GLOSSARY

Dehydration Level describes deficit severity using a defined measure; mass percentage, symptoms and biomarkers are not identical measurements.

Percentage mass loss is pre-exercise minus post-exercise mass, divided by pre-exercise mass and multiplied by one hundred. It differs from a sweat rate corrected for drinks and urine. Under standardized short-session conditions it helps estimate deficit, but does not directly measure fat burning or exact intracellular water. Specify the reference mass and distinguish the percentage from an hourly loss rate.

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.