GLOSSARY

Hyperhydration is increased body water above baseline, potentially planned but not automatically beneficial or safe.

Body water is not completely fixed: drinking, food, excretion and activity change it. Hypohydration describes a reduced-water state, whereas dehydration can describe the process producing it, although everyday usage overlaps. Athletes benefit from starting suitably hydrated and avoiding substantial deficits or excessive intake. The terminology does not require chasing a single unchanging water value throughout every session.

Intake exceeding losses and excretory capacity can retain excess water and dilute blood sodium. Sodium-containing drinks do not make unlimited drinking safe. Gaining body mass during prolonged exercise while drinking heavily warrants review. Severe headache, confusion or impaired consciousness requires urgent assessment rather than automatically giving more water. Symptoms alone cannot reliably distinguish dehydration from exercise-associated hyponatremia.

The kidneys regulate water and solute excretion to stabilize the internal environment, alongside thirst and vasopressin signaling. They do not create new water. Exercise, illness and some medicines can alter these responses. Fluid swallowed is therefore not identical to fluid retained, and increased urine after substantial drinking can represent normal regulation rather than proof that water cannot hydrate the body.