GLOSSARY

Hydration Marker is a measure associated with hydration, without necessarily having perfect sensitivity or specificity.

No single field marker precisely captures every aspect of hydration at all times. Trends in mass, thirst, urine and drinking history are more interpretable together than as isolated observations. Standardize sampling time and comparison conditions. Screening identifies a need for further review; one color, number or device message does not establish a diagnosis or justify forcing excessive fluid intake.

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.

Urine specific gravity compares sample density with reference water, unlike osmolality, which reflects particle number. Glucose, protein and other substances can influence interpretation. Use suitable equipment and consistent methods. A result after suddenly drinking a large volume may differ from the earlier state and cannot alone establish whole-body adequacy or deficit. The two urine measures should not be treated as interchangeable units.