GLOSSARY

Sweat Loss Estimation is a practical approximation of sweat loss, not error-free direct collection of all body sweat.

Sweating varies with intensity, heat, humidity, clothing, heat acclimation and individual characteristics. Sweat volume and sodium concentration are different measurements: the heaviest sweater does not necessarily have the most concentrated sweat. Total loss depends on both. Salt marks on clothing provide a clue, not a substitute for valid testing or repeated records from comparable training sessions.

Practical sweat estimation compares pre- and post-session mass using the same scale, dry skin and minimal clothing, while recording drinking and urine. Wet clothing, food and very long sessions introduce error. This estimates whole-body loss. A patch at one skin site does not automatically represent the entire body's sweating or composition without a validated sampling and interpretation method.

A simple sweat-volume estimate adds fluid drunk to body-mass loss and subtracts urine, then divides by duration to obtain a rate. It approximates a kilogram of water as a liter. This is not a conversion for fat or every body-mass change. Fuel use and respiratory losses increasingly limit the estimate during prolonged activity, so calculated sweat rates remain context-dependent approximations.