GLOSSARY

Sweating Response is the onset, amount and pattern of sweating in response to heat or exercise, modified by acclimation.

Record comparable routes in different weather separately; dry body mass, drinks and duration aid interpretation, whereas wet clothing is not an exact measure of losses or cooling.

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.