
Plus optional environmental context (temperature, humidity) and equipment context (sport, kit) on the Assessment record.

Outputs

Sweat Rate in L/hr.
Total Fluid Loss in L.

How to run a clean test

Detail in the calculator article; the short version:

Pre-test weighing in dry kit.
Steady workout of known duration and intensity (60 to 90 minutes at race-effort or tempo).
Log all fluid intake to the mL.
No urination during the test if possible.
Post-test weighing in the same dry kit.

The arithmetic the calculator does: sweat rate = (pre weight minus post weight + fluid intake) scaled to per hour.

What context to log

For the result to be useful, the environmental_context and equipment_context fields matter as much as the numbers:

Temperature and humidity on the day.
Whether it was indoor or outdoor.
Sport (bike vs run vs swim have different sweat physiology).
Race-equivalent kit if you can.

A sweat rate measured at 18C in light wind in cycling kit tells you very little about what you will sweat at 32C in race conditions. Grepiac stores the context so you can compare apples to apples.

When to retest

Once per season as baseline.
Again on a hot day.
After heat acclimation (sweat rate goes up, sweat sodium drops).
Before a destination race that differs from training conditions.